DIGITAL ASIC SENSOR PLATFORM

• US 20130211213A1
• Filed: 02/07/2013
• Published: 08/15/2013
• Est. Priority Date: 02/10/2012
• Status: Active Grant

• Current Assignee: Senseonics, Incorporated (Senseonics Holdings, Inc.)
• Original Assignee: Senseonics, Incorporated (Senseonics Holdings, Inc.)
• Inventors: DeHennis, Andrew, Colvin, Arthur E. Jr.
• Granted Patent: US 9,693,714 B2
• Time in Patent Office: Days
• US Class Current: 600/316
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/076 Permanent implantations telemetry using implanted circuitry A61B5/0031; implanted stimulators for therapy A61N1/3605, A61N1/362, A61N1/372
• CPC Class Codes: A61B 5/1451 for interstitial fluid
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/14556 by fluorescence A61B5/14555 takes precedence
• CPC Class Codes: A61B 5/1459 invasive, e.g. introduced into the body by a catheter A61B5/1464 takes precedence
• CPC Class Codes: A61B 5/6861 Capsules, e.g. for swallowing or implanting
• CPC Class Codes: A61B 5/7225 Details of analog processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation A61B5/30, A61B5/316 take precedence; transformers for specific applications H01F38/00; amplifiers H03F

Abstract

The present invention relates to an optical sensor that may be implanted within a living animal (e.g., a human) and may be used to measure the concentration of an analyte in a medium within the animal. The optical sensor may wirelessly receive and may be capable of bi-directional data communication. The optical sensor may include a semiconductor substrate in which various circuit components, one or more photodectors and/or a light source may be fabricated. The circuit components fabricated in the semiconductor substrate may include a comparator, an analog to digital converter, a temperature transducer, a measurement controller, a rectifier and/or a nonvolatile storage medium. The comparator may output a signal indicative of the difference between the outputs of first and second photodetectors. The measurement controller may receive digitized temperature, photodetector and/or comparator measurements and generate measurement information, which may be wirelessly transmitted from the optical sensor.

Claims

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

indicator molecules having an optical characteristic responsive to the concentration of the analyte, the indicator molecules being configured to interact with the analyte in the medium within the living animal when the optical sensor is implanted within the living animal;

a semiconductor substrate;

a first photodetector mounted on or fabricated in the semiconductor substrate and configured to output a first analog light measurement signal indicative of the amount of light received by the first photodetector;

a second photodetector mounted on or fabricated in the semiconductor substrate and configured to output a second analog light measurement signal indicative of the amount of light received by the second photodetector, wherein the first and second photodetectors are symmetrically arranged relative to a center line running between the first and second photodetectors;

a light source configured to emit excitation light to the indicator molecules from an emission point aligned on the center line running between the first and second photodetectors;

a temperature transducer mounted on or fabricated in the semiconductor substrate and configured to output an analog temperature measurement signal indicative of a temperature of the optical sensor;

a comparator fabricated in the semiconductor substrate and configured to output an analog light difference measurement signal indicative of a difference between the first and second analog light measurement signals;

an analog to digital converter (ADC) fabricated in the semiconductor substrate and configured to convert (i) the analog temperature measurement signal to a digital temperature measurement signal, (ii) the first analog light measurement signal to a first digital light measurement signal, (iii) the second analog light measurement signal to a second digital light measurement signal and (iv) the analog light difference measurement signal to a digital light difference measurement signal;

an inductive element;

an input/output circuit fabricated in the semiconductor substrate and configured to wirelessly transmit via the inductive element measurement information and wirelessly receive via the inductive element a measurement command and power; and

a measurement controller fabricated in the semiconductor substrate and configured to;

(i) in accordance with the measurement command, control the light source;

(ii) generate the measurement information in accordance with (a) the digital temperature measurement signal, (b) the first digital light measurement signal, (c) the second digital light measurement signal and (d) the digital light difference measurement signal; and

(iii) control the input/output circuit to wirelessly transmit the measurement information.

2. The optical sensor of claim 1, wherein the optical sensor is a chemical or biochemical sensor.

3. The optical sensor of claim 1, wherein the first and second photodetectors are fabricated in the semiconductor substrate.

4. The optical sensor of claim 3, wherein the first and second photodetectors are photodiodes that have been monolithically formed in the semiconductor substrate using a complimentary metal oxide semiconductor (CMOS) process.

5. The optical sensor of claim 1, further comprising light source mounting pads on the semiconductor substrate and configured such that the light source, when mounted on the light source mounting pads, has an emission point aligned on the center line running between the first and second photodetectors;

and

wherein the light source is mounted on the light source mounting pads.

6. The optical sensor of claim 1, further comprising an isolation trough that electrically separates the first and second photodetectors.

7. The optical sensor of claim 1, further comprising a nonvolatile storage medium fabricated in the semiconductor substrate.

8. The optical sensor of claim 7, wherein the nonvolatile storage medium has stored therein measurement calibration information, and the measurement controller is configured to control the light source in accordance with the measurement command and the measurement calibration information.

9. The optical sensor of claim 7, wherein the nonvolatile storage medium has stored therein identification information, the input/output circuit is configured to wirelessly transmit via the inductive element the identification information and the measurement controller is configured to control the input/output circuit to wirelessly transmit the identification information.

10. The optical sensor of claim 1, wherein the temperature transducer is a band-gap based temperature transducer fabricated in the semiconductor substrate.

11. The optical sensor of claim 1, wherein the comparator is a transimpedance amplifier.

12. The optical sensor of claim 1, wherein the input/output circuit comprises a rectifier fabricated in the semiconductor substrate.

13. The optical sensor of claim 12, wherein the rectifier is a Schottky diode.

14. The optical sensor of claim 1, wherein the measurement information is digital measurement information.

15. The optical sensor of claim 1, wherein the indicator molecules are signal channel indicator molecules, and the optical sensor further comprises reference channel indicator molecules configured to not interact with the analyte in the medium within the living animal when the optical sensor is implanted within the living animal;

wherein the light source is configured to emit the excitation light to the signal channel indicator molecules and reference channel indicator molecules when turned on, the first photodetector is configured to receive excitation light emitted by the signal channel indicator molecules, and the second photodetector is configured to receive excitation light emitted by the reference channel indicator molecules.

16. The optical sensor of claim 1, wherein the living animal is a living human being.

17. The optical sensor of claim 1, wherein the medium is interstitial fluid.

18. The optical sensor of claim 17, wherein the analyte is glucose.

19. The optical sensor of claim 17, wherein the analyte is oxygen.

20. The optical sensor of claim 1, wherein the medium is blood.

21. The optical sensor of claim 1, wherein the indicator molecules are fluorescent indicator molecules.

22. The optical sensor of claim 1, wherein the optical sensor has a size and shape that permits said sensor to be implanted within the living animal and wherein the measurement information is indicative of the concentration of the analyte in the medium within the living animal.

23. The optical sensor of claim 1, wherein the inductive element comprises a coil.

24. The optical sensor of claim 1, wherein the inductive element further comprises a ferrite core, and the coil is formed on the ferrite core.

25. A method of controlling an optical sensor implanted within a living animal to measure a concentration of an analyte in a medium within the living animal, the method comprising:

(a) wirelessly receiving, by way of an inductive element and an input/output circuit of the optical sensor implanted within the living animal, a measurement command and power, wherein the input/output circuit is fabricated in a semiconductor substrate of the optical sensor;

(b) following receipt of the measurement command, turning a light source of the optical sensor on and off one or more times, wherein the light source is configured to, when turned on, irradiate indicator molecules having an optical characteristic responsive to the concentration of the analyte with excitation light, the indicator molecules being configured to interact with the analyte in the medium within the living animal when the optical sensor is implanted within the living animal;

(c) while the light source is turned on;

(i) generating, by way of a temperature transducer mounted on or fabricated in the semiconductor substrate, a first analog temperature measurement signal indicative of a temperature of the optical sensor;

(ii) generating, by way of a first photodetector mounted on or fabricated in the semiconductor substrate, a first analog light measurement signal indicative of the amount of light received by the first photodetector;

(iii) generating, by way of a second photodetector mounted on or fabricated in the semiconductor substrate, a second analog light measurement signal indicative of the amount of light received by the second photodetector; and

(iv) generating, by way of a comparator fabricated in the semiconductor substrate, an analog light difference measurement signal indicative of a difference between the first and second analog light measurement signals; and

(d) while the light source is turned off;

(i) generating, by way of the temperature transducer, a second analog temperature measurement signal indicative of a temperature of the optical sensor;

(ii) generating, by way of the first photodetector, a first analog ambient light measurement signal indicative of the amount of light received by the first photodetector; and

(iii) generating, by way of the second photodetector, a second analog ambient light measurement signal indicative of the amount of light received by the second photodetector;

(e) while the light source is turned on or turned off;

(i) converting, by way of an analog to digital converter (ADC) fabricated in the semiconductor substrate, the first analog temperature measurement signal to a first digital temperature measurement signal;

(ii) converting, by way of the ADC, the first analog light measurement signal to a first digital light measurement signal;

(iii) converting, by way of the ADC, the second analog light measurement signal to a second digital light measurement signal;

(iv) converting, by way of the ADC, the analog light difference measurement signal to a digital light difference measurement signal;

(v) converting, by way of the ADC, the second analog temperature measurement signal to a second digital temperature measurement signal;

(vi) converting, by way of the ADC, the first ambient analog light measurement signal to a first digital ambient light measurement signal; and

(vii) converting, by way of the ADC, the second analog ambient light measurement signal to a second digital ambient light measurement signal;

(f) generating, by way of a measurement controller fabricated in the semiconductor substrate, measurement information in accordance with (i) the first digital temperature measurement signal, (ii) the first digital light measurement signal, (iii) the second digital light measurement signal, (iv) the digital light difference measurement signal, (v) the second digital temperature measurement signal, (vi) the first digital ambient light measurement signal and (vii) the second digital ambient light measurement signal; and

(g) transmitting, by way of the input/output circuit and inductive element, the measurement information;

wherein steps (a) through (g) are performed while the optical sensor is implanted within the living animal, and the measurement information is indicative of the concentration of the analyte in the medium within the living animal.

26. The method of claim 25, wherein the optical sensor is a chemical or biochemical sensor.

27. The method of claim 25, further comprising:

reading calibration information stored in a nonvolatile storage medium fabricated in the semiconductor substrate; and

controlling the light source in accordance with the calibration information.

28. The method of claim 25, further comprising transmitting, by way of the input/output circuit and inductive element, identification information stored in a nonvolatile storage medium fabricated in the semiconductor substrate.

29. The method of claim 25, further comprising:

while the light source is turned on, generating an analog light source bias measurement signal; and

while the light source is turned on or turned off, converting, by way of the ADC, the analog light source bias measurement signal to a digital light source bias measurement signal;

wherein the measurement information is generated in accordance with the digital light source bias measurement signal.

30. The method of claim 25, further comprising determining, by way of a field strength measurement circuit, whether the wirelessly received power is sufficient to perform steps (b) through (g).

31. The method of claim 25, wherein the indicator molecules are signal channel indicator molecules, and the method further comprises:

irradiating the signal channel indicator molecules and reference channel indicator molecules of the optical sensor with excitation light emitted by the light source when turned on, wherein the reference channel indicator molecules are configured to not interact with the analyte in the medium within the living animal when the optical sensor is implanted within the living animal;

receiving, by the first photodetector, light emitted by the signal channel indicator molecules; and

receiving, by the second photodetector, light emitted by the reference channel indicator molecules.

32. The method of claim 25, wherein the living animal is a living human being.

33. The method of claim 25, wherein the medium is interstitial fluid.

34. The method of claim 33, wherein the analyte is glucose.

35. The method of claim 33, wherein the analyte is oxygen.

36. The method of claim 25, wherein the medium is blood.

37. The method of claim 25, wherein the indicator molecules are fluorescent indicator molecules.

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

indicator molecules having an optical characteristic responsive to the concentration of the analyte, the indicator molecules being configured to interact with the analyte in the medium within the living animal when the optical sensor is implanted within the living animal;

a semiconductor substrate;

a photodiode fabricated in the semiconductor substrate and configured to output an analog light measurement signal indicative of the amount of light received by the photodiode;

a light source configured to emit excitation light to the indicator molecules;

an analog to digital converter fabricated in the semiconductor substrate and configured to convert the analog light measurement signal to a digital light measurement signal;

an inductive element;

an input/output circuit fabricated in the semiconductor substrate and configured to wirelessly transmit via the inductive element measurement information and wirelessly receive via the inductive element a measurement command and power; and

a measurement controller fabricated in the semiconductor substrate and configured to;

(i) in accordance with the measurement command, control the light source;

(ii) generate the measurement information in accordance with the digital light measurement signal; and

(iii) control the input/output circuit to wirelessly transmit the measurement information.

39. The sensor of claim 38, wherein the photodiode has been monolithically formed in the semiconductor substrate using a complimentary metal oxide semiconductor (CMOS) process.

40. The sensor of claim 38, further comprising light source mounting pads on the semiconductor substrate, wherein the light source is mounted on the light source mounting pads.

41. The sensor of claim 38, further comprising a nonvolatile storage medium fabricated in the semiconductor substrate.