Patent Publication Number: US-11642054-B2

Title: Wire-assembly apparatus for invasive biosensors

Description:
INCORPORATION BY REFERENCE TO RELATED APPLICATIONS 
     Any and all priority claims identified in the Application Data Sheet, or any correction thereto, are hereby incorporated by reference under 37 CFR 1.57. This application is a continuation of U.S. application Ser. No. 15/362,944, filed Nov. 29, 2016. The aforementioned application is incorporated by reference herein in its entirety, and is hereby expressly made a part of this specification. 
    
    
     FIELD 
     The present disclosure generally relates to invasive biosensors and more specifically to an apparatus for assembling wires for invasive biosensors. 
     BACKGROUND 
     Invasive biosensors, such as sensors for wearable glucose monitoring devices, include thin wires that are insertable into a patient&#39;s skin. Sensing circuitry reads biological information about the patient via the thin wires. Once an invasive biosensor is inserted into a patient&#39;s skin, the electrical connections between the wires and circuitry remain exposed to potential moisture that may significantly affect the biosensor performance. For example, many electrochemical-based sensors may have performance impacts relating to calibration offsets or increases in the noise floor level due to moisture-caused current leakage within the electronics enclosure. The impact is particularly high for biosensors included in wearable devices that may be exposed to perspiration on the patient&#39;s skin, weather, and other sources of moisture typically experienced by human skin. In addition to this consideration, the size of the device is always a practical consideration for wearables. To accommodate the required sensing circuitry, power source, and the like to process the biological information, wearable glucose monitoring devices may include multiple parts that are connected together to form working devices. Not only does the use of multiple parts cause the devices to be bulky, but it also creates multiple areas for possible moisture ingress (e.g., seals between parts). 
     SUMMARY 
     Various examples are described for apparatuses to assemble sensor wires for invasive biosensors. For example, one disclosed apparatus for a biosensor includes a sensor wire and a rigid member. The rigid member is attached to the sensor wire and includes a contact surface. The contact surface is sized to enable a suction head of a robotic placement device to create a vacuum seal on the contact surface for lifting the sensor wire and rigid member. 
     Another disclosed device includes a wearable monitoring device including a printed circuit board disposable in a housing having a planar surface for positioning the wearable monitoring device on a patient&#39;s skin. The device also includes a sensor wire including one or more electrodes electrically coupled, at a connection point on a printed circuit board, to circuitry disposed on the printed circuit board. The sensor wire includes distal end that is insertable into the patient&#39;s skin. The device also includes a rigid member connected to the printed circuit board and the sensor wire. The rigid member is positioned on the printed circuit board such that the connection point is between the printed circuit board and a coupling surface of the rigid member. The rigid member includes a contact surface opposite the coupling surface. The contact surface is sized to enable a suction head of a robotic placement device to create a vacuum seal on the contact surface for positioning the rigid member on the printed circuit board. 
     One disclosed method for assembling a biosensor includes receiving a sensor wire and a rigid member. The sensor wire includes a distal end for insertion into a patient&#39;s skin and a proximal end connected to the rigid member. The method also includes creating, by a suction head of a robotic placement device, a vacuum seal on a surface of the rigid member for grasping the rigid member. The method also includes positioning, by the robotic placement device and using the vacuum seal, the sensor wire and the rigid member on a printed circuit board. The method also includes applying, by the robotic placement device, a force on the rigid member in a direction of the printed circuit board to cause a pressure-sensitive adhesive between the rigid member and the printed circuit board to bond the rigid member to the printed circuit board. 
     A further disclosed device includes a glucose monitoring system including a sensor wire having a first portion injectable into a patient&#39;s skin. The first portion includes means for generating glucose information. The glucose monitoring system also includes positioning means for enabling a suction head of a robotic placement device to position the sensor wire on a printed circuit board and electronically couple the sensor wire to circuitry disposed on the printed circuit board for determining a glucose level for the patient. The positioning means is physically coupled to the sensor wire to enable the robotic placement device to lift the positioning means and the sensor wire. 
     These illustrative examples are mentioned not to limit or define the scope of this disclosure, but rather to provide examples to aid understanding thereof. Illustrative examples are discussed in the Detailed Description, which provides further description. Advantages offered by various examples may be further understood by examining this specification. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated into and constitute a part of this specification, illustrate one or more certain examples and, together with the description of the example, serve to explain the principles and implementations of the certain examples. 
         FIG.  1    shows a side, cross-sectional view of an illustrative example of an invasive biosensor including a wire-assembly apparatus according to some aspects of the present disclosure. 
         FIGS.  2 A through  2 D  show different cross-sectional views of an example wire-assembly apparatus according to some aspects of the present disclosure. 
         FIG.  3    shows a side, cross-sectional view of an example of a potted wire-assembly apparatus according to some aspects of the present disclosure. 
         FIG.  4    shows an example method of assembling a biosensor with a wire-assembly apparatus according to some aspects of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Examples are described herein in the context of sensor wire assemblies for invasive biosensors. Those of ordinary skill in the art will realize that the following description is illustrative only and is not intended to be in any way limiting. Reference will now be made in detail to implementations of examples as illustrated in the accompanying drawings. The same reference indicators will be used throughout the drawings and the following description to refer to the same or like items. 
     In the interest of clarity, not all of the routine features of the examples described herein are shown and described. It will, of course, be appreciated that in the development of any such actual implementation, numerous implementation-specific decisions must be made in order to achieve the developer&#39;s specific goals, such as compliance with application- and business-related constraints, and that these specific goals will vary from one implementation to another and from one developer to another. 
     Illustrative Example of an Invasive Biosensor Including a Wire Assembly Apparatus 
     One example invasive sensor shown in  FIG.  1    is a biosensor  100 , such as a glucose sensor. The biosensor  100  includes a sensor wire  102  including a proximal end  102   a  that is electrically coupled to a printed circuit board (“PCB”)  104 . A distal end  102   b  of the sensor wire  102  is injected into a patient&#39;s skin  106  to measure biological parameters (e.g., glucose levels) in the interstitial fluid of subcutaneous tissue  108  beneath the skin  106 . Although the skin  106  is depicted in  FIG.  1   , the skin  106  is not a part of the biosensor  100 , as indicated by the dashed lines. The sensor wire  102  may also be physically coupled to a rigid member  110  or other positioning means for enabling the sensor wire  102  to be picked up and positioned in a desired location during assembly of the biosensor  100 . 
     During assembly of the biosensor  100 , the rigid member  110  provides a contact surface that enables the sensor wire  102  to be lifted by a suction head of a robotic placement device, such as a pick-and-place tool or machine, and positioned on the PCB  104 . For example, the sensor wire  102 &#39;s outer diameter may be large enough to transmit electrical signals from the interstitial fluid to the PCB  104 , but too small to be grasped by the robotic placement device. A surface of the rigid member  110  is therefore adhered to the sensor wire  102  to enable the robotic placement device to pick both the rigid member  110  and the sensor wire  102  for placement on the PCB  104 . 
     The sensor wire  102  is positioned on the PCB  104  to electrically couple to sensing circuitry  114  on the PCB  104 . The rigid member  110  is positioned to cover a connection point  112  between the sensor wire  102  and the sensing circuitry  114 . In some aspects, the connection point  112  is a conductive pad on the PCB  104  at which the sensor wire  102  is electronically coupled to the sensing circuitry  114 . In some aspects, the sensor wire  102  and the sensing circuitry  114  are physically connected at the connection point  112 . In additional and alternative aspects, the sensor wire  102  and the sensing circuitry  114  are physically separate, but electrically coupled through one or more connection paths of the connection point  112 . Although not shown in  FIG.  1   , potting material may be injected around the rigid member  110  to provide a moisture barrier for the connection point  112 . Non-limiting examples of the potting material include epoxy, silicone, acrylic, polyurethane, or other means for providing a moisture barrier to the connection point  112   
     In some aspects, the sensing circuitry  114  includes a processing device and a computer-readable medium, such as a memory chip, read-only memory (“ROM”), random access memory (“RAM”), or an application-specific integrated circuit (“ASIC”), coupled to the processing device. The processing device may execute computer-executable program instructions stored in memory, such as executing one or more computer programs. Such processing devices may comprise a microprocessor, a digital signal processor (“DSP”), an application-specific integrated circuit (“ASIC”), field programmable gate arrays (“FPGAs”), state machines, or other processing means for processing electrical signals received from the electrodes  120 ,  122 . The PCB  104  and the sensing circuitry  114  are disposed in a housing  116  of the biosensor  100 . The housing  116  may be compact in size for placing on the skin  106 . The housing  116  includes a surface  118  having a substantially planar surface. In various cases, the substantially planar shape enables the biosensor  100  to be placed on the skin  106 . Although the housing  116  is shown in  FIG.  1    as having a rectangular cross-sectional shape, the housing  116  may include other cross-sectional shapes that serve the same functions as described herein. The housing  116  may be made of any suitable material for housing the biosensor  100 . Non-limiting examples of materials that may be suitable for the housing  116  include polyethylene, polyvinyl chloride (“PVC”), polypropylene, nylon, polyurethane, polycarbonate, steel, aluminum, and other plastics and metals. The biosensor  100  may be secured to the skin  106  using an adhesive, band, strap, or other securing means. In some aspects, the biosensor  100  is worn for extended period of time (e.g., days, weeks, months, etc.). The sensor wire  102  may include a length of substantially between 5 millimeters to 25 millimeters. In various cases, the sensor wire  102 &#39;s length within the specified range enables the sensor wire  102  to extend from beneath the skin  106  to the sensing circuitry  114  with allowance for the patient&#39;s movement. In one example, the sensor wire  102  includes an outer diameter, with coating, of approximately 170 microns for the electrode  120  and an outer diameter of approximately 100 microns for the electrode  122 . In additional examples, the sensor wire  102  generally has a maximum outer diameter approximately between 100 microns and 300 microns. The sensor wire  102 &#39;s thickness, or gauge, within the specified ranges may be selected to enable the sensor wire  102  to remain injected into the skin  106  during this period with minimal discomfort. 
     The sensor wire  102  extends from the PCB  104  to the skin  106  through the housing  116 . The sensor wire  102  may include one or more electrodes, chemicals, or other means for generating biological information. In this example, the sensor wire  102  includes two electrodes  120 ,  122  that are inserted into the skin  106  to expose the electrodes  120 ,  122  to the interstitial fluid in the subcutaneous tissue  108 . Electrode  122  includes at least a portion of the sensor wire  102  having a platinum or platinum coating and electrode  120  includes a silver/silver-chloride (Ag/AgCl) material that covers a part of electrode  120 . The electrode  122 &#39;s platinum material is inert to prevent corrosion and may act as a catalyst for a reaction of proton reduction. The electrode  120 &#39;s silver/silver-chloride material may cause a reaction between the silver material and the silver-chloride material to enable high current to pass through the electrode  120 . In some aspects, a reactive material, such as glucose oxidase (“GOX”), is also coated on the electrode  122  to create reaction products with glucose present in the interstitial fluid. When a voltage is applied to the electrodes  120 ,  122 , an electrical current is generated based on the amount of these reaction products generated by the glucose/GOX reaction. The electrical current is routed through the sensor wire  102  to the sensing circuitry  114 . The sensing circuitry  114  may use the strength of the current to determine the patient&#39;s glucose levels. Although glucose level measurements are described in this example, the biosensor  100  may be configured to measure other biological parameters without departing from the scope of the present disclosure. Similarly, while the chemical materials applied onto the sensor wire  102  to form the electrodes  120 ,  122  and the reactive material coated onto the electrodes  120 ,  122  may be suitable for a glucose sensor, other material may be used according to other examples, based on the application of the biosensor  100 . 
     This illustrative example is given to introduce the reader to the general subject matter discussed herein and the disclosure is not limited to this example. The following sections describe various additional non-limiting examples and examples of systems and methods for wire assemblies for invasive biosensors. 
     Turning now to  FIGS.  2 A through  2 D ,  FIG.  2 A  shows a cross-sectional top view of the sensor wire  102  and the rigid member  110  prior to its assembly on the PCB  104  of  FIG.  1   . The rigid member  110  is attached to the sensor wire  102  to enable a robotic placement device to pick up, or otherwise lift the sensor wire  102  through the rigid member  110 . For example, the rigid member  110  includes a contact surface  200  that the robotic placement device may use to pick up the rigid member  110 . In some aspects, the contact surface  200  includes a substantially planar or smooth surface. In various cases, the substantially planar or smooth surface enables a suction head of the robotic placement device grip the contact surface  200  and form a vacuum seal on the rigid member  110 . The suction head may create the vacuum seal by contacting the contact surface  200  and creating a suction force to form a seal that couples the suction head to the contact surface  200 . The suction force created by the suction head may be strong enough to enable the robotic placement device to lift the rigid member  110  using the vacuum seal. In other aspects, the contact surface  200  may include a protrusion, depression, or may be otherwise shaped to correspond to the suction head&#39;s shape to enable the suction head to form the vacuum seal. The rigid member  110 &#39;s minimum size may be dependent on the suction head&#39;s size, but may be large enough to enable the suction head to form the vacuum seal on the contact surface  200 . The rigid member  110 &#39;s maximum size may be dependent on the PCB  104 &#39;s size. For example, in some aspects, the rigid member  110  is small enough to cover only the PCB  104 &#39;s electrical connections at the connection point  112 . In another example, the rigid member  110  is large enough to cover an entire surface of the PCB  104 . In some aspects, the rigid member  110  includes a side or diameter length between approximately one millimeter and 10 millimeters. In additional aspects, the rigid member  110  is proportional to the sensor wire  102  length, such as a side measuring half the length of the sensor wire  102 , or less. The contact surface  200  in  FIG.  2 A  is shown as spanning the rigid member  110 &#39;s entire surface, though the contact surface  200  may include only a portion of the surface without departing from the scope of the present disclosure. Similarly, though the rigid member  110  is shown as having a rectangular cross-section, the rigid member  110  may have any shape that provides a sufficient contact surface  200  for forming the vacuum seal to lift the rigid member  110  and the sensor wire  102  together. 
     The rigid member  110  has a rigidity to enable the suction head to create a sufficient vacuum seal for lifting the rigid member  110  and the sensor wire  102  in a controlled manner. For example, the rigid member  110  is rigid such that the rigid member does not deform in response to the suction force applied on the contact surface  200  by the suction head. The rigid member  110 &#39;s stability in response to the suction force may enable the suction head to maintain control of the sensor wire  102 &#39;s orientation to precisely position the sensor wire  102  and the rigid member  110  on the PCB  104 . The rigid member  110 &#39;s rigidity may depend on one or both of the rigid member  110 &#39;s thickness and the material forming the rigid member  110 . For example, the rigid member  110 &#39;s thickness may be inversely proportional to the density of the material (e.g., a denser material may be used for a thinner rigid member  110  while a less dense material may necessitate a thicker rigid member  110 ). Non-limiting examples of material that may be used for the rigid member  110  include polycarbonate, polyurethane, polyvinyl chloride, or other suitable materials. In some aspects, the material is non-conductive to electrically isolate the electrical connections at the connection point  112 . 
       FIGS.  2 B and  2 C  show a cross-sectional bottom view of the sensor wire  102  and the rigid member  110 . The sensor wire  102  is adhered to a coupling surface  202  positioned on a side of the rigid member  110  opposite the contact surface  200 . The coupling surface  202  includes means for coupling the rigid member  110  to the PCB  104 . For example, in  FIG.  2 B , adhesive  204  may bond the rigid member  110  to the PCB  104 . The adhesive  204  may be positioned on the coupling surface  202  proximate to the sensor wire  102 . Non-limiting examples of adhesives  204  include epoxy, glue, and other means for bonding the rigid member  110  onto the PCB  104 . In some aspects, the adhesive  204  is pressure-sensitive adhesive to activate in response to a pressure force applied to the rigid member  110 . For example, the adhesive  204  may be activated to form a bond with the PCB  104  in response to the robotic placement device applying a force on the contact surface  200  while positioning the rigid member  110  onto the PCB  104 . In some aspects, the adhesive  204  is contiguously applied on the coupling surface  202  to bond both of the electrodes  120 ,  122  to the rigid member  110  as shown in  FIG.  2 B . In other aspects, the adhesive may be applied in separate applications  204   a ,  204   b  to individually bond the electrodes  120 ,  122 , respectively, to the rigid member  110  as shown in  FIG.  2 C . 
     In some aspects, the adhesive  204  is non-conductive to prevent the adhesive from shorting the electrical connections of the sensing circuitry  114 . In additional aspects, the adhesive  204  includes a conductive material that is intentionally positioned to enable additional connections of the sensing circuitry  114 . For example, the adhesive  204  may be positioned on the rigid member  110  to provide a connection point between two components in the sensing circuitry  114  when the rigid member  110  is bonded to the PCB  104 . In further aspects, the adhesive  204  may include one or more types of adhesive (e.g., a non-conductive material and a conductive material). The adhesive  204  may be pre-laminated, or otherwise pre-applied, onto the rigid member  110  or applied to the rigid member  110  during assembly of the biosensor  100 . Although the adhesive  204  is shown in  FIGS.  2 B and  2 C  as positioned on the rigid member  110  prior to being installed on the PCB  1  prior to being installed on the PCB  104 , the adhesive may  204  alternatively, or additionally, be positioned on the PCB  104  prior to installation. 
       FIG.  2 D  shows a cross-sectional side view of the sensor wire  102  and the rigid member  110 . Means for coupling the sensor wire  102  and the rigid member  110 , such as adhesive  206 , may be included between the sensor wire  102  and the rigid member  110 . In some aspects, the adhesive  206  is of the same or similar type as the adhesive  204 . The adhesives  204 ,  206  may include non-toxic materials to enable the biosensor  100  to be wearable on the skin without risk of irritation or other damage to the patient. Although the adhesives  204 ,  206  are described as separate adhesives, in some aspects, the adhesives  204 ,  206  is the same adhesive. For example, the adhesives  204 ,  206  may include a pressure-sensitive adhesive. The sensor wire  102  may be pressed against the coupling surface  202  to activate the contacted portion of the adhesives  204 ,  206  and to bond the sensor wire  102  to the rigid member  110 . The remaining adhesives  204 ,  206  may remain inactive until a pressure is applied to the rigid member  110  to adhere the rigid member  110  to the PCB  104 . 
       FIG.  3    shows a zoomed in view of the biosensor  100  of  FIG.  1    proximate to the connection point  112  between the sensor wire  102  and the sensing circuitry  114 . The rigid member  110  is positioned on the PCB  104  such that the connection point  112  is between the rigid member  110  and the PCB  104 . In some aspects, a potting material  300  is positioned proximate to the rigid member  110  as shown in  FIG.  3   . For example, the potting material  300  may be injected on top of and around the rigid member  110  to pot the rigid member  110  to the PCB  104 . In some aspects, the potting material  300  includes a non-conductive material to prevent a short in the electrical connections at the connection point  112 . The potting material  300  may provide a moisture barrier for the electrical connections on the PCB  104  at the connection point  112 . Although the potting material  300  is shown as positioned only proximate to the rigid member  110 , the potting material  300  may be applied to coat the components across the entire surface of the PCB  104 . 
       FIG.  4    is a flow chart of a process for assembling the biosensor  100 . The process is described with respect to  FIGS.  1 - 3   , though other implementations are possible without departing from the scope of the present disclosure. 
     In block  400 , the sensor wire  102  and the rigid member  110  are received. The sensor wire  102  and the rigid member  110  may be received by a robotic placement device, e.g., on an assembly line. In some aspects, the sensor wire  102  and the rigid member  110  are received as a single assembly with the sensor wire  102  and the rigid member  110  attached by the adhesive  206 . In other aspects, the sensor wire  102  and the rigid member  110  are received separately and the adhesive  206  may be subsequently applied to the sensor wire  102  or the rigid member  110  to connect the sensor wire  102  and the rigid member  110 . The sensor wire  102  may include one or more chemicals operable as the electrodes  120 ,  122 . The sensor wire  102  may also include additional chemicals, such as a reactive material (e.g., glucose oxidase) to react with interstitial fluid beneath the skin  106 . In some aspects, the chemicals forming the electrodes  120 ,  122  and the reactive material are pre-applied to the sensor wire  102  prior to being received by the robotic placement device. In other aspects, the sensor wire  102  may be received as a bare wire and the chemicals may be subsequently applied during the assembly of the biosensor  100 . The rigid member  110  may include the adhesive  204  on the coupling surface  202 . In some aspects, the rigid member  110  is received with the adhesive  204  pre-applied to the coupling surface  202 . In other aspects, the adhesive  204  is applied subsequent to the rigid member  110  being received. In further aspects, the adhesive  204  is pressure-sensitive. 
     In block  402 , a vacuum seal is created on the contact surface  200  of the rigid member. The vacuum seal may be created between a suction head of a robotic placement device and the contact surface. The suction head may apply a suction force on the contact surface  200  to form a seal that adheres the suction head to the suction head. 
     In block  404 , the sensor wire  102  and the rigid member  110  are positioned on the PCB  104  using the vacuum seal. For example, the robotic placement device may maintain the suction force on the contact surface  200  as the robotic placement device moves the rigid member  110  and the sensor wire  102  to, and positions them on, the PCB  104 . The robotic placement device may position the sensor wire  102  on the PCB  104  such that the proximal end  102   a  is placed to electronically couple with the sensing circuitry  114  on the PCB  104  at the connection point  112 . In some aspects, the sensor wire  102  is positioned on the PCB  104  prior to the sensing circuitry  114  being positioned on the PCB  104 . In other aspects, the sensing circuitry  112  may be positioned prior to the sensor wire  102  being positioned on the PCB  104 . The rigid member  110  may be positioned on the PCB  104  such that the connection point  112  is located between the rigid member  110  and the PCB  104 . 
     In block  406 , a force is applied on the rigid member  110  to bond the rigid member  110  to the PCB  104 . For example, the force may be applied by the robotic placement device to the contact surface  200  in the direction of the PCB  104 . The suction head may maintain the vacuum seal on the contact surface  200  as the force is applied to maintain the connection between the robotic placement device and the rigid member  110 . The force applied by the robotic placement device may activate the pressure-sensitive adhesive  204  between the rigid member  110  and the PCB  104  to bond the rigid member  110  to the PCB  104 . In some aspects, the rigid member  110  includes the adhesive  204  on the coupling surface  202  prior to the rigid member  110  and the sensor wire  102  being positioned on the PCB  104  as described in block  404 . In additional and alternative aspects, the rigid member includes the adhesive  204  or additional adhesive on the PCB  104  prior to the rigid member  110  and the sensor wire  102  being positioned on the PCB  104 . Upon adhering the rigid member  110  and the sensor wire  102  to the PCT  104 , the force may be removed from the contact surface  200 . In some aspects, the force is removed simultaneously with a release of the vacuum seal created on the contact surface  200  as described in block  402 . 
     In some aspects, the rigid member  110  is potted to the PCB  104 . For example, a potting material may be applied on and around the rigid member  110  to create a moisture barrier for the connection point  112  located between the rigid member  110  and the PCB  104 . Subsequent to any additional electronic components being connected to the PCB  104 , the PCB  104  including the sensor wire  102  and the rigid member  110  may be disposed in the housing  116  to complete the biosensor  100 &#39;s assembly. 
     The foregoing description of some examples has been presented only for the purpose of illustration and description and is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Numerous modifications and adaptations thereof will be apparent to those skilled in the art without departing from the spirit and scope of the disclosure. 
     Reference herein to an example or implementation means that a particular feature, structure, operation, or other characteristic described in connection with the example may be included in at least one implementation of the disclosure. The disclosure is not restricted to the particular examples or implementations described as such. The appearance of the phrases “in one example,” “in an example,” “in one implementation,” or “in an implementation,” or variations of the same in various places in the specification does not necessarily refer to the same example or implementation. Any particular feature, structure, operation, or other characteristic described in this specification in relation to one example or implementation may be combined with other features, structures, operations, or other characteristics described in respect of any other example or implementation. 
     Use herein of the word “or” is intended to cover inclusive and exclusive OR conditions. In other words, A or B or C includes any or all of the following alternative combinations as appropriate for a particular usage: A alone; B alone; C alone; A and B only; A and C only; B and C only; and all three of A and B and C.