Patent Publication Number: US-2022211305-A1

Title: Self-powered analyte sensor and devices using the same

Description:
RELATED APPLICATION 
     The present application claims priority to U.S. application Ser. No. 14/529,427 filed Oct. 31, 2014, which claims priority to U.S. Provisional Application No. 61/922,404 filed Dec. 31, 2013, both entitled “Self-Powered Analyte Sensor and Devices Using the Same,” and the disclosure of which are incorporated herein by reference for all purposes. 
    
    
     BACKGROUND 
     The detection and/or monitoring of glucose levels or other analytes, such as lactate, oxygen, A1C, or the like, in certain individuals is vitally important to their health. For example, the monitoring of glucose is particularly important to individuals with diabetes. Diabetics generally monitor glucose levels to determine if their glucose levels are being maintained within a clinically safe range, and may also use this information to determine if and/or when insulin is needed to reduce glucose levels in their bodies or when additional glucose is needed to raise the level of glucose in their bodies. 
     Devices have been developed for the automatic monitoring of analyte(s), such as glucose, in bodily fluid such as in the blood stream or in interstitial fluid (“ISF”), or other biological fluid. Some of these analyte measuring devices are configured so that at least a portion of the devices are positioned below a skin surface of a user, e.g., in a blood vessel or in the subcutaneous tissue of a user, so that the monitoring is accomplished in vivo. 
     Measurement of analyte(s), such as glucose, by a monitoring device requires power. Current monitoring devices require an external power source to power the sensing circuitry and store the measured values in a memory for later retrieval by a display device. 
     SUMMARY 
     An analyte monitoring device in certain embodiments includes a self-powered analyte sensor having at least a portion in fluid contact with interstitial fluid under a skin surface, and sensor electronics operatively coupled to the self-powered analyte sensor, configured to receive signals generated by the self-powered analyte sensor, and to communicate data corresponding to analyte level monitored by the self-powered analyte sensor, the sensor electronics including: a buffering circuit operatively coupled to the self-powered analyte sensor for receiving the generated signals from the self-powered analyte sensor, and a radio frequency identification device (RFID) circuit operatively coupled to the buffering circuit and configured to communicate data corresponding to the generated signals associated with the monitored analyte level. 
     An analyte monitoring device in certain embodiments of the present disclosure includes a self-powered analyte sensor, and sensor electronics operatively coupled to the self-powered analyte sensor configured to receive signals generated by the self-powered analyte sensor and to communicate data corresponding to analyte level monitored by the self-powered analyte sensor, where the sensor electronics transitions from an inactive state to an active state when powered by a remote power source and upon receipt of a query signal from the remote power source, and in response to the query signal, communicates data corresponding to the generated signals associated with the monitored analyte level to the remote power source. 
     In certain embodiments, the self-powered analyte sensor is configured to continuously generate signals corresponding to monitored analyte level when in fluid contact with interstitial fluid. 
     In certain embodiments, the self-powered analyte sensor generates the signals corresponding to monitored analyte level when the sensor electronics are in the inactive state. 
     In certain embodiments, the sensor electronics are not operational when in the inactive state. 
     In certain embodiments, the sensor electronics include a buffering circuit operatively coupled to the self-powered analyte sensor for receiving the generated signals from the self-powered analyte sensor. 
     In certain embodiments, the sensor electronics includes a radio frequency identification device (RFID) circuit operatively coupled to the buffering circuit and configured to communicate data corresponding to the generated signals associated with the monitored analyte level. 
     In certain embodiments, the analyte monitoring device further includes a housing enclosing the self-powered sensor and the sensor electronics, wherein the housing is sealed to inhibit moisture from entering the housing. 
     In certain embodiments, the query signal includes an RFID signal. 
     In certain embodiments, the sensor electronics transition from the active state to the inactive state when the sensor electronics is not within the range of the remote power source. 
     In certain embodiments, the self-powered sensor is configured to generate the signals when in contact with the interstitial fluid and when the sensor electronics is in the inactive state. 
     In certain embodiments, the analyte monitoring device includes a housing enclosing the self-powered sensor and the sensor electronics, the housing including one or more mechanical components for physically detachably engaging with a remote device. 
     In certain embodiments, the remote device includes the remote power source. 
     In certain embodiments, the one or more mechanical components include one or more of a releasable latch, a releasable arm, or a releasable lock. 
     An analyte monitoring device, in certain embodiments, includes a self-powered analyte sensor having at least a portion in fluid contact with interstitial fluid under a skin surface, and sensor electronics operatively coupled to the self-powered analyte sensor configured to receive signals generated by the self-powered analyte sensor and to communicate data corresponding to analyte level monitored by the self-powered analyte sensor, the sensor electronics including: a buffering circuit operatively coupled to the self-powered analyte sensor for receiving the generated signals from the self-powered analyte sensor; and a radio frequency identification device (RFID) circuit operatively coupled to the buffering circuit and configured to communicate data corresponding to the generated signals associated with the monitored analyte level, where the sensor electronics transitions from an inactive state to an active state when powered by a remote power source and upon receipt of a query signal from the remote power source, and in response to the query signal, communicates data corresponding to the generated signals associated with the monitored analyte level to the remote power source. 
     In certain embodiments of the present disclosure, using the signals generated by the oxidation reaction of the self-powered sensor accumulated over time and stored in a capacitor device, sufficient charge is accumulated to drive the sensor electronics for processing signals related to the monitored analyte level, including storing, filtering, processing and communicating to a remote location. In this manner, sensor electronics coupled to the self-powered analyte sensor does not require a separate power source such as a battery to power the sensor electronics for processing signals related to the monitored analyte level including storing the generated and processed signals. 
     In some embodiments, a remote device such as a display device is configured to generate a magnetic field which, when positioned in close proximity to the sensor electronics, latches a switch in the sensor electronics to drive the charge stored in the sensor electronics capacitor device (generated from the self-powered sensor) to connect the remaining portions of the sensor electronics, effectively powering the sensor electronics solely from the charge stored in the capacitor that was generated by the self-powered sensor. 
     In a further embodiment, the self-powered sensor and sensor electronics are provided in a sealed housing and which does not include electronic components susceptible to sterilization processes for the sensor, and that would otherwise degrade or damage such electronic components. In this manner, in certain embodiments, a single enclosed housing including sensor electronics and the analyte sensor are provided which can be sterilized together using a single sterilization technique without damaging or degrading the components of the on body sensor device. 
     A method of monitoring analyte levels, in certain embodiments, includes transcutaneously positioning an analyte sensor in fluid contact with interstitial fluid under a skin surface, accumulating charge for a predetermined time period in a capacitor device in sensor electronics, the capacitor device in signal communication with the analyte sensor and receiving signals from the analyte sensor, detecting a magnetic field exceeding a threshold level, latching a switch provided in the sensor electronics to couple the capacitor device in the sensor electronics to sensor signal processing components when the detected magnetic field exceeds the threshold level, and connecting the capacitor device to the sensor signal processing components to provide power to the sensor signals processing components with the accumulated charge in the capacitor device. 
     A device for monitoring analyte level, in certain embodiments, includes an analyte sensor for transcutaneous positioning in fluid contact with interstitial fluid, sensor electronics including: sensor signal processing components, a capacitor device operatively coupled to the analyte sensor to accumulate charge for a predetermined time period, and a switch configured to latch, when a magnetic field exceeding a threshold level is detected, to couple the capacitor device to sensor signal processing components, where when the switch is latched, the capacitor device is configured to provide power to the sensor signals processing components with the accumulated charge in the capacitor device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an analyte monitoring system for real time analyte (e.g., glucose) measurement, data acquisition and/or processing in accordance with embodiments of the present disclosure; 
         FIG. 2  is a block diagram of an analyte monitoring system including a self-powered analyte sensor and RFID data communication module in accordance with embodiments of the present disclosure; 
         FIG. 3  illustrates the buffering circuit of the analyte monitoring system shown in  FIG. 2  in accordance with embodiments of the present disclosure; 
         FIG. 4  illustrates the RFID circuit of the analyte monitoring system shown in  FIG. 2  in accordance with embodiments of the present disclosure; 
         FIG. 5  illustrates an application specific integrated circuit (ASIC) which incorporates the RFID functionality of  FIG. 4  in a single circuit in accordance with embodiments of the present disclosure; 
         FIG. 6  illustrates a sensor interface resistor capacitor (RC) network to interface between the self-powered sensor and the ASIC shown in  FIG. 5  that incorporates the functions of the buffering circuit and the RFID circuit (shown in  FIGS. 2-4 ) in accordance with certain embodiments of the present disclosure; 
         FIG. 7  is a graph comparing the results of a first calibration test measured by directly contacting the intervening resistor with a precision voltmeter, and a second calibration test obtained by remotely powering the RFID and buffering circuits through an external power source in accordance with embodiments of the present disclosure; 
         FIG. 8  illustrates a sealed, waterproof on body sensor electronics housing including the self-powered sensor, the buffering circuit and the RFID circuit and antenna described above in conjunction with  FIGS. 2-5  in certain embodiments of the present disclosure; 
         FIG. 9  illustrates a sealed, waterproof on body sensor electronics housing including the self-powered sensor, the buffering circuit and the RFID circuit and antenna described above in conjunction with  FIGS. 2-5 , and further including a data communication component coupled to the on body sensor electronics housing in certain embodiments of the present disclosure; 
         FIG. 10  illustrates an analyte monitoring system including a self-powered analyte sensor, on body sensor electronics and reader device in accordance with embodiments of the present disclosure; 
         FIG. 11  illustrates an embodiment of the sensor electronics and self-powered analyte sensor of  FIG. 10  in accordance with embodiments of the present disclosure; 
         FIG. 12  illustrates a fully implantable self-powered sensor and sensor electronics in accordance with certain embodiments of the present disclosure; 
         FIG. 13  is a flow chart illustrating a method of monitoring a level of an analyte of a user in accordance with embodiments of the present disclosure; and 
         FIG. 14  is a flow chart illustrating a method of monitoring a level of an analyte of a user in accordance with embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Before the present disclosure is described in detail, it is to be understood that this disclosure is not limited to particular embodiments described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present disclosure will be limited only by the appended claims. 
     Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the disclosure. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges as also encompassed within the disclosure, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the disclosure. 
     Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present disclosure, the preferred methods and materials are now described. All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the publications are cited. 
     It must be noted that as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. 
     The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present disclosure is not entitled to antedate such publication by virtue of prior disclosure. Further, the dates of publication provided may be different from the actual publication dates which may need to be independently confirmed. 
     As will be apparent to those of skill in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of the present disclosure. 
     The figures shown herein are not necessarily drawn to scale, with some components and features being exaggerated for clarity. 
       FIG. 1  shows an exemplary in vivo-based analyte monitoring system  100  in accordance with embodiments of the present disclosure. As shown, in certain embodiments, analyte monitoring system  100  includes on body electronics  110  electrically coupled to in vivo analyte sensor  101  (a proximal portion of which is shown in  FIG. 1 ) and attached to adhesive layer  140  for attachment on a skin surface on the body of a user. On body electronics  110  includes on body housing  119 , that defines an interior compartment. Also shown in  FIG. 1  is insertion device  150  that, when operated, transcutaneously positions a portion of analyte sensor  101  through a skin surface and in fluid contact with ISF, and positions on body electronics  110  and adhesive layer  140  on a skin surface. In certain embodiments, on body electronics  110 , analyte sensor  101  and adhesive layer  140  are sealed within the housing of insertion device  150  before use, and in certain embodiments, adhesive layer  140  is also sealed within the housing or itself provides a terminal seal of the insertion device  150 . Devices, systems and methods that may be used with embodiments herein are described, e.g., in U.S. patent application Ser. No. 12/807,278, which published as U.S. Patent Application Publication No. 2011/0213225, the disclosure of which is incorporated herein by reference for all purposes. 
     Referring back to the  FIG. 1 , analyte monitoring system  100  includes display device  120  which includes a display  122  to output information to the user, an input component  121  such as a button, actuator, a touch sensitive switch, a capacitive switch, pressure sensitive switch, jog wheel or the like, to input data or command to display device  120  or otherwise control the operation of display device  120 . It is noted that some embodiments may include display-less devices or devices without any user interface components. These devices may be functionalized to store data as a data logger and/or provide a conduit to transfer data from on body electronics and/or a display-less device to another device and/or location. Embodiments will be described herein as display devices for exemplary purposes which are in no way intended to limit the embodiments of the present disclosure. It will be apparent that display-less devices may also be used in certain embodiments. 
     In certain embodiments, on body electronics  110  may be configured to store some or all of the monitored analyte related data received from analyte sensor  101  in a memory during the monitoring time period, and maintain it in memory until the usage period ends. In such embodiments, stored data is retrieved from on body electronics  110  at the conclusion of the monitoring time period, for example, after removing analyte sensor  101  from the user by detaching on body electronics  110  from the skin surface where it was positioned during the monitoring time period. In such data logging configurations, real time monitored analyte level is not communicated to display device  120  during the monitoring period or otherwise transmitted from on body electronics  110 , but rather, retrieved from on body electronics  110  after the monitoring time period. 
     In certain embodiments, input component  121  of display device  120  may include a microphone and display device  120  may include software configured to analyze audio input received from the microphone, such that functions and operation of the display device  120  may be controlled by voice commands. In certain embodiments, an output component of display device  120  includes a speaker for outputting information as audible signals. Similar voice responsive components such as a speaker, microphone and software routines to generate, process and store voice driven signals may be provided to on body electronics  110 . 
     In certain embodiments, display  122  and input component  121  may be integrated into a single component, for example a display that can detect the presence and location of a physical contact touch upon the display such as a touch screen user interface. In such embodiments, the user may control the operation of display device  120  by utilizing a set of pre-programmed motion commands, including, but not limited to, single or double tapping the display, dragging a finger or instrument across the display, motioning multiple fingers or instruments toward one another, motioning multiple fingers or instruments away from one another, etc. In certain embodiments, a display includes a touch screen having areas of pixels with single or dual function capacitive elements that serve as LCD elements and touch sensors. 
     Display device  120  also includes data communication port  123  for wired data communication with external devices such as remote terminal (personal computer)  170 , for example. Example embodiments of the data communication port  123  include USB port, mini USB port, RS-232 port, Ethernet port, Firewire port, or other similar data communication ports configured to connect to the compatible data cables. Display device  120  may also include an integrated in vitro glucose meter, including in vitro test strip port  124  to receive an in vitro glucose test strip for performing in vitro blood glucose measurements. 
     Referring still to  FIG. 1 , display  122  in certain embodiments is configured to display a variety of information—some or all of which may be displayed at the same or different time on display  122 . In certain embodiments the displayed information is user-selectable so that a user can customize the information shown on a given display screen. Display  122  may include but is not limited to graphical display  138 , for example, providing a graphical output of glucose values over a monitored time period (which may show important markers such as meals, exercise, sleep, heart rate, blood pressure, etc.), numerical display  132 , for example, providing monitored glucose values (acquired or received in response to the request for the information), and trend or directional arrow display  131  that indicates a rate of analyte change and/or a rate of the rate of analyte change, e.g., by moving locations on display  122 . 
     As further shown in  FIG. 1 , display  222  may also include date display  135  providing for example, date information for the user, time of day information display  139  providing time of day information to the user, battery level indicator display  133  which graphically shows the condition of the battery (rechargeable or disposable) of the display device  120 , sensor calibration status icon display  134  for example, in monitoring systems that require periodic, routine or a predetermined number of user calibration events, notifying the user that the analyte sensor calibration is necessary, audio/vibratory settings icon display  136  for displaying the status of the audio/vibratory output or alarm state, and wireless connectivity status icon display  137  that provides indication of wireless communication connection with other devices such as on body electronics, data processing module  160 , and/or remote terminal  170 . As additionally shown in  FIG. 1 , display  122  may further include simulated touch screen buttons  125 ,  126  for accessing menus, changing display graph output configurations or otherwise for controlling the operation of display device  120 . 
     Referring back to  FIG. 1 , in certain embodiments, display  122  of display device  120  may be additionally, or instead of visual display, configured to output alarm notifications such as alarm and/or alert notifications, glucose values etc, which may be audible, tactile, or any combination thereof. In one aspect, the display device  120  may include other output components such as a speaker, vibratory output component and the like to provide audible and/or vibratory output indication to the user in addition to the visual output indication provided on display  122 . Further details and other display embodiments can be found in, e.g., U.S. patent application Ser. No. 12/871,901, U.S. provisional application Nos. 61/238,672, 61/247,541, 61/297,625, the disclosures of each of which are incorporated herein by reference for all purposes. 
     After the positioning of on body electronics  110  on the skin surface and analyte sensor  101  in vivo to establish fluid contact with ISF (or other appropriate body fluid), on body electronics  110  in certain embodiments is configured to wirelessly communicate analyte related data (such as, for example, data corresponding to monitored analyte level and/or monitored temperature data, and/or stored historical analyte related data) when on body electronics  110  receives a command or request signal from display device  120 . In certain embodiments, on body electronics  110  may be configured to at least periodically broadcast real time data associated with monitored analyte level which is received by display device  120  when display device  120  is within communication range of the data broadcast from on body electronics  110 , i.e., it does not need a command or request from a display device to send information. 
     For example, display device  120  may be configured to transmit one or more commands to on body electronics  110  to initiate data transfer, and in response, on body electronics  110  may be configured to wirelessly transmit stored analyte related data collected during the monitoring time period to display device  120 . Display device  120  may in turn be connected to a remote terminal  170  such as a personal computer and functions as a data conduit to transfer the stored analyte level information from the on body electronics  110  to remote terminal  170 . In certain embodiments, the received data from the on body electronics  110  may be stored (permanently or temporarily) in one or more memory of the display device  120 . In certain other embodiments, display device  120  is configured as a data conduit to pass the data received from on body electronics  110  to remote terminal  170  that is connected to display device  120 . 
     Referring still to  FIG. 1 , also shown in analyte monitoring system  100  are data processing module  160  and remote terminal  170 . Remote terminal  170  may include a personal computer, a server terminal a laptop computer or other suitable data processing devices including software for data management and analysis and communication with the components in the analyte monitoring system  100 . For example, remote terminal  170  may be connected to a local area network (LAN), a wide area network (WAN), or other data network for uni-directional or bi-directional data communication between remote terminal  170  and display device  120  and/or data processing module  160 . 
     Remote terminal  170  in certain embodiments may include one or more computer terminals located at a physician&#39;s office or a hospital. For example, remote terminal  170  may be located at a location other than the location of display device  120 . Remote terminal  170  and display device  120  could be in different rooms or different buildings. Remote terminal  170  and display device  120  could be at least about one mile apart, e.g., at least about 10 miles apart, e.g., at least about 100 miles apart. For example, remote terminal  170  could be in the same city as display device  120 , remote terminal  170  could be in a different city than display device  120 , remote terminal  170  could be in the same state as display device  120 , remote terminal  170  could be in a different state than display device  120 , remote terminal  170  could be in the same country as display device  120 , or remote terminal  170  could be in a different country than display device  120 , for example. 
     In certain embodiments, a separate, optional data communication/processing device such as data processing module  160  may be provided in analyte monitoring system  100 . Data processing module  160  may include components to communicate using one or more wireless communication protocols such as, for example, but not limited to, infrared (IR) protocol, Bluetooth® protocol, Zigbee® protocol, and 802.11 wireless LAN protocol. Additional description of communication protocols including those based on Bluetooth® protocol and/or Zigbee® protocol can be found in U.S. Patent Publication No. 2006/0193375 incorporated herein by reference for all purposes. Data processing module  160  may further include communication ports, drivers or connectors to establish wired communication with one or more of display device  120 , on body electronics  110 , or remote terminal  170  including, for example, but not limited to USB connector and/or USB port, Ethernet connector and/or port, FireWire connector and/or port, or RS-232 port and/or connector. 
     In certain embodiments, data processing module  160  is programmed to transmit a polling or query signal to on body electronics  110  at a predetermined time interval (e.g., once every minute, once every five minutes, or the like), and in response, receive the monitored analyte level information from on body electronics  110 . Data processing module  160  stores in its memory the received analyte level information, and/or relays or retransmits the received information to another device such as display device  120 . More specifically in certain embodiments, data processing module  160  may be configured as a data relay device to retransmit or pass through the received analyte level data from on body electronics  110  to display device  120  or a remote terminal (for example, over a data network such as a cellular or WiFi data network) or both. 
     In certain embodiments, on body electronics  110  and data processing module  160  may be positioned on the skin surface of the user within a predetermined distance of each other (for example, about 1-12 inches, or about 1-10 inches, or about 1-7 inches, or about 1-5 inches) such that periodic communication between on body electronics  110  and data processing module  160  is maintained. Alternatively, data processing module  160  may be worn on a belt or clothing item of the user, such that the desired distance for communication between the on body electronics  110  and data processing module  160  for data communication is maintained. In a further aspect, the housing of data processing module  160  may be configured to couple to or engage with on body electronics  110  such that the two devices are combined or integrated as a single assembly and positioned on the skin surface. In further embodiments, data processing module  160  is detachably engaged or connected to on body electronics  110  providing additional modularity such that data processing module  160  may be optionally removed or reattached as desired. 
     Referring again to  FIG. 1 , in certain embodiments, data processing module  160  is programmed to transmit a command or signal to on body electronics  110  at a predetermined time interval such as once every minute, or once every 5 minutes or once every 30 minutes or any other suitable or desired programmable time interval to request analyte related data from on body electronics  110 . When data processing module  160  receives the requested analyte related data, it stores the received data. In this manner, analyte monitoring system  100  may be configured to receive the continuously monitored analyte related information at the programmed or programmable time interval, which is stored and/or displayed to the user. The stored data in data processing module  160  may be subsequently provided or transmitted to display device  120 , remote terminal  170  or the like for subsequent data analysis such as identifying frequency of periods of glycemic level excursions over the monitored time period, or the frequency of the alarm event occurrence during the monitored time period, for example, to improve therapy related decisions. Using this information, the doctor, healthcare provider or the user may adjust or recommend modification to the diet, daily habits and routines such as exercise, and the like. 
     In another embodiment, data processing module  160  transmits a command or signal to on body electronics  110  to receive the analyte related data in response to a user activation of a switch provided on data processing module  160  or a user initiated command received from display device  120 . In further embodiments, data processing module  160  is configured to transmit a command or signal to on body electronics  110  in response to receiving a user initiated command only after a predetermined time interval has elapsed. For example, in certain embodiments, if the user does not initiate communication within a programmed time period, such as, for example about 5 hours from last communication (or 10 hours from the last communication, or 24 hours from the last communication), the data processing module  160  may be programmed to automatically transmit a request command or signal to on body electronics  110 . Alternatively, data processing module  160  may be programmed to activate an alarm to notify the user that a predetermined time period of time has elapsed since the last communication between the data processing module  160  and on body electronics  110 . In this manner, users or healthcare providers may program or configure data processing module  160  to provide certain compliance with analyte monitoring regimen, so that frequent determination of analyte levels is maintained or performed by the user. 
     In certain embodiments, when a programmed or programmable alarm condition is detected (for example, a detected glucose level monitored by analyte sensor  101  that is outside a predetermined acceptable range indicating a physiological condition which requires attention or intervention for medical treatment or analysis (for example, a hypoglycemic condition, a hyperglycemic condition, an impending hyperglycemic condition or an impending hypoglycemic condition), the one or more output indications may be generated by the control logic or processor of the on body electronics  110  and output to the user on a user interface of on body electronics  110  so that corrective action may be timely taken. In addition to or alternatively, if display device  120  is within communication range, the output indications or alarm data may be communicated to display device  120  whose processor, upon detection of the alarm data reception, controls the display  122  to output one or more notification. 
     In certain embodiments, control logic or microprocessors of on body electronics  110  include software programs to determine future or anticipated analyte levels based on information obtained from analyte sensor  101 , e.g., the current analyte level, the rate of change of the analyte level, the acceleration of the analyte level change, and/or analyte trend information determined based on stored monitored analyte data providing a historical trend or direction of analyte level fluctuation as function time during monitored time period. Predictive alarm parameters may be programmed or programmable in display device  120 , or the on body electronics  110 , or both, and output to the user in advance of anticipating the user&#39;s analyte level reaching the future level. This provides the user an opportunity to take timely corrective action. 
     Information, such as variation or fluctuation of the monitored analyte level as a function of time over the monitored time period providing analyte trend information, for example, may be determined by one or more control logic or microprocessors of display device  120 , data processing module  160 , and/or remote terminal  170 , and/or on body electronics  110 . Such information may be displayed as, for example, a graph (such as a line graph) to indicate to the user the current and/or historical and/or and predicted future analyte levels as measured and predicted by the analyte monitoring system  100 . Such information may also be displayed as directional arrows (for example, see trend or directional arrow display  131 ) or other icon(s), e.g., the position of which on the screen relative to a reference point indicated whether the analyte level is increasing or decreasing as well as the acceleration or deceleration of the increase or decrease in analyte level. This information may be utilized by the user to determine any necessary corrective actions to ensure the analyte level remains within an acceptable and/or clinically safe range. Other visual indicators, including colors, flashing, fading, etc., as well as audio indicators including a change in pitch, volume, or tone of an audio output and/or vibratory or other tactile indicators may also be incorporated into the display of trend data as means of notifying the user of the current level and/or direction and/or rate of change of the monitored analyte level. For example, based on a determined rate of glucose change, programmed clinically significant glucose threshold levels (e.g., hyperglycemic and/or hypoglycemic levels), and current analyte level derived by an in vivo analyte sensor, the system  100  may include an algorithm stored on computer readable medium to determine the time it will take to reach a clinically significant level and will output notification in advance of reaching the clinically significant level, e.g., 30 minutes before a clinically significant level is anticipated, and/or 20 minutes, and/or 10 minutes, and/or 5 minutes, and/or 3 minutes, and/or 1 minute, and so on, with outputs increasing in intensity or the like. 
     Referring again back to  FIG. 1 , in certain embodiments, software algorithm(s) for execution by data processing module  160  may be stored in an external memory device such as an SD card, micro-SD card, compact flash card, XD card, Memory Stick card, Memory Stick Duo card, or USB memory stick/device including executable programs stored in such devices for execution upon connection to the respective one or more of the on body electronics  110 , remote terminal  170  or display device  120 . In a further aspect, software algorithms for execution by data processing module  160  may be provided to a communication device such as a mobile telephone including, for example, WiFi or Internet enabled smart phones or personal digital assistants (PDAs) as a downloadable application for execution by the downloading communication device. 
     Examples of smart phones include Windows®, Android™, iPhone® operating system, Palm® WebOS™, Blackberry® operating system, or Symbian® operating system based mobile telephones with data network connectivity functionality for data communication over an Internet connection and/or a local area network (LAN). PDAs as described above include, for example, portable electronic devices including one or more microprocessors and data communication capability with a user interface (e.g., display/output unit and/or input unit, and configured for performing data processing, data upload/download over the internet, for example. In such embodiments, remote terminal  170  may be configured to provide the executable application software to the one or more of the communication devices described above when communication between the remote terminal  170  and the devices are established. 
     In still further embodiments, executable software applications may be provided over-the-air (OTA) as an OTA download such that wired connection to remote terminal  170  is not necessary. For example, executable applications may be automatically downloaded as software download to the communication device, and depending upon the configuration of the communication device, installed on the device for use automatically, or based on user confirmation or acknowledgement on the communication device to execute the installation of the application. The OTA download and installation of software may include software applications and/or routines that are updates or upgrades to the existing functions or features of data processing module  160  and/or display device  120 . 
     Referring back to remote terminal  170  of  FIG. 1 , in certain embodiments, new software and/or software updates such as software patches or fixes, firmware updates or software driver upgrades, among others, for display device  120  and/or on body electronics  110  and/or data processing module  160  may be provided by remote terminal  170  when communication between the remote terminal  170  and display device  120  and/or data processing module  160  is established. For example, software upgrades, executable programming changes or modification for on body electronics  110  may be received from remote terminal  170  by one or more of display device  120  or data processing module  160 , and thereafter, provided to on body electronics  110  to update its software or programmable functions. For example, in certain embodiments, software received and installed in on body electronics  110  may include software bug fixes, modification to the previously stalled software parameters (modification to analyte related data storage time interval, resetting or adjusting time base or information of on body electronics  110 , modification to the transmitted data type, data transmission sequence, or data storage time period, among others). 
     Further embodiments, details and configurations of the analyte monitoring system can be found in U.S. patent application Ser. No. 12/807,278, which published as U.S. Patent Application Publication No. 2011/0213225, the disclosure of which is incorporated herein by reference for all purposes. 
       FIG. 2  is a block diagram of an analyte monitoring system including a self-powered analyte sensor and RFID data communication module in accordance with one embodiment of the present disclosure. As shown in  FIG. 2 , in certain embodiments, the analyte monitoring system  200  includes self-powered sensor  210  operatively coupled to buffering circuit  220  that is further provided in signal communication with RFID circuit  230 . The self-powered sensor  210 , the buffering circuit  220  and the RFID circuit  230  in certain embodiments may be provided in a single on body sensor electronics housing, with a portion of the self-powered sensor  210  positioned under the skin surface of a user and in fluid contact with interstitial fluid. The single on body sensor electronics housing in certain embodiments is a waterproof housing. Referring back to  FIG. 2 , also shown is an external power source and Reader device (“reader”)  240  which in certain embodiments, includes an RFID reader that is capable of radiating an RF field, and when in proximity to an RFID device, receives data communication back from the RFID device using the RF field. 
     In certain embodiments, self-powered sensor  210  includes at least a working electrode and a counter electrode and power is generated as a result of the oxidation reaction between the working and counter electrodes. Additional details on the structure, operation and configurations of self-powered sensor  210  can be found in U.S. patent application Ser. No. 12/393,921, published as US 2010/0213057, U.S. patent application Ser. No. 13/087,190 published as US 2011/0257495, and U.S. patent application Ser. No. 13/299,119 published as US 2012-0157801, the disclosures of each of which are incorporated herein by reference for all purposes. 
     For example, in certain embodiments, self-powered sensor  210  generates an average current of about 10 nA to about 100 nA with an average voltage of about 100 mV to about 300 mV, resulting in an average power output of about 1 nW to 30 nW. It is to be understood that the current, voltage and power ranges described herein are representative and the disclosure is not limited to the ranges mentioned herein. In certain embodiments, a low current may be desired for the electrode pair utilized for measuring analyte levels. In such embodiments, a second working electrode and counter electrode pair may be included in the self-powered sensor  210 , and be configured for higher current output for power generation. 
     Referring to  FIG. 2 , in certain embodiments, the self-powered sensor  210  operates continuously, without the use of an external power source, to generate current signals that are proportional to the analyte concentration in the bodily fluid that the self-powered sensor  210  is placed in contact therewith. The RFID circuit  230  and the buffering circuit  220 , in certain embodiments, remain dormant or in an inactive or nonoperational state while the self-powered sensor  210  is generating the current signals. In certain embodiments, when Reader  240  is positioned in close proximity to the RFID circuit  230  of the on body sensor electronics such that the RFID circuit  230  is within the RF field radiated from the Reader  240 , the RFID circuit is configured to query the self-powered sensor  210  through the buffering circuit  220  to receive the measured sensor current signal, and sends or returns the measured sensor current signal (received from the self-powered sensor  210  via the buffering circuit  220 ) to the Reader  240 . As described further below and also shown in  FIG. 6 , self-powered sensor  210 , in certain embodiments, is connected to an R/C (resistor/capacitor) load providing a return current path for self-powered sensor  210 . Measured voltage across the R/C load generated when the generated current flows through the R/C load, provides one or more signals which is passed (through the buffering circuit  220 ) to the RFID circuit  230 . In certain embodiments, the signals communicated by the RFID circuit  230  in response to the query from the Reader  240  include analog signals generated by the self-powered sensor corresponding to the monitored analyte levels digitized for data transmission, measured temperature data, and calibration code information. 
       FIG. 3  illustrates the buffering circuit  220  of the analyte monitoring system  200  shown in  FIG. 2  in accordance with embodiments of the present disclosure. As shown, buffering circuit  220  shown in  FIG. 3  is an instrumentation operational amplifier (OPA) used to isolate the self-powered sensor  210  ( FIG. 2 ) from the RFID circuit  230  ( FIG. 2 ). The input buffers may include one or more operational amplifiers with high impedance to isolate the signals from the self-powered sensor  210  from the RFID circuit  230 , and maintain the accuracy of the monitored analyte level readings generated by the self-powered sensor  210 . In certain embodiments the buffering circuit  220  is a close to unity gain amplifier and passes the analog voltage signals to RFID circuit  230 . 
       FIG. 4  illustrates the RFID circuit  230  of the analyte monitoring system shown in  FIG. 2  in accordance with embodiments of the present disclosure. Referring to  FIG. 4 , the RFID circuit  230  in certain embodiments includes an antenna and an RFID chip. The RFID circuit  230  also includes a voltage reference used to raise the bias potential for the buffering circuit  220  and for the analog front end circuitry of the RFID chip, as well as a precision voltage regulator. In operation, when the Reader  240  is positioned in close proximity to the RFID circuit  230 , the RF field radiated from the Reader  240  provides the necessary power to operate the buffering circuit  220  and the RFID circuit  230 . Further, signals received from the Reader  240  initialize the RFID circuit  230  by resetting the digital circuits and setting the digital bits of the memory and registers of the RFID circuit  230 . RFID query commands are sent to the RFID circuit  230 , and in response, the RFID circuit  230  transmits the digitized signals associated with the monitored analyte level to the Reader  240 . 
       FIG. 5  illustrates an application specific integrated circuit (ASIC) which incorporates the function of the RFID circuit shown in  FIG. 4  and the function of the buffering circuit  220  shown in  FIG. 3  in a single ASIC configuration  500 . In certain embodiments, ASIC  500  includes an ISO 15693 RFID front-end circuitry, a magnetic field energy saving circuit, DC power management (regulators), sensor digital control, analog to digital and digital to analog converters and an analog front end circuitry. An IOS 15963 RFID front-end circuitry provides wireless access for Reader  240  to acquire digitized data from the ASIC  500 . A magnetic field energy saving circuit coverts the magnetic field energy received from the Reader  240  to DC power to supply power to the ASIC  500  when Reader  240  is in proximity. A DC power management circuit utilizes the DC power generated at the magnetic field energy saving circuit to provide stable and filtered DC power for the ASIC  500 . A sensor digital control circuit initializes and programs ASIC  500 , controls the analog to digital processing and analog front end gain, and provides digitized data to the RFID front-end circuitry. An analog to digital converter (ADC) converts the analog signals to a corresponding digital signal for the RFID front-end backscatter modulation and a digital to analog converter (DAC) is used to compensate error due to analog front end offset voltage. An analog front end circuitry amplifies the analog signals received from self-powered sensor  210  for ADC conversion. 
       FIG. 6  illustrates a sensor interface resistor capacitor (RC) network to interface between the self-powered sensor  210  and the ASIC shown in  FIG. 5  that incorporates the functions of the buffering circuit  220  and the RFID circuit  230  (shown in  FIGS. 2-4 ) in accordance with certain embodiments of the present disclosure. In particular, in certain embodiments, a resistor bridge circuit with two resistor arms  600  is provided between the ASIC  500  of  FIG. 5  with the self-powered sensor  210 . The resistor bridge circuit provides bias for both inputs of the ASIC  500  and allows for maintenance of accuracy of the analyte measurement signal even at low current levels. The voltage across the ASIC input terminals D_in 1 , D_in 2  is the sensor voltage across resistor R to be proportional to the sensor current received from the self-powered sensor  210 . The bias voltage provided to both input arms of the ASIC  500  maintains a constant differential voltage for a given resistance. An R/C sensor load is connected in parallel with self-powered sensor  210  and in series between the bridge circuit and one input of the ASIC  500 . The voltage variations across the R/C load applies to the differential voltage between the two inputs of the ASIC  500  and corresponds to the sensor measurement signal received by the ASIC  500 . The resistor bridge further provides a compensation voltage to cancel any leakage current effect when there is bias current flowing out or in through the inputs of the ASIC  500 . 
       FIG. 7  is a graph comparing the results of a first calibration test measured by directly contacting the intervening resistor with a precision voltmeter, and a second calibration test obtained by remotely powering the RFID and buffering circuits through an external power source. Referring to  FIG. 7 , the test included a self-powered sensor with a glucose oxide anode and a carbon cathode and an intervening 5MΩ resistor. The self-powered sensor was immersed in a buffer solution and glucose aliquots were added. The test was repeated (1) for a directly contacted intervening resistor and (2) by remotely powering RFID and buffering circuits. Self-powered sensor and corresponding circuitry configurations were tested to determine the accuracy and potential for signal loss by utilizing RFID communication versus direct contact communication. The test configurations had an external power source attached thereto to test the calibration of the test configurations. 
       FIG. 8  illustrates a sealed, waterproof on body sensor electronics housing  800  including the self-powered sensor, the buffering circuit and the RFID circuit and antenna described above in conjunction with  FIGS. 2-5  in certain embodiments of the present disclosure. Referring to  FIG. 8 , a portion of the self-powered sensor extends from the sealed on body sensor electronics housing, and upon positioning of the sensor electronics housing, the sensor portion that extends from the housing is positioned under the skin surface and in contact with the interstitial fluid. In this manner, in certain embodiments, the sealed sensor electronics housing including sensor electronics such as the buffering circuit and the RFID circuit can be sterilized with gamma ray or e-bam radiation as the housing does not include a memory device that may be susceptible to such sterilization. 
       FIG. 9  illustrates a sealed, waterproof on body sensor electronics housing  900  including the self-powered sensor, the buffering circuit and the RFID circuit and antenna described above in conjunction with  FIGS. 2-5 , and further including a data communication device  910  coupled to the on body sensor electronics housing in certain embodiments of the present disclosure. Referring to  FIG. 9 , the sealed on-body sensor electronics housing may be coupled with a data communication device that may be reversibly snapped onto the sealed sensor electronics housing, or alternatively detachably attached with mechanical features such as grooves, latches, locks arms and the like. 
     The data communication device in certain embodiments includes RFID power source and reader device, and alternatively, also include an RF data communication module. In certain embodiments, the RFID power source and reader device may be programmed or is programmable to query the sensor electronics to retrieve sensor signals corresponding to monitored analyte level at a predetermined or programmed or programmable time interval, which, upon receipt, may also retransmit or communicate the received sensor signals to a remote location, for example, using the RF data communication module within the data communication device. In certain embodiments, alarms and projected measurement values can be determined based upon the stored analyte level measurements. In certain embodiments, the data communication device may be powered separately and remotely for extended life. 
     In the manner described above, self-powered sensor is configured to operate with a buffering circuit and RFID circuit, where upon receipt of a query signal from the Reader device (that provides RF field), the RFID circuit and the buffer circuit transition into active operational mode to retrieve the sensor signal from the self-powered sensor and to provide data related to monitored analyte level corresponding to the retrieved sensor signal to the Reader device. Further, in certain embodiments of the present disclosure, self-powered sensor and electronics assembly are provided in a single waterproof housing that meets or exceeds IPX-7 level, which can be sterilized using a single sterilization technique without potential damage to the assembly since the assembly does not include a memory device that may be susceptible to the suitable gamma ray or e-beam sterilization. 
       FIG. 10  illustrates an analyte monitoring system including a self-powered analyte sensor, on body sensor electronics and reader device in accordance with embodiments of the present disclosure. Referring to  FIG. 10 , sensor electronics  110  includes a capacitor  1021  and resistor  1022 , wherein the voltage  1012  generated by the analyte sensor runs through the resistor  1022  to charge capacitor  1021  which stores charge resulting in the current signals generated by the self-powered analyte sensor  101 . Capacitor  1021  is sized to store sufficient charge to power sensor electronics  110  for a time period sufficient to measure and store analyte values monitored by the analyte sensor, without the use of any external power supply such as a battery. In certain embodiments, the sensor electronics  110  includes a switch  1023 . Switch  1023 , when activated, switches or latches the power loop from charging the capacitor  1021  via the self-powered analyte sensor  101 , to a circuit loop whereby the capacitor  1021  discharges to flow through a power management module  1025 , which in certain embodiments, includes a voltage multiplier to increase the voltage from capacitor  1021  to a sufficiently high voltage for operation of sensor electronics  110  to read and store a measured analyte value. For example, in certain embodiments, for operation of the sensor electronics  110 , approximately 500 mV is used as the minimum charging input voltage from the sensor, and the 500 mV is doubled in the power management module  1025  to power on sensor electronics circuits. 
     Sensor electronics  110  for measurement, processing and storage of signals corresponding to monitored analyte level includes power management module  1025 , a sensor input buffer  1026 , control circuits  1027 , an analog-to-digital (A/D) converter  1028 , a memory  1029  and a data output module  1030 . In certain embodiments, power management module  1025  is configured to multiply, regulate and detect the charge stored or accumulated in capacitor  1021  before powering the entire sensor circuitry of sensor electronics  110 . Sensor input buffer  1026  includes an instrumental operational amplifier of high impedance and a resistor bridge network, which acts as a buffer between analyte sensor  101  and A/D converter  1028 . The resistor bridge provides reference voltage (Vcc/2) for the inputs of the instrumental operation amplifier. One of the arms of the resistor bridge is connected to input of the instrumental operation amplifier through a sensor load R/C circuit. 
     Sensor input buffer  1026  is used due to the low analyte current level generated at analyte sensor corresponding to the measurement of an analyte level, to minimize the impact on the analyte current measurement. Since the input impedance of the instrumental operation amplifier is very high, the sensor current will not flow (through) in or out of the inputs of the instrumental amplifier when the sensor is connected. Thus, the sensor current measurement will not be affected by the external circuits connected to the sensor. 
     A/D converter  1028  converts the analog analyte current signals from analyte sensor  101  via the signal input buffer  1026 , to a digital value to be stored on memory  1029 . Data output module  1030  is utilized to transmit, either via direct contact or wirelessly, data stored on memory  1029  to display device  120  or other electronic device with a compatible physical and/or wireless input port. 
     Control circuits  1027  control the signal flow among the various sensor electronics  110  components, including the sensor input buffer  1026 , A/D converter  1028 , memory  1029 , and data output module  1030 . In certain embodiments, control circuit  1027  is configured to initialize digital settings and start measurement, to control the gain of the instrumental operation amplifier to provide amplified analog signal for A/D converter  1028 , and to store the converted digital data into memory  1029  and upload the data from the memory  1029  to display device  120 . 
     In certain embodiments, sensor electronics  110  uses approximately 100 μW for approximately 100 ms (approximately 10 microjoules) to measure and store an analyte measurement. Self-powered analyte sensor  101 , in certain embodiments, generates approximately 25 nW, which would take approximately 400 s (7 minutes) to accumulate the 10 microjoules necessary to measure and store the analyte measurement. In such embodiments, the analyte monitoring system  100  can be configured to measure and store an analyte measurement at least every 7 minutes without the need of a battery or other external power source. 
     Still referring to  FIG. 10 , and as illustrated in  FIG. 1 , analyte monitoring system  100  includes display device  120 . Display device  120  may be configured to transmit a signal to the sensor electronics  110  to activate switch  1023  to begin measurement and storage of an analyte value. In certain embodiments, display device  120  may include a magnetic field generator  1041 , and switch  1023  may be a magnetic switch, where upon activation of the magnetic field generator  1041 , the magnetic switch switches operation of sensor electronics  110  from charging the capacitor  1021  to measurement and storage of an analyte value. Switch  1023  is connected to sensor  101  through R 1 , which limits the charging current, before magnetic field presents next to it. In such way, the sensor will charge the capacitor  1021  in most time. Since the sensor can only generate ultra-low current, it will take a long time to fully charge the capacitor  1021 . The magnetic field generator  1041  in certain embodiments includes conductive wire loops and soft iron. The magnetic field is generated with a current from a direct current (DC) current source  1043  flowing through the conductive wire loops, while the soft iron enhances the magnetic field. 
     In further embodiments, sensor electronics  110  also includes a wire loop  1024 , which, upon detection of current flowing through the wire loop  1024  due to magnetic switching of switch  1023 , generates a magnetic pulse signal. The magnetic pulse signal is detected by the display device  120  to confirm that the magnetic actuation of the switch  1023  and confirm the magnetic field generator  1041  signal was received at the sensor electronics  110 . When switch  1023  is connected to wire loop  1024 , the initial pulse signal in the form of the magnetic field will disturb the magnetic field produced by the magnetic field generator  1041 . The magnetic field will cause current change across the conductive loop wire  1024 . The sensor-on detector  1044  will detect the current changes to confirm the switch  1023  status change. 
     In certain embodiments, the magnetic pulse signal is detected by a sensor-on detector  1044  of the display device  120 . The display device  1042  displays how many times the user activates the sensor electronics  110 , and the day and time information from the last activation time. Since the capacitor  1021  charging will take a certain amount of time, activation spaced too close together will not provide sufficient time for capacitor  1021  to be fully charged. In certain embodiments, microprocessor  1045  is configured to turn on DC current generator  1043 , detect sensor-on detector  1044  status, monitor battery voltage, download the data from sensor electronics  110  and operate the display device  1042 . Display device  120  may further include a display  1042 , microprocessor  1045 , data input module  1046  and battery  1047 . 
       FIG. 11  illustrates an embodiment of the sensor electronics  110  and self-powered analyte sensor  101  of  FIG. 10 . Referring to  FIG. 11 , self-powered analyte sensor  101  and sensor electronics  110  including wire loop  1024 , magnetic switch  1023 , capacitor  1021 , resistor  1022 , a physical data output  1030  and electronics  1020  including power management module  1025 , sensor input buffer  1026 , control circuits  1027 , A/D converter  1028  and memory  1029  are integrated into a single device. In other embodiments, analyte sensor  101  is separate from the sensor electronics  110  and is physically and/or electrically coupled with the sensor electronics  110  before, during or after transcutaneous insertion through the skin surface. 
     In other embodiments, sensor electronics  110  components are located on two or more separate devices. For example, in certain embodiments, a first device may include analyte sensor  101  integrated with sensor electronics  110  components including wire loop  1024 , switch  1023 , capacitor  1021 , resistor  1022  and physical data output  1030 , while a second device which is configured to be physically coupled to the first device, includes electronics  1020  including power management module  1025 , sensor input buffer,  1026 , control circuits  1027 , A/D converter  1028  and memory  1029 . The second device may include a physical data input that is physically coupled with physical data output  1030  to facilitate transfer of data and signals between the first and second device. Further, second device may further include an output, either physical contacts or wireless communication, such as radio frequency (RF), which communicates with display device  120 . 
       FIG. 12  illustrates a fully implantable self-powered sensor and sensor electronics in accordance with certain embodiments of the present disclosure. In certain embodiments, self-powered sensor  1210  and sensor electronics including buffer circuit  1220 , RFID circuit  1230  and antenna  1240  are provided in a sealed housing  1200  and configured to be fully implantable under skin surface  1290 . As described in detail above, self-powered sensor  1210  and sensor electronics are configured to be externally powered via magnetic field provided by Reader  1250 . In this manner, in certain embodiments, self-powered sensor  1210  and sensor electronics to be configured for long-term implantation beneath a skin surface  1290  of a user. In certain embodiments, implantable self-powered sensor  1210  receives an RF signal  1270  request from Reader  1250 , and transmits a return RF signal  1280  for receipt at the Reader antenna  1260 . Return RF signal  1280  includes the sensor data measured by the self-powered sensor  1210 . In certain embodiments, sensor electronics may be a single ASIC within the sealed housing  1200 . 
       FIG. 13  is a flow chart illustrating analyte monitoring in certain embodiments of the present disclosure. Referring to  FIG. 13 , after transcutaneous positioning of a self-powered analyte sensor ( 1310 ), the oxidation reaction between the working and counter electrodes of the self-powered analyte sensor generates current signals that is then used by the sensor electronics to charge a capacitor for powering the sensor electronics ( 1320 ). Referring back to  FIG. 13 , periodically, the sensor electronics receive a signal to measure a current analyte level ( 1330 ). In certain embodiments, the signal is generated automatically at periodic intervals, and in other embodiments, the signal is generated based on a command from a display device. Upon receipt of the signal, a switch in the sensor electronics is activated, which switches the flow of power between the self-powered sensor and capacitor to discharge the capacitor to power the sensor electronics ( 1340 ). Upon activation of the sensor electronics, the current signal measured at the self-powered sensor representative of a current analyte level is detected by the sensor electronics ( 1350 ). The measured current signal of the self-powered sensor is converted to a digital value ( 1360 ) by the A/D converter of the sensor electronics. The digital value is then stored in memory ( 1370 ) for later retrieval or transmission to a display device. 
       FIG. 14  is a flow chart illustrating analyte monitoring in certain embodiments of the present disclosure. As shown in  FIG. 14 , after transcutaneous positioning of a self-powered analyte sensor ( 1410 ), the oxidation reaction between the working and counter electrodes of the self-powered analyte sensor generates current signals. The generated current signals are used by the sensor electronics to charge a capacitor for storage of power for powering the sensor electronics ( 1420 ). Periodically, the sensor electronics detect a signal generated by a magnetic field generator corresponding to a command to measure a current analyte level ( 1430 ). Upon receipt of the magnetic field generated signal, the magnetic switch in the sensor electronics is activated, which switches the flow of power between the self-powered sensor and capacitor to discharge the capacitor to power the sensor electronics ( 1440 ). The reversed flow from the capacitor flows through a wire loop, which in turn generates a magnetic field signal indicative of a verification of connection of the magnetic switch. Upon activation of the magnetic switch, and subsequent activation of the sensor electronics, the current signal measured at the self-powered sensor representative of a current analyte level is detected by the sensor electronics ( 1450 ). The measured current signal of the self-powered sensor is converted to a digital value ( 1460 ) by the A/D converter of the sensor electronics. The digital value is then stored in memory ( 1470 ) for later retrieval or transmission to a display device. 
     In the manner described above, in accordance with embodiments of the present disclosure, solely using the signals generated by the oxidation reaction of the self-powered sensor, the generated signals provide sufficient power to drive the sensor electronics for processing signals related to the monitored analyte level, including storing, filtering, processing and for communication to a remote location. In this manner, in certain embodiments, sensor electronics coupled to the self-powered analyte sensor does not require a separate power source such as a battery to power the sensor electronics for processing signals related to the monitored analyte level including storing the generated and processed signals. In further embodiments, a remote device such as a display device is configured to generate a magnetic field which, when positioned in close proximity to the sensor electronics, latches a switch in the sensor electronics to drive the charge stored in the sensor electronics capacitor (generated from the self-powered sensor) to connect the remaining portions of the sensor electronics, effectively powering the sensor electronics solely from the charge stored in the capacitor that was generated by the self-powered sensor. 
     In a further embodiment, an on body sensor device including the self-powered sensor and sensor electronics is provided in a sealed housing and which does not include electronic components susceptible to sterilization processes for the sensor, and that would otherwise degrade or damage such electronic components. In this manner, in certain embodiments, a single enclosed housing including sensor electronics and the analyte sensor are provided which can be sterilized together using a single sterilization technique without damaging or degrading the components of the on body sensor device. 
     An analyte monitoring device in certain embodiments includes a self-powered analyte sensor having at least a portion in fluid contact with interstitial fluid under a skin surface, and sensor electronics operatively coupled to the self-powered analyte sensor, configured to receive signals generated by the self-powered analyte sensor, and to communicate data corresponding to analyte level monitored by the self-powered analyte sensor, the sensor electronics including: a buffering circuit operatively coupled to the self-powered analyte sensor for receiving the generated signals from the self-powered analyte sensor, and a radio frequency identification device (RFID) circuit operatively coupled to the buffering circuit and configured to communicate data corresponding to the generated signals associated with the monitored analyte level. 
     An analyte monitoring device in certain embodiments of the present disclosure includes a self-powered analyte sensor, and sensor electronics operatively coupled to the self-powered analyte sensor configured to receive signals generated by the self-powered analyte sensor and to communicate data corresponding to analyte level monitored by the self-powered analyte sensor, where the sensor electronics transitions from an inactive state to an active state when powered by a remote power source and upon receipt of a query signal from the remote power source, and in response to the query signal, communicates data corresponding to the generated signals associated with the monitored analyte level to the remote power source. 
     In certain embodiments, the self-powered analyte sensor is configured to continuously generate signals corresponding to monitored analyte level when in fluid contact with interstitial fluid. 
     In certain embodiments, the self-powered analyte sensor generates the signals corresponding to monitored analyte level when the sensor electronics are in the inactive state. 
     In certain embodiments, the sensor electronics are not operational when in the inactive state. 
     In certain embodiments, the sensor electronics include a buffering circuit operatively coupled to the self-powered analyte sensor for receiving the generated signals from the self-powered analyte sensor. 
     In certain embodiments, the sensor electronics includes a radio frequency identification device (RFID) circuit operatively coupled to the buffering circuit and configured to communicate data corresponding to the generated signals associated with the monitored analyte level. 
     In certain embodiments, the analyte monitoring device further includes a housing enclosing the self-powered sensor and the sensor electronics, wherein the housing is sealed to inhibit moisture from entering the housing. 
     In certain embodiments, the query signal includes an RFID signal. 
     In certain embodiments, the sensor electronics transition from the active state to the inactive state when the sensor electronics is not within the range of the remote power source. 
     In certain embodiments, the self-powered sensor is configured to generate the signals when in contact with the interstitial fluid and when the sensor electronics is in the inactive state. 
     In certain embodiments, the analyte monitoring device includes a housing enclosing the self-powered sensor and the sensor electronics, the housing including one or more mechanical components for physically detachably engaging with a remote device. 
     In certain embodiments, the remote device includes the remote power source. 
     In certain embodiments, the one or more mechanical components include one or more of a releasable latch, a releasable arm, or a releasable lock. 
     An analyte monitoring device, in certain embodiments, includes a self-powered analyte sensor having at least a portion in fluid contact with interstitial fluid under a skin surface, and sensor electronics operatively coupled to the self-powered analyte sensor configured to receive signals generated by the self-powered analyte sensor and to communicate data corresponding to analyte level monitored by the self-powered analyte sensor, the sensor electronics including: a buffering circuit operatively coupled to the self-powered analyte sensor for receiving the generated signals from the self-powered analyte sensor; and a radio frequency identification device (RFID) circuit operatively coupled to the buffering circuit and configured to communicate data corresponding to the generated signals associated with the monitored analyte level, where the sensor electronics transitions from an inactive state to an active state when powered by a remote power source and upon receipt of a query signal from the remote power source, and in response to the query signal, communicates data corresponding to the generated signals associated with the monitored analyte level to the remote power source. 
     In certain embodiments of the present disclosure, using the signals generated by the oxidation reaction of the self-powered sensor accumulated over time and stored in a capacitor device, sufficient charge is accumulated to drive the sensor electronics for processing signals related to the monitored analyte level, including storing, filtering, processing and communicating to a remote location. In this manner, sensor electronics coupled to the self-powered analyte sensor does not require a separate power source such as a battery to power the sensor electronics for processing signals related to the monitored analyte level including storing the generated and processed signals. 
     In some embodiments, a remote device such as a display device is configured to generate a magnetic field which, when positioned in close proximity to the sensor electronics, latches a switch in the sensor electronics to drive the charge stored in the sensor electronics capacitor device (generated from the self-powered sensor) to connect the remaining portions of the sensor electronics, effectively powering the sensor electronics solely from the charge stored in the capacitor that was generated by the self-powered sensor. 
     In a further embodiment, the self-powered sensor and sensor electronics are provided in a sealed housing and which does not include electronic components susceptible to sterilization processes for the sensor, and that would otherwise degrade or damage such electronic components. In this manner, in certain embodiments, a single enclosed housing including sensor electronics and the analyte sensor are provided which can be sterilized together using a single sterilization technique without damaging or degrading the components of the on body sensor device. 
     A method of monitoring analyte levels, in certain embodiments, includes transcutaneously positioning an analyte sensor in fluid contact with interstitial fluid under a skin surface, accumulating charge for a predetermined time period in a capacitor device in sensor electronics, the capacitor device in signal communication with the analyte sensor and receiving signals from the analyte sensor, detecting a magnetic field exceeding a threshold level, latching a switch provided in the sensor electronics to couple the capacitor device in the sensor electronics to sensor signal processing components when the detected magnetic field exceeds the threshold level, and connecting the capacitor device to the sensor signal processing components to provide power to the sensor signals processing components with the accumulated charge in the capacitor device. 
     A device for monitoring analyte level, in certain embodiments, includes an analyte sensor for transcutaneous positioning in fluid contact with interstitial fluid, sensor electronics including: sensor signal processing components, a capacitor device operatively coupled to the analyte sensor to accumulate charge for a predetermined time period, and a switch configured to latch, when a magnetic field exceeding a threshold level is detected, to couple the capacitor device to sensor signal processing components, where when the switch is latched, the capacitor device is configured to provide power to the sensor signals processing components with the accumulated charge in the capacitor device. 
     Various other modifications and alterations in the structure and method of operation of this disclosure will be apparent to those skilled in the art without departing from the scope and spirit of the embodiments of the present disclosure. Although the present disclosure has been described in connection with particular embodiments, it should be understood that the present disclosure as claimed should not be unduly limited to such particular embodiments. It is intended that the following claims define the scope of the present disclosure and that structures and methods within the scope of these claims and their equivalents be covered thereby.