Substrate sensor

• US 7,079,881 B2
• Filed: 11/04/2002
• Issued: 07/18/2006
• Est. Priority Date: 09/12/1997
• Status: Expired due to Term

• Current Assignee: Alfred E. Mann Foundation For Scientific Research
• Original Assignee: Alfred E. Mann Foundation For Scientific Research
• Inventors: Shah, Rajiv, Schulman, Joseph H., Byers, Charles L., Gord, John C., Canfield, Lyle Dean
• Primary Examiner(s): Schaetzle, Kennedy
• Application Number:
  US10/288,038
• Publication Number:
  US 20030078484A1
• Time in Patent Office: 1,352 Days
• Field of Search: 600/309, 600/347, 600/365, 600/373, 600/374, 600/393, 600/345
• US Class Current: 600/347
• CPC Class Codes: A61B 2560/0219 of externally powered implanted units
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/14865 invasive, e.g. introduced into the body by a catheter or needle or using implanted sensors
• CPC Class Codes: A61B 5/4839 combined with drug delivery
• CPC Class Codes: A61M 5/1723 using feedback of body parameters, e.g. blood-sugar, pressure measurement of body parameters A61B5/00
• CPC Class Codes: A61N 1/05 for implantation or insertion into the body, e.g. heart electrode A61N1/06 takes precedence
• CPC Class Codes: A61N 1/36585 controlled by two or more physical parameters
• CPC Class Codes: A61N 1/372 Arrangements in connection with the implantation of stimulators
• CPC Class Codes: A61N 1/3754 Feedthroughs
• CPC Class Codes: H01L 23/3107 the device being completely enclosed
• CPC Class Codes: H01L 29/0657 characterised by the shape of the body
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2924/19041 being a capacitor

Abstract

An implantable substrate sensor has electronic circuitry and electrodes formed on opposite sides of a substrate. A protective coating covers the substrate, effectively hermetically sealing the electronic circuitry under the coating. Exposed areas of the electrodes are selectively left uncovered by the protective coating, thereby allowing such electrodes to be exposed to body tissue and fluids when the sensor is implanted in living tissue. The substrate on which the electronic circuitry and electrodes are formed is the same substrate or “chip” on which an integrated circuit (IC) is formed, which integrated circuit contains the desired electronic circuitry. Such approach eliminates the need for an hermetically sealed lid or cover to cover hybrid electronic circuitry, and allows the sensor to be made much thinner than would otherwise be possible. In one embodiment, two such substrate sensors may be placed back-to-back, with the electrodes facing outward. As required, capacitors that form part of the sensor'"'"'s electronic circuits are formed on the substrate by placing metalization layers and a dielectric in vacant areas of the substrate surface.

Claims

1. An implantable sensor assembly, comprising:

a first sensor having a first surface and a second surface, the second surface having at least one electrode;

a second sensor having a first surface and a second surface, the second surface having at least one electrode, the first surface of the second sensor being aligned with and directly opposing the first surface of the first sensor such that the second surfaces of the first and second sensors face out from the sensor assembly;

wherein current flowing through the electrodes electrochemically reacts with at least one substance in proximity to exposed surface areas of the electrodes; and

wherein the sensor assembly further includes a catalyst placed in proximity to the exposed surface areas of the electrodes for catalyzing an electrochemical reaction between the current flowing through the electrodes and at least one substance in proximity to exposed surface areas of the electrodes.

2. The implantable sensor assembly recited in claim 1, wherein the electrodes convert a sensed parameter to a detectable signal.

3. The implantable sensor assembly recited in claim 1, wherein the catalyst is an enzyme.

4. The implantable sensor assembly recited in claim 3, wherein the enzyme is glucose oxidase.

5. The implantable sensor assembly recited in claim 1, wherein the at least one substance is oxygen.

6. The sensor assembly recited in claim 1, wherein the electrodes apply an electrical pulse to a substance in contact with the electrodes.

7. The sensor assembly recited in claim 6, wherein the substance is living tissue.

8. A sensor assembly, comprising:

a first substrate sensor having a first surface and a second surface, the second surface having at least one electrode for converting a sensed parameter to a detectable signal;

a second substrate sensor having a first surface and a second surface, the second surface having at least one electrode for converting a sensed parameter to a detectable signal, at least a portion of the first surface of the second substrate sensor being directly opposed to at least a portion of the first surface of the first substrate sensor such that the second surfaces of the first and second substrate sensors face out from the sensor assembly in substantially opposite directions;

wherein current flowing through the electrodes electrochemically reacts with at least one substance in proximity to the electrodes; and

wherein the sensor assembly further includes a catalyst placed in proximity to the electrodes for catalyzing an electrochemical reaction between the current flowing through the electrodes and at least one substance in proximity to the electrodes.

9. The sensor assembly recited in claim 8, wherein the catalyst is an enzyme.

10. The sensor assembly recited in claim 9, wherein the enzyme is glucose oxidase.

11. The sensor assembly recited in claim 8, wherein the at least one substance is oxygen.

12. A sensor assembly, comprising:

a first substrate sensor having an electrode surface and a circuit surface;

a second substrate sensor having an electrode surface and a circuit surface, at least a portion of the circuit surface of the second substrate sensor facing at least a portion of the circuit surface of the first substrate sensor such that the electrode surfaces of the first and second substrate sensors face out from the sensor assembly in substantially opposite directions;

wherein the electrode surfaces include electrodes for converting a sensed parameter to a detectable signal;

wherein current flowing through the electrodes electrochemically reacts with at least one substance in proximity to the electrodes; and

further including a catalyst placed in proximity to the electrodes for catalyzing an electrochemical reaction between the current flowing through the electrodes and at least one substance in proximity to the electrodes.

13. The sensor assembly recited in claim 12, wherein the catalyst is an enzyme.

14. The sensor assembly recited in claim 13, wherein the enzyme is glucose oxidase.

15. The sensor assembly recited in claim 12, wherein the at least one substance is oxygen.

16. The sensor assembly recited in claim 12, wherein the electrodes apply an electrical pulse to a substance in contact with the electrodes.

17. The sensor assembly recited in claim 16, wherein the substance is living tissue.

18. The sensor assembly recited in claim 12, further including an outer casing enclosing the first and second substrate sensors, the outer casing having at least one window pocket formed therein in proximity to an exposed surface area of the electrode surface of the first substrate sensor.

19. The sensor assembly recited in claim 18, further including at least one additional window pocket formed in the outer casing in proximity to an exposed surface area of the electrode surface of the second substrate sensor.

20. The sensor assembly of claim 18, wherein the outer casing is a membrane.

21. A sensor assembly, comprising:

a first substrate sensor having an electrode surface and a circuit surface;

a second substrate sensor having an electrode surface and a circuit surface, at least a portion of the circuit surface of the second substrate sensor facing at least a portion of the circuit surface of the first substrate sensor such that the electrode surfaces of the first and second substrate sensors face out from the sensor assembly in substantially opposite directions; and

an outer casing enclosing the first and second substrate sensors, the outer casing having at least one window pocket formed therein in proximity to an exposed surface area of the electrode surface of the first substrate sensor;

wherein a catalyst is placed within the at least one window pocket, the catalyst for catalyzing an electrochemical reaction between a current flowing on the electrode surface of the first substrate sensor and at least one substance entering the at least one window pocket from outside the sensor assembly.

22. A sensor assembly, comprising:

a first substrate sensor having an electrode surface and a circuit surface;

a second substrate sensor having an electrode surface and a circuit surface, at least a portion of the circuit surface of the second substrate sensor facing at least a portion of the circuit surface of the first substrate sensor such that the electrode surfaces of the first and second substrate sensors face out from the sensor assembly in substantially opposite directions;

an outer casing enclosing the first and second substrate sensors, the outer casing having at least one window pocket formed therein in proximity to an exposed surface area of the electrode surface of the first substrate sensor; and

at least one additional window pocket formed in the outer casing in proximity to an exposed surface area of the electrode surface of the second substrate sensor;

wherein a catalyst is placed within the at least one additional window pocket for catalyzing an electrochemical reaction between a current flowing on the electrode surface of the second substrate sensor and at least one substance entering the at least one additional window pocket from outside the sensor assembly.

23. A sensor assembly, comprising:

a first substrate sensor having an electrode surface and a circuit surface;

a second substrate sensor having an electrode surface and a circuit surface, at least a portion of the circuit surface of the second substrate sensor facing at least a portion of the circuit surface of the first substrate sensor such that the electrode surfaces of the first and second substrate sensors face out from the sensor assembly in substantially opposite directions;

an outer casing enclosing the first and second substrate sensors, the outer casing having at least one window pocket formed therein in proximity to an exposed surface area of the electrode surface of the first substrate sensor; and

an inner casing situated between the substrate sensors and the outer casing, the inner casing holding a conductive substance in contact with exposed surface areas of the electrode surfaces of both the first and second substrate sensors.

24. A sensor assembly, comprising:

a first substrate sensor having an electrode surface and a circuit surface;

a second substrate sensor having an electrode surface and a circuit surface, at least a portion of the circuit surface of the second substrate sensor facing at least a portion of the circuit surface of the first substrate sensor such that the electrode surfaces of the first and second substrate sensors face out from the sensor assembly in substantially opposite directions;

wherein each of the first and second substrate sensors includes;

an integrated circuit (IC), the IC comprising a semiconductor substrate having an active surface on which electronic circuitry is formed and a non-active surface where electronic circuitry is not formed, the active surface of the substrate comprising the circuit surface of the sensor;

sensor electrodes formed on the non-active surface of the semiconductor substrate, the non-active surface comprising the electrode surface of the sensor;

a first plurality of apertures having conductive surfaces for electrically connecting the sensor electrodes with the electronic circuitry formed on the active surface of the IC; and

a plurality of conductive pads and a second plurality of apertures having conductive surfaces for making electrical connection with and providing operating power to the electronic circuitry formed on the semiconductor substrate from a location outside of the sensor assembly.

25. The sensor assembly of claim 24, further including a protective coating that covers all areas of the surface of the semiconductor substrate except for selected portions of the sensor electrodes.

26. The sensor assembly of claim 25, wherein the protective coating includes at least one layer of a biocompatible encapsulation material selected from the group consisting essentially of alumina, zirconia, or alloys of alumina and/or zirconia.

27. The sensor assembly of claim 25, wherein the conductive pads are not covered by the protective coating.

28. The sensor assembly of claim 24, wherein the first plurality of apertures pass through the body of the semiconductor substrate.

29. The sensor assembly of claim 28, wherein the first plurality of apertures are stair-stepped apertures.

30. A sensor assembly, comprising:

a first substrate sensor having an electrode surface and a circuit surface;

a second substrate sensor having an electrode surface and a circuit surface, at least a portion of the circuit surface of the second substrate sensor facing at least a portion of the circuit surface of the first substrate sensor such that the electrode surfaces of the first and second substrate sensors face out from the sensor assembly in substantially opposite directions;

an outer casing enclosing the first and second substrate sensors, the outer casing having at least one window pocket formed therein in proximity to an exposed surface area of the electrode surface of the first substrate sensor; and

an inner casing situated between the substrate sensors and the outer casing, the inner casing holding a conductive substance in contact with exposed surface areas of the electrode surfaces of both the first and second substrate sensors;

wherein the inner casing is a membrane.

31. A sensor assembly, comprising:

a first substrate sensor having an electrode surface and a circuit surface;

a second substrate sensor also having an electrode surface and a circuit surface, at least a portion of the circuit surface of the second substrate sensor being opposed to at least a portion of the circuit surface of the first substrate sensor such that the electrode surfaces of both the first and second substrate sensors face out from the sensor assembly;

a first casing covering the circuit surfaces and the electrode surfaces;

a conductive solution held within the first casing, the conductive solution being in contact with exposed surface areas of the electrode surfaces of both the first and second substrate sensors;

a second casing covering the first casing, the second casing having at least one window pocket formed therein in proximity to an exposed surface area of the electrode surface of the first substrate sensor and at least one window pocket formed therein in proximity to an exposed surface area of the electrode surface of the second substrate sensor; and

a catalyst placed within the window pockets, the catalyst for catalyzing an electrochemical reaction between a current flowing on the electrode surfaces and at least one substance entering the window pockets from outside the sensor assembly.

32. The sensor assembly of claim 31, wherein each of the first and second substrate sensors includes:

an integrated circuit (IC), the IC comprising a semiconductor substrate having an active surface on which electronic circuitry is formed and a non-active surface where electronic circuitry is not formed, the active surface of the substrate comprising the circuit surface of the sensor;

sensor electrodes formed on the non-active surface of the semiconductor substrate, the non-active surface comprising the electrode surface of the sensor;

a first plurality of apertures having conductive surfaces for electrically connecting the sensor electrodes with the electronic circuitry formed on the active surface of the IC; and

a plurality of conductive pads and a second plurality of apertures having conductive surfaces for making electrical connection with and providing operating power to the electronic circuitry formed on the semiconductor substrate from a location outside of the sensor assembly.

33. The sensor assembly of claim 32, further including a protective coating that covers all areas of the surface of the semiconductor substrate except for selected portions of the sensor electrodes.

34. The sensor assembly of claim 33, wherein the plurality of conductive pads are not covered by the protective coating.

35. The sensor assembly of claim 34, wherein each end of the substrate includes a pair of the conductive pads.

36. The sensor assembly of claim 33, wherein the protective coating includes at least one layer of a biocompatible encapsulation material selected from the group consisting essentially of alumina, zirconia, or alloys of alumina and/or zirconia.

37. The sensor assembly of claim 32, wherein the first plurality of apertures pass through the body of the semiconductor substrate.

38. The sensor assembly of claim 37, wherein the first plurality of apertures are stair-stepped apertures.

39. The sensor assembly of claim 32, wherein the second plurality of apertures are non-linear apertures that respectively electrically connect each of the plurality of pads with the electronic circuitry.

40. The sensor assembly of claim 32, wherein the electronic circuitry comprises a CMOS integrated circuit, and wherein the semiconductor substrate comprises a portion of a semiconductor wafer on which the CMOS integrated circuit is formed.