Patent Publication Number: US-11639647-B2

Title: Self-powered sensors for detecting downhole parameters

Description:
BACKGROUND 
     Obtaining logging data by wireline is a costly process since the drilling assembly has to be pulled out of the wellbore first to run the wireline assembly. This also means that logging data cannot be obtained while drilling. There is also a risk of the wireline assembly getting stuck inside the hole along with all its expensive sensors, instrumentation thereby significantly adding to the cost of drilling a well. 
     More recent surveying and logging tools used in downhole environments consist of Measurement While Drilling (MWD) tools and Logging While Drilling (LWD) tools. The basic MWD tool measures wellbore parameters such as tool face orientation, inclination, azimuth, as well as environmental data such as internal temperature, tool vibration. Some dedicated near bit tools provide measurements of additional drilling parameters such as weight on bit (WOB), bit torque, etc. Typical LWD tools measure formation parameters such as gamma ray, neutron density/porosity, resistivity and nuclear magnetic resonance. The LWD tools come in combo packages, where the drilling engineer has the option of choosing the LWD tools required for a given well section. 
     However, data obtained by the MWD/LWD might not stay constant and may change over time due to drilling and other operations performed inside a wellbore. For example, data acquired by MWD/LWD sensors at certain depths along a wellbore may change over time. Therefore, it is not possible to obtain real-time information of these parameters at these depths unless the MWD/LWD sensors are run again at these depths, which is very costly and not feasible. 
     In wireline operations, the power to the wireline sensors and instrumentation are provided by a wired power line that extends from the power source at the surface all the way down to the well depth. The power to MWD and LWD is provided by rechargeable lithium battery packs and/or turbine/alternator. One of the major drawbacks of lithium batteries is their cost. Moreover, lithium batteries suffer from ageing, which depends on the number of charge-discharge cycles the battery has undergone. Also, lithium batteries expire resulting in large volumes of contaminated waste. Therefore, the usage of lithium batteries not only has significant costs in their production life cycle but also has a negative impact on the environment. Mechanical failure rates of batteries are also generally high and can be expected to be higher downhole given the harsh environments they are exposed to. Turbines/alternators harness the kinetic energy of a fluid flow to generate electricity. Therefore, they can only generate electricity when there is a fluid flow inside a drillstring, and the power produced depends on the speed of the fluid flow. Heavy muds and lost circulation material in a drillstring, for example, can significantly reduce the speed of flow in a drillstring and might even block the pathway through the turbines/alternators. 
     SUMMARY 
     One or more embodiments may be directed toward a sensor array for sensing environmental parameters along a drillstring. In some embodiments, the sensor array may include an outer collar having a plurality of moveable member retainers formed therein. A plurality of moveable members may be movably disposed in the plurality of moveable member retainers. An inner ring may be rotatably supported within the outer collar. A plurality of bearing elements may be retained on an outer surface of the inner ring, the plurality of bearing elements positioned to displace the plurality of moveable members relative to the plurality of moveable member retainers in response to relative rotation between the inner ring and the outer collar. A plurality of shape memory material elements may be provided, each shape memory material element arranged in one of the plurality of moveable member retainers. The sensor array may also include a plurality of distance sensors, each distance sensor disposed in a respective moveable member retainer of the plurality of moveable member retainers and between a respective shape memory material element in the respective moveable member retainer and a respective moveable member movably disposed in the moveable member retainer. Each distance sensor may include a first sensing element and a second sensing element arranged in opposing relation, the first sensing element and the second sensing element separated by a gap that is responsive to a shape change of a respective shape memory material element and a displacement of the respective moveable member. 
     In some embodiments of the sensor array, the shape change of each shape memory material element may reflect the environmental parameters. 
     In some embodiments of the sensor array, the plurality of shape memory material elements may be formed of multiple shape memory materials having different responses to the environmental parameters. 
     In some embodiments of the sensor array, the first sensing element may include a magnetic detector and the second sensing element may include a magnetic target. In some embodiments of the sensor array, the magnetic detector may be configured to detect a magnetic field across the gap between the magnetic detector and the magnetic target. In some embodiments of the sensor array, an output of the magnetic detector may be a function of the magnetic field. 
     In some embodiments of the sensor array, the first sensing element may include a ground electrode detector and the second sensing element may include a drive electrode target. In some embodiments of the sensor array, the ground electrode detector may be configured to detect a capacitance across the gap between the ground electrode detector and the drive electrode target. In some embodiments of the sensor array, an output of the ground electrode detector may be a function of the capacitance. 
     In some embodiments of the sensor array, the first sensing element may include an optical transducer detector and the second sensing element may include an optical reflector target. In some embodiments of the sensor array, the optical transducer detector may be configured to generate an emitted optical signal, the emitted optical signal may traverse the gap, the emitted optical signal may be reflected from the optical reflector target, the reflected optical signal may traverse the gap, and the optical transducer detector may detect the emitted optical signal after an optical elapsed time. In some embodiments of the sensor array, an output of the optical transducer detector may be a function of the optical elapsed time. 
     In some embodiments of the sensor array, the first sensing element may include an acoustic transducer detector and the second sensing element may include an acoustic reflector target. In some embodiments of the sensor array, the acoustic transducer detector may be configured to generate an emitted acoustic signal, the emitted acoustic signal may traverse the gap, the emitted acoustic signal may be reflected from the acoustic reflector target, the reflected acoustic signal may traverse the gap, and the acoustic transducer detector may detect the emitted acoustic signal after an acoustic elapsed time. In some embodiments of the sensor array, an output of the acoustic transducer detector may be a function of the acoustic elapsed time. 
     Some embodiments of the sensor array may further include a plurality of extension mechanisms positioned in each of the plurality of moveable member retainers, where each extension mechanism may be configured to return the respective moveable member to an extended position after contact between one of the plurality of bearing elements and the respective moveable member is released. 
     In some embodiments of the sensor array, each of the plurality of shape memory material elements may be formed of shape memory materials including at least one of a shape-memory alloy, a shape-memory polymer, a shape-memory gel, a shape-memory ceramic, a liquid crystal elastomer, or MXene, or combinations thereof. 
     In some embodiments of the sensor array, the shape change of the plurality of shape memory material elements may reflect at least one of temperature, pressure, stress, strain, current, voltage, magnetic field, pH, humidity, composition, or light, thereby changing the gap. 
     In some embodiments of the sensor array, the outer collar may include a first inner surface, a second inner surface portion in opposed relation to the first inner surface, and a third inner surface connecting the first inner surface to the second inner surface. In some embodiments of the sensor array, the plurality of bearing elements may be distributed among at least two of the inner surfaces. 
     In some embodiments of the sensor array, for each of the plurality of distance sensors, the first sensing element may be a detector and the second sensing element may be a target. 
     In some embodiments of the sensor array, for each of the plurality of distance sensors, the detector may be disposed on the respective shape memory material element and the target may be disposed on the respective moveable member. 
     In some embodiments of the sensor array, within the plurality of distance sensors, the first sensing elements may include at least two of a magnetic detector, a ground electrode detector, an optical transducer detector, and an acoustic transducer detector. 
     In some embodiments of the sensor array, the plurality of moveable members may have convex surfaces for contact with the plurality of bearing elements. 
     Some embodiments of the sensor array may further include a plurality of extension mechanisms positioned in each of the plurality of moveable member retainers, where each extension mechanism may be configured to apply a biasing force to the respective moveable member in a direction towards the inner ring. 
     In some embodiments of the sensor array, the extension mechanisms may include one or more springs disposed within the moveable member retainer and arranged to apply the biasing force to the moveable members. 
     In some embodiments of the sensor array, the plurality of bearing elements may be positioned to support rotation of the inner ring relative to the outer collar. 
     In some embodiments of the sensor array, at least one raceway may be formed in the outer collar to receive the plurality of bearing elements and guide movement of the plurality of bearing elements. 
     In some embodiments of the sensor array, at least a portion of the plurality of moveable member retainers may intersect the at least one raceway to enable the plurality of bearing elements to releasably contact at least a portion of the plurality of moveable members. 
     Some embodiments of the sensor array may further include at least one communications device for transmitting and receiving signals. In some embodiments of the sensor array, the at least one communications device may be carried by the outer collar. 
     In some embodiments of the sensor array, a first fraction of the plurality of moveable member retainers may be disposed on an inner surface of the outer collar. In some embodiments of the sensor array, a first fraction of the plurality of bearing elements may be configured and arranged such that, during rotation, the first fraction of the plurality of bearing elements travels along the inner surface of the outer collar and contacts a first fraction of the plurality of moveable members within the first fraction of the plurality of moveable member retainers. 
     In some embodiments of the sensor array, the first fraction of the plurality of moveable member retainers may be disposed within a first raceway on the inner surface of the outer collar such that the first fraction of the plurality of moveable members extend into the first raceway. In some embodiments of the sensor array, the first fraction of the plurality of bearing elements may be configured and arranged such that, during rotation, the first fraction of the plurality of bearing elements travels along the first raceway and contacts the first fraction of the plurality of moveable members. 
     In some embodiments of the sensor array, the first fraction of the plurality of moveable member retainers may be disposed on a middle inner surface of the outer collar. In some embodiments of the sensor array, a second fraction of the plurality of moveable member retainers may be disposed on a top inner surface of the outer collar. In some embodiments of the sensor array, a second fraction of the plurality of bearing elements may be configured and arranged such that, during rotation, the second fraction of the plurality of bearing elements travels along the top inner surface of the outer collar and contacts a second fraction of the plurality of moveable members within the second fraction of the plurality of moveable member retainers. In some embodiments of the sensor array, a third fraction of the plurality of moveable member retainers may be disposed a bottom inner surface of the outer collar. In some embodiments of the sensor array, a third fraction of the plurality of bearing elements may be configured and arranged such that, during rotation, the third fraction of the plurality of bearings travels along the bottom inner surface of the outer collar and contacts a third fraction of the plurality of moveable members within the third fraction of the plurality of moveable member retainers. 
     In some embodiments of the sensor array, a first fraction of the plurality of shape memory material elements in the first fraction of moveable member retainers may include a first shape memory material having a first response to the environmental parameters. In some embodiments of the sensor array, a second fraction of the plurality of shape memory material elements in the second fraction of moveable member retainers may include a second shape memory material having a second response to the environmental parameters. In some embodiments of the sensor array, a third fraction of the plurality of shape memory material elements in the third fraction of moveable member retainers may include a third shape memory material having a third response to the environmental parameters. 
     One or more embodiments may be directed toward a power array for generating power along a drillstring. In some embodiments, the power array may include an outer collar having a plurality of moveable member retainers formed therein. A plurality of moveable members may be movably disposed in the plurality of moveable member retainers. An inner ring may be rotatably supported within the outer collar. A plurality of bearing elements may be retained on an outer surface of the inner ring, the plurality of bearing elements positioned to displace the plurality of moveable members relative to the plurality of moveable member retainers in response to relative rotation between the inner ring and the outer collar. The power array may also include a plurality of power generation components. Each power generation component may be arranged and configured such that, in response to the relative rotation, the plurality of bearing elements displace a respective moveable member into a respective moveable member retainer, generating an electric charge. 
     In some embodiments of the power array, the plurality of power generation components may be configured to generate the electric charge via one or more of: a triboelectric effect resulting from contact between a first frictional material and a second frictional material having different polarities; a piezoelectric effect resulting from compression or flexion of a piezoelectric material; or a magnetostrictive effect resulting from compression of a magnetostrictive material to generate a magnetic field that is converted to the electric charge. 
     In some embodiments of the power array, the plurality of power generation components may include: the plurality of bearing elements formed of or coated with the first frictional material; and the plurality of the moveable members formed of or coated with the second frictional material. 
     In some embodiments of the power array, the plurality of power generation components may include: the plurality of moveable member retainers formed of or coated with the first frictional material; and the plurality of moveable members formed of or coated with the second frictional material. 
     In some embodiments of the power array, the plurality of power generation components may include: a piezoelectric base disposed in the respective moveable member retainer that generates the electric charge when compressed by the respective moveable member. 
     In some embodiments of the power array, the plurality of power generation components may include: a piezoelectric nanoribbon base disposed in the respective moveable member retainer that generates the electric charge when compressed or flexed by the respective moveable member. 
     In some embodiments of the power array, the plurality of power generation components may include: a magnetostrictive base disposed in the respective moveable member retainer that generates electricity when the compression of the magnetostrictive base by the respective moveable member generates the magnetic field and the magnetic field is converted to the electric charge by a planar pick-up coil or a solenoid disposed near the magnetostrictive base. 
     In some embodiments of the power array, the outer collar may include a first inner surface, a second inner surface portion in opposed relation to the first inner surface, and a third inner surface connecting the first inner surface to the second inner surface. In some embodiments of the power array, the plurality of bearing elements may be distributed among at least two of the inner surfaces. 
     In some embodiments of the power array, the plurality of moveable members may have convex surfaces for contact with the plurality of bearing elements. 
     Some embodiments of the power array may further include a plurality of extension mechanisms positioned in each of the plurality of moveable member retainers, where each extension mechanism may be configured to apply a biasing force to the respective moveable member in a direction towards the inner ring. 
     In some embodiments of the power array, the extension mechanisms may include a spring disposed within the respective moveable member retainer and arranged to apply the biasing force to the respective moveable member. 
     Some embodiments of the power array may further include a plurality of extension mechanisms positioned in each of the plurality of moveable member retainers, where each extension mechanism may be configured to return the respective moveable member to an extended position after contact between one of the plurality of bearing elements and the respective moveable member is released. 
     In some embodiments of the power array, the plurality of bearing elements may be positioned to support rotation of the inner ring relative to the outer collar. 
     In some embodiments of the power array, at least one raceway may be formed in the outer collar to receive the plurality of bearing elements and guide movement of the plurality of bearing elements. 
     Some embodiments of the power array may further include one or more power storage units. 
     Some embodiments of the power array may further include a sub shaped as a hollow pipe that defines a flow and has a connector on each axial end for connection to the drillstring. In some embodiments of the power array, the outer collar may be disposed radially around the sub. 
     One or more embodiments may include a self-powered sensor array for sensing environmental parameters along a drillstring. In some embodiments, the self-powered sensor array may include an outer collar having a plurality of moveable member retainers formed therein. A plurality of moveable members may be movably disposed in the plurality of moveable member retainers. An inner ring may be rotatably supported within the outer collar. A plurality of bearing elements may be retained on an outer surface of the inner ring. Each bearing element may be positioned to displace the moveable members relative to the moveable member retainers in response to relative rotation between the inner ring and the outer collar. A plurality of shape memory material elements may be provided, each shape memory material element arranged in a respective moveable member retainer of a first fraction of the plurality of moveable member retainers. The self-powered sensor array may also include a plurality of distance sensors. Each distance sensor may be disposed in the respective moveable member retainer and between the shape memory material element in the respective moveable member retainer and a respective moveable member movably disposed in the respective moveable member retainer. Each distance sensor may include a first sensing element and a second sensing element arranged in opposing relation, the first sensing element and the second sensing element separated by a gap that is responsive to a shape change of the respective shape memory material element and a displacement of the respective moveable member. The self-powered sensor array may also include a plurality of power generation components. Each power generation component may be arranged in relation to one of a second fraction of the plurality of moveable member retainers. The power generation component may be configured such that, in response to the relative rotation, the plurality of bearing elements displace a particular moveable member into a particular moveable member retainer, generating an electric charge. 
     In some embodiments of the self-powered sensor array, each of the plurality of shape memory material elements may be formed of shape memory materials including at least one of a shape-memory alloy, a shape-memory polymer, a shape-memory gel, a shape-memory ceramic, a liquid crystal elastomer, or MXene, or combinations thereof. 
     In some embodiments of the self-powered sensor array, the shape change of each shape memory material element may reflect the environmental parameters. 
     In some embodiments of the self-powered sensor array, the plurality of shape memory material elements may be formed of multiple shape memory materials having different responses to the environmental parameters. 
     In some embodiments of the self-powered sensor array, the plurality of distance sensors may include one or more of: a magnetic distance sensor including a magnetic detector and a magnetic target arranged in opposing relation, the magnetic distance sensor configured to detect a magnetic field across the gap and to generate an output of the magnetic distance sensor that is a function of the magnetic field; a capacitive distance sensor including a ground electrode detector and a drive electrode target, the capacitive distance sensor configured to detect a capacitance across the gap and to generate an output of the capacitive distance sensor that is a function of the capacitance; an acoustic distance sensor including an acoustic transducer detector and an acoustic reflector target, the acoustic distance sensor configured to measure an acoustic elapsed time across the gap and to generate an output of the acoustic distance sensor that is a function of the acoustic elapsed time; or an optical distance sensor including an optical transducer detector and an optical reflector target, the optical distance sensor configured to measure an optical elapsed time across the gap and to generate an output of the optical distance sensor that is a function of the optical elapsed time. 
     In some embodiments of the self-powered sensor array, the plurality of power generation components may include one or more of: a first triboelectric module including the plurality of bearing elements formed of or coated with a first frictional material and the particular moveable member formed of or coated with a second frictional material, that generates the electric charge via contact between the first frictional material and the second frictional material having different polarities; a second triboelectric module including the particular moveable member formed of or coated with the first frictional material and the particular moveable member retainer formed of or coated with the second frictional material, that generates the electric charge via contact between the first frictional material and the second frictional material having different polarities; a third triboelectric module including the particular moveable member retainer and the particular moveable member are each formed of or coated with alternating segments of the first frictional material and the second frictional material, that generates the electric charge via contact between the first frictional material and the second frictional material having different polarities; a piezoelectric base disposed in the particular moveable member retainer that generates the electric charge when compressed by the particular moveable member; a piezoelectric nanoribbon base disposed in the particular moveable member retainer that generates the electric charge when compressed or flexed by the particular moveable member; or a magnetostrictive base disposed in the particular moveable member retainer that generates the electric charge when compression of the magnetostrictive base by the particular moveable member generates a magnetic field and the magnetic field is converted to the electric charge by a planar pick-up coil or a solenoid disposed near the magnetostrictive base. 
     In some embodiments of the self-powered sensor array, the first fraction of the plurality of moveable member retainers may be disposed on a top inner surface of the outer collar and a bottom inner surface of the outer collar. In some embodiments of the sensor array, the second fraction of the plurality of moveable member retainers may be disposed on a middle inner surface of the outer collar. 
     In some embodiments of the self-powered sensor array, a first fraction of the plurality of shape memory material elements may be disposed in the plurality of moveable member retainers located on the top inner surface of the outer collar includes a first shape memory material having a first response to the environmental parameters. In some embodiments of the self-powered sensor array, a second fraction of the plurality of shape memory material elements may be disposed in the plurality of moveable member retainers located on the bottom inner surface of the outer collar includes a second shape memory material having a second response to the environmental parameters. 
     In some embodiments of the self-powered sensor array, the shape change of the plurality of shape memory material elements may reflect at least one of temperature, pressure, stress, strain, current, voltage, magnetic field, pH, humidity, composition, or light, thereby changing the gap. 
     In some embodiments of the self-powered sensor array, the outer collar may include a first inner surface, a second inner surface portion in opposed relation to the first inner surface, and a third inner surface connecting the first inner surface to the second inner surface. In some embodiments of the self-powered sensor array, the plurality of bearing elements may be distributed among at least two of the inner surfaces. 
     In some embodiments of the self-powered sensor array, for each of the plurality of distance sensors, the first sensing element may be a detector and the second sensing element may be a target. 
     In some embodiments of the self-powered sensor array, for each of the plurality of distance sensors, the detector may be disposed on the respective shape memory material element and the target may be disposed on the respective moveable member. 
     In some embodiments of the self-powered sensor array, the first fraction of the plurality of moveable member retainers may be disposed on a middle inner surface of the outer collar. In some embodiments of the sensor array, the second fraction of the plurality of moveable member retainers may be disposed on a top inner surface of the outer collar and a bottom inner surface of the outer collar. 
     One or more embodiments may be directed toward a sensing system for sensing environmental parameters along a drillstring. In some embodiments, the sensing system may include a plurality of sensor arrays and a receiver that receives the signal from the communications device within each of the plurality of sensor arrays. In some embodiments of the sensing system, each of the plurality of sensor arrays may include an outer collar having a plurality of moveable member retainers formed therein. A plurality of moveable members may be movably disposed in the plurality of moveable member retainers. An inner ring may be rotatably supported within the outer collar. A plurality of bearing elements may be retained on an outer surface of the inner ring, the plurality of bearing elements positioned to displace the plurality of moveable members relative to the plurality of moveable member retainers in response to relative rotation between the inner ring and the outer collar. A plurality of shape memory material elements may be provided, each shape memory material element arranged in one of the plurality of moveable member retainers. Each of the plurality of sensor arrays may also include a plurality of distance sensors, each distance sensor disposed in a respective moveable member retainer of the plurality of moveable member retainers and between a respective shape memory material element in the respective moveable member retainer and a respective moveable member movably disposed in the moveable member retainer. Each distance sensor may comprise a first sensing element and a second sensing element arranged in opposing relation, the first sensing element and the second sensing element separated by a gap that is responsive to a shape change of a respective shape memory material element and a displacement of the respective moveable member. Each of the plurality of sensor arrays may also include a communications device that transmits a signal that includes sensor data output from each distance sensor. 
     In some embodiments of the sensing system, the communications device within one or more of the plurality of sensor arrays may be further configured to receive at least one of an instructional signal from the receiver or an incoming data signal from other sensor arrays of the plurality of sensor arrays along the drillstring. 
     In some embodiments of the sensing system, each of the plurality of sensor arrays may serve as a node within a sensor network such that the nodes relay information between the plurality of sensor arrays and the receiver. 
     One or more embodiments may be directed toward a sensing system for sensing environmental parameters along a drillstring. In some embodiments, the sensing system may include a plurality of self-powered sensor arrays and a receiver that receives the signal from the communications device within each of the plurality of self-powered sensor arrays. In some embodiments of the sensing system, each of the plurality of self-powered sensor arrays may include an outer collar having a plurality of moveable member retainers formed therein. A plurality of moveable members may be movably disposed in the plurality of moveable member retainers. An inner ring may be rotatably supported within the outer collar. A plurality of bearing elements may be retained on an outer surface of the inner ring, each bearing element positioned to displace the moveable members relative to the moveable member retainers in response to relative rotation between the inner ring and the outer collar. A plurality of shape memory material elements may be provided, each shape memory material element arranged in a respective moveable member retainer of a first fraction of the plurality of moveable member retainers. Each of the plurality of self-powered sensor arrays may also include a plurality of distance sensors, each distance sensor disposed in the respective moveable member retainer and between the shape memory material element in the respective moveable member retainer and a respective moveable member movably disposed in the respective moveable member retainer. Each distance sensor may comprise a first sensing element and a second sensing element arranged in opposing relation, the first sensing element and the second sensing element separated by a gap that is responsive to a shape change of the respective shape memory material element and a displacement of the respective moveable member. Each of the plurality of self-powered sensor arrays may also include a plurality of power generation components. Each power generation component may be arranged in relation to one of a second fraction of the plurality of moveable member retainers. The power generation component may be configured such that, in response to the relative rotation, the plurality of bearing elements displace a particular moveable member into a particular moveable member retainer, generating an electric charge. Each of the plurality of self-powered sensor arrays may also include a communications device that transmits a signal that includes the gap of each distance sensor. 
     In some embodiments of the sensing system, each of the plurality of self-powered sensor arrays may serve as a node within a sensor network such that the nodes relay information between the plurality of self-powered sensor arrays and the receiver. 
     In some embodiments of the sensing system, the communications device within one or more of the plurality of self-powered sensor arrays may be further configured to receive at least one of an instructional signal from the receiver or an incoming data signal from other self-powered sensor arrays of the plurality of self-powered sensor arrays along the drillstring. 
     One or more embodiments may be directed to a method for sensing environmental parameters with a self-powered sensor array. In some embodiments, the method may include disposing a self-powered sensor array on a drillstring, wherein the self-powered sensor array includes an outer collar and an inner ring; disposing the drillstring with the self-powered sensor array in a wellbore; and rotating the outer collar with respect to the inner ring. The method may also include producing mechanical energy in the self-powered sensor array by bearing elements that physically interact with movable members as a result of the relative rotation between the outer collar and the inner ring and converting the mechanical energy to electrical energy by power generation components in the self-powered sensor array. The method may further include generating an output reflecting gaps probed by distance sensors in the self-powered sensor array, where the gaps are responsive to shape changes of shape memory material elements resulting from environmental parameters within the wellbore and displacements of moveable members resulting from the relative rotation. 
     One or more embodiments may be directed to a method for sensing of environmental parameters. In some embodiments, the method may include disposing a plurality of self-powered sensor arrays on a drillstring, wherein each of the self-powered sensor arrays comprise an outer collar and an inner ring; disposing the drillstring with the plurality of self-powered sensor arrays in a wellbore; and rotating the outer collar with respect to the inner ring of each of the plurality of self-powered sensor arrays. The method may also include producing mechanical energy in each of the plurality of self-powered sensor arrays by bearing elements of each of the plurality of self-powered sensor arrays that physically interact with movable members of the self-powered sensor array as a result of the relative rotation between the outer collar and the inner ring of each of the plurality of self-powered sensor arrays. The method may further include generating an output reflecting gaps probed by distance sensors in each of the plurality of self-powered sensor arrays, where the gaps are responsive to shape changes of shape memory material elements resulting from environmental parameters within the wellbore and displacements of moveable members resulting from the relative rotation between the outer collar and the inner ring of each of the plurality of self-powered sensor arrays. 
     In some embodiments, the method also includes storing the electrical energy in one or more power storage units in each of the plurality of self-powered sensor arrays and powering the plurality of distance sensors with at least a portion of the electrical energy stored in the energy storage of each respective self-powered sensor array. 
     Other aspects and advantages of the invention will be apparent from the following description and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    depicts an embodiment of an array from multiple perspectives. 
         FIG.  2 A  depicts a cross section of an embodiment of a sensor array. 
         FIGS.  2 B and  2 C  depict cross sections of an embodiment of a bearing element and an embodiment of a sensor moveable member. 
         FIGS.  3 A and  3 B  depict an embodiment of multiple arrays along a drillstring. 
         FIGS.  4 A and  4 B  depict two views of an embodiment of a sensor array. 
         FIGS.  5 A- 5 F  depict cross sections of an embodiment of a sensor moveable member. 
         FIGS.  6 A- 6 F  depict cross sections of multiple embodiment of a sensor moveable member. 
         FIG.  7 A  depicts a cross section of an embodiment of a power array. 
         FIGS.  7 B and  7 C  depict cross sections of an embodiment a bearing element and an embodiment a power moveable member. 
         FIGS.  8 A- 8 J  depict cross sections of multiple embodiment of a power moveable member. 
         FIG.  9 A- 9 D  depicts embodiments of an array along a drillstring. 
         FIG.  10    depicts an embodiment of an array. 
         FIG.  11    depicts an embodiment of a system having arrays along a drillstring. 
         FIGS.  12 A- 12 D  depict cross sections of multiple embodiment of a moveable member. 
         FIGS.  12 E- 12 F  depict cross sections of multiple embodiment of a sensor moveable member. 
         FIGS.  13 A and  13 B  depict a cross section of embodiments of an array around a drillstring. 
         FIG.  14    depicts a cross section of an embodiment of a power array. 
         FIG.  15    depicts a cross section of an embodiment of a memory capsule. 
     
    
    
     Throughout the figures, similar numbers are typically used for similar components. 
     DETAILED DESCRIPTION 
     One or more embodiment may be directed toward a self-powered sensor array (SPSAs) for detecting downhole parameters. The SPSAs may consist of distance sensors and shape-memory materials (SMMs) to detect downhole parameters such as temperature, pressure, composition (e.g., concentration of gases), and pH. The distance sensors may utilize magnetic, capacitive, acoustic, or optical sensing, while the shape-memory material may be a shape-memory alloy, shape-memory polymer, shape-memory gel, shape-memory ceramic, liquid crystal elastomer, or MXene or combinations thereof. A distance detected by the distance sensor changes due to the shape reconfigurability of the SMM in response to external downhole stimuli. Therefore, the distance sensor output changes in response to external downhole stimuli. 
     Moreover, SPSAs may exploit the rotation of the drillstring assembly during drilling a hydrocarbon well and harvest the resulting energies to generate electricity to power the distance sensors and potentially other instrumentation. The SPSA provides clear advantages over current downhole power generation methods such as batteries and turbines with respect to size, cost, mobility, temperature/pressure tolerance, and potential downhole applications. 
     Broadly, the SPSA may be comprised of two structures: an inner ring fixedly coupled to a rotating member, such as a drill pipe or production tubing; and an outer collar that envelops the inner ring, may not contact the rotating member, may not change position relative to the rotating member, and frictionlessly couples with the inner member. The inner ring may further comprise a plurality of bearing elements fixedly connected to the outer surface(s). The outer collar may further comprise sensor(s) for detecting a downhole wellbore condition using SMM(s) and a moveable power generator that may generate power upon frictionless contact from a bearing element. 
     Moreover, the SPSA may improve upon the current limitations/challenges of automation/digitalization in drilling and the fourth industrial revolution (4IR). For example, batteries cannot power the Industrial internet-of-things (IoT) at scale. Since the SPSAs may be self-powered, they may be placed all along the drillstring assembly for distributed sensing of downhole parameters while drilling. 
     By deploying multiple SPSAs all along the drillstring, a real-time profile of the wellbore may be obtained during the drilling process. Such real-time data profiles may enable drilling operations to take advantage of emerging technologies aligned with the 41R, such as big data analytics and artificial intelligence to transform this data to high-value, actionable insights. 
     Disclosed here is an array that may be deployed along a drillstring. The array may be a sensor array, a power array, or an SPSA. 
     One or more embodiments of an array may be directed toward a sensor array for detecting downhole parameters. Each of the sensor arrays may include one or more pairs of distance sensor(s) and shape-memory material(s) (SMMs). The distance sensors may employ magnetic, capacitive, acoustic, or optical sensing. Additionally, the SMMs may change shape due to downhole parameters like temperature, pressure, composition (e.g., concentration of gases), or pH. When the SMM changes shape due to downhole parameters, a distance measured by the distance sensor changes. Therefore, the distance sensor output changes depending on the shape reconfigurability of the SMM in response to the external downhole stimuli. 
     One or more embodiments of an array may be directed toward as a power array for generating power. A power array may exploit the rotation of the drillstring assembly during drilling a hydrocarbon well by harvesting the resulting energies to generate electricity. Such electricity may power any device, such as distance sensors and other instrumentation. 
     One or more embodiments of an array may be an SPSA, which combines a sensor array and a power array to create a sensor device that that is self-powered. An SPSA may exploit the rotation of the drillstring assembly by harvesting the resulting energies to generate electricity to power a sensor array as well as other instrumentation. 
     In one or more embodiments, sensor arrays or SPSAs may be placed all along the drillstring forming a sensing system. This sensor system may obtain real-time distributed sensing data of downhole parameters while drilling. Such real-time data may be used to more effectively monitor the well, allowing more immediate response in the event of a status change. Moreover, such real-time data may enable drilling operations to utilize emerging technologies, such as big data analytics and artificial intelligence, to transform the data into high-value, actionable conclusions. 
       FIG.  1 A  depicts an embodiment of an array  100  from an isometric side view. Array  100  includes an inner ring  110  located radially within an outer collar  150 . Array  100  may be a sensor array, a power array, or an SPSA. 
       FIGS.  2 A- 2 C  depict an embodiment of an inner ring  210  and an outer collar  250 . 
       FIG.  2 A  depicts an embodiment of a sensor array  200  where half of outer collar  250  is cut away. On inner ring  210  are bearing elements in the form of bearings  220  located on three outer surfaces: a top outer surface  214 , a middle outer surface  212 , and a bottom outer surface  216 . Additionally, a first fraction of bearings  220  are on middle outer surface  212 , a second fraction of bearings  220  are on top outer surface  214 , and a third fraction of bearings  220  are on bottom outer surface  216 . In some embodiments, bearings  220  may be positioned to support rotation of inner ring  210  relative to outer collar  250 . 
     Within outer collar  250  are three surfaces: a top inner surface  254 , a middle inner surface  252 , and a bottom inner surface  256 . Outer collar  250  has sensor moveable members  260  located on two surfaces: a top inner surface  254  and a bottom inner surface  256 . A third surface, a middle inner surface  252  does not have sensor moveable members. Instead, middle inner surface  252  has a raceway  253 . Raceway  253  serves to hold inner ring  210  in place relative to outer collar  250 . The details of such a connection are detailed further. 
     Each sensor moveable member  260  is moveably located within a moveable member retainer in the form of a sensor moveable member retainer  265 . Also within each sensor moveable member retainer  265  is a shape memory material element  270  and a distance sensor  280 . Sensor moveable members  260  have convex surfaces for contact with bearings  220 . 
     Sensor array  200  is a combination of inner ring  210  and outer collar  250 . Inner ring  210  may be located radially within outer collar  250 . First fraction of bearings  220  on middle outer surface  212  of inner ring  210  are in the raceway  253  on middle inner surface  252  of outer collar  250 . Second fraction of bearings  220  on top outer surface  214  of inner ring  210  are in contact with top inner surface  254  of outer collar  250 , while third fraction of bearings  220  on bottom outer surface  216  of inner ring  210  are in contact with bottom inner surface  256  of outer collar  250 . This alignment allows second fraction of bearings  220  on top outer surface  214  of inner ring  210  to interact with a first fraction of sensor moveable members  260  on top inner surface  254  of outer ring  250 . Additionally, this alignment allows third fractions of bearings  220  on top outer surface  214  of inner ring  210  to interact with a second fraction of sensor moveable members  260  on bottom inner surface  256  of outer ring  250 . 
       FIG.  2 B  depicts a cross-section of a bearing  220  in inner ring  210 . Bearing  220  is located in a corresponding bearing retainer  225  defined by inner ring  210 . One having skill in the art will appreciate the relative sizes and geometries of bearing  220  and bearing retainer  225  to allow both free, low-friction movement and retention of bearing  220  within bearing retainer  225 . 
     Further, bearing retainers  225  may not be indicated in each figure for clarity and brevity. One having skill in the art will appreciate each bearing  220  depicted in this disclosure may be located within a bearing retainer that may not be specifically depicted or described. 
       FIG.  2 C  depicts a cross section of sensor moveable member  260  in outer collar  250 . Sensor moveable member  260  is held within a corresponding sensor moveable member retainer  265 , which is defined by outer collar  250 . Within sensor moveable member retainer  265  is a shape memory material element  270  and a distance sensor  280 . An output of distance sensor  280  may be affected by an extension distance d between sensor moveable member  260  and distance sensor  280 . Sensor moveable member  265  is configured to move up and down within corresponding sensor moveable member retainer  265 . More details of sensor moveable member  260 , shape memory material element  270 , and distance sensor  280  will be discussed further. 
     One or more embodiments of inner ring  210  and outer collar  250  may be formed from one or more metallic, non-metallic, or composite materials, or a combination of more than one material. One or more embodiments of inner ring  210  and outer collar  250  may be formed from materials able to operate at conditions commonly experienced in the downhole environment, such as high temperatures (for example, &gt;150° C.), high pressures (&gt;5000 psi), or both. One or more embodiments of inner ring  210  and outer collar  250  may be formed from one or more low-friction materials. One or more embodiments of inner ring  210  and outer collar  250  may be formed from one or more materials having high abrasion resistance, high wear resistance, or both. 
     In one or more embodiments, sensor moveable member  260  may be formed of one or more elastomeric, polymeric, or composite materials, or a combination of more than one material. One or more embodiments of sensor moveable member  260  may be formed from one or more low-friction materials. One or more embodiments of sensor moveable member  260  may be formed from Teflon®, Kapton®, polyester, or a combination. 
     For illustration purposes,  FIG.  3 A  shows a sensing system or a power system including multiple SPSMs, power arrays, or sensor arrays  300  placed along a drillstring  390  to allow distributed sensing of downhole parameters while drilling. Drillstring  390  is suspended in a wellbore  393  from a derrick  391 . Drillstring  390  includes a drill bit  395  to cut rock formations and drill pipes  120  connected to form a conduit. Drill pipes  397  can interface with the subs ( 905  in  FIG.  9 A ) attached to SPSMs  300 . Drillstring  390  may have several other tools not specifically mentioned but known in the art. Drillstring  390  may be rotated within wellbore  393  by a top drive  399  (or by a rotary table on a rig floor in other implementations), which will result in rotation of drill bit  395 , enabling drill bit  395  to advance cutting of the rock formation. As drillstring  390  is rotated, a structure of each SPSM  300  that is coupled to drillstring  390  via the crossover sub also rotates. Energy harvesters in SPSM  300  convert the mechanical energy from the rotation of the drillstring  390  into electrical energy. The energy harvesters may be triboelectric energy harvesters based on applying friction between two materials with opposed electron affinities, piezoelectric energy harvesters based on applying mechanical stresses to piezoelectric materials, or magnetostrictive energy harvesters based on applying mechanical stresses to magnetostrictive materials. 
       FIG.  3 B  depicts a cross-section of sensor array  300 , with an inner ring  310  with bearings  320  and an outer collar  350 , radially outside inner ring  310 . Inner ring  310  is connected to a drillstring  390  that may be attached to a drill bit  395 . 
     While drilling a well, drillstring  390  rotates. In one or more embodiments, inner ring  310  may be connected to drillstring  390 . During drilling, inner ring  310  may then rotate with drillstring  390  within outer collar  350 . Given the essentially negligible friction between inner ring  310  and outer collar  350  due to bearings  320 , outer collar  350  may remain essentially rotationally stationary, while inner ring  310  may rotate with the drillstring  390 . In one or more embodiments, outer collar  350  may be connected to drillstring  390 . During drilling a well, outer collar  350  may rotate with drillstring  390  around inner ring  310 . Given the essentially negligible friction between inner ring  310  and outer collar  350  due to bearings  320 , inner ring  310  may remain essentially rotationally stationary, while outer collar  350  may rotate with drillstring  390 . 
       FIGS.  4 A and  4 B  depict how an inner ring  410  and an outer collar  450  of a sensor array  400  interact when inner ring  410  rotates within outer collar  450  due to the rotation of the drillstring ( FIG.  3 A ). 
       FIG.  4 A  shows inner ring  410  within outer collar  450  of sensor array  400 . Inner ring  410  has bearings  420  and outer collar  450  has moveable members in the form of sensor moveable members  460 . Curved surface A, indicated with a dashed line, shows the location of the curved cross-section of sensor array  400  depicted in  FIG.  4 B . 
       FIG.  4 B  depicts a curved cross section of sensor array  400  through inner ring  410  and outer collar  450  at dashed line A. Inner ring  410  has a top outer surface  414  and a bottom outer surface  416 , both studded with bearings  420  within bearing retainers (not depicted). Outer collar  450  has a top inner surface  454  and a bottom inner surface  456  both studded with moveable members in the form of sensor moveable members  460  within sensor moveable member retainers  465  defined by outer collar  450 . Opposite sensor moveable member  460  within each sensor moveable member retainer  465  is a distance sensor  480  associated with a shape memory material element  470  in the form of a shape memory material base. An arrow  495  indicates the rotational motion of inner ring  410  relative to outer collar  450 . 
     In one or more embodiments, when a bearing  420  contacts a sensor moveable member  460 , sensor moveable member  460  may be displaced into a corresponding sensor moveable member retainer  465  toward a respective distance sensor  480 . Such movement decreases an extension distance ( FIG.  2 C ) to a minimum extension distance between sensor moveable member  460  and respective distance sensor  480 . After bearing  420  moves beyond sensor moveable member  460 , sensor moveable member  460  returns to its original, extended position in corresponding sensor moveable member retainer  465 . 
     In one or more embodiments, each sensor moveable member  460  located on top inner surface  454  of outer collar  450  may be configured and arranged such that, during rotation of inner ring  410 , bearings  420  located on top outer surface  414  of inner ring  410  push each sensor moveable member  460  upward into a corresponding sensor moveable member retainer  465 . Similarly, each sensor moveable member  460  located on bottom inner surface  456  of outer collar  450  may be configured and arranged such that, during rotation of inner ring  410 , bearings  420  located on bottom outer surface  416  of inner ring  410  push each sensor moveable member  460  downward into a corresponding sensor moveable member retainer  465 . In one or more embodiments, moveable members  460  of outer collar  450  move inward into/outward from corresponding sensor moveable member retainer  465  when in contact/not in contact with bearings  420  of inner ring  410 . 
     Furthermore, recall how the movement of inner ring  410  in relation to outer collar  450  occurs as inner ring  410  rotates with the rotation of a drillstring ( FIG.  3 A ). This rotation of inner ring  410  causes bearings  420  to make contact with moveable members  460  of outer collar  450 , pushing sensor moveable members  460  into sensor moveable member retainers  465 . 
     After bearings  420  are no longer contacting sensor moveable members  460 , sensor moveable members  460  may move outward from sensor moveable member retainers  465  and return to their original, extended position. In one or more embodiments, sensor moveable members  460  may return to their original, outward, non-compressed position due to a spring beneath sensor moveable members  460 , elasticity of the sensor moveable members  460 , or some other possible means. One or more embodiments for returning sensor moveable members  460  to their original, extended position are depicted in  FIGS.  12 A- 12 F  and discussed further. 
     This contact and release results in moveable members  460  moving in and out/out and in from sensor moveable member retainers  465  many times over the course of a drilling operation. 
     In one or more embodiments, moveable members  460 , including any additional structures (such as a distance sensor component like a magnet, electrode, or reflector as discussed further), may not contact the shape memory material base  470  or distance sensor  480 . In some embodiments, upon contact with bearings  420 , moveable members  460  may deflect into sensor moveable member retainers  465  without contacting distance sensors  480 . 
     As noted above, distance sensors herein may be associated with, disposed upon, or connected to a shape memory material element  470 . Shape memory materials are a large class of materials that change shape in response to external stimulus, and then return to their original shape when the external stimuli is removed. Some examples of the external stimuli that can induce this recoverable shape change in shape memory materials include temperature, pressure, stress, strain, current, voltage, magnetic field, pH, humidity, electrochemicals, composition (e.g., concentration of gases), light, or radiation. Moreover, shape memory materials can be designed to respond and change shape due to only a single, particular stimulus. Additionally, the shape-changing property of shape memory materials does not require an external application of energy, such as electricity, making them useful for low-power applications. Other key advantages of shape memory materials may include chemical stability, biodegradability, recyclability, high strength to weight ratio, excellent extent of deformation, superior corrosion resistance, low density, adjustable degradation rate, high tolerance to fatigue, low cost, the ability to be three-dimensional (3D) or four-dimensional (4D) printed, or a combination of these properties. 
       FIGS.  5 A- 5 F  depict a cross-section of a bearing  520  on an inner ring  510  interacting with a moveable member in the form of a sensor moveable member  560  within a moveable member retainer  565  defined by an outer collar  550 . Sensor moveable member  560  is opposite a distance sensor  580  atop a shape memory member element  570 . Arrow  595  depicts the movement direction of inner ring  510  relative to outer collar  550 . 
     Comparing  FIG.  4 B  with  FIGS.  5 A-C , various embodiments for the location of shape memory material elements  470 ,  570  are envisioned. For example, in  FIG.  4 B , the shape memory material element  470  is disposed within a moveable member retainer  465  having a base, where the shape memory material element  470  may be indirectly stimulated by wellbore conditions (temperature, etc.). In other embodiments, such as illustrated in  FIGS.  5 A-C , the shape memory element  570  may be disposed within moveable member retainer  565  lacking a base such that a portion of the shape memory material may be directly stimulated by wellbore conditions (pressure, composition, etc.). 
       FIGS.  5 A- 5 C  sequentially depict an interaction between sensor moveable member  560  and bearing  520  due to the rotation of inner ring  510 .  FIG.  5 A  depicts sensor moveable member  560  before being contacted by bearing  520 .  FIG.  5 B  depicts sensor moveable member  560  while being contacted by bearing  520 .  FIG.  5 C  depicts sensor moveable member  560  after being contacted by bearing  520 . A gap  575  is depicted between sensor moveable member  560  and distance sensor  580  as may be detected by distance sensor  580  (detailed further).  FIG.  5 B  indicates distance d 1  between sensor moveable member  560  and distance sensor  580 , as may be detected by distance sensor  580  (detailed further). In  FIGS.  5 A- 5 C , shape memory material element  570  is at a first state based on response to an external stimulus (such as an environmental parameter). 
       FIGS.  5 D- 5 F  depict a cross-section of the same components undergoing the same sequence of interactions between sensor moveable member  560  and bearing  520  due to the movement of inner ring  510 . A gap  575  is again depicted between sensor moveable member  560  and distance sensor  580  as may be detected by distance sensor  580  (detailed further). However, due to a change in external stimulus (such as an environmental parameter), shape memory material element  570  may change dimensions (such as an increase in thickness). Therefore, in  FIG.  5 E , distance d 2  between sensor moveable member  560  and distance sensor  580  is smaller than distance d 1  in  FIG.  5 B . 
     In one or more embodiments, shape memory material element  570  may experience a recoverable shape change due to environmental parameters such as temperature, pressure, stress, strain, current, voltage, magnetic field, pH, humidity, electrochemicals, composition (such as gas content), light, radiation, or some other external stimulus. In one or more embodiments, shape memory material element  570  may be fine-tuned by precise control of microstructure, crystallographic texture, or both, to react predictably to external stimulus such as an environmental parameter. 
     In one or more embodiments, gap  575  between distance sensor  580  and sensor moveable member  560  (including any additional structures on sensor moveable member  560  discussed further below) may change due to both the change in dimension of shape memory material element  570  and the displacement of sensor moveable member  560  into sensor moveable member retainer  565  by bearing  520 . 
     In one or more embodiments, the minimum extension distance d 1 , d 2  between distance sensor  580  and sensor moveable member  560  (including any additional structures on sensor moveable member  560  discussed further below) may only change due to the change in dimension of shape memory material element  570 . 
     In one or more embodiments, shape memory material element  570  may be tuned to be sensitive to a single external stimulus. In one or more embodiments, any shape change (such as expansion or contraction) of shape memory material element  570  may be due only to a single external stimulus. In one or more embodiments, a change in the minimum extension distance between distance sensor  580  and sensor moveable member  560  (say, from d 1  to d 2 ) may be due essentially only to the single, intended external stimulus. 
     In one or more embodiments, shape memory material element  570  may change shape many times during a single deployment if the external downhole stimuli (meaning the environmental parameter) changes throughout the deployment. In one or more embodiments, shape memory material element  570  may change shape many times during a single deployment if the external downhole stimuli repeats a cycle. In one or more embodiments, such a repeated cycle of external downhole stimuli may be: the external downhole stimuli begins at a first state, varies from the first state, and returns to the first state. 
     In one or more embodiments, shape change of a shape memory material may be essentially fully recoverable when the environmental parameter returns to a first state. Here, “essentially” may mean recovery of greater than 99% (for example, of greater than 99.9%, of greater than 99.99%, and on) of the shape change that occurred with the increase of the environmental parameter from the first state. One having skill in the art will appreciate, the absolute value of the “first state” of an environmental parameter may be equal to essentially zero (for example, for stress, strain, or voltage) or may be equal to a non-zero, baseline value (for example, for temperature, humidity, or nitrogen pressure) such as the value measured prior to entering the wellbore. 
     In one or more embodiments, shape memory material element  570  may be a coating applied to a base region within moveable member retainer  565 . In one or more embodiments, shape memory material element  570  may be a shape memory material base formed from a shape memory material and inserted into a base region within moveable member retainer  565 . In one or more embodiments, shape memory material element  570  may be enclosed in a flexible structure such as a diaphragm, a membrane, or a cavity. 
     In one or more embodiments, shape memory material element  570  may be formed of a shape memory material with a non-linear response to an environmental parameter. In one or more embodiments, minimum extension distance d 1  may remain unchanged until a change in the magnitude of the environmental parameter triggers a shape change of shape memory material element  570 . In one or more embodiments, shape memory material element  570  may be formed of a shape memory material with a step-wise response to an environmental parameter. In one or more embodiments, minimum extension distance d 1  may change in essentially discrete steps because particular magnitudes of the environmental parameter trigger a shape change of shape memory material element  570  with a step-wise response to the environmental parameter. 
     In one or more embodiments, each shape memory material element  570  may be formed of one or more shape memory materials, such as a shape-memory alloy, a shape-memory polymer, a shape-memory gel, a shape-memory ceramic, a liquid crystal elastomer, an MXene, or a composite, alloy, derivative, or combination thereof. In some embodiments, each shape memory material element  570  may be formed of one or more shape memory materials, such as a shape memory polymer composite incorporating nanosized fillers such as carbon-based nanostructures (for example, carbon nanotubes, carbon fibers, carbon black, or graphene), metal oxide nanoparticles (for example, Fe 3 O 4 , TiO 2 , or ZnO), noble metal-based nanostructures (for example, gold and silver), cellulose nanocrystals; Nitinol (Ni—Ti alloys), or a combination of multiple fillers; a copper-based alloy (for example, Cu—Zn—Al, Cu—Al—Ni, or Ti—Ni—Cu); an iron-based alloy (such as Fe—Ni—C, Fe—Mn—Si, or Fe—Mn—Si—Cr—Ni); or an elastomer (such as a dielectric or magnetic elastomer), or a composite, alloy, derivative, or combination thereof. 
     In one or more embodiments, each shape memory material element  570  may be formed of one or more shape memory materials in the form of smart material(s) that demonstrate a shape memory effect, superelasticity, or both. Such smart materials may undergo a solid state phase change similar that of a molecular re-arrangement, but with the molecules remaining closely packed. These materials may exist, for example, in two different phases (a austenitic “parent phase” and a martensitic “daughter phase”) with three different crystal structures (twinned martensite, de-twinned martensite, and austenite), resulting in a total of six possible transformations. 
     In one or more embodiments, each shape memory material element  570  may be formed from one or more commercially available smart structures, such as BioMetal Helix™; Mitsubishi Corporation Fashion, Co., Ltd. DiAPLEX®; CRG Industries Veriflex®, Verilyte™, and Veritex™; Lubrizol Advanced Materials Tecoflex®; Composite Technology Development, Inc. TEMBO®; Norland Products NOA-63; Furukawa Techno Material NT (Ni—Ti) alloys; Jameco Electronics Ni—Ti alloys; Shape Memory Medical shape memory polymers; G.Rau GMBH &amp;Co. smart materials; Nitinol, Dynalloy, Inc. Flexinol® and Ni—Ti alloys; or SAES Getters SmartFlex®. 
     In one or more embodiments, each shape memory material element  570  may be formed of only one class of shape memory material per external parameter. In one or more embodiments, shape memory material elements  570  may be formed of only one class of shape memory material per external parameter. 
     In one or more embodiments, sensor array ( FIG.  4 A ) may include shape memory material elements  570  of a single type at multiple radial locations (meaning within multiple sensor moveable members retainers  565 ) around inner ring  510 . Such an arrangement may help detect wellbore conditions around a wellbore ( FIG.  2 A ) in an oriented way. This embodiment is discussed further. 
     As discussed previously,  FIGS.  5 A- 5 F  depicted how a sensor array ( FIG.  4 A,  4 B ) may sense environmental parameters during the drilling process. In summary, shape memory material element  570  may respond to an external downhole stimuli by altering (expanding or contracting) its structure. Consequently, there may be a change in the minimum extension distance between sensor moveable member  560  and distance sensor  580 , from for example d 1  to d 2 , as sensor moveable member  560  is pushed into moveable member retainer  565  by bearing  520  at the point of maximum displacement of sensor moveable member  560 . 
     However, the distance sensor itself may employ one or more distance sensing methodology (for example, optical, electrode, magnetic, or others) to detect a minimum extension distance or a change of the minimum extension distance, or may have an output of the distance sensor affected by the minimum extension distance.  FIGS.  6 A- 6 C  depict distance sensors employing three different distance sensor technologies (magnetic, capacitive, and optical/acoustic, respectively) that may be used in one or more embodiments. Additionally, one having skill in the art will appreciate many additional distance sensor methods that may be used in distance sensor  580 . 
       FIGS.  6 A- 6 F  each depict a cross-section of a bearing  620  on an inner ring  610  prior to interacting with a moveable member in the form of a sensor moveable member  660  on outer collar  650 . Sensor moveable member  660  is located in a sensor moveable member retainer  665 , opposite a distance sensor  680   a ,  680   c ,  680   e  atop a shape memory member base  670 . A gap  675  between a first sensing element and a second sensing element of distance sensor  680   a ,  680   c ,  680   e  is measured by distance sensor  680   a ,  680   c ,  680   e .  FIGS.  6 A,  6 C, and  6 E  depict sensor moveable member  660  prior to engagement with bearing  620 .  FIGS.  6 B,  6 D, and  6 F  depict the same sensor moveable member  660  as in  FIGS.  6 A,  6 C, and  6 E  at the point of maximum engagement with bearing  620  where gap  675  equals extension distance da, dc, de. 
     As a drillstring ( FIG.  3 A ) rotates, bearing  620  of inner ring  610  contacts sensor moveable member  660  of outer collar  650 . Such contact pushes sensor moveable member  660  into sensor moveable member retainer  665 , decreasing gap  675  between the components of distance sensor  680   a ,  680   c ,  680   e . Where sensor moveable member  660  has been fully pushed into sensor moveable member retainer  665 , gap  675  may be the minimum extension distance da, dc, de between the components of distance sensor  680   a ,  680   c ,  680   e.    
     In some embodiments, an output of distance sensor  680   a ,  680   c ,  680   e  may be based on a constant measure of gap  675 , the minimum extension distance da, dc, de, or on a change of the minimum extension distance ( FIGS.  5 B and  5 E ). In one or more embodiments, sensor array ( FIG.  3 A ) may evaluate the output of distance sensor  680   a ,  680   c ,  680   e  to determine the change of minimum extension distance da, dc, de from a first value d 1  to a second value d 2  as in  FIGS.  5 B and  5 E , and ultimately calculate the environmental parameter(s) reflected in the shape memory material element  670  shape change. Thus, in some embodiments, sensor array ( FIG.  3 A ) may employ one or more distance sensors  680   a ,  680   c ,  680   e  to indirectly detect one or more environmental parameter(s). One having skill in the art will appreciate how to adapt the process described here when the extension distance da, dc, de increases between d 1  (without a stimulus) and d 2  (with stimulus) (meaning, d 2  is greater than d 1 ) due to a contraction of shape memory material element  670 . 
     As discussed above, stimulus such as an environmental parameter may change the size of shape memory material element  670 . In one or more embodiments, a shape change of shape memory material element  670  may alter minimum extension distance da, dc, de, as was show in  FIGS.  5 B and  5 E , previously. Thus, the output of distance sensor  680   a ,  680   c ,  680   e  may ultimately reflect a stimulus, such as an environmental parameter, that altered a shape of shape memory material element  670 . 
     In one or more embodiments, each distance sensor  680   a ,  680   c ,  680   e  may include a first sensing element and a second sensing element. In one or more embodiments, a first sensing element may be a detector  682   a ,  682   c ,  682   e  and a second sensing element may be a target  684   a ,  684   c ,  684   e . In one or more embodiments, the first sensing element and second sensing element (such as detector  682   a ,  682   c ,  682   e  and target  684   a ,  684   c ,  684   e ) may be arranged in opposing relation and may be separated by gap  675 . In one or more embodiments, gap  675  may be responsive to expansion of shape memory material element  670  and displacement of sensor moveable member  660  by bearing  620 . In one or more embodiments, at the point of maximum displacement of sensor moveable member  660 , gap  675  may be equal to an extension distance da, dc, de. 
       FIGS.  6 A and  6 B  depict a magnetic distance sensor  680   a ;  FIGS.  6 C and  6 D  depict a capacitive distance sensor  680   c ; and  FIGS.  6 E and  6 F  depict an optical or an acoustic distance sensor  680   e.    
       FIGS.  6 A and  6 B  depict magnetic distance sensor  680   a  employing a detector in the form of a magnetic detector  682   a  atop shape memory member base  670  opposite a target in the form of a magnetic target  684   a  (such as a permanent magnet) attached to sensor moveable member  660 . In some embodiments, magnetic detector  682   a  and magnetic target  684   a  may be in opposing relation and may be separated by gap  675 .  FIG.  6 A  depicts magnetic distance sensor  680   a  prior to engagement between bearing  620  and moveable member  660 .  FIG.  6 B  depicts the same magnetic distance sensor  680   a  at the point of maximum displacement of sensor moveable member  660 . Extension distance da between magnetic detector  682   a  and magnetic target  684   a  is also shown. One or more embodiments of sensor array ( FIG.  4 A ) may include one or more magnetic distance sensors. 
     One or more embodiments of magnetic detector  682   a  may be a micro-electro-mechanical systems (MEMS)-type magnetic distance sensor. One or more embodiments of magnetic detector  682   a  may be a flexible MEMS device. A flexible magnetic detector  682   a  may change shape along with shape memory member base  670 . 
     Magnetic target  684   a  attached to sensor moveable member  660  may be any component that is able to be detected by magnetic detector  682   a . In one or more embodiments, magnetic target  684   a  may be a magnet attached to a base of sensor moveable member  660 . In one or more embodiments, magnetic target  684   a  may be a permanent magnet attached to a base of sensor moveable member  660 . In one or more embodiments, magnetic target  684   a  may be a magnetic material attached to a base of sensor moveable member  660 . In one or more embodiments, magnetic target  684   a  may be a magnetic coating on a base of sensor moveable member  660 . 
     In one or more embodiments, magnetic detector  682   a  may detect a magnetic field originating from magnetic target  684   a  across gap  675 . In one or more embodiments, this magnetic field strength may be used to determine the size of gap  675  including the extension distance da between magnetic detector  682   a  and magnetic target  684   a . In one or more embodiments, the output of magnetic distance sensor  680   a  may be used to determine the size of gap  675  including extension distance da between magnetic detector  682   a  and magnetic target  684   a.    
     In one or more embodiments, magnetic distance sensor  680   a  may detect the magnetic field originating from magnetic target  684   a . In one or more embodiments, prior to the introduction of an external stimulus, magnetic detector  682   a  may be closest to magnetic target  684   a  when sensor moveable member  660  is fully pushed into sensor moveable member retainer  665  as in  FIG.  6   b   . In one or more embodiments, prior to the introduction of an external stimulus, magnetic detector  682   a  may thus detect a maximum magnetic field when sensor moveable member  660  is fully pushed into sensor moveable member retainer  665 . In one or more embodiments, the output of magnetic distance sensor  680   a  may be used to determine extension distance da prior to the introduction of an external stimulus in the form of an environmental parameter. 
     In one or more embodiments, when shape memory material element  670  has expanded due to external parameters, the maximum magnetic field detected by magnetic detector  682   a  may be greater than a maximum magnetic field prior to expansion of shape memory material element  670 . Consequently, in one or more embodiments, an increase in the maximum magnetic field detected by magnetic detector  682   a  may correlate with expansion of shape memory member element  670  due to changes in environmental parameter(s). In one or more embodiments, the output of magnetic distance sensor  680   a  may be used to determine the size of gap  675  including extension distance da between magnetic detector  682   a  and magnetic target  684   a . In one or more embodiments, the output of magnetic distance sensor  680   a  may be used to determine extension distance da after the introduction of an external stimulus in the form of an environmental parameter. 
     In one or more embodiments, sensor array ( FIG.  3 A ) may evaluate the output of magnetic distance sensor  680   a  to determine the change of extension distance da from d 1  to d 2 , and ultimately calculate the environmental parameter(s) reflected in the shape memory material element  670  expansion. Thus, in some embodiments, sensor array ( FIG.  3   ) may employ one or more magnetic distance sensors  680   a  to indirectly detect one or more environmental parameter(s). One having skill in the art will appreciate how to adapt the process described here when the extension distance da increases between d 1  (without a stimulus) and d 2  (with stimulus) (meaning, d 2  is greater than d 1 ) due to a contraction of shape memory material element  670 . 
     In one or more embodiments, the output of magnetic distance sensor  680   a  may be transmitted to a receiver ( FIG.  11   ), so the receiver may determines the change of extension distance da from d 1  to d 2 , and ultimately calculate the environmental parameter(s) reflected in the shape memory material element  670  expansion. 
     In one or more embodiments, sensor array ( FIG.  4 A ) may include multiple magnetic distance sensors  680   a . Thus, in one or more embodiments, sensor array (FIG.  4 A) may use multiple magnetic distance sensors  680   a  to repeatedly measure the maximum magnetic field between magnetic detector  682   a  and magnetic target  684   a  to determine a change in the extension distance da from d 1 , d 2 . In such a system, the multiple measurements of a change in the extension distance da may result in total distance sensor output that is stronger, less noisy, or both. 
       FIGS.  6 C and  6 D  depict a capacitive distance sensor  680   c  employing a detector in the form of a ground electrode detector  682   c  atop shape memory member base  670  opposite a target in the form of a drive electrode target  684   c  on the base of sensor moveable member  660 .  FIG.  6 C  depicts capacitive distance sensor  680   c  prior to engagement between bearing  620  and moveable member  660 .  FIG.  6 D  depicts the same capacitive distance sensor  680   c  at the point of maximum displacement of sensor moveable member  660 . Extension distance dc between ground electrode detector  682   c  and drive electrode target  684   c  is also shown. One or more embodiments of sensor array ( FIG.  4 A ) may include one or more capacitive distance sensors. 
     In some embodiments, drive electrode target  684   c  may be formed of a conductive material, such as a metal, a conductive polymer, or a conductive ceramic. In some embodiments, drive electrode target  684   c  may be attached to or coated on the base of sensor moveable member  660 . In some embodiments, drive electrode target  684   c  on the base of sensor moveable member  660  conducts electricity, thus serves as an electrode. In some embodiments, ground electrode  684   c  on the base of sensor moveable member  660  may serve as a drive electrode. 
     In some embodiments, ground electrode detector  682   c  may be located within sensor moveable member retainer  665 . In some embodiments, ground electrode detector  682   c  may be located atop shape memory material element  670 . In some embodiments, ground electrode detector  682   c  may serve as a ground electrode. 
     In some embodiments, drive electrode target  684   c  and ground electrode detector  682   c  may act as a parallel-plate capacitor, with drive electrode target  684   c  and ground electrode detector  682   c  separated by a non-conductive region (meaning, the air gap between drive electrode target  684   c  and ground electrode detector  682   c ). In some embodiments, drive electrode target  684   c  and ground electrode detector  682   c  may be in opposing relation and may be separated by gap  675 . In some embodiments, when a voltage is applied to drive electrode target  684   c , an electric field may be produced across gap  675  between drive electrode target  684   c  and ground electrode detector  682   c , such that capacitive distance sensor  680   c  behaves as a parallel-plate capacitor. In one or more embodiments, this capacitance may be used to determine a size of gap  675  including an extension distance dc between drive electrode target  684   c  and ground electrode detector  682   c . In one or more embodiments, the output of capacitive distance sensor  680   c  may be used to determine the size of gap  675  including extension distance dc between drive electrode target  684   c  and ground electrode detector  682   c.    
     In one or more embodiments, capacitive distance sensor  680   c  may detect a capacitance between drive electrode target  684   c  and ground electrode detector  682   c  when a voltage is applied to drive electrode target  684   c . In one or more embodiments, prior to the introduction of an external stimulus, ground electrode detector  682   c  may be closest to drive electrode target  684   c  when sensor moveable member  660  is fully pushed into sensor moveable member retainer  665  as in  FIG.  6 D . In one or more embodiments, prior to the introduction of an external stimulus, ground electrode detector  682   c  may thus detect a maximum capacitance when sensor moveable member  660  is fully pushed into sensor moveable member retainer  665 . In one or more embodiments, the output of capacitive distance sensor  680   c  may be used to determine extension distance dc between ground electrode detector  682   c  and drive electrode target  684   c . In one or more embodiments, the output of capacitive distance sensor  680   c  may be used to determine extension distance dc prior to the introduction of an external stimulus in the form of an environmental parameter. 
     In one or more embodiments, when shape memory material element  670  has expanded due to stimulus caused by environmental parameters, the maximum capacitance detected by ground electrode detector  682   c  may be greater than a maximum capacitance prior to expansion of shape memory material element  670 . Consequently, in one or more embodiments, an increase in the maximum capacitance detected by ground electrode detector  682   c  may correlate with expansion of shape memory member base  670  due to changes in environmental parameter(s). In one or more embodiments, the output of capacitive distance sensor  680   c  may be used to determine extension distance dc after the introduction of an external stimulus in the form of an environmental parameter. 
     In one or more embodiments, sensor array ( FIG.  3 A ) may evaluate the output of capacitive distance sensor  680   c  to determine the change of extension distance dc from d 1  to d 2 , and ultimately calculate the environmental parameter(s) reflected in the shape memory material element  670  expansion. Thus, in some embodiments, sensor array ( FIG.  3   ) may employ one or more capacitive distance sensor  680   c  to indirectly detect one or more environmental parameter(s). 
     In one or more embodiments, the output of capacitive distance sensor  680   c  may be transmitted to a receiver ( FIG.  11   ), so the receiver may determines the change of extension distance dc from d 1  to d 2 , and ultimately calculate the environmental parameter(s) reflected in the shape memory material element  670  expansion. 
     In one or more embodiments, sensor array ( FIG.  4 A ) may include multiple capacitive distance sensors  680   c . Thus, in one or more embodiments, sensor array ( FIG.  4 A ) may use multiple capacitive distance sensor  680   c  to repeatedly measure the maximum capacitance between ground electrode detector  682   c  and drive electrode target  684   c  to determine a change in the extension distance dc from d 1 , d 2 . In such a system, the multiple measurements of a change in the extension distance dc may result in total distance sensor output that is stronger, less noisy, or both. 
       FIGS.  6 E and  6 F  depicts an optical/acoustic distance sensor  680   e  employing a detector in the form of an optical/acoustic detector  682   e  atop shape memory member base  670  opposite a target in the form of an optical/acoustic target  684   e  (such as an optical or acoustic reflector) attached to sensor moveable member  660 . In some embodiments, optical/acoustic transceiver detector  682   e  and optical/acoustic reflector target  684   e  may be in opposing relation and may be separated by gap  675 .  FIGS.  6 E and  6 F  may depict either an optical or an acoustic distance sensor  680   e  because the overall geometry and function may be similar.  FIG.  6 E  depicts optical/acoustic distance sensor  680   e  prior to engagement between bearing  620  and moveable member  660 .  FIG.  6 F  depicts the same optical/acoustic distance sensor  680   e  at the point of maximum displacement of sensor moveable member  660 . Extension distance de between optical/acoustic detector  682   e  and optical/acoustic target  684   a  is also shown. One or more embodiments of sensor array ( FIG.  4 A ) may include one or more optical distance sensors. One or more embodiments of sensor array ( FIG.  4 A ) may include one or more acoustic distance sensors. 
     In one or more embodiments, optical/acoustic target  684   e  may be an optical reflector. In one or more embodiments, optical reflector target  684   e  may formed of any material that reflects a majority of transmitted light waves, such as a metallic, dielectric, or enhanced metallic material. 
     In one or more embodiments, optical/acoustic detector  684   e  may be an optical transceiver that incorporates both an optical emitter and an optical receiver. In one or more embodiments, optical transceiver detector  682   e  may emit and detect a reflected optical signal. In one or more embodiments, optical transceiver detector  682   e  may measure the duration elapsed between emission and detection of a light wave, specifically the time from transmission by the transmitter within optical transceiver detector  682   e , propagate across gap  675 , reflection off optical reflector target  684   e , propagate across gap  675  again, and detection by the receiver within optical transceiver detector  682   e . In one or more embodiments, this elapsed duration may be used to determine extension distance de between optical transceiver detector  682   e  and optical reflector target  684   e . In one or more embodiments, the output of optical/acoustic distance sensor  680   e  may be used to determine the size of gap  675  including extension distance de between optical transceiver detector  684   e  and optical reflector target  684   e.    
     In one or more embodiments, optical/acoustic target  684   e  may be an acoustic reflector. In one or more embodiments, acoustic reflector target  684   e  may be any surface that can be coated to be flat and rigid, so that acoustic waves bounce off acoustic reflector target  684   e  creating an echo. In one or more embodiments, acoustic reflector target  684   e  may be formed of any material that may be made sufficiently flat and rigid. 
     In one or more embodiments, optical/acoustic detector  684   e  may be an acoustic transceiver that incorporates both an acoustic emitter and an acoustic receiver. In one or more embodiments, acoustic transceiver detector  682   e  may emit and detect a reflected acoustic signal. In one or more embodiments, acoustic transceiver detector  682   e  may measure the duration elapsed between emission and detection of a sound wave, specifically the time from transmission by the transmitter within acoustic transceiver detector  682   e , propagate across gap  675 , reflection off acoustic reflector target  684   e , propagate across gap  675  again, and detection by the receiver within acoustic transceiver detector  682   e . In one or more embodiments, this elapsed duration may be used to determine a size of gap  675  including an extension distance de between acoustic transceiver detector  682   e  and acoustic reflector target  684   e . In one or more embodiments, the output of acoustic distance sensor  680   e  may be used to determine extension distance de between acoustic transceiver detector  684   e  and acoustic reflector target  684   e.    
     In one or more embodiments, optical/acoustic distance sensor  680   e  may detect the elapsed duration between emission of light/sound from optical/acoustic transceiver detector  682   e , reflection off target  684   e , and detection by optical/acoustic transceiver detector  682   e . In one or more embodiments, prior to the introduction of an external stimulus, optical/acoustic transceiver detector  682   e  may be closest to target  684   e  when sensor moveable member  660  is fully pushed into sensor moveable member retainer  665  as in  FIG.  6 F . In one or more embodiments, prior to the introduction of an external stimulus, optical/acoustic transceiver detector  682   e  may thus detect a shortest elapsed time between emission and detection of light/sound when sensor moveable member  660  is fully pushed into sensor moveable member retainer  665 . In one or more embodiments, the output of optical/acoustic distance sensor  680   e  may be used to determine extension distance de prior to the introduction of an external stimulus in the form of an environmental parameter. 
     In one or more embodiments, when shape memory material element  670  has expanded due to external parameters, a minimum duration between emission and detection detected by optical/acoustic transceiver detector  682   e  may be less than a minimum duration between emission and detection prior to expansion of shape memory material element  670 . This change may be because the expansion of the shape memory material element  670  reduces the distance the light/acoustic wave has to travel from the optical/acoustic transceiver detector  682   e  to optical/acoustic reflector target  684   e  and back to optical/acoustic transceiver detector  682   e.    
     Consequently, in one or more embodiments, a decrease in the minimum duration between emission and detection detected by optical/acoustic transceiver detector  682   e  may correlate with expansion of shape memory member base  670  due to changes in environmental parameter(s). In one or more embodiments, the output of optical/acoustic distance sensor  680   e  may be used to determine extension distance de after the introduction of an external stimulus in the form of an environmental parameter. 
     In one or more embodiments, sensor array ( FIG.  3 A ) may evaluate the output of optical/acoustic distance sensor  680   e  to determine the change of extension distance de from d 1  to d 2 , and ultimately calculate the environmental parameter(s) reflected in the shape memory material element  670  expansion. Thus, in some embodiments, sensor array ( FIG.  3   ) may employ one or more optical/acoustic distance sensors  680   e  to indirectly detect one or more environmental parameter(s). One having skill in the art will appreciate how to adapt the process described here when the extension distance de increases between d 1  (without a stimulus) and d 2  (with stimulus) (meaning, d 2  is greater than d 1 ) due to a contraction of shape memory material element  670 . 
     In one or more embodiments, the output of optical/acoustic distance sensor  680   e  may be transmitted to a receiver ( FIG.  11   ), so the receiver may determines the change of extension distance de from d 1  to d 2 , and ultimately calculate the environmental parameter(s) reflected in the shape memory material element  670  expansion. 
     In one or more embodiments, sensor array ( FIG.  4 A ) may include multiple optical/acoustic distance sensors  680   e . Thus, in one or more embodiments, sensor array ( FIG.  4 A ) may use multiple optical/acoustic distance sensors  680   e  to repeatedly measure the duration between emission and detection using optical/acoustic transceiver detector  682   e  to determine a change in the extension distance de from d 1 , d 2 . In such a system, the multiple measurements of a change in the extension distance de may result in total distance sensor output that is stronger, less noisy, or both. 
     In one or more embodiments, sensor array ( FIG.  4 A ) may include multiple distance sensors  680   a ,  680   c ,  680   e  of a single type at multiple locations (meaning within multiple sensor moveable members retainers  665 ) around inner ring  610 . Such an arrangement may help detect wellbore conditions around a wellbore ( FIG.  2 A ) in an oriented way. An additional discussion of the arrangement of distance sensors around sensor array can be found further. 
     In one or more embodiments, sensor array ( FIG.  4 A ) may include one or more commercially available ultra-low power distance sensors with power consumptions in the range of 100 μW up to several W. In one or more embodiments, sensor array ( FIG.  4 A ) including one or more distance sensors  680   a ,  680   c ,  680   e  may be powered by a power array that locally captures the rotational energy of a drillstring ( FIG.  3   ) as discussed further. 
     In one or more embodiments, distance sensor  680   a ,  680   c ,  680   e  may continuously measure the output of detector  684   a ,  684   c ,  684   e . Thus, in one or more embodiments, distance sensor  680   a ,  680   c ,  680   e  may continuously measure gap  675 . In one or more embodiments, the cyclical displacement of sensor moveable member  660  within sensor moveable member retainer  665  (meaning, movement in and out of sensor moveable member retainer  665 ) may continually calibrate the output of each distance sensor  680   a ,  680   c ,  680   e . In some embodiments, the output of detector  684   a ,  684   c ,  684   e  when sensor moveable member  660  is in the original, extended position may be used to calibrate distance sensor  680   a ,  680   c ,  680   e.    
     In one or more embodiments, the cyclical displacement of sensor moveable member  660  within sensor moveable member retainer  665  (meaning, movement in and out of sensor moveable member retainer  665 ) may be utilized to generate a data time stamp. In one or more embodiments, the cyclical displacement of sensor moveable member  660  within sensor moveable member retainer  665  (meaning, movement in and out of sensor moveable member retainer  665 ) may be used to synchronize all distance sensor  680   a ,  680   c ,  680   e  within sensor array  400  ( FIG.  4 A ). 
     In one or more embodiments, distance sensor  680   a ,  680   c ,  680   e  may include one or more flexible device. In one or more embodiments, distance sensor  680   a ,  680   c ,  680   e  may include one or more MEMS device. In one or more embodiments, detector  684   a ,  684   c ,  684   e  may be a flexible device. In one or more embodiments, detector  684   a ,  684   c ,  684   e  may reflect the shape change of shape memory material element  670 . 
       FIGS.  7 A- 7 C  depict an embodiment of an inner ring  710  and an outer collar  750  of a power array  700 . 
       FIG.  7 A  depicts an embodiment of a power array  700  where half of outer collar  750  is cut away. On inner ring  710  are bearings  720  located on three outer surfaces: a top outer surface  714 , a middle outer surface  712 , and a bottom outer surface  716 . Additionally, a first fraction of bearings  720  are on middle outer surface  712 , a second fraction of bearings  720  are on top outer surface  714 , and a third fraction of bearings  720  are on bottom outer surface  716 . In some embodiments, bearings  720  may be positioned to support rotation of inner ring  710  relative to outer collar  750 . 
     Within outer collar  750  are three surfaces: a top inner surface  754 , a middle inner surface  752 , and a bottom inner surface  756 . Outer collar  750  has moveable members in the form of power moveable members  760  located on two surfaces: a top inner surface  754  and a bottom inner surface  756 . A third surface, a middle inner surface  752  does not have power moveable members. Instead, middle inner surface  752  has a raceway  753 . Raceway  753  serves to hold inner ring  710  in place relative to outer collar  750 . The details of such a connection are detailed further. 
     Each power moveable member  760  is moveably located within a moveable member retainer in the form of a power moveable member retainer  765 . Also within each power moveable member retainer  765  is a power generation component  730 . Power moveable members  760  have convex surfaces for contact with bearings  720 . 
     Power array  700  is a combination of inner ring  710  and outer collar  750 . Inner ring  710  may be located radially within outer collar  750 . First fraction of bearings  720  on middle outer surface  712  of inner ring  710  are in the raceway  753  on middle inner surface  752  of outer collar  760 . Second fraction of bearings  720  on top outer surface  714  of inner ring  710  are in contact with top inner surface  754  of outer collar  750 , while third fraction of bearings  720  on bottom outer surface  716  of inner ring  710  are in contact with bottom inner surface  756  of outer collar  750 . This alignment allows the second and third fractions of bearings  720  on top outer surface  714  and bottom outer surface  716  of inner ring  710  to interact with a first fraction of power moveable members  760  located on top inner surface  754  of outer ring  750  and a second fraction of power moveable members  760  located on bottom inner surface  756  of outer ring  750 . 
       FIG.  7 B  depicts a cross-section of a bearing  720  in inner ring  710 . Bearing  720  is located in a corresponding bearing retainer  725  defined by inner ring  710 . One having skill in the art will appreciate the relative sizes and geometries of bearing  720  and bearing retainer  725  to allow both free, low-friction movement and retention of bearing  720  within bearing retainer  725 . 
     Further, bearing retainer  725  may not be indicated in each figure for clarity and brevity. One having skill in the art will appreciate each bearing  720  depicted in this disclosure may be located within a bearing retainer that may not be specifically indicated or described. 
       FIG.  7 C  depicts a cross section of power moveable member  760  in outer collar  750 . Power moveable member  760  is held within a corresponding power moveable member retainer  765 , which is defined by outer collar  750 . Within power moveable member retainer  765  is a power generation component  730 . Power moveable member  765  is configured to move up and down within corresponding power moveable member retainer  765 . More details of power generation component  730  will be discussed further. 
     As above, after bearings  720  are no longer contacting power moveable members  760 , power moveable members  760  may move outward from power moveable member retainers  765  and return to their original, extended position. In one or more embodiments, power moveable members  760  may return to their original, outward, non-compressed position due to a spring beneath sensor moveable members  760 , elasticity of the sensor moveable members  460 , or some other possible means. One or more embodiments for returning power moveable members  760  to their original, extended position are depicted in  FIGS.  12 A- 12 F  and discussed further. 
     One or more embodiments of inner ring  710  and outer collar  750  may be formed from one or more metallic, non-metallic, or composite materials, or a combination of more than one material. One or more embodiments of inner ring  710  and outer collar  750  may be formed from materials able to operate at conditions commonly experienced in the downhole environment, such as high temperatures (for example, &gt;150° C.), high pressures (&gt;5000 psi), or both. One or more embodiments of inner ring  710  and outer collar  750  may be formed from one or more low-friction materials. One or more embodiments of inner ring  710  and outer collar  750  may be formed from one or more materials having high abrasion resistance, high wear resistance, or both. 
     In one or more embodiments, power moveable member  760  may be formed of one or more elastomeric, polymeric, or composite materials, or a combination of more than one material. One or more embodiments of power moveable member  760  may be formed from one or more low-friction materials. One or more embodiments of power moveable member  760  may be formed from Teflon®, Kapton®, polyester, or a combination. 
     In one or more embodiments, power array  700  may continue generating electricity as long as power moveable members  760  are in motion. 
       FIGS.  8 A- 8 J  depict a cross section of an inner ring  810  with a bearing  820  and an outer collar  850  with a moveable member in the form of a power moveable member  860 .  FIGS.  8 A- 8 J  depicts different power generation component  830   a ,  830   c ,  830   e ,  830   g ,  830   i , according to one or more embodiments.  FIGS.  8 A,  8 C,  8 E,  8 G, and  8 I  depict power generation component  830   a ,  830   c ,  830   e ,  830   g ,  830   i  before bearing  820  contacts power moveable member  860 .  FIGS.  8 B,  8 D,  8 F,  8 H, and  8 J  depict the same power generation component  830   a ,  830   c ,  830   e ,  830   g ,  830   i  at the point of maximum displacement of power moveable member  860  due to contact with bearing  820 . 
       FIGS.  8 A- 8 F  generate electricity using friction resulting from contact between frictional material A and frictional material B via the triboelectric effect. Frictional material A and frictional material B may have a large difference in polarity, such as opposite polarities, in one or more embodiments. Generating electricity by friction is based on the triboelectric effect, where an object becomes electrically charged after it contacts another material through friction. When they contact, charges move from one material to the other. Some materials have a tendency to gain electrons, while others have a tendency to lose electrons. If frictional material A has a higher polarity than frictional material B, then electrons are injected from frictional material B into frictional material A. This results in oppositely charged surfaces. When these two materials are separated, there is a current flow, when a load is connected between the materials, due to the imbalance in charges between the two materials. The current flow continues until the potential of both the materials are equal. When the two materials move towards each other again, there will again be a current flow, although in the opposite direction. Therefore, in one or more embodiment, this contact and separation motion of two materials may be used to generate electricity. 
     In one or more embodiments, frictional material A and frictional material B may be materials such as polyamide, polytetrafluoroethylene (PTFE), polyethylene terephthalate (PET), polydimethylacrylamide (PDMA), polydimethylsiloxane (PDMS), Polyimide, Carbon Nanotubes, copper, silver, aluminum, lead, elastomer, Teflon, Kapton, nylon, polyester, or a combination, derivative, or composite thereof. 
     In  FIGS.  8 A and  8 B , power moveable member  860  is connected to outer collar  850  by spring  831 . In one or more embodiments, bearing  820  may be formed of or coated with frictional material A and power moveable member  860  may be formed of or coated with frictional material B. As the drillstring assembly rotates, bearing  820  makes contact with power moveable member  860 , causing power moveable member  860  to move up and down within power moveable member retainer  865 . In one or more embodiments, the power generation component  830   a  may be a bearing  860  formed of or coated with frictional material A and power moveable member  860  formed of or coated with frictional material B. In one or more embodiments, power moveable member  860  may be round such as a bearing. In one or more embodiments, spring  831  may ensure maximum contact between power moveable member  860  and bearing  820 . In one or more embodiments, spring  831  may compress and expand multiple times over the course of a drilling operation. This movement may cause contact between frictional material A and frictional material B and therefore, the generation of electricity. In one or more embodiments, electricity may be generated via friction resulting from contact between power moveable member  860  and bearing  820 . 
     In  FIGS.  8 C and  8 D , power moveable member  860  is partially coated with frictional material B  835   c  and power moveable member retainer  865  is partially coated with frictional material A  833   c . As the drillstring assembly rotates, bearing  820  makes contact with power moveable member  860 , causing power moveable member  860  to move up and down within power moveable member retainer  865 . This movement results in contact between frictional material A and frictional material B, generating electricity. In one or more embodiments, the power generation component  830   c  may be power moveable member retainer  865  partially coated with frictional material A and power moveable member  860  formed of or coated with frictional material B. In one or more embodiments, power moveable member  860  may be formed of or coated with frictional material B and power moveable member retainer  865  may be formed of or coated with frictional material A. In one or more embodiments, electricity may be generated via friction resulting from contact between frictional material B of power moveable member  860  and frictional material B of power moveable member retainer  865 . 
     In  FIGS.  8 E and  8 F , power moveable member  860  is coated with alternating segments of frictional material A and frictional material B  835   e . Power moveable member retainer  865  is also coated with alternating segments of frictional material A and frictional material B  833   e . As the drillstring assembly rotates, bearing  820  makes contact with power moveable member  860 , causing power moveable member  860  to move up and down within power moveable member retainer  865 . The sliding motion of the alternating segments on both power moveable member  860  and power moveable member retainer  865  triggers contact between frictional materials A and B, resulting in the generation of electricity. In one or more embodiments, the power generation component  830   e  may be alternating segments of frictional material A and frictional material B on power moveable member  860  and power moveable member retainer  865 . In one or more embodiments, power moveable member  860  and power moveable member retainer  865  may each be formed of or coated with alternating segments of frictional material A and frictional material B. In one or more embodiments, electricity may be generated via friction resulting from contact between frictional material A and frictional material B on both power moveable member  860  and power moveable member retainer  865 . 
     Instead of triboelectricity,  FIGS.  8 G- 8 J  employ piezoelectric or magnetostrictive materials to generate electricity. 
     Piezoelectricity is the conversion of mechanical stress into electric charge. Piezoelectric materials are materials that exhibit piezoelectricity.  FIGS.  8 G and  8 H  depict power moveable member  860  connected to outer collar  850  by piezoelectric base  837  within power moveable member retainer  865 . Power moveable member  860  has a curved surface at both ends. As the drillstring assembly rotates, bearing  820  makes contact with power moveable member  860 , causing power moveable member  860  to move up and down within power moveable member retainer  865 . This movement results in contact of power moveable member  860  with piezoelectric base  837  that stresses and unstresses piezoelectric base  837 . This cycle of stress within piezoelectric base  837  generates electricity. In one or more embodiments, one or more power generation component  830   g  may be piezoelectric base  837 . In one or more embodiments, electricity may be generated via piezoelectricity resulting from stress in piezoelectric base  837  by power moveable member  860 . In one or more embodiments, piezoelectric base  837  may be formed of quartz, langasite, lithium niobate, titanium oxide, lead zirconate titanate, or any other material exhibiting piezoelectricity. 
     Piezoelectric nanoribbons generate electricity when flexed and stressed.  FIGS.  8 I and  8 J  depict power moveable member  860  connected to outer collar  850  by piezoelectric nanoribbon base  839 . As the drillstring assembly rotates, bearing  820  makes contact with power moveable member  860 , causing power moveable member  860  to move up and down within power moveable member retainer  865 . Contact between bearing  820  and power moveable member  860  results in flexing, stressing, or both of piezoelectric nanoribbon base  839 . In one or more embodiments, one or more power generation component  830   i  may be piezoelectric nanoribbon base  839 . In one or more embodiments, piezoelectric nanoribbon base  839  may be formed of ceramic nanoribbons, such as lead zirconate titanate. In one or more embodiments, piezoelectric nanoribbon base  839  may be encased in a flexible elastomer (not depicted). 
     Magnetostrictive materials are materials that exhibit magnetostriction. Magnetostriction is the generation of a magnetic field due to mechanical stress. This induced magnetic field may be converted to a voltage by a planar pick-up coil or a solenoid placed in the vicinity of the magnetostrictive material. In one or more embodiments, one or more power generation component may be magnetostrictive base (not depicted). In one or more embodiments, Terfenol-D (Tb x Dy 1-x Fe 2  (x≈0.3)), galfenol (meaning predominantly Fe and Ga alloys), metallic glass alloys (such as Metglas® alloy), or any other material that show magnetostrictive properties may be employed in a power array. In some embodiments, the magnetostrictive material employed in a power array may be a commercially available product. 
     In one or more embodiments, generated analogue electrical signals may be converted from an analog to a digital signal. In one or more embodiments, analogue to digital conversion may be performed using electronics well known in the art, such as an analog-to-digital converter (ADC) or a bridge rectifier circuit employing diodes. 
     One or more embodiments of the power array may include one or more electrical storage units that store the electrical energy generated by the power array. In one or more embodiments, the storage unit may be used as a regulated power source even when the drillstring is not rotating. In one or more embodiments, the storage unit may be either a regular di-electric capacitor de-rated for use at high temperatures, a ceramic, an electrolytic, or a super capacitor. 
     In one or more embodiments, by storing the generated power in the storage unit(s), power may be provided continuously to the components, including the sensor(s), instrumentation, communication devices, or a combination thereof. 
     In some embodiments, an amount of power generated depends on the relative motion between inner ring and outer collar. Thus, factors such as rate of penetration in different formations of the drillstring, drilling hydraulics and rheology of the formation, wellbore cleaning efficiency, and vibration and shock may influence this relative motion. 
     In one or more embodiments, a power output of power array may depend on the principle of energy harvesting utilized (static electric, piezoelectric, magnetostrictive); size and design of the power array; materials used for energy harvesting; frequency of the energy trigger to drive the materials; or a combination of these factors. In one or more embodiments, a power output may depend on energy storage capacity of the electrical storage unit, power management and type; sampling rate of the distance sensors; type of distance sensors; or a combination of these factors. In one or more embodiments, a distance sensor included may be a magnetic distance sensor fabricated as a MEMS device, which may require much less power than some alternatives. 
     In one or more embodiments. the power array may generate power up to several watts instantaneously, depending on the frequency of interaction between bearings and power moveable members in power array. The particular design of a power array may provide a stable and continuous power supply to any power-requiring devices, including distance sensor(s) or instrumentation during drilling. Further, in one or more embodiments, the power array may store generated power that, in the absence of drilling that rotates the drillstring or any other relative motion, energy storage unit(s) such as the capacitor may act as a regulated power source. 
     In one or more embodiments. the power array may be optimized regarding size, design, advanced materials used for energy harvesting, frequency of operation, energy storage capacity of the energy storage unit(s), power management, sampling rate of the distance sensors, or a combination thereof. In one or more embodiments, the power array may power one or more distance sensors, such as magnetic distance sensors, optical distance sensors, acoustic distance sensors, capacitive distance sensors, or other distance sensors known in the art. In one or more embodiments. the power array may power one or more additional sensors, such as magnetic sensors, optical sensors, electrical sensors, pressure sensors, temperature sensors, acoustic sensors, accelerometers sensors, or gyroscopic sensors, or other sensors known in the art. 
     In one or more embodiments. the power array may power wireless communication as discussed further. In one or more embodiments, the power array may generate and store additional power during lower power mode(s) (such as sensing) and then deliver extra power during higher power modes (such as transmission) for one or more high power mode(s) (such as transmission of RF communications). Such power optimization, in one or more embodiments, may be performed by power management circuitry. 
     In one or more embodiments, more than one fundamental energy harvesting principle may be combined within a single power array. 
     In one or more embodiments, an array such as a sensor array, a power array, or an SPSA, may be directly connected to a drillstring. In one or more embodiments, an array such as a sensor array, a power array, or an SPSAs, may be attached to or be part of a sub, such as crossover sub, that may be inserted into a drillstring. 
       FIG.  9 A  depicts an array  900  such as a sensor array, a power array, or an SPSAs arranged around a drillstring  990  atop drill bit  995 . Array  900  includes inner ring  910  and outer collar  950 . Array  900  is attached to sub  905 . Sub  905  is connected to drillstring  990  via a first connector  907  and a second connector  909 . 
       FIGS.  9 B- 9 D  depicts how array  900  may be connected to a drillstring  990  via a crossover sub  905 . In some embodiments, said crossover sub may be a pin-box type sub ( FIG.  9 B ), pin-pin type sub ( FIG.  9 C ), or box-box type sub ( FIG.  9 D ). 
       FIG.  9 B  depicts sub  905   b  including array  900 . First connector  907   b  is a pin-type connector. Second connector  909   b  is a box-type connector. Thus, sub  905   b  is a pin-box type sub. 
       FIG.  9 C  depicts sub  905   c  including array  900 . First connector  907   c  is a pin-type connector. Second connector  909   c  is a pin-type connector. Thus, sub  905   c  is a pin-pin type sub. 
       FIG.  9 D  depicts sub  905   d  including array  900 . First connector  907   d  is a box-type connector. Second connector  909   d  is a box-type connector. Thus, sub  905   d  is a box-box type sub. 
     Consider  FIG.  10   , which depicts additional potential components of an array  1000  of any type disclosed herein, including a sensor array ( FIG.  2   ), a power array ( FIG.  7   ), or an SPSA ( FIG.  14   ).  FIG.  10    depicts array  1000 , including inner ring  1010  with bearings  1020  and outer collar  1050  with moveable members  1060  (either sensor or power moveable members). 
     As depicted, in one or more embodiments, communication device  1002  and electronics  1004  may be folded within and carried by outer collar  1050 . In one or more embodiments, communication device  1002 , electronics  1004 , or both may be carried by outer collar  1050 . In one or more embodiments, communication device  1002 , electronics  1004 , or both may be folded within outer collar  1050 . 
     In one or more embodiments, distance sensors, additional sensors, instrumentation, and signal processing circuits of array  1000  may be included in electronics  1004 . In one or more embodiments, electronics  1004  may be fabricated on a flexible substrate and thus may be flexible. One or more embodiments of electronics  1004  may be fabricated from one or more of metal-polymer conductors, organic polymers, printable polymers, metal foils, transparent thin-film materials, glasses, 2D materials (such as graphene and MXene), silicon, fractal metal dendrites, or derivatives, alloys, composites, and combinations thereof. 
     In one or more embodiments, output of a power array ( FIG.  7   ) may be a digital signal. In one or more embodiments, this digital signal may be stored in a power storage unit, such as a regular dielectric capacitor de-rated for use at high temperatures, a ceramic, an electrolytic, or a super capacitor. By storing the generated energy in a power storage unit, power may be provided continuously to any components requiring outside power, such as distance sensors, other sensors, instrumentation, and communication devices. 
     In one or more embodiments, power storage unit(s) (not depicted) may provide power to one or more devices such as low power signal processing circuitry. In one or more embodiments, this low power signal processing circuitry may perform a number of tasks, including conditioning the data, storing the data in local memory, performing power management, or a combination of tasks. In one or more embodiments, power management may include interfacing with the power array and storage unit to deliver the appropriate system voltages and load currents to the circuit blocks in an efficient manner. 
     In one or more embodiments, electronics  1004  may include low power signal processing circuitry. In one or more embodiments, the low power signal processing circuitry included in electronics  1004  may be CMOS-based, microcontroller-based, digital signal processor (DSP)-based, field programmable gate array (FPGA)-based, application-specific integrated circuit (ASIC)-based, complex programmable logic device (CPLD)-based, system-on-chip (SoC)-based, or a combination thereof. 
     Array  1000  may further include the ability to wirelessly communicate with other components, such as with other arrays ( FIG.  11   ) along a drillstring, with a receiver, or both. In some embodiments, the receiver (not depicted) may be located apart from the array(s), such as at the surface of the wellbore. Wireless technologies such as Wi-Fi, Bluetooth, Bluetooth Low Energy, or ZigBee may be employed for high speed data transfer due to the amount of power that may be generated and stored by a power array in a downhole drilling environment. 
     In one or more embodiments, array  1000  may include one or more communications device  1002 . In one or more embodiments, communications device  1002  may include an antenna. In one or more embodiments, communications device  1002  may include a communications module with electronics or a processor for running communications device  1002 . In one or more embodiments, electronics  1004  may include circuitry necessary for communications device  1002 . 
     In one or more embodiments, communications device  1002  may transmit and receive data from downhole to uphole and uphole to downhole. In one or more embodiments, an antenna may transmit and receive data from downhole to uphole and uphole to downhole. 
     In one or more embodiments, communications device  1002  may include a transceiver (not depicted). In one or more embodiments, the transceiver may employ one or more low-power wireless communication technologies, such as low-power Wi-Fi, Bluetooth, Bluetooth Low Energy, ZigBee, or other low-power wireless technologies known in the art. 
     One having skill in the art will appreciate how higher frequencies allow for a better quality signal and a longer transmission distance. However, higher frequency communication signals also may have higher attenuation and higher power requirements. Here, “higher frequency” is intended to mean frequencies of up to 1 gigahertz (GHz). Also, the communication frequency of antenna within communications device  1002  may require optimization to ensure both high quality data transmission and appropriate power requirements. In one or more embodiments, the communication signal transmitted by antenna  1002  may have a higher frequency. 
     Given the power constraints of array  1000 , one or more embodiments of array  1000  may include power management of communications device  1002  including antenna, electronics, processor, and other components of communications device  1002 . 
     In one or more embodiments, array  1000  may not be continuously broadcasting from communications device  1002 . In one or more embodiments, array  1000  may not simultaneously broadcast from communications device  1002  and perform the sensing operations discussed previously ( FIG.  6 A- 6 F ). 
     In one or more embodiments, communications device  1002  may have an “active” mode, a “stand by” mode, a “sleep” mode, or a combination of these. In one or more embodiments, “active” mode may be when communications device  1002  transmits data, receives data, or both via an antenna. In some embodiments, “active” mode may have a short duration, since there may only be a few short tasks. In one or more embodiments, “stand-by” mode may be when communications device  1002  is ready to re-enter “active” mode, but is not actively transmitting from the antenna. In some embodiments, “stand by” mode may have a longer duration than “active” mode. In one or more embodiments, “sleep” mode may be when communications device  1002  is not prepared to transmit via the antenna and thus may have a very low power consumption. In some embodiments, “sleep” mode may have a longer duration than “stand by” mode. In some embodiments, communications device  1002  may be in “sleep” mode while performing the sensing operations discussed previously ( FIG.  6 A- 6 C ). 
     In one or more embodiments, the energy saved during “stand by” mode, “sleep” mode, or both may be use to power communication module (not depicted) in “active” mode. 
     In one or more embodiments, an antenna within communications device  1002  may transmit/receive a signal from downhole to uphole and uphole to downhole. In one or more embodiments, the signal may be received by the antenna within communications device  1002 . In one or more embodiments, this signal may be transmitted in a continuous mode (such as during drilling), semi-continuous mode (such as on a periodic or intermittent basis), a burst mode (such as if data is stored locally, then transmitted in large packets), or other communication modes known in the art. 
       FIG.  11    depicts a sensing system  1101  including a receiver  1103  and multiple arrays  1100  that may be placed all along drillstring  1190 . In one or more embodiments, system  1101  includes components both above and below ground  1196 . In one or more embodiments, each of the arrays  1100  may be a sensor array, a power array, an SPSA, or a combination therein. In  FIG.  11   , three arrays  1100  are depicted on drillstring  1190 . 
     In one or more embodiments, arrays  1100  may be located at particular intervals along drillstring  1190 . Locating arrays  1100  along drillstring  1190 , in some embodiments, may help obtain real-time distributed data via sensors that incorporate distance sensors with SMM in one or more of arrays  1100 . 
     There may be data that could be transmitted along the drillstring  1090  wirelessly. One or more embodiments of arrays  1100  may wirelessly move data along drillstring  1090 . In one or more embodiments, arrays  1100  may serve as nodes within a relay formed from sensing system  1101 . In such a system according to one or more embodiments, data may be transmitted along drillstring  1090  between arrays  1100  serving as nodes from the bottom to the surface and from the surface to the bottom. In such a system according to one or more embodiments, data may be transmitted along drillstring  1090  between arrays  1100  serving as nodes and receiver  1103 . 
     In one or more embodiments, arrays  1100  may be located along drillstring  1190  at intervals based on the maximum distance data may be transmitted from one array  1100  to another array  1100 . In one or more embodiments, transmission between arrays  1100  along the length of drillstring method of transmitting data along drillstring  1195  may be independent of drilling. 
     In one or more embodiment, sensing system  1101  may further include smart, miniature mobile devices (MMD) (not depicted) having a communication module that can be injected into wells to carry commanding signals to downhole equipment such as arrays  1100 . Such miniature mobile devices may carry commanding signals to arrays  1100  to activate/configure to arrays  1100  as well as read data outputs from to arrays  1100 . In one or more embodiments, MMDs may interface or improve the signal between arrays  1100  and receiver  1103 . 
       FIGS.  12 A- 12 F  depict a cross section of an array ( FIG.  1   ) having an outer collar  1250  having a moveable member  1260  (either a sensor moveable member or a power moveable member) within a moveable member retainer  1265 .  FIGS.  12 A and  12 B ;  FIGS.  12 C and  12 D ; and  FIGS.  12 E and  12 F  each depict an extension mechanism  1261  for applying a biasing force to return moveable member  1260  to the original, extended position when not pushed by bearing  1220  into moveable member retainer  1265 .  FIGS.  12 E and  12 F  depict the same extension mechanisms  1261  as in  FIGS.  12 C and  12 D , however moveable member  1260  is in the form of a sensor moveable member.  FIGS.  12 A,  12 C, and  12 E  depict moveable member  1260  in the original, extended position, prior to (or following) engagement with bearing  1220 .  FIGS.  12 B,  12 D, and  12 F  depict the same moveable member  1260  as in  FIGS.  12 A,  12 C, and  12 E  respectively at the point of maximum engagement with bearing  1220 . 
     In  FIGS.  12 A and  12 B , moveable member  1260  is connected to moveable member retainer  1265  with an extension mechanism  1261  in the form of a large spring  1263 . Thus, the biasing force is generated by large spring  1263 . In  FIG.  12 A , large spring  1263  is fully extended prior to (or following) engagement between bearing  1220  and moveable member  1260 . Thus, moveable member  1260  is in the original, extended position. In  FIG.  12 B , upon engagement between moveable member  1260  and bearing  1220 , large spring  1263  is elastically compressed into moveable member retainer  1265 . This compression of large spring  1263  generates potential energy that is stored in large spring  1263 . Once bearing  1220  moves past (and is thus no longer in contact with) moveable member  1260 , the extension of large spring  1263  causes moveable member  1260  to return to the original, extended position. Further, large spring  1263  may make the up and down movement of moveable member  1260  within moveable member retainer  1265  smooth. Since the compression and release of large spring  1263  may be assumed to be entirely elastic, this compression cycle of large spring  1263  may be repeated a very large number of times. In some embodiments, large spring  1263  may further constrain moveable member  1260  within moveable member retainer  1265 . In some embodiments, large spring  1263  may be the mechanism to keep moveable member  1260  in the original, extended position when not pushed by bearing  1220  into moveable member retainer  1265 . 
     In  FIGS.  12 C- 12 F , moveable member  1260  is connected to moveable member retainer  1265  by an extension mechanism  1261  that includes movement tracks  1267 , movement track bearings  1269 , and small springs  1268 . Two or more movement tracks  1267  are located on the interior sides of moveable member retainer  1265 . Such movement tracks  1267  connect moveable member  1260  to moveable member retainer  1265 . Further, movement track bearings  1269  may make the up and down movement of moveable member  1260  within moveable member retainer  1265  smooth. In some embodiments, movement track(s)  1267  may further constrain moveable member  1260  within moveable member retainer  1265 . In some embodiments, the connection between moveable member  1260  and movement tracks  1267  may include movement track bearing(s)  1269 . In some embodiments, moveable member  1260  may be located on one or more movement tracks  1267  along an inner surface(s) of moveable member retainer  1665 . In some embodiments, movement track bearing(s)  1269  may be located between moveable member  1260  and movement track(s)  1267 . 
     In  FIGS.  12 C and  12 D , within each movement track  1267  is a small spring  1268  and a movement track bearing  1269  attached to moveable member  1260 . Thus, the biasing force is generated by small springs  1268 . In  FIG.  12 C , the small springs  1268  are fully extended prior to (or following) engagement between bearing  1220  and moveable member  1260 . Thus, moveable member  1260  is in the original, extended position. In  FIG.  12 D , upon engagement between moveable member  1260  and bearing  1220 , each small spring  1268  is elastically compressed within movement track  1267  by movement track bearing  1269 . This compression of small spring  1268  generates potential energy that is stored in small spring  1268 . Once bearing  1220  moves past (and is thus no longer in contact with) moveable member  1260 , the extension of each of the small springs  1268  within movement track  1267  pushes movement track bearing  1269 , ultimately causing moveable member  1260  to return to the original, extended position. Since the compression and release of small springs  1268  may be assumed to be entirely elastic, this compression cycle of small springs  1268  may be repeated a very large number of times. 
       FIGS.  12 E- 12 F  depict a similar extension mechanism  1261  that includes a pair of movement tracks  1267  (including small springs  1268  and movement track bearings  1269 ) as in  FIGS.  12 C and  12 D . Again, the biasing force is generated by small springs  1268 . However, these moveable member  1260  are in the form of a sensor moveable member  660 , such as those discussed previously and depicted in  FIGS.  6 A- 6 F .  FIG.  12 E  depicts sensor moveable member  1260  prior to (or following) engagement with a bearing  1220 , while  FIG.  12 F  depicts sensor moveable member  1260  at the point of maximum engagement between sensor moveable member  1260  and bearing  1220 . A distance sensor  1280  includes a target  1284  and a detector  1282 . Target  1284  is on a base of sensor moveable member  1260  and detector  1282  is on top of a shape memory material element  1270  within moveable member retainer  1265 . Target  1284  and detector  1282  may be of any type known in the art, such as those depicted in  FIGS.  6 A- 6 F  and discussed previously. Extension distance d between the components of distance sensor  1280  is indicated in  FIG.  12 F . 
     In some embodiments, the stiffness of small spring(s)  1268 , the geometry of movement track  1267 , or both may constrain sensor moveable member  1260  to only move within moveable member retainer  1265  toward and away from shape memory material element  1270 . In one or more embodiments, for a set expansion of shape memory material element  1270 , the maximum and minimum extension distance d may be dictated by the stiffness of small spring(s)  1268 , the geometry of (such as the length and the position of) movement track  1267 , or both. 
     In one or more embodiments, extension distance d may be non-zero when shape memory material element  1270  is maximally expanded in response to environmental parameters. Thus, in one or more embodiments, there may be no contact between the components of distance sensor  1280  (meaning between target  1284  and detector  1282 ), even when shape memory material base  1270  is maximally expanded in response to environmental parameters. In some embodiments, the stiffness of small spring(s)  1268 , the geometry of movement track  1267 , or both may prevent contact between the components of distance sensor  1280 , meaning between target  1284  and detector  1282 . In some embodiments, the stiffness of small spring(s)  1268 , the geometry of movement track  1267 , or both may dictate a minimum extension distance d when shape memory material element  1270  is maximally expanded in response to environmental parameters. 
     In some embodiments, small spring(s)  1268  and/or large spring(s)  1263  may have any size or shape. In some embodiments, the stiffness of small spring(s)  1268  and/or large spring(s)  1263  may be optimized to maximize the up and down motion within moveable member retainer  1265 . In some embodiments, small spring(s)  1268  and/or large spring(s)  1263  may minimize motion retardation and experience compression and extension at the same time. In some embodiments, small spring(s)  1268  and/or large spring(s)  1263  may be any type of spring, such as a compression spring, an extension spring, a torsion spring, a Belville spring, or a combination. In some embodiments, small spring(s)  1268  and/or large spring(s)  1263  may be formed from one or more elastic materials. In some embodiments, small spring(s)  1268  and/or large spring(s)  1263  may have any spring constant. In some embodiments, small spring(s)  1268  and/or large spring(s)  1263  of a power moveable member may contribute to the momentum of frictional material A contacting frictional material B therefore, thereby increasing the charge transfer between frictional material A and frictional material B. 
     In some embodiments, small spring(s)  1268  and/or large spring(s)  1263  may store mechanical energy in the form of potential energy and release it as the restorative force, resulting in a constant spring coefficient. In some embodiments, small spring(s)  1268  and/or large spring(s)  1263  may produce restorative forces directly proportional to the spring  1268 ,  1263  displacement. Thus, in some embodiments, small spring(s)  1268  and/or large spring(s)  1263  may generally obey Hook&#39;s law. 
     In some embodiments, small spring(s)  1268  and/or large spring(s)  1263  may produce restorative forces that are not proportional to the displacement of the spring  1268 ,  1263 . In some embodiments, small spring(s)  1268  and/or large spring(s)  1263  may store mechanical energy in the form of potential energy and provide restorative forces according to the needs of particular embodiment(s). In some embodiments, small spring(s)  1268  and/or large spring(s)  1263  may produce restorative forces that are not directly proportional to their displacement. Thus, in some embodiments, small spring(s)  1268  and/or large spring(s)  1263  may generally not obey Hook&#39;s law. 
     One having skill in the art will appreciate additional mechanisms that may be used to return moveable member  1260  to the original, extended position when not engaged with bearing  1220 . 
       FIG.  13 A  depicts a cross section of an array ( FIG.  1   ) having an inner ring  1310  and outer collar  1350  arranged around drillstring  1390 . Inner ring  1310  has bearings on three surfaces of inner ring  1310 : a first fraction of bearings  1322   a  on a middle outer surface; a second fraction of bearings  1324   a  on a top outer surface; and a third fraction of bearings  1346   a  on a bottom outer surface. First fraction of bearings  1322   a  is within a raceway  1352   a  located on the middle inner surface of outer collar  1350 . First fraction of bearings  1322   a  within raceway  1352   a  serves to frictionlessly couple and maintain proper alignment of inner ring  1310  and outer collar  1350 . Raceway  1352   a  does not contain moveable members of either type. Second fraction of bearings  1324   a  and third fractions of bearings  1326   a  are not located within a raceway. However, the paths of second fraction of bearings  1324   a  and third fractions of bearings  1326   a  do contain moveable members, either sensor moveable members, power moveable members, or both. 
       FIG.  13 B  depicts a cross section of an array ( FIG.  1   ) having an inner ring  1310  and outer collar  1350  arranged around drillstring  1390 . Inner ring  1310  has bearings on three surfaces of inner ring  1310 : a first fraction of bearings  1322   b  on a middle outer surface; a second fraction of bearings  1324   b  on a top outer surface; and a third fraction of bearings  1346   b  on a bottom outer surface. First fraction of bearings  1322   b  is within a first raceway  1352   b  located on the middle inner surface of outer collar  1350 . Second fraction of bearings  1324   b  is within a second raceway  1354   b  located on the top inner surface of outer collar  1350 . Third fraction of bearings  1326   b  is within a third raceway  1356   b  located on the top inner surface of outer collar  1350 . First fraction of bearings  1322   b  within first raceway  1352   b , second fraction of bearings  1324   b  within second raceway  1354   b , and third fraction of bearings  1326   b  within third raceway  1356   b  all serve to frictionlessly couple and maintain proper alignment of inner ring  1310  and outer collar  1350 . Any or all of first raceway  1352   b , second raceway  1354   b , and third raceway  1356   b  may contain moveable members, either sensor moveable members, power moveable members, or both. 
     In one or more embodiments, bearings on inner ring may be within a corresponding raceway on outer collar. In one or more embodiments, bearings on inner ring may not be located within a corresponding raceway on outer collar. In one or more embodiments, raceways may have moveable members (of any type) that extend into the path of bearings. In one or more embodiments, raceways lack moveable members. In one or more embodiments, a raceway may contain either sensor moveable members or power moveable members. In one or more embodiments, a raceway may contain both sensor moveable members and power moveable members. In one or more embodiments, raceway(s) may serve to frictionlessly couple inner ring to outer collar. In one or more embodiments, arrays may include one or more raceways. In one or more embodiments, arrays may not include a raceway. In one or more embodiments, inner ring may be frictionlessly coupled to outer collar via some other method known in the art. 
     In one or more embodiments, bearings that move within a raceway may have a first diameter and bearings that move without a raceway may have a second diameter, where the first and second diameters are unequal. In one or more embodiments, the first bearing diameter (for bearings that move within a raceway) may be greater than a second bearing diameter (for bearings that do not move within a raceway). 
     In one or more embodiments, a raceway on the bottom inner surface may help prevent vibration or shock from damaging the array. 
     In one or more embodiments, a raceway on the middle inner surface may be beneficial when the array is in a deviated or horizontal orientation. 
       FIG.  14    depicts an embodiment of an SPSA  1400 , which may be seen as a combination of a sensor array and a power array.  FIG.  14    depicts SPSA  1400  where half of outer collar  1450  is cut away. SPSA  1400  includes two forms of moveable members: sensor moveable members  1460  and power moveable members  1462 . In some embodiments, sensor moveable members  1460  and power moveable members  1462  may have convex surfaces for contact with bearings  1420 . 
     Each sensor moveable member  1460  is moveably located within a moveable member retainer in the form of a sensor moveable member retainer  1465 . Also within each sensor moveable member retainer  1465  is a shape memory material element  1470 . 
     Additionally, within each sensor moveable member retainer  1465  is a distance sensor that includes a first sensing element in the form of a detector  1482  and a second sensing element in the form of a target  1484 . Detector  1482  and target  1484  are arranged in opposing relation. Detector  1482  and target  1484  are separated by a gap  675  ( FIGS.  6 A- 6 F ) that is responsive to a shape change of the shape memory material element  1470  and a displacement of the respective sensor moveable member  1460 . 
     Each sensor moveable member  1460  is connected to sensor moveable member retainer  1465  with an extension mechanism that includes movement tracks  1467 , movement track bearings  1469 , and small springs  1468 . Such an extension mechanism is depicted in  FIGS.  12 C- 12 F  and described previously. Two movement tracks  1467  are located on the interior sides of sensor moveable member retainer  1465 . Such movement tracks  1467  connect sensor moveable member  1460  to sensor moveable member retainer  1465 . 
     Contact between bearing  1420  and sensor moveable member  1460  displaces sensor moveable member  1460  relative to sensor moveable member retainer  1465  in response to relative rotation between inner ring  1410  and outer collar  1450 . Such displacement reduces gap  675  ( FIGS.  6 A- 6 F ) between detector  1482  and target  1484 , which is measured by detector  1482 . In the depicted embodiment, gap  675  ( FIGS.  6 A- 6 F ) is measured using a magnetic distance sensor  1482  and a magnetic target  1484  as depicted in  FIGS.  6 A and  6 B  and as discussed previously. In one or more embodiments, sensor moveable members  1460  of SPSA  1400  may measure gap  675  ( FIGS.  6 A- 6 F ) using one or more distance sensing methodology, such as those depicted in  FIGS.  6 A- 6 F  and discussed previously. 
     Each power moveable member  1462  is moveably located within a moveable member retainer in the form of a power moveable member retainer  1466 . 
     Each power moveable member  1462  is connected to power moveable member retainer  1466  with an extension mechanism in the form of a large spring  1463 . Such an extension mechanism is depicted in  FIGS.  12 A and  12 B  and described previously. 
     Contact between bearing  1420  and power moveable member  1462  may generate energy in response to relative rotation between inner ring  1410  and outer collar  1450  in one or more ways. First, contact between bearing  1420  and power moveable member  1462  displaces the power moveable member  1462  relative to power moveable member retainer  1466 . Such a displacement may be harnessed to generate electricity as depicted in  FIGS.  8 C- 8 J  and discussed previously. Further, energy may be generated via friction caused by contact between bearing  1420  and power moveable member  1462 . In the depicted embodiment, energy is generated via friction between power moveable members  1462  and bearings  1420  as depicted in  FIGS.  8 A and  8 B  and as discussed previously. In one or more embodiments, power moveable members  1462  of SPSA  1400  may harness the relative rotation between inner ring  1410  and outer collar  1450  to generate energy in one or more methods, such as those depicted in  FIGS.  8 A- 8 J  and discussed previously. 
     On inner ring  1410  are bearing elements in the form of bearings  1420  located on three outer surfaces: a top outer surface  1414 , a middle outer surface  1412 , and a bottom outer surface  1416 . Additionally, a first fraction of bearings  1420  are on middle outer surface  1412 , a second fraction of bearings  1420  are on top outer surface  1414 , and a third fraction of bearings  1420  are on bottom outer surface  1416 . 
     Within outer collar  1450  are three surfaces: a top inner surface  1454 , a middle inner surface  1452 , and a bottom inner surface  1456 . All three surfaces  1454 ,  1452 ,  1456  of outer collar  1450  have moveable members in moveable member retainers, but the type of moveable members and moveable member retainers varies. Outer collar  1450  has sensor moveable members  1460  in sensor moveable member retainers  1465  on two surfaces: top inner surface  1454  and bottom inner surface  1456 . However, middle inner surface  1452  has power moveable members  1462  within power moveable member retainers  1466 . 
     Sensor array  1400  is a combination of inner ring  1410  and outer collar  1450 . Inner ring  1410  may be located radially within outer collar  1450 . First fraction of bearings  1420  on middle outer surface  1412  of inner ring  1410  are opposite middle inner surface  1452  of outer collar  1450 ; second fraction of bearings  1420  on top outer surface  1414  of inner ring  1410  are opposite top inner surface  1454  of outer collar  1450 ; and third fraction of bearings  1420  on bottom outer surface  1416  of inner ring  1410  are opposite bottom inner surface  1456  of outer collar  1450 . This alignment allows second fraction of bearings  1420  on top outer surface  1414  of inner ring  1410  to contact a first fraction of sensor moveable members  1460  on top inner surface  1454  of outer ring  1450 . Additionally, this alignment allows a third fraction of bearings  1420  on bottom outer surface  1416  of inner ring  1410  to contact a second fraction of sensor moveable members  1460  on bottom inner surface  1456  of outer ring  1450 . Finally, this alignment allows first fraction of bearings  1420  on middle outer surface  1412  of inner ring  1410  to contact a first fraction of power moveable members  1462  on middle inner surface  1452  of outer ring  1450 . 
     Referring to  FIG.  15   , each memory capsule  1500  may include modules such as a microcontroller  1544 , a transceiver  1548 , and a rechargeable power source  1552 . These modules may be manufactured on the same substrate to form a system-on-chip package. The package can be made very small using techniques such as segmenting and stacking of modules and interconnection of the modules with short signal paths known as through-chip via or through-silicon via. These techniques allow the same chip area to be used for all the different modules without compromises in material selection, resulting in seamless interlayer communication for interoperability of diverse modules. Transceiver  1548  allows memory capsule  1500  to communicate with SPSM  100 . Rechargeable power source  1552  provides power to microcontroller  1544  and transceiver  1548 . Rechargeable power source  1552  may be a capacitor-based energy storage, such as a supercapacitor. Microcontroller  1544  includes a processor, memory, and other circuitry. Memory capsule  1500  includes a protective outer shell  1540  around the electronics package. Protective shell  1540  may be a container made of a material or having an exterior coated with a material that can withstand continuous exposure to the harsh downhole environment. A protective shell can be formed with chemical coatings such as polymers and/or epoxy, resin-based materials, or any material that can withstand continuous exposure to the harsh downhole environment. Memory capsule  1500  is shown as having a spherical shape. However, memory capsule  1500  is not limited to this shape. Memory capsule  1500  could have an oblong shape or cube shape, for example. In cases where memory capsule  1500  may need to exit through a nozzle in a drill bit, capsule  1500  may be sized to pass through the nozzle of the drill bit. In some cases, capsule  1500  may be flexible so that it can be squeezed through the passage of the nozzle. This may allow memory capsule  1500  to be slightly larger than the passage diameter of the nozzle. Memory capsule  1500  has low power requirements since it only contains a transceiver, a microcontroller, and a rechargeable power storage, making capsule  1500  suitable for IoT platforms. The power storage can be recharged using energies harvested by the capsule from flowing with the drilling fluid. For example, memory capsule  1500  could include a small turbine to harvest energy. 
     In general, the amount of stored data in a sensor array/SPSM  100 ,  200 ,  300 ,  400 ,  700 ,  900 ,  1400  that can be transferred to a mobile memory capsule  1500  is limited. In this case, sensor array/SPSM  100 ,  200 ,  300 ,  400 ,  700 ,  900 ,  1400  can use processing-in-memory (PIM) architecture. In PIM, large volumes of data is computed, analyzed, and turned into information and real-time insights by bringing computation closer to the data, instead of moving the data across to the CPU. This way, the data needed to be transferred from a SPSM to a memory capsule could be largely reduced along with the required power for data transmission. The data from the different sensors in sensor array/SPSM  100 ,  200 ,  300 ,  400 ,  700 ,  900 ,  1400  may be stored in the SPSM memory separated by unique headers that identify the source of the sensor data. Not all the sensor data has to be transferred to the memory capsule. Instead, a snapshot of the data, such as maximum, minimum, average values or anomalies that would still provide valuable data to the driller at the surface, may be transferred. The data in the memory capsules can be static random-access memory (SRAM), where the data will remain as long as the capsules are powered. They can be integrated on-chip as random access memory (RAM) or cache memory in microcontrollers, Application Specific Integrated Circuits (ASICS), Field Programmable Gate Arrays (FPGAs), or Complex programmable logic devices (CPLDs). 
     For the purpose of data gathering by the memory capsules, the transceivers in sensor array/SPSM  100 ,  200 ,  300 ,  400 ,  700 ,  900 ,  1400  preferably support short-range wireless data transfer with ultra-low latency and ultra-low power requirements. Some methods include ultra-wideband (UWB) communication with short pulses rather than carrier frequencies. The electric and/or magnetic dipole antennas are also optimized for ultra-low latency and ultra-low power data transfer. Examples include, wide-band microstrip, wide-band monopole antenna over a plate, wide-slot UWB antenna, stacked patch UWB antenna, taper slot (TSA) UWB antenna, elliptical printed monopole UWB antenna, metamaterial (MTM) structure UWB antennas, and dielectric resonator antennas (DRAs). 
     Prior to data transfer from sensor array/SPSMs  100 ,  200 ,  300 ,  400 ,  700 ,  900 ,  1400  to memory capsules  1500 , a command may be sent from the surface to change antennas in the array of sensor arrays/SPSMs  100 ,  200 ,  300 ,  400 ,  700 ,  900 ,  1400  into transmit mode to enable transfer of data from sensor arrays/SPSMs  100 ,  200 ,  300 ,  400 ,  700 ,  900 ,  1400  to memory capsules  1500  when memory capsules  1500  are flowing with drilling fluid inside the well. Alternatively, specific capsules may be deployed into the well ahead of data gathering memory capsules. The specific capsules may send commands to SPSMs  100 ,  200 ,  300 ,  400 ,  700 ,  900 ,  1400  from inside the well to change antennas in SPSMs into transmit mode. The data gathering memory capsules can then flow past SPSMs  100 ,  200 ,  300 ,  400 ,  700 ,  900  and collect data from the SPSMs. Some methods may also include ultra-fast wake up and data transfer times so that a memory capsule can send a signal to change the transceiver status of a sensor array/SPSM  100 ,  200 ,  300 ,  400 ,  700 ,  900 ,  1400  to ‘active’ from its ‘sleep’ status and then obtain data. The memory capsules ‘listen’ to the data transmission to receive and store the data in their internal memories and then travel back to the surface with the data. 
     Returning to  FIG.  1   . One or more embodiments of array  100  may be designed so as not to allow outside fluids to flow into the spacing or voids between inner ring  110  and outer collar  160 . One having skill in the art will appreciate the many methods to prevent fluids from going inside the system comprising inner ring  110  and outer collar  160 , such as may be used in existing downhole friction bearing designs. 
     In one or more embodiments, inner ring  110  and/or outer collar  150  may be formed using multiple parts, enabling inner ring  110  to be disposed within outer collar  150 . In one or more embodiments, inner ring  110  and/or outer collar  150  may be flexible, enabling inner ring  110  to be disposed within outer collar  150 . 
     Embodiments of inner ring  210 ,  310 ,  410 ,  510 ,  610 ,  710 ,  810 ,  910 ,  1210 ,  1310 ,  1410  depicted herein include bearing elements in the form of bearings  220 ,  320 ,  420 ,  520 ,  620 ,  720 ,  820 ,  920 ,  1220 ,  1320 ,  1420  with a roughly spherical geometry (meaning, ball bearings). However, one having skill in the art will appreciate any shape or geometry of bearing elements may be employed. In one or more embodiments, bearings  220 ,  320 ,  420 ,  520 ,  620 ,  720 ,  820 ,  920 ,  1220 ,  1320 ,  1420  within inner ring  210 ,  310 ,  410 ,  510 ,  610 ,  710 ,  810 ,  910 ,  1210 ,  1310 ,  1410  may include any combination of ball bearing(s), roller bearing(s) including cylindrical roller(s), taper roller(s), spherical roller(s), or any other bearing geometry well known in the art. 
     Returning to  FIG.  2 A , in some embodiments, inner ring  210  may have any number of bearings  220  on any outer surface. In some embodiments, inner ring  210  may have bearings  220  on top outer surface  214 , middle outer surface  212 , or bottom outer surface  216 , or any combination of these outer surfaces  214 ,  212 ,  216 . 
     In one or more embodiments, a first fraction of bearings  220  may be on a first surface and a second fraction of bearings  220  may be on a second surface. In one or more embodiments, a first fraction of bearings  220  may be on a first surface, a second fraction of bearings  220  may be on a second surface, and a third fraction of bearings  220  may be on a third surface. 
     In one or more embodiments, a first fraction of bearings  220  may be on middle outer surface  212 . In one or more embodiments, a first fraction of bearings  220  may be on middle outer surface  212 , a second fraction of bearings  220  may be on top outer surface  214 , and a third fraction of bearings  220  may be on bottom outer surface  216 . 
     In one or more embodiments, a fraction of a total number of bearings  220  located on each surface may be equal. In one or more embodiments, a fraction of a total number of bearings  220  located on each surface may be unequal. In one or more embodiments, a fraction of a total number of bearings  220  located on two or more surfaces may be equal. In one or more embodiments, a fraction of a total number of bearings  220  located on two or more surfaces may be unequal. 
     In one or more embodiments, bearings  220  on each surface may be evenly spaced. In one or more embodiments, bearings  220  on each surface may be unevenly spaced. In one or more embodiments, bearings  220  on one or more surface may be evenly spaced. In one or more embodiments, bearings  220  on one or more surface may be unevenly spaced. 
     In  FIG.  2 A , bearings  220  on top outer surface  214 , middle outer surface  212 , and bottom outer surface  216  are roughly radially aligned. In one or more embodiments, bearings may be roughly radially aligned. In one or more embodiments, bearings may not be roughly radially aligned. In one or more embodiments, bearings on a first and a second surface may be roughly radially aligned, while bearings on a third surface may not be roughly aligned. In one or more embodiments, bearings on some surface(s) may be roughly radially aligned, while bearings on other surface(s) may not be roughly aligned. 
     In one or more embodiments, a fraction of a total number of moveable members (of any type) located on each surface may be equal. In one or more embodiments, a fraction of a total number of moveable members (of any type) located on each surface may be unequal. In one or more embodiments, a fraction of a total number of moveable members (of any type) located on two or more surfaces may be equal. In one or more embodiments, a fraction of a total number of moveable members (of any type) located on two or more surfaces may be unequal. 
     In one or more embodiments, moveable members (of any type) on each surface may be evenly spaced. In one or more embodiments, moveable members (of any type) on each surface may be unevenly spaced. In one or more embodiments, moveable members (of any type) on one or more surface may be evenly spaced. In one or more embodiments, moveable members (of any type) on one or more surface may be unevenly spaced. 
     In  FIG.  2 A , moveable members  260  on top inner surface  254 , middle inner surface  252 , and bottom inner surface  256  are roughly radially aligned. In one or more embodiments, moveable members (of any type) may be roughly radially aligned. In one or more embodiments, moveable members (of any type) may not be roughly radially aligned. In one or more embodiments, moveable members (of any type) on a first and a second surfaces may be roughly radially aligned, while moveable members (of any type) on a third surface may not be roughly aligned. In one or more embodiments, moveable members (of any type) on some surfaces may be roughly radially aligned, while moveable members (of any type) on a third surface may not be roughly aligned. 
     In one or more embodiments, moveable members on each surface may be either sensor moveable members or power moveable members. In one or more embodiments, moveable members on each surface may be both sensor moveable members and power moveable members. In one or more embodiments, moveable members on a first surface may be sensor moveable members and moveable members on a second surface may be power moveable members. In one or more embodiments, moveable members on a first surface may be sensor moveable members; moveable members on a second surface may be power moveable members; and a third surface may have a raceway for aligning the inner ring and the outer collar that contain no moveable members. In one or more embodiments, moveable members on a top inner surface and a bottom inner surface may be sensor moveable members and moveable members on a middle inner surface may be power moveable members. 
     One or more embodiments of inner ring  210  and outer ring  250  may be formed of the same material(s). In one or more embodiments, inner ring  210  and outer ring  250  may each be formed of different materials. 
     One or more embodiments of inner ring  210  may each be formed of two or more materials. One or more embodiments of outer ring  250  may each be formed of two or more materials. 
     One or more embodiments of inner ring  210  and outer ring  250  may include one or more partial or complete coatings. Such a coating may, for instance, increase wear resistance for higher-friction region(s) such as raceway(s). 
     One or more embodiments depicted here have bearings  220  on inner ring  210  and moveable members  260  on outer collar  250 . In one or more embodiments, the bearings may be on the inner ring, while the moveable members (of any type) may be on the outer collar. In one or more embodiments, the bearings may be on the outer collar, while the moveable members (of any type) may be on the inner ring. In one or more embodiments, the bearings may be on both the inner ring and on the outer collar. In one or more embodiments, the moveable members (of any type) may be on both the inner ring and on the outer collar. In one or more embodiments, the moveable members of one type may be on the inner ring and the moveable members of the other type may be on the outer collar. 
       FIG.  2 A  depicts inner ring  210  roughly shaped as an open cylinder, also known as a hollow cylinder. In one or more embodiments, the inner ring may be roughly shaped as an open cylinder. In one or more embodiments, the inner ring may be roughly shaped as a torus or a toroid having any polygonal cross section, such as a triangular toroid, a square toroid, a rectangular toroid, or a hexagonal toroid. One having skill in the art will appreciate the corresponding shape of the outer collar needed to accommodate each of these shapes. Also, one having skill in the art will appreciate that the number of outer surfaces of the inner ring and the number of inner surfaces of the outer ring may depend on the shape of the inter ring. 
     One or more embodiments depicted here have an inner ring with three outer surfaces and an outer collar with three inner surfaces. One having skill in the art will appreciate that one or more embodiments the inter ring having an alternative geometry may have a different number of outer surfaces. Also one or thus the outer collar may similarly have a different number of inner surfaces). 
     One or more embodiments depicted here have an inner ring with three outer surfaces and an outer collar with three inner surfaces, where the number of surfaces is equal. One or more embodiments will have an inner ring and an outer collar with an equal number of surfaces. One or more embodiments will have an inner ring and an outer collar with a different number of surfaces. 
     Returning to  FIGS.  3 A and  3 B , sensor array  300  as depicted is located outside of drillstring  390 . One or more embodiments of sensor array  300  may be located inside drillstring  390  with either inner ring  310  or outer collar  350  connected to the inside of drillstring  390 . One having skill in the art will appreciate how the geometry and relative orientations of inner ring  310  and outer collar  350  change when sensor array  300  is located within drillstring  390 . 
     One or more embodiments depicted here have inner ring  310  located between outer collar  350  and drillstring  390 . One or more embodiments with sensor array  300  outside wellbore  390  have inner ring  310  located outside of outer collar  350  and drillstring  390 , thus towards the wellbore. One or more embodiments with sensor array  300  inside wellbore  390  have inner ring  310  located outside of outer collar  350  and drillstring  390 , thus towards the fluid flow. 
     Frequently, the radial space in a wellbore outside the drillstring may be moderately or significantly constrained. Further, a sensor array with a small radial thickness may enable maximum fluid bypass, prevent the accumulation of cuttings, or both. In one or more embodiments, inner ring  310  and outer collar  350  may not significantly extend radially outwards from the drillstring assembly. (To that end, the diagrams depicted herein are not to scale and may be enlarged in the radial direction for visual clarity.) One or more embodiments of sensor array  300  may be configured to allow maximum drilling fluid bypass, thus minimizing the impact on drilling fluid flow through the borehole past sensor array  300 . 
     One or more embodiments of outer collar  350  may include flutes on one or more fluid-exposed surfaces. Such flutes may allow cuttings to pass through without obstruction. 
     In one or more embodiments, moveable members (of any type) may not be significantly compressible. In one or more embodiments, moveable members (of any type) may be formed of one or more materials able to withstand the downhole environment. Some important features of the material(s) forming moveable members (of any type) may include the ability to operate at high temperature (&gt;150° C.), the ability to operate at high pressure (&gt;5000 psi), high abrasion resistance, or high wear resistance. Some example materials for a moveable member (of any type) may include steel, titanium, silicon carbide, aluminum silicon carbide, Inconel, Pyroflask, any thermally-stable polymer, or any alloys, composites, derivatives, or analogues therein. 
     In one or more embodiments, bearings may not be significantly compressible. In one or more embodiments, bearings may be formed of one or more materials able to withstand the downhole environment. Some important features of the material(s) forming bearings  420  may include the ability to operate at high temperature (&gt;150° C.), the ability to operate at high pressure (&gt;5000 psi), high abrasion resistance, or high wear resistance. Some example materials for bearings may include steel, titanium, silicon carbide, aluminum silicon carbide, Inconel, Pyroflask, any thermally-stable polymer, or any alloys, composites, derivatives, or analogues therein. 
     Returning to  FIG.  4 A , sensor array  400  may have space restrictions. Additionally, undesirable interference may occur if a single shape memory material element  470  is attempting to measure more than one environmental parameter. Also, SMMs and thus, shape memory material element  470 , do not require application of an external power source such as a battery for operation. Thus, each shape memory material base  470  may be small in size. Consequently, one or more embodiments of sensor array  400  may include multiple shape memory material elements  470  formed from a variety of SMM materials. In such a system, each shape memory material element  470  may measure a specific environmental parameter. Consequently, one or more embodiments of sensor array  400  may follow the following general confirmations: 
     i) In one or more embodiments, sensor array  400  may be formed such that every shape memory material element  470  is formed of the same SMM to measure a single environmental parameter. Also, in one or more embodiments of sensor array  400 , every distance sensor  480  may employ the same distance sensing methodology.
 
ii) In one or more embodiments, sensor array  400  may be formed such that every shape memory material element  470  is formed of the same SMM to measure a single environmental parameter. Also, in one or more embodiments of sensor array  400 , distance sensors  480  may employ more than one distance sensing methodology. Using multiple distance sensing methodologies may allow for improved data correlation and greater redundancy, which may result in more accurate measurement of the single environmental parameter.
 
iii) In one or more embodiments, sensor array  400  may be formed such that multiple SMMs are used to form the shape memory material elements  470 . In one or more embodiments, each SMM, and thus each shape memory material elements  470 , may measure one specific environmental parameter. Additionally, one or more embodiments of sensor array  400  may measure multiple environmental parameters by including multiple shape memory material elements  470 . Also, in one or more embodiments of sensor array  400 , every distance sensor  480  may employ the same distance sensing methodology.
 
iv) In one or more embodiments, sensor array  400  may be formed such that multiple SMMs are used to form the shape memory material elements  470 . In one or more embodiments, each SMM, and thus each shape memory material element  470 , may measure one specific environmental parameter. Additionally, one or more embodiments of sensor array  400  may measure multiple environmental parameters by including multiple shape memory material elements  470 . Also, in one or more embodiments of sensor array  400 , distance sensors  480  may employ more than one distance sensing methodology.
 
     As an illustrative example of configuration (iv) above, consider one or more embodiments of sensor array  400  having 12 slots arranged around outer collar  450 . Here, “a slot” refers to the repeated combination of components arranged around outer collar  450  that are housed within each of the plurality of moveable member retainers  465 , such as a moveable member in the form of a sensor moveable member  460 , a distance sensor  480 , and a shape memory material element  470 . Each shape memory material element  470  may be formed of a single SMM selected to deform in response to a single environmental parameter. In one or more embodiments, outer collar  450  may accommodate the following 12 slots within sensor array  400 : 
     Slot 1: SMM 1 for detecting environmental parameter 1 using distance sensing methodology 1; 
     Slot 2: SMM 1 for detecting environmental parameter 1 using distance sensing methodology 2; 
     Slot 3: SMM 1 for detecting environmental parameter 1 using distance sensing methodology 3; 
     Slot 4: SMM 2 for detecting environmental parameter 2 using distance sensing methodology 1; 
     Slot 5: SMM 2 for detecting environmental parameter 2 using distance sensing methodology 2; 
     Slot 6: SMM 2 for detecting environmental parameter 2 using distance sensing methodology 3; 
     Slot 7: SMM 3 for detecting environmental parameter 3 using distance sensing methodology 1; 
     Slot 8: SMM 3 for detecting environmental parameter 3 using distance sensing methodology 2; 
     Slot 9: SMM 3 for detecting environmental parameter 3 using distance sensing methodology 3; 
     Slot 10: SMM 4 for detecting environmental parameter 4 using distance sensing methodology 1; 
     Slot 11: SMM 4 for detecting environmental parameter 4 using distance sensing methodology 2; and 
     Slot 12: SMM 4 for detecting environmental parameter 4 using distance sensing methodology 3. 
     For sensor array  400  to detect an environmental parameter, shape memory material element  470  may need to be directly or indirectly exposed to that environmental parameter. However, uncontrolled exposure of the interior of sensor array  400  to the environmental parameter may be detrimental to some components. One or more embodiments of sensor array  400  may allow direct exposure of shape memory material element  470  to the environmental parameter in a controlled manner. Such controlled exposure may help protect all components while allowing sufficient exposure of shape memory material element  470  by the environmental parameter. One or more embodiments of sensor array  400  may include housing design elements or other means of controlled conveyance of the environmental parameter that are well known in the art. 
     In one or more embodiments, sensor array  400  may include small ports or openings into outer collar  450  to allow environmental parameter (for example, a gas or liquid) to be conveyed to shape memory material element  470 . In one or more embodiments, outer collar  450  may include a gas inlet, a gas outlet, and a membrane between the inlet and the outlet to allow the environmental parameter (for example, a gas or a liquid) to be conveyed to shape memory material element  470 . In one or more embodiments, a part of outer collar  450  forming the base of moveable member retainer  465  may be formed of a gas permeable membrane atop which shape memory material element  470  may be located. In one or more embodiments, the part of outer collar  450  forming the base of moveable member retainer  465  may include a port atop a gas permeable membrane located atop shape memory material element  470 . 
     Some other methods of controlled exposure of shape memory material element  470  to the environmental parameter may include a thin membrane; a protruded port; a protruded port with a thin membrane at the tip; a protruded membrane; an additional material inside a port to indirectly transfer an environmental parameter like temperature or vibration; a liquid material inside a port to indirectly transfer an environmental parameter like temperature or vibration; or a liquid material sensitive to an environmental parameter like temperature sandwiched between a membrane and a solid material also sensitive to the environmental parameter. In one or more embodiments, sensor array  400  may not directly expose shape memory material element  470  to the stimulus but still may be able to transfer the stimulus to shape memory material element  470 . 
     Returning to  FIGS.  5 A- 5 E , in one or more embodiments, a second stimulus may also impact the shape of shape memory material element  570 , potentially to a lesser degree, in addition to the shape change due to the first, intended external stimulus. In one or more embodiments, if a change in minimum extension distance (say, from d 1  to d 2 ) may be due to a first, intended external stimulus and a second, unintended external stimulus, sensor array  500  may apply a calibration factor to correct each measured minimum extension distance (meaning, both d 1  and d 2 ) so the extension distances only reflect the first, intended external stimulus. In such a situation, one or more embodiments of sensor array  500  may apply a calibration to the output from distance  580  that removes the impact of the second stimulus. 
     Consider as an illustrative example, one or more embodiments of sensor array  500  having a shape memory material element  570  formed from a shape memory material that experiences a significant shape change with the application of an external gas pressure. Thus, pressure is the first, intended external stimulus this shape memory material was selected to reflect. Additionally, like most materials, this shape memory material also volumetrically expands when it experiences an increase in temperature due to an increase in the kinetic energy of the atoms within the material. The degree of volumetric expansion of shape memory material due to increased temperature may be experimentally determined for a pressure-sensitive shape memory material element  570 , in order to generate a temperature calibration. One or more embodiments of sensor array  500  may also include a device that is able to measure the temperature, such as a solid state temperature sensor or a second shape memory material element  570 , distance sensor  580 , and sensor moveable member  560  configuration intended to measure temperature. Thus, one or more embodiments of sensor array  500  may apply a temperature calibration for the pressure-sensitive shape memory material element  570  in order to remove the effects of the external temperature on the size of gap  575  from the minimum extension distance d 1 , d 2  determined by distance sensor  580 . 
     In one or more embodiments, the shape change of shape memory material element  570  may be an expansion or a contraction with an increase of an environmental parameter, depending upon the shape memory properties of the shape memory material used to form shape memory material element  570 . In one or more embodiments, increase of an environmental parameter may cause an expansion of shape memory material base  570  that decreases a minimum extension distance. In one or more embodiments, increase of an environmental parameter may cause a contraction of shape memory material element  570  that increases a minimum extension distance. In one or more embodiments, change of an environmental parameter may cause an expansion of shape memory material element  570  that decreases gap  575  and decreases a minimum extension distance, such as depicted in  FIGS.  5 A and  5 B  from d 1  to d 2 . In one or more embodiments, change of an environmental parameter may cause an contraction of shape memory material element  570  that increases a minimum extension distance. 
     Returning to  FIGS.  6 A- 6 C : One or more embodiments of detector  682   a ,  682   c ,  682   e  may be linked directly to shape memory member base  670 , such as directly attached. One or more embodiments of detector  682   a ,  682   c ,  682   e  may be linked indirectly to shape memory member base  670 , such as having one or more intermediate layers between detector  682   a ,  682   c ,  682   e  and shape memory member base  670 . 
     In one or more embodiment, one or more distance sensors  680   a ,  682   c ,  682   e  may be low-power sensors. 
     Embodiments herein depict an array as including a single inner ring and a single outer ring. One or more embodiments of the array may include more than one inner ring within a single outer ring. One or more embodiments of the array may include more than one inner ring and more than one outer ring, with each inner ring disposed radially within a single outer ring. One or more embodiments of the array may include more than one inner ring and more than one outer ring, with one or more inner rings disposed radially within each outer ring. Such a device may be said to have multiple layers, with each layer including a single outer ring and one or more inner rings disposed within the outer ring. One or more embodiments of a sensor array having multiple layers may be configured such that each layer of the sensor array detects a specific parameter at many radial positions around the wellbore. 
     One or more embodiments of an array may include mounts, springs, rubber/elastomer/foam pads, wire ropes, or a combination of these to mitigate or isolate vibrations in the housing containing the shape memory material element, the distance sensor, or both. One or more embodiments may employ different methods to isolate vibrations from sensors and instrumentation, such as those employed by measurement and logging while drilling (MWD/LWD) systems. 
     One or more embodiments of an array may include an accelerometer, a gyroscope, or both. Such components may detect the position, vibration, orientation, or a combination of these of the system. In some embodiments, parameters such as system position, vibration, or orientation may be used to distinguish between tripping in/out and drilling. During tripping in/out, a command may be provided to the microcontroller/microprocessor to provide regulated power from the capacitor, or any type of storage, to the sensor module. 
     In one or more embodiment, an array may further include additional sensors to measure temperature, pressure, vibration, strain, magnetic field, electric field, or a combination. In one or more embodiment, one or more of these additional sensors may any type known in the art, such as solid-state sensors or MEMS sensors. In one or more embodiment, output from one or more of these additional sensors may be used to apply calibrations that remove the impact of secondary, unintended external parameters on shape memory material elements. 
     One or more embodiments of an array may include a microcontroller. One or more embodiments of the array may include an internal clock. In one or more embodiments of a sensor array, data derived from a signal from distance sensors ( FIGS.  6 A- 6 C ) may be tagged, such as including unique headers or stamps for different sources. In one or more embodiments of a sensor array, data derived from a signal from distance sensors ( FIGS.  6 A- 6 C ) time stamping that may be synchronized with GPS time stamping. Such GPS time stamping is frequently employed at drilling locations, such as on drilling rigs. 
     Returning to  FIG.  7   , in some embodiments, inner ring  710  may have any number of bearings  720  on any outer surface. In some embodiments, inner ring  710  may have bearings  720  on top outer surface  714 , middle outer surface  712 , or bottom outer surface  716 , or any combination of the outer surfaces. 
     In one or more embodiments, a first fraction of bearings  720  may be on a first surface and a second fraction of bearings  720  may be on a second surface. In one or more embodiments, a first fraction of bearings  720  may be on a first surface, a second fraction of bearings  720  may be on a second surface, and a third fraction of bearings  720  may be on a third surface. 
     In one or more embodiments, a first fraction of bearings  720  may be on middle outer surface  712 . In one or more embodiments, a first fraction of bearings  720  may be on middle outer surface  712 , a second fraction of bearings  720  may be on top outer surface  714 , and a third fraction of bearings  720  may be on bottom outer surface  716 . 
     Returning to  FIG.  10   , in one or more embodiments, antenna within communications device  1002  may be polymer-based, paper-based, PET-based, textile-based, carbon nanotube (CNT)-based, artificial magnetic conductor-based, kapton-based, nickel-based metamaterial, or a combination. 
     In one or more embodiments, antenna within communications device  1002  may be directional, omni-directional, or point-to-point. 
     In one or more embodiments, antenna within communications device  1002  may be a planar antenna, such as a monopole, a dipole, an inverted, a ring, a spiral, a meander, or a patch antenna. 
     In one or more embodiments, antenna within communications device  1002  may be a compact antenna on a flexible substrate. In one or more embodiments, antenna within communications device  1002  may be used to transmit and receive sensor information. In one or more embodiments, the transmitted data may include raw distance sensor data, environmental parameter data, or both. 
     In one or more embodiments, sensitive components of sensor array  1000  may be housed in a separate compartment or area of sensor array  1000 . In one or more embodiments, electronics  1004  may be housed in a separate compartment or area of sensor array  1000 . Such separation may help ensure sensitive components such as electronics  1004  are not influenced by, damaged by, or both influenced and damaged by exposure to the environmental parameter(s). 
     In one or more embodiments, contact between the outer collar and the borehole may help enhance the relative motion between the inner ring and the outer collar because the outer collar may experience more friction. Moreover, in one or more embodiments, the inner ring and the drillstring assembly would be “on top” of the outer collar, which may increase this relative motion. 
     While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.