ANALYTE SENSOR

• US 20160242685A1
• Filed: 02/24/2015
• Published: 08/25/2016
• Est. Priority Date: 02/24/2015
• Status: Active Grant

• Current Assignee: Senseonics, Incorporated (Senseonics Holdings, Inc.)
• Original Assignee: Senseonics, Incorporated (Senseonics Holdings, Inc.)
• Inventors: DeHennis, Andrew, Tankiewicz, Szymon, Whitehurst, Todd
• Granted Patent: US 9,901,293 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61B 2560/0214 of power generation or supply
• CPC Class Codes: A61B 5/0002 Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network A61B5/07 takes precedence; transmission systems for measured values G08C; transmission H04B; transmission of digital information H04L; wireless communication networks H04W
• CPC Class Codes: A61B 5/0075 by spectroscopy, i.e. measuring spectra, e.g. Raman spectroscopy, infrared absorption spectroscopy A61B5/0071 takes precedence
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/1459 invasive, e.g. introduced into the body by a catheter A61B5/1464 takes precedence

Abstract

Sensors and methods for measurement of an analyte in a medium within a living animal are described. The sensor may include an inductive element that may receive power from an external device. The sensor may also include a charge storage device (CSD) and a memory. The sensor may perform analyte measurements initiated by the external device using power received from the external device and convey the analyte measurements to the external device using the inductive element. The sensor also may perform autonomous analyte measurements using the on board charge device'"'"'s power and store the autonomous analyte measurements in the memory. The sensor may convey one or more stored analyte measurements to the external device using the inductive element using power received from the external device. The sensor may include a CSD-powered clock and a CSD-powered measurement scheduler that initiate the autonomous analyte measurements.

Claims

1. A sensor for implantation within a living animal and measurement of an analyte in a medium within the living animal, the sensor comprising:

an analyte indicator configured to exhibit a detectable property based on the amount or concentration of the analyte in the medium;

sensor elements configured to generate an analyte measurement signal based on the detectable property exhibited by the analyte indicator;

an inductive element configured to produce a current when in an electrodynamic field generated by an external device;

an input/output circuit configured to wirelessly convey measurement information to the external device via the inductive element;

a measurement controller; and

a charge storage device;

wherein the measurement controller is configured to;

(i) control the sensor elements to generate a first analyte measurement signal using power provided by the charge storage device while the inductive element is not in an electrodynamic field generated by the external device;

(ii) generate first measurement information based on the first analyte measurement signal; and

(iii) control the input/output circuit to wirelessly convey the first measurement information to the external device while the inductive element is in an electrodynamic field generated by the external device.

2. The sensor of claim 1, further comprising a nonvolatile storage medium.

3. The sensor of claim 2, wherein the measurement controller is further configured to store the first measurement information in the nonvolatile storage medium.

4. The sensor of claim 3, wherein the measurement controller is further configured to:

control the sensor elements to generate a second analyte measurement signal using the power provided by the charge storage device while the inductive element is not in an electrodynamic field generated by the external device;

generate second measurement information based on the second analyte measurement signal;

store the second measurement information in the nonvolatile storage medium; and

control the input/output circuit to wirelessly convey the second measurement information to the external device while the inductive element is in an electrodynamic field generated by the external device.

5. The sensor of claim 1, wherein the measurement controller is further configured to:

control the sensor elements to generate a second analyte measurement signal while the inductive element is in an electrodynamic field generated by the external device;

generate second measurement information based on the second analyte measurement signal; and

control the input/output circuit to wirelessly convey the second measurement information to the external device while the inductive element is in an electrodynamic field generated by the external device.

6. The sensor of claim 1, further comprising a clock that is powered by the charge storage device.

7. The sensor of claim 6, wherein the clock is a low-power oscillator, real time clock.

8. The sensor of claim 6, further comprising a measurement scheduler that is powered by the charge storage device and configured to issue a first autonomous measurement command based on an output of the clock, wherein the measurement controller is configured to control the sensor elements to generate the first analyte measurement signal in response to the first autonomous measurement command.

9. The sensor of claim 8, wherein the measurement scheduler is configured to issue autonomous measurement commands at periodic intervals based on the output of the clock.

10. The sensor of claim 8, further comprising a power switch configured to switch one or more of the sensor elements, the input/output circuit, and the measurement controller from being powered by externally supplied power to being powered by the charge storage device in response to the first autonomous measurement command.

11. The sensor of claim 1, wherein the input/output circuit comprises:

a capacitor; and

a tuning capacitor bank configured to dynamically tune an LC tank circuit comprising the inductive element and the capacitor and to change a resonant frequency of the LC tank circuit.

12. The sensor of claim 11, wherein the tuning capacitor bank comprises a varactor diode.

13. The sensor of claim 11, wherein the input/output circuit comprises an over-temperature protection circuit configured to control the tuning capacitor bank to detune the LC tank circuit so as to reduce power delivered by the LC tank circuit in the case of overheating of the sensor.

14. The sensor of claim 1, wherein detectable property exhibited by the analyte indicator is an optical characteristic responsive to the amount or concentration of the analyte in the medium, and the sensor elements comprise:

a first photodetector configured to output an analog light measurement signal indicative of the amount of light received by the first photodetector; and

a first light source configured to emit first excitation light to the analyte indicator.

15. The sensor of claim 14, wherein the sensor elements further comprise a second light source configured to emit second excitation light to the analyte indicator, wherein the first and second excitation lights have different wavelengths.

16. The sensor of claim 14, wherein the sensor elements further comprise a second photodetector configured to output an analog light measurement signal indicative of the amount of light received by the second photodetector.

17. The sensor of claim 16, further comprising:

a first optical filter configured to cover a photosensitive side of the first photodetector and to allow light having a first wavelength to pass through; and

a second optical filter configured to cover a photosensitive side of the second photodetector and to allow light having a second wavelength to pass through,

wherein the first and second wavelengths are different.

18. The sensor of claim 17, wherein the first and second optical filters are coated on the photosensitive sides of the first and second photodetectors, respectively.

19. The sensor of claim 14, further comprising a semiconductor substrate, wherein the first photodetector is fabricated in the semiconductor substrate.

20. The sensor of claim 1, wherein the input/output circuit comprises:

a rectifier configured to convert an alternating current produced by the inductive element while the inductive element is in an electrodynamic field generated by the external device to a direct current; and

a charger configured to recharge the charge storage device using the direct current generated by the rectifier.

21. The sensor of claim 1, wherein the sensor elements comprise:

photodetectors symmetrically arranged on either side of a center line running between the photodetectors; and

light sources having emission points on the center line.

22. The sensor of claim 1, wherein the first measurement information includes a time-stamp identifying the time at which the first measurement information was generated.

23. The sensor of claim 1, further comprising an analog to digital converter (ADC) configured to convert an analog analyte measurement signal to a digital analyte measurement signal.

24. The sensor of claim 1, wherein the sensor elements comprise:

a first temperature transducer configured to output a first analog temperature measurement signal indicative of a temperature of the sensor; and

a second temperature transducer configured to output a second analog temperature measurement signal indicative of the temperature of the sensor.

25. The sensor of claim 1, wherein the inductive element is a coil.

26. The sensor of claim 25, wherein the charge storage device and semiconductor substrate are located within the coil.

27. The sensor of claim 1, wherein the medium is interstitial, intravascular, or intraperitoneal fluid.

28. The sensor of claim 1, wherein the analyte is glucose.

29. The sensor of claim 1, wherein the input/output circuit comprises a monitor configured to detect whether the voltage of the charge storage device is above or below a threshold.

30. A method of using a sensor to measure an analyte in a medium within a living animal, the method comprising:

controlling the sensor elements of the sensor to generate a first analyte measurement signal using power provided by a charge storage device of the sensor while an inductive element of the sensor is not in an electrodynamic field generated by an external device, wherein the sensor elements are configured to generate the first analyte measurement signal based on a detectable property exhibited by an analyte indicator of the sensor, and the analyte indicator is configured to exhibit the detectable property based on the amount or concentration of the analyte in the medium;

generating first measurement information based on the first analyte measurement signal; and

controlling an input/output circuit of the sensor to wirelessly convey the first measurement information to the external device via the inductive element while the inductive element is in an electrodynamic field generated by the external device.

31. The method of claim 30, further comprising:

storing the first measurement information in a nonvolatile storage medium of the sensor;

controlling the sensor elements to generate a second analyte measurement signal using power provided by the charge storage device while the inductive element is not in an electrodynamic field generated by the external device;

generating second measurement information based on the second analyte measurement signal; and

controlling the input/output circuit of the sensor to wirelessly convey the stored second measurement information to the external device via the inductive element while the inductive element is in an electrodynamic field generated by the external device.

32. The method of claim 31, further comprising:

issuing an autonomous measurement command based on the output of a clock that is powered by the charge storage device; and

switching the sensor elements from being powered by externally supplied power to being powered by the charge storage device in response to the autonomous measurement command.

33. A sensor for implantation within a living animal and measurement of an analyte in a medium within the living animal, the sensor comprising:

an analyte indicator configured to exhibit a detectable property based on the amount or concentration of the analyte in the medium;

sensor elements configured to generate an analyte measurement signal based on the detectable property exhibited by the analyte indicator;

a measurement controller;

a non-volatile storage medium;

a charge storage device; and

a measurement scheduler that is powered by the charge storage device and is configured to issue an autonomous measurement command;

wherein the measurement controller is configured to;

(i) control the sensor elements to generate a first analyte measurement signal using power provided by the charge storage device in response to the autonomous measurement command;

(ii) generate first measurement information based on the first analyte measurement signal; and

(iii) store the first measurement information in the non-volatile storage medium.

34. The sensor of claim 33, further comprising a clock that is powered by the charge storage device, wherein the measurement scheduler is configured to use an output of the clock to determine when to issue the measurement command.

35. The sensor of claim 33, further comprising a power switch configured to switch one or more of the sensor elements and the measurement controller from being powered by the external device to being powered by the charge storage device in response to the autonomous measurement command.

36. A method of using a sensor to measure an analyte in a medium within a living animal, the method comprising:

using a charge storage device of the sensor to power a measurement scheduler;

using the measurement scheduler to issue an autonomous measurement command;

controlling sensor elements of the sensor to generate a first analyte measurement signal using power provided by the charge storage device in response to the autonomous measurement command, wherein the first analyte measurement signal is based on a detectable property exhibited by an analyte indicator of the sensor, and the analyte indicator is configured to exhibit the detectable property based on the amount or concentration of the analyte in the medium;

generating first measurement information based on the first analyte measurement signal; and

storing the first measurement information in a non-volatile storage medium of the sensor.

37. The method of claim 36, further comprising using the charge storage device to power a clock, wherein using the measurement scheduler to issue an autonomous measurement command comprises using an output of the clock to determine when to issue the measurement command.

38. The method of claim 36, further comprising switching sensor elements of the sensor from being powered by an external device to being powered by the charge storage device in response to the autonomous measurement command.