406. In some non-limiting embodiments, the housing 406 may include one or more cutouts or recesses, and the one or more indicator structures 409 may be located (partially or entirely) in the cutouts or recesses. In some embodiments, the one or more indicator structures 409 may be porous and may allow the analyte (e.g., glucose) in the first medium (e.g., interstitial fluid) to diffuse into the one or more indicator structures 409.

In some embodiments, the analyte sensor 100 may include a transceiver interface for communicating with the transceiver 101. In some embodiments, the transceiver 101 may be an electronic device that communicates with the analyte sensor 100 to power the analyte sensor 100 and/or receive measurement data (e.g., photodetector and/or temperature sensor readings) from the analyte sensor 100. In some embodiments, the transceiver 101 may calculate one ore more analyte concentrations from the measurement data received from the analyte sensor 100. However, it is not required that the transceiver 101 perform the analyte concentration calculations itself, and, in some alternative embodiments, the transceiver 101 may additionally or alternatively convey/relay the measurement data received from the analyte sensor 100 to another device (e.g., the display device 107) for calculation of analyte concentrations. In other alternative embodiments, the analyte sensor 100 may perform the analyte concentration calculations and convey the calculated analyte concentrations to the transceiver 101.

In some embodiments, the transceiver interface of the analyte sensor 100 may include an antenna for wireless communication with the transceiver 101. In some of alternative embodiments (e.g., transcutaneous embodiments), the transceiver interface may include a wired connection between the analyte sensor 100 and the transceiver 101.

In some embodiments (e.g., embodiments in which the analyte sensor 100 is a fully implantable sensing system), the transceiver 101 may implement a passive telemetry for communicating with the analyte sensor 100 via an inductive magnetic link for power and/or data transfer. In some embodiments, as shown in FIGS. 2A and 2B, the transceiver interface of the analyte sensor 100 may include an inductor 517, which may be, for example, a ferrite based micro-antenna. In some embodiments, as shown in FIGS. 2A and 2B, the inductor 517 may include a conductor 518 in the form of a coil and a magnetic core 519. In some non-limiting embodiments, the core 519 may be, for example and without limitation, a ferrite core. In some embodiments, the inductor 517 may be connected to circuitry (e.g., an application specification integrated circuit (ASIC)) of the analyte sensor 100. In some embodiments, the analyte sensor 100 may not include a battery, and, as a result, the analyte sensor 100 may rely on the transceiver 101 to provide power for the analyte sensor 100 of the system 105 and a data link to convey data from the analyte sensor 100 to the transceiver 101.

In some non-limiting embodiments, the transceiver 101 may provide energy to run the analyte sensor 100 via a magnetic field. In some embodiments, the magnetic external device-implantable device link can be considered as “weakly coupled transformer” type. In some non-limiting embodiments, the transceiver 101 and analyte sensor 100 may communicate using near field communication (e.g., at a frequency of 13.56 MHz, which can achieve high penetration through the skin and is a medically approved frequency band) for power transfer. However, this is not required, and, in other embodiments, different frequencies may be used for powering and communicating with the analyte sensor 100.

Although in some embodiments, as illustrated in FIGS. 1A-2B, the analyte sensor 100 may be a fully implantable sensor, this is not required, and, in some alternative embodiments, the analyte sensor 100 may be a transcutaneous device having a wired connection to the transceiver 101. For example, in some alternative embodiments, the analyte sensor 100 may be located in or on a transcutaneous needle (e.g., at the tip thereof). In these embodiments, instead of wirelessly communicating using inductors, the analyte sensor 100 and transceiver 101 may communicate using one or more wires connected between the transceiver 101 and the transcutaneous needle that includes the analyte sensor 100. For another example, in some alternative embodiments, the analyte sensor 100 may be located in a catheter (e.g., for intravenous blood glucose monitoring) and may communicate (wirelessly or using wires) with the transceiver 101.

In some embodiments, as shown in FIGS. 2A and 2B, the analyte sensor 100 may include a substrate 516. In some non-limiting embodiments, the substrate 516 may be a circuit board (e.g., a printed circuit board (PCB) or flexible PCB) on which one or more of circuit components (e.g., analog and/or digital circuit components) may be mounted or otherwise attached. However, in some alternative embodiments, the substrate 516 may be a semiconductor substrate.

In some embodiments, as shown in FIG. 2B, the analyte sensor 100 may include one or more light sources (e.g., one or more analyte excitation light sources 411 and/or one or more interferent excitation light sources 418), and one or more of the light sources may be mounted on or fabricated within in the substrate 516. In some embodiments, the analyte sensor 100 may include one or more photodetectors (e.g., photodiodes, phototransistors, photoresistors, or other photosensitive elements), and one or more of the photodetectors may be mounted on or fabricated in the substrate 516. In some embodiments, the photodetectors may include one or more analyte photodetectors 415 and/or one or more interferent photodetectors 407. In some embodiments, the In some non-limiting embodiments, one or more light sources may be mounted on the substrate 516, one or more photodetectors may be fabricated within the substrate 516, and all or a portion of the circuit components may be fabricated within the substrate 516.

Although the analyte sensor 100′ illustrated in FIGS. 2A and 2B has one substrate 516, this is not required, and, in some alternative embodiments, the analyte sensor 100′ may include more than one substrate 516 (e.g., more than one semiconductor substrate). In some non-limiting alternative embodiments, a portion of the photodetectors (e.g., one or more photodetectors 415) may be on or in a first substrate, and a portion of the photodetectors (e.g., one or more photodetectors 407) may be on or in a second substrate that is separate and distinct from the first substrate. In some non-limiting alternative embodiments, one or more light sources (e.g., one or more analyte excitation light sources 411) may be on the first substrate, and one or more light sources (e.g., one or more interferent excitation light sources 418) may be on the second substrate that is separate and distinct from the first substrate.

FIG. 3 is a schematic view illustrating the layout of substrate 516 that is a semiconductor substrate embodying aspects of the present invention. As shown in FIG. 3, the semiconductor substrate 516 may have one or more of circuit components fabricated therein. For instance, the fabricated circuit components 620 may include analog and/or digital circuitry. Also, in some embodiments in which the substrate 516 is a semiconductor substrate, in addition to the circuit components 620 fabricated in the semiconductor substrate, circuit components may be mounted or otherwise attached to the semiconductor substrate. In other words, in some semiconductor substrate embodiments, a portion or all of the circuit components, which may include discrete circuit elements, an integrated circuit (e.g., an application specific integrated circuit (ASIC)) and/or other electronic components (e.g., a non-volatile memory), may be fabricated in the semiconductor substrate with the remainder of the circuit components is secured to the semiconductor substrate, which may provide communication paths between the various secured components.

In some embodiments, as shown in FIG. 4, the one or more indicator structures 409 (e.g., polymer grafts or hydrogels) of the analyte sensor 100 may include one or more analyte indicators 410. In some embodiments, the analyte indicator 410 may produce (e.g., exhibit) one or more detectable properties (e.g., optical properties) that vary in accordance with the amount or concentration of the analyte in proximity to the one or more indicator structures 409. In some non-limiting embodiments, in response to being irradiated with analyte excitation light 412, the analyte indicator 410 may emit an amount of analyte emission light 414 that varies in accordance with the amount or concentration of the analyte in proximity to the one or more indicator structures 409. In some embodiments, the analyte emission light 414 may be within an analyte emission wavelength range. In some embodiments, the analyte indicator 410 may include one or more analyte indicator molecules (e.g., fluorescent analyte indicator molecules), which may be distributed throughout the indicator structure 409. In some non-limiting embodiments, the one or more analyte indicator molecules may be configured to reversibly bind the analyte, and the one or more detectable properties produced may be indicative of whether the analyte is bound. In some non-limiting embodiments, the analyte emission light 414 may be fluorescent light. In some non-limiting embodiments, the analyte indicator 410 may be a phenylboronic-based analyte indicator. However, a phenylboronic-based analyte indicator is not required, and, in some alternative embodiments, the implantable device 100 may include a different analyte indicator, such as, for example and without limitation, a glucose oxidase-based indicator, a glucose dehydrogenase-based indicator, or a glucose binding protein-based indicator.

In some embodiments, as shown in FIG. 4, the analyte sensor 100 may include one or more analyte excitation light sources 411 that emit the analyte excitation light 412 over an excitation wavelength range of at least the analyte indicator 410. In some non-limiting embodiments, the wavelength range may include wavelengths that interact with at least the analyte indicator 410 in the indicator structure 409. In some non-limiting embodiments, the analyte excitation light 412 may be, for example and without limitation, ultraviolet (UV) light.

In some embodiments, the analyte sensor 100 may include one or more analyte detectors configured to detect a detectable property of the analyte indicator 410 and output an analyte signal indicative of the amount or concentration of the analyte in the medium within the living animal. In some embodiments, as shown in FIG. 4, the one or more analyte detectors of the analyte sensor 100 may include one or more analyte photodetectors 415. In some non-limiting embodiments, the one or more analyte photodetectors 415 may be configured to output an analyte signal indicative of an amount of the analyte emission light 414 received by the one or more analyte photodetectors 415. In some non-limiting embodiments, the one or more analyte photodetectors 415 may be configured to output an analyte signal indicative of an amount of the analyte emission light 414 received by the one or more analyte photodetectors 415 because one or more optical filters may prevent light outside the analyte emission wavelength range (i.e., light outside the wavelength range of the analyte emission light 414 emitted by the analyte indicator 410) from reaching the one or more analyte photodetectors 415. In some embodiments, as the amount of analyte emission light 414 emitted by the analyte indicator 410 varies in in accordance with the amount or concentration of the analyte in proximity to the indicator structure 409, the analyte signal output by the one or more analyte photodetectors 415 may be indicative of an amount or concentration of the analyte in the first medium in proximity to the indicator structure 409. In some embodiments, the circuit components (e.g., circuit components 620) of the analyte sensor 100 may include one or more circuit components (e.g., an analog-to-digital converter) configured to convert the analyte signal into one or more analyte measurements.

In some embodiments, one or more interferents (e.g., insulin or blood) in the first medium (e.g., interstitial fluid) may interfere with accurate measurement of the analyte (e.g., glucose) in the first medium. In some non-limiting embodiments, the analyte sensor 100 may measure the amount or concentration of one or more interferents in proximity to the one or more indicator structures 409. In some non-limiting embodiments, as shown in FIG. 4, the one or more indicator structures 409 of the analyte sensor 100 may include one or more interferent indicators 413 that may be used to measure the amount or concentration of one or more interferents. In some non-limiting embodiments, as shown in FIG. 4, the one or more indicator structures 409 of the analyte sensor 100 may include one or more of a first interferent indicator 413a and a second interferent indicator 413b that may be used to measure the amount or concentration of a first interferent and a second interferent, respectively.

In some embodiments, the first interferent indicator 413a may produce (e.g., exhibit) one or more detectable properties (e.g., optical properties) that vary in accordance with the amount or concentration of a first interferent in proximity to the one or more indicator structures 409. In some non-limiting embodiments, the first interferent indicator 413a may emit an amount of first interferent emission light 416 that varies in accordance with the amount or concentration of the first interferent in proximity to the one or more indicator structures 409. In some embodiments, the first interferent emission light 416 may be within a first interferent emission wavelength range. In some embodiments, the first interferent indicator 413a may include one or more first interferent indicator molecules (e.g., fluorescent interferent indicator molecules), which may be distributed throughout the indicator structure 409. In some non-limiting embodiments, the one or more first interferent indicator molecules may be configured to reversibly bind the first interferent, and the one or more detectable properties produced may be indicative of whether the first interferent is bound. In some non-limiting embodiments, the first interferent indicator 413a may be a phenylboronic-based interferent indicator. However, a phenylboronic-based interferent indicator is not required, and, in some alternative embodiments, the implantable device 100 may include a different first interferent indicator.

In some embodiments, the second interferent indicator 413b may produce (e.g., exhibit) one or more detectable properties (e.g., optical properties) that vary in accordance with the amount or concentration of a second interferent in proximity to the one or more indicator structures 409. In some non-limiting embodiments, the first and second interferents may be different interferents. In some non-limiting embodiments, the first interferent may be insulin, and the second interferent may be blood. In some non-limiting embodiments, the second interferent indicator 413b may emit an amount of second interferent emission light 417 that varies in accordance with the amount or concentration of the second interferent in proximity to the one or more indicator structures 409. In some embodiments, the second interferent emission light 417 may be within a second interferent emission wavelength range. In some embodiments, the second interferent indicator 413b may include one or more second interferent indicator molecules (e.g., fluorescent interferent indicator molecules), which may be distributed throughout the indicator structure 409. In some non-limiting embodiments, the one or more second interferent indicator molecules may be configured to reversibly bind the second interferent, and the one or more detectable properties produced may be indicative of whether the second interferent is bound. In some non-limiting embodiments, the second interferent indicator 413b may be a phenylboronic-based interferent indicator. However, a phenylboronic-based interferent indicator is not required, and, in some alternative embodiments, the implantable device 100 may include a different first interferent indicator.

In some embodiments, as shown in FIG. 4, the first interferent indicator 413a may emit the first interferent emission light 416 in response to being irradiated with the analyte excitation light 412 emitted by the one or more analyte excitation light sources 411. In some embodiments, the first excitation wavelength range of the analyte excitation light 412 may include wavelengths that interact with at least the first interferent indicator 413a in the indicator structure 409. In some embodiments, as shown in FIG. 4, the second interferent indicator 413b may emit the second interferent emission light 417 in response to being irradiated with the analyte excitation light 412 emitted by the one or more analyte excitation light sources 411. In some embodiments, the first excitation wavelength range of the analyte excitation light 412 may include wavelengths that interact with at least the second interferent indicator 413b in the indicator structure 409.

In some embodiments, the analyte sensor 100 may include one or more interferent detectors configured to detect a detectable property of the one or more interferent indicators 413 and output an interferent signal indicative of the amount or concentration of the interferent in the medium within the living animal. In some embodiments, as shown in FIG. 4, the one or more interferent detectors of the analyte sensor 100 may include one or more interferent photodetectors 407. In some embodiments, as shown in FIG. 4, the one or more interferent photodetectors 407 may include one or more first interferent photodetectors 407a. In some non-limiting embodiments, the one or more first interferent photodetectors 407a may be configured to output a first interferent signal indicative of an amount of the first interferent emission light 416 (e.g., fluorescent light) received by the one or more first interferent photodetectors 407a. In some non-limiting embodiments, the one or more first interferent photodetectors 407a may be configured to output a first interferent signal indicative of an amount of the first interferent emission light 416 received by the one or more first interferent photodetectors 407a because one or more optical filters may prevent light outside the wavelength range of the first interferent emission light 416 emitted by the first interferent indicator 413a from reaching the one or more first interferent photodetectors 407a. In some embodiments, the analyte emission wavelength range of the analyte emission light 414 may be different than the first interferent emission wavelength range of the first interferent emission light 416 (e.g., the analyte emission wavelength range and the first interferent emission wavelength range may be non-overlapping wavelength ranges). In some embodiments, as the amount of first interferent emission light 416 emitted by the first interferent indicator 413a varies in in accordance with the amount or concentration of the first interferent in proximity to the indicator structure 409, the first interferent signal output by the one or more first interferent photodetectors 407a may be indicative of an amount or concentration of a first interferent in a medium in proximity to the indicator structure 409. In some embodiments, the circuit components (e.g., circuit components 620) of the analyte sensor 100 may include one or more circuit components (e.g., an analog-to-digital converter) configured to convert the first interferent signal into one or more first interferent measurements.

In some embodiments, as shown in FIG. 4, the one or more interferent photodetectors 407 may additionally or alternatively include one or more second interferent photodetectors 407b. In some non-limiting embodiments, the one or more second interferent photodetectors 407b may be configured to output a second interferent signal indicative of an amount of the second interferent emission light 417 (e.g., fluorescent light) received by the one or more second interferent photodetectors 407b. In some non-limiting embodiments, the one or more second interferent photodetectors 407b may be configured to output a second interferent signal indicative of an amount of the second interferent emission light 417 received by the one or more second interferent photodetectors 407b because one or more optical filters may prevent light outside the wavelength range of the second interferent emission light 417 emitted by the second interferent indicator 413b from reaching the one or more second interferent photodetectors 407b. In some embodiments, the second interferent emission wavelength range of the second interferent emission light 417 may different than the analyte emission wavelength range of the analyte emission light 414 and different than the first interferent emission wavelength range of the first interferent emission light 416 (e.g., the wavelength ranges may be non-overlapping wavelength ranges). In some embodiments, as the amount of second interferent emission light 417 emitted by the second interferent indicator 413b varies in in accordance with the amount or concentration of the second interferent in proximity to the indicator structure 409, the second interferent signal output by the one or more second interferent photodetectors 407b may be indicative of an amount or concentration of a second interferent in the medium in proximity to the indicator structure 409. In some embodiments, the circuit components (e.g., circuit components 620) of the analyte sensor 100 may include one or more circuit components (e.g., an analog-to-digital converter) configured to convert the second interferent signal into one or more second interferent measurements.

In some embodiments, as shown in the FIG. 4, the analyte sensor 100 may include one or more light source drivers 424. In some embodiments, the one or more light source drivers 424 may be mounted on or fabricated in one or more substrates 516 of the analyte sensor 100 (e.g., one light source driver 424 per substrate 516). In some embodiments, the one or more light source drivers 424 may drive the one or more analyte excitation light sources 411 to emit the analyte excitation light 412. In some embodiments, the one or more light source drivers 424 may drive one or more of the analyte excitation light sources 411 under the control of one or more measurement controllers (e.g., a measurement controller may be mounted on or fabricated on each substrate 516 and may control any light source driver 424 mounted on or fabricated on the same substrate 516). In some non-limiting embodiments, all or a portion of one or more of the light source driver 424 and the measurement controller may be included in the circuit components 620 fabricated in a semiconductor substrate 516 of the analyte sensor 100 (see FIG. 3).

In some alternative embodiments, as shown in FIGS. 5A and 5B, the analyte sensor 100 may include one or more interferent excitation light sources 418. In some of these alternative embodiments, the wavelength range of the analyte excitation light source 411 may not include wavelengths that interact with one or more of the first and second interferent indicators 413a and 413b. In some of these alternative embodiments, as shown in FIG. 5A, the analyte indicator 410 may emit analyte emission light 412 in response to being irradiated by analyte excitation light 412, but the first and second interferent indicators 413a and 413b may not respond to the analyte emission light 412. In some embodiments, as shown in FIG. 5B, the one or more interferent excitation light sources 418 may emit interferent excitation light 419 over an excitation wavelength range of one or more of the first and second interferent indicators 413a and 413b. In some non-limiting embodiments, the wavelength range may include wavelengths that interact with one or more of the first and second interferent indicators 413a and 413b of the indicator structure 409. In some non-limiting embodiments, the interferent excitation light 419 may be, for example and without limitation, red or blue light. In some non-limiting embodiments, the wavelength range of the interferent excitation light 419 may be different than the wavelength range of the analyte excitation light 412. In some non-limiting embodiments, the wavelength range of the interferent excitation light 419 and the wavelength range of the analyte excitation light 412 may be non-overlapping wavelength ranges. In some of these alternative embodiments, as shown in FIG. 5B, the first and second interferent indicators 413a and 413b may emit first and second interferent emission light 416 and 417, respectively, in response to being irradiated by the interferent excitation light 419, but the analyte indicator 410 may not respond to the interferent excitation light 419.

In some embodiments, as shown in the FIGS. 5A and 5B, the one or more light source drivers 424 of the analyte sensor 100 may drive the one or more analyte excitation light sources 411 and/or the one or more interferent excitation light sources 418 to emit the analyte excitation light 412 and interferent excitation light 419, respectively. In some embodiments, the one or more light source drivers 424 may drive the one or more analyte excitation light sources 411 and/or the one or more interferent excitation light sources 418 under the control of one or more measurement controllers. In some embodiments, as shown in FIGS. 5A and 5B, the analyte sensor 100 (e.g., the measurement controller(s) and/or light source driver(s) 1424 of the implantable device 100) may be configured such that the one or more analyte excitation light sources 411 and the one or more interferent excitation light sources 418 emit the analyte excitation light 412 and interferent excitation light 419 at different times. For example, the one or more analyte excitation light sources 411 may emit the analyte excitation light 412 during first time periods, and the one or more interferent excitation light sources 418 may emit the interferent excitation light 419 during second time periods that are different than the first time periods. In one non-limiting embodiment, the analyte sensor 100 may cycle through the first and second time periods multiple times (e.g., 30 times) during a measurement period (e.g., 1 second). In some non-limiting embodiments, the cycle may additionally include third time periods during which both the analyte and interferent excitation light sources 411 and 418 are off. However, the analyte and interferent excitation light sources 411 and 418 are not required to emit the excitation light 412 and 419 at different times, and, in some alternative embodiments, the analyte sensor 100 (e.g., the measurement controller(s) and/or light source driver(s) 1424 of the implantable device 100) may be configured such that the one or more analyte excitation light sources 411 and the one or more interferent excitation light sources 418 emit the analyte excitation light 412 and interferent excitation light 419 simultaneously.

In some alternative embodiments, as shown in FIGS. 6A-6C, the analyte sensor 100 may include one or more first interferent excitation light sources 418a and one or more second interferent excitation light sources 418b. In some of these alternative embodiments, the wavelength range of the analyte excitation light source 411 may not include wavelengths that interact with the first and second interferent indicators 413a and 413b. In some of these alternative embodiments, as shown in FIG. 6A, the analyte indicator 410 may emit analyte emission light 412 in response to being irradiated by analyte excitation light 412, but the first and second interferent indicators 413a and 413b may not respond to the analyte emission light 412. In some of these alternative embodiments, as shown in FIG. 6B, the one or more first interferent excitation light sources 418a may emit first interferent excitation light 419a over an excitation wavelength range of the first interferent indicator 413a. In some non-limiting embodiments, the wavelength range may include wavelengths that interact with the first interferent indicator 413a of the indicator structure 409. In some of these alternative embodiments, as shown in FIG. 6B, the first interferent indicator 413a may emit first interferent emission light 416 in response to being irradiated by the first interferent excitation light 419a, but the analyte indicator 410 and the second interferent indicator 413b may not respond to the first interferent excitation light 419a. In some of these alternative embodiments, as shown in FIG. 6C, the one or more second interferent excitation light sources 418b may emit second interferent excitation light 419b over an excitation wavelength range of the second interferent indicator 413b. In some non-limiting embodiments, the wavelength range may include wavelengths that interact with the second interferent indicator 413b of the indicator structure 409. In some of these alternative embodiments, as shown in FIG. 6C, the second interferent indicator 413b may emit second interferent emission light 417 in response to being irradiated by the second interferent excitation light 419b, but the analyte indicator 410 and the first interferent indicator 413a may not respond to the second interferent excitation light 419b. In some non-limiting embodiments, the wavelength range of the analyte excitation light 412, the wavelength range of the first interferent excitation light 419a, and the wavelength range of the second interferent excitation light 419b may all be different. In some non-limiting embodiments, the wavelength range of the analyte excitation light 412, the wavelength range of the first interferent excitation light 419a, and the wavelength range of the second interferent excitation light 419b may be non-overlapping wavelength ranges.

In some embodiments, as shown in the FIGS. 6A-6C, the one or more light source drivers 424 of the analyte sensor 100 may drive the one or more analyte excitation light sources 411, the one or more first interferent excitation light sources 418a, and/or the one or more second interferent excitation light sources 418b to emit the analyte excitation light 412, the first interferent excitation light 419a, and the second interferent excitation light 419b, respectively. In some embodiments, the one or more light source drivers 424 may drive the one or more analyte excitation light sources 411, the one or more first interferent excitation light sources 418a, and the one or more second interferent excitation light sources 418b under the control of one or more measurement controllers. In some embodiments, as shown in FIGS. 6A-6C, the analyte sensor 100 (e.g., the measurement controller(s) and/or light source driver(s) 1424 of the implantable device 100) may be configured such that the one or more analyte excitation light sources 411, the one or more first interferent excitation light sources 418a, and the one or more second interferent excitation light sources 418b emit the analyte excitation light 412, the first interferent excitation light 419a, and the second interferent excitation light 419b at different times. For example, the one or more analyte excitation light sources 411 may emit the analyte excitation light 412 during first time periods, the one or more first interferent excitation light sources 418a may emit the first interferent excitation light 419a during second time periods that are different than the first time periods, and the one or more second interferent excitation light sources 418b may emit the second interferent excitation light 419 during third time periods that are different than the first and second time periods. In one non-limiting embodiment, the analyte sensor 100 may cycle through the first, second, and third time periods multiple times (e.g., 30 times) during a measurement period (e.g., 1 second). In some non-limiting embodiments, the cycle may additionally include fourth time periods during which all of the analyte and interferent excitation light sources 411, 418a, and 418b are off. However, the analyte and interferent excitation light sources 411, 418a, and 418b are not required to emit the excitation light 412 and 419 at different times, and, in some alternative embodiments, the analyte sensor 100 (e.g., the measurement controller(s) and/or light source driver(s) 1424 of the implantable device 100) may be configured such that the one or more analyte excitation light sources 411, the one or more first interferent excitation light sources 418a, and the one or more second interferent excitation light sources 418b emit the analyte excitation light 412, the first interferent excitation light 419a, and the second interferent excitation light 419b simultaneously. In some other alternative embodiments, the analyte sensor 100 may be configured such that two of the excitation light sources 411, 418a, and 418b (e.g., the first and second interferent excitation light sources 418a and 418b) emit excitation light (e.g., the first and second interferent excitation light 419a and 419b) simultaneously and the other one of the excitation light sources 411, 418a, and 418b (e.g., the analyte excitation light source 411) emits analyte excitation light 412 at a different time.

FIGS. 7A-7C are perspective, side, and cross-sectional views, respectively, of an analyte sensor 100″ that is a second non-limiting example of the analyte sensor 100 of the analyte monitoring system 50. FIGS. 7D, 7E, and 7F are perspective and side views, respectively, of an analyte sensor 100′″ that is a third non-limiting example of the analyte sensor 100 of the analyte monitoring system 50. In some embodiments, as shown in FIGS. 7A-7F, the analyte sensor 100 may include more than one substrate 516. In some embodiments, as shown in FIG. 7D, the analyte sensor 100 may include two or more indicator structures 409. In some embodiments, as shown in FIGS. 7E and 7F, the analyte sensor 100 may include a substrate 516 for each of the two or more indicator structures 409.

In some embodiments, as shown in FIGS. 7A-7C, the analyte sensor 100 may include one substrate 516 on one side of an inductor 517 and another substrate 516 on an opposite side of the inductor 517. Also, in some embodiments, as shown in FIGS. 7A-7C, the analyte sensor 100 may additionally or alternatively have one or more circuit components 722 (e.g., capacitors) mounted to the inductor 517.

In some alternative embodiments, as shown in FIGS. 7D-7F, the implantable device 100 may include two or more substrates 516 on one side of an inductor 517. In some non-limiting embodiments, as shown in FIG. 7E, one or more analyte photodetectors 415, one or more first interferent photodetectors 407a, and/or one or more second interferent photodetectors 407b may be mounted on or fabricated in each of the two or more substrates 516. However, this is not required, and, in some alternative embodiments, the one or more analyte photodetectors 415 may be mounted on or fabricated in only one of the substrates 516, and the one or more first interferent photodetectors 407a and/or one or more second interferent photodetectors 407b may be mounted on or fabricated in only another one of the substrates 516.

FIGS. 7G-7I illustrate non-limiting examples of the indicator structures 409 of an analyte sensor 100 including two or more indicator structures 409. In some embodiments in which the analyte sensor 100 includes two or more indicator structures 409 (e.g., analyte sensor 100′″), each of the two or more indicator structures 409 may be the same. For example, as shown in FIG. 7G, each of the two or more indicator structures 409 may include one or more of an analyte indicator 410, a first interferent indicator 413a, and a second interferent indicator 413b. In some alternative embodiments, in which the analyte sensor 100 includes two or more indicator structures 409 (e.g., analyte sensor 100′″), two or more of the indicator structures 409 may be different. For example, as shown in FIG. 7H, one indicator structure 409a may include an analyte indicator 410, and another indicator structure 409b may include one or more of a first interferent indicator 413a and a second interferent indicator 413b. For another example, as shown in FIG. 7I, a first indicator structure 409a may include an analyte indicator 410 (and may not include any interferent indicators 413), a second indicator structure 409b may include a first interferent indicator 413a (and may include neither an analyte indicator 410 nor a second interferent indicator 413b), and a third indicator structure 409c may include a second interferent indicator 413b (and may include neither an analyte indicator 410 nor a first interferent indicator 413a).

In some embodiments, one or more of the indicator structures 409, light source(s) 411 and 418, photodetectors 407a, 407b, 415, circuit components, and substrates 516 of the analyte sensor 100 may include some or all of the features described in one or more of U.S. application Ser. No. 15/709,679, filed on Sep. 20, 2017, U.S. application Ser. No. 14/629,943, filed on Feb. 24, 2015, U.S. application Ser. No. 14/594,674, filed on Jan. 12, 2015, U.S. application Ser. No. 13/761,839, filed on Feb. 7, 2013, U.S. application Ser. No. 13/937,871, filed on Jul. 9, 2013, U.S. application Ser. No. 13/650,016, filed on Oct. 11, 2012, and U.S. application Ser. No. 14/142,017, filed on Dec. 27, 2013, all of which are incorporated by reference in their entireties. Similarly, the structure, function, and/or features of the sensor housing 406, analyte sensor 100, and/or transceiver 101 may be as described in one or more of U.S. application Ser. Nos. 13/761,839, 13/937,871, 13/650,016, and 14/142,017. Although not shown in FIGS. 1B-7I, in some embodiments, the analyte sensor 100 (e.g., the circuit components of the analyte sensor 100) may include one or more temperature transducers capable of measuring temperature. Although in some aspects, as illustrated in FIGS. 1B-7I, the analyte sensor 100 may be an optical sensor, this is not required, and, in one or more alternative aspects, sensor 100 may be a different type of analyte sensor, such as, for example, an electrochemical sensor, a diffusion sensor, or a pressure sensor.

In some alternative embodiments, instead of (or in addition to) the one or more interferent detectors being configured to detect a detectable property of the one or more interferent indicators 413, the one or more interferent detectors (e.g., the one or more first interferent photodetectors 418a and/or the one or more second interferent photodetectors 418b) configured to output an interferent signal indicative of the amount or concentration of the interferent in the medium within the living animal may be absorption or reflectance sensors. For example, insulin has an absorption peak, and the one or more interferent sensor may measure the extent to which the interstitial fluid absorbs one or more wavelengths of light. In some non-limiting embodiments in which the one or more interferent detectors include absorption or reflectance sensors, the analyte sensor 100 may not include the one or more interferent indicators 413.

FIG. 8 is a schematic view of an external transceiver 101 according to a non-limiting embodiment. In some aspects, as shown in FIG. 8, the transceiver 101 may have a connector 902, such as, for example, a Micro-Universal Serial Bus (USB) connector. The connector 902 may enable a wired connection to an external device, such as a personal computer or a display device 107 (e.g., a smartphone).

The transceiver 101 may exchange data to and from the external device through the connector 902 and/or may receive power through the connector 902. The transceiver 101 may include a connector integrated circuit (IC) 904, such as, for example, a USB-IC, which may control transmission and receipt of data through the connector 902. The transceiver 101 may also include a charger IC 906, which may receive power via the connector 902 and charge a battery 908 (e.g., lithium-polymer battery). In some aspects, the battery 908 may be rechargeable, may have a short recharge duration, and/or may have a small size.

In some aspects, the transceiver 101 may include one or more connectors in addition to (or as an alternative to) Micro-USB connector 904. For example, in one alternative embodiment, the transceiver 101 may include a spring-based connector (e.g., Pogo pin connector) in addition to (or as an alternative to) Micro-USB connector 904, and the transceiver 101 may use a connection established via the spring-based connector for wired communication to a personal computer or a display device 107 (e.g., a smartphone) and/or to receive power, which may be used, for example, to charge the battery 908.

In some aspects, as shown in FIG. 8, the transceiver 101 may have a wireless communication IC 910, which enables wireless communication with an external device, such as, for example, one or more personal computers or one or more display devices 107 (e.g., a smartphone). In one non-limiting embodiment, the wireless communication IC 910 may employ one or more wireless communication standards to wirelessly transmit data. The wireless communication standard employed may be any suitable wireless communication standard, such as an ANT standard, a Bluetooth standard, or a Bluetooth Low Energy (BLE) standard (e.g., BLE 4.0). In some non-limiting aspects, the wireless communication IC 910 may be configured to wirelessly transmit data at a frequency greater than 1 gigahertz (e.g., 2.4 or 5 GHz). In some aspects, the wireless communication IC 910 may include an antenna (e.g., a Bluetooth antenna). In some non-limiting aspects, the antenna of the wireless communication IC 910 may be entirely contained within the housing (e.g., housing 206 and 220) of the transceiver 101. However, this is not required, and, in alternative aspects, all or a portion of the antenna of the wireless communication IC 910 may be external to the transceiver housing.

In some aspects, the transceiver 101 may include a display interface, which may enable communication by the transceiver 101 with one or more display devices 107. In some aspects, the display interface may include the antenna of the wireless communication IC 910 and/or the connector 902. In some non-limiting aspects, the display interface may additionally include the wireless communication IC 910 and/or the connector IC 904.

In some aspects, as shown in FIG. 8, the transceiver 101 may include voltage regulators 912 and/or a voltage booster 914. The battery 908 may supply power (via voltage booster 914) to radio-frequency identification (RFID) reader IC 916, which uses the inductor 103 to convey information (e.g., commands) to the sensor 101 and receive information (e.g., measurement information) from the sensor 100. In some non-limiting aspects, the sensor 100 and transceiver 101 may communicate using near field communication (NFC) (e.g., at a frequency of 13.56 MHz). In the illustrated embodiment, the inductor 103 is a flat antenna. In some non-limiting aspects, the antenna may be flexible. However, the inductor 103 of the transceiver 101 may be in any configuration that permits adequate field strength to be achieved when brought within adequate physical proximity to the inductor 114 of the sensor 100. In some aspects, the transceiver 101 may include a power amplifier 918 to amplify the signal to be conveyed by the inductor 103 to the sensor 100.

In some aspects, as shown in FIG. 8, the transceiver 101 may include a processor 920 and a memory 922 (e.g., Flash memory). In some non-limiting aspects, the memory 922 may be non-volatile and/or capable of being electronically erased and/or rewritten. In some non-limiting aspects, the processor 920 may be, for example and without limitation, a peripheral interface controller (PIC) microcontroller. In some aspects, the processor 920 may control the overall operation of the transceiver 101. For example, the processor 920 may control the connector IC 904 or wireless communication IC 910 to transmit data via wired or wireless communication and/or control the RFID reader IC 916 to convey data via the inductor 103. The processor 920 may also control processing of data received via one or more of the inductor 103, connector 902, and wireless communication IC 910.

In some aspects, the transceiver 101 may include a sensor interface, which may enable communication by the transceiver 101 with an analyte sensor 100. In some aspects, the sensor interface may include the inductor 103. In some non-limiting aspects, the sensor interface may additionally include the RFID reader IC 916 and/or the power amplifier 918. However, in some alternative aspects where there exists a wired connection between the analyte sensor 100 and the transceiver 101 (e.g., transcutaneous aspects), the sensor interface may include the wired connection.

In some aspects, as shown in FIG. 8, the transceiver 101 may include a display 924 (e.g., liquid crystal display and/or one or more light emitting diodes), which processor 920 may control to display data (e.g., analyte levels). In some aspects, the transceiver 101 may include a speaker 926 (e.g., a beeper) and/or a vibration motor 928, which may be activated, for example, in the event that an alarm condition (e.g., detection of a hypoglycemic or hyperglycemic condition) is met. The transceiver 101 may also include one or more additional sensors 930, which may include an accelerometer, temperature sensor, and/or one or more interferent sensors, that may be used in the processing performed by the processor 920. In some non-limiting embodiments in which the one or more additional sensors 930 of the transceiver 101 include one or more interferent sensors, the one or more interferent sensors may generate one or more interferent measurements indicative of a level of one or more interferents (e.g., a first interferent and/or a second interferent) in the first medium (e.g., interstitial fluid). In some non-limiting embodiments in which the one or more additional sensors 930 include one or more interferent sensors, the one or more interferent sensors may be include absorption or reflectance sensors. For example, insulin has an absorption peak, and the one or more interferent sensors may measure the extent to which the interstitial fluid absorbs one or more wavelengths of light. In some non-limiting embodiments in which the one or more additional sensors 930 include one or more interferent sensors, the interferent measurements generated by the one or more interferent sensors of the additional sensors 930 may be in addition, or as an alternative, to interferent measurements generated by the analyte sensor 100.

In some aspects, the transceiver 101 may be a body-worn transceiver that is a rechargeable, external device worn over the sensor implantation or insertion site. In some aspects, the transceiver 101 may be placed using an adhesive patch or a specially designed strap or belt. In some non-limiting aspects, the transceiver 101 may supply power to the proximate sensor 100. In some non-limiting aspects, power may be supplied to the sensor 100 through an inductive link (e.g., an inductive link of 13.56 MHz). However, it is not required that the sensor 100 receive power from the transceiver 101 (e.g., in the case of a battery-powered sensor).

In some embodiments, the transceiver 101 of the analyte monitoring system 50 may receive one or more sensor measurements indicative of an amount, level, or concentration of an analyte in a first medium (e.g., interstitial fluid (ISF)) in proximity to the analyte sensor 100. In some non-limiting embodiments, the one or more sensor measurements may include, for example and without limitation, light and/or temperature measurements (e.g., one or more measurements indicative of the level of analyte emission light 414 from one or more analyte indicators 410 as measured by one or more analyte photodetectors 415, one or more measurements indicative of the level of first interferent emission light from one or more first interferent indicators 413a as measured by one or more first interferent photodetectors 407a, one or more measurements indicative of the level of second interferent emission light from one or more second interferent indicators 413b as measured by one or more second interferent photodetectors 407b, and/or one or more temperature measurements as measured by one or more temperature transducers). In some embodiments, the transceiver 101 may receive the sensor measurements from the analyte sensor 100 periodically (e.g., every 1, 2, 5, 10, 15, or 20 minutes). However, this is not required, and, in some alternative aspects, the transceiver 101 may receive one or more sensor measurements (e.g., by swiping, hovering, or otherwise bringing the transceiver 101 in proximity to the sensor 101).

In some embodiments, the transceiver 101 may use the received sensor measurements to calculate a first medium analyte level (e.g., an ISF analyte level). In some embodiments, the transceiver 101 may use the calculated first medium analyte level and at least one or more previously calculated first medium analyte levels to calculate a rate of change of the first medium analyte level (“M1_ROC”). In some non-limiting embodiments, to calculate M1_ROC, the transceiver 101 may use just the calculated first medium analyte level and the most recent previously calculated first medium analyte level and determine M1_ROC as the difference between the calculated first medium analyte level and most recent previously calculated first medium analyte level divided by the time difference between a time stamp for the calculated first medium analyte level and a time stamp for the most recent previously calculated first medium analyte level. In some alternative embodiments, to calculate M1_ROC, the transceiver 101 may use the calculated first medium analyte level and a plurality of the most recent previously calculated first medium analyte levels. In some non-limiting embodiments, the plurality of the most recent previously calculated ISF analyte levels may be, for example and without limitation, the previous two calculated first medium analyte levels, the previous 20 calculated first medium analyte levels, or any number of previously calculated ISF analyte levels in between (e.g., the previous 5 calculated first medium analyte levels). In other alternative embodiments, to calculate M1_ROC, the transceiver 101 may use the calculated first medium analyte level and the previously calculated first medium analyte levels that were calculated during a time period. In some non-limiting embodiments, the time period may be, for example and without limitation, the last one minute, the last 60 minutes, or any amount of time in between (e.g., the last 25 minutes). In some embodiments where the transceiver 101 uses the calculated first medium analyte level and more than one previously calculated first medium analyte levels to calculate M1_ROC, the transceiver 101 may use, for example, linear or non-linear regression to calculate M1_ROC.

In some embodiments, the transceiver 101 may convert the calculated first medium analyte level into a second medium analyte level (e.g., a blood analyte level) by performing a lag compensation, which compensates for the lag between a second medium analyte level and an first medium analyte level (e.g., the lag between a blood analyte level and an ISF analyte level). In some embodiments, the transceiver 101 may calculate the second medium analyte level using at least the calculated first medium analyte level and the calculated M1_ROC. In some non-limiting embodiments, the transceiver 101 may calculate the second medium analyte level as M1_ROC/p₂+(1+p₃/p₂)*M1_analyte, where p₂is analyte diffusion rate, p₃is the analyte consumption rate, and M1_analyte is the calculated first medium analyte level.

In some embodiments, one or more interferents (e.g., insulin and blood) in the first medium (e.g., ISF) may affect the lag between the second medium analyte level and the first medium analyte level. For example and without limitation, one or more interferents in the first medium may affect the transfer of the analyte from the second medium (e.g., blood) to the first medium (e.g., interstitial fluid) in proximity to the sensor 100. In some embodiments, the analyte monitoring system 50 may use one or more interferent measurements indicative of the amount or concentration of one or more interferents in the first medium to improve the calculation of second medium analyte levels. In some non-limiting embodiments, the analyte monitoring system 50 may use one or more interferent measurements indicative of the amount or concentration of one or more interferents in the first medium to improve the conversion of a first medium analyte level to second medium analyte level.

In some embodiments, the transceiver 101 may use one or more analyte measurements (e.g., generated using the analyte signal output by the one or more analyte photodetectors 415) and one or more interferent measurements (e.g., one or more first interferent measurements generated using the first interferent signal output by the one or more first interferent photodetectors 407a and/or one or more second interferent measurements generated using the second interferent signal output by the one or more second interferent photodetectors 407b) received from the analyte sensor 100 to calculate a second medium analyte level. In some non-limiting embodiments, the transceiver 101 may adjust a conversion function used to calculate a second medium analyte level based on one or more interferent measurements. In some non-limiting embodiments, the transceiver 101 may adjust the conversion function by adjusting one or more parameters (e.g., one or more of the analyte diffusion rate and analyte consumption rate parameters) of the conversion function. In some non-limiting embodiments, the transceiver 101 may adjust one or more of p₂and p₃(or one or more of 1/p₂and p₃/p₂) in the conversion function that calculates a second medium analyte level as M1_ROC/p₂+(1+p₃/p₂)*M1_analyte. In some alternative embodiments, the transceiver 101 may select one of a plurality of conversion functions based on one or more interferent measurements.

In some embodiments, the transceiver 101 may calculate the second medium analyte level (e.g., blood analyte level) using at least one or more analyte measurements and one or more interferent measurements received from the analyte sensor 100. In some non-limiting embodiments, the transceiver 101 may calculate one or more interferent levels in the first medium using at least the one or more interferent measurements. In some non-limiting embodiments, interferent measurements may include one or more first interferent measurements and one or more second interferent measurements, and the transceiver 101 may calculate a first interferent level in the first medium using at least the one or more first interferent measurements and a second interferent level in the first medium using at least the one or more second interferent measurements. In some non-limiting embodiments, the transceiver 101 may calculate the second medium analyte level using at least one or more analyte measurements and the one or more calculated interferent levels (e.g., one or more calculated first interferent levels and/or one or more calculated second interferent levels). In some non-limiting embodiments, the transceiver 101 may adjust one or more parameters of the conversion function (e.g., one or more of the analyte diffusion rate and the analyte consumption rate) based on at least the one or more calculated interferent levels and may use the adjusted conversion function and the one or more analyte measurements to calculate the second medium analyte level. In some non-limiting alternative embodiments, the transceiver