APPLICATION OF ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY IN SENSOR SYSTEMS, DEVICES, AND RELATED METHODS

• US 20130331676A1
• Filed: 02/27/2013
• Published: 12/12/2013
• Est. Priority Date: 06/08/2012
• Status: Abandoned Application

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: Morgan, Wayne A., Shah, Rajiv, Chen, Paris
• Application Number:
  US13/778,611
• Publication Number:
  US 20130331676A1
• Time in Patent Office: Days
• US Class Current: 600/365
• CPC Class Codes: A61B 2562/0214 Capacitive electrodes
• CPC Class Codes: A61B 2562/04 Arrangements of multiple sensors of the same type
• CPC Class Codes: A61B 5/0537 Measuring body composition by impedance, e.g. tissue hydration or fat content
• CPC Class Codes: A61B 5/0538 invasively, e.g. using a catheter
• CPC Class Codes: A61B 5/14503 invasive, e.g. introduced into the body by a catheter or needle or using implanted sensors A61B5/1459, A61B5/1464, A61B5/1473, A61B5/1482, A61B5/14865 take 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
• CPC Class Codes: A61B 5/1473 invasive, e.g. introduced into the body by a catheter A61B5/1482 takes precedence
• 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 5/1495 Calibrating or testing of in-vivo probes
• CPC Class Codes: A61B 5/4839 combined with drug delivery
• CPC Class Codes: A61B 5/6849 in combination with a needle set
• CPC Class Codes: A61B 5/6852 Catheters
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/7221 Determining signal validity, reliability or quality A61B5/7207 and A61B5/7217 take precedence
• 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
• CPC Class Codes: A61B 5/7242 using integration
• CPC Class Codes: A61B 5/746 Alarms related to a physiological condition, e.g. details of setting alarm thresholds or avoiding false alarms alarms per se G08B
• CPC Class Codes: A61M 2005/1726 the body parameters being measured at, or proximate to, the infusion site
• CPC Class Codes: A61M 5/14244 adapted to be carried by the patient, e.g. portable on the body
• CPC Class Codes: A61M 5/14276 : specially adapted for implantation
• CPC Class Codes: A61M 5/1582 : Double lumen needles
• 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: G01N 27/026 : Dielectric impedance spectroscopy electrochemical impedance spectroscopy for measuring corrosion G01N17/02
• CPC Class Codes: G01N 27/028 : Circuits therefor measuring impedance per se G01R27/02
• CPC Class Codes: G01N 27/416 : Systems G01N27/27 takes precedence
• CPC Class Codes: G01N 27/4163 : checking the operation of, or calibrating, the measuring apparatus G01N27/3274, G01N27/4175 and G01N33/0006 take precedence
• CPC Class Codes: G01N 33/49 : Blood chemical methods for determining blood cell populations G01N33/5094; chemical analysis of blood groups or blood types G01N33/80
• CPC Class Codes: G01N 33/66 : involving blood sugars, e.g. galactose
• CPC Class Codes: G01N 33/96 : involving blood or serum control standard
• CPC Class Codes: G01R 35/00 : Testing or calibrating of apparatus covered by the other groups of this subclass
• CPC Class Codes: G01R 35/005 : Calibrating; Standards or reference devices, e.g. voltage or resistance standards, "golden" references G01R33/0035, G01R35/002 take precedence

Abstract

A diagnostic Electrochemical Impedance Spectroscopy (EIS) procedure is applied to measure values of impedance-related parameters for one or more sensing electrodes. The parameters may include real impedance, imaginary impedance, impedance magnitude, and/or phase angle. The measured values of the impedance-related parameters are then used in performing sensor diagnostics, calculating a highly-reliable fused sensor glucose value based on signals from a plurality of redundant sensing electrodes, calibrating sensors, detecting interferents within close proximity of one or more sensing electrodes, and testing surface area characteristics of electroplated electrodes. Advantageously, impedance-related parameters can be defined that are substantially glucose-independent over specific ranges of frequencies. An Application Specific Integrated Circuit (ASIC) enables implementation of the EIS-based diagnostics, fusion algorithms, and other processes based on measurement of EIS-based parameters.

Claims

1. A sensor system, comprising:

a subcutaneous or implanted sensor, said sensor having a plurality of independent working electrodes, a counter electrode, and a reference electrode; and

sensor electronics operably coupled to said sensor and including;

electronic circuitry configured to selectively perform an electrochemical impedance spectroscopy (EIS) procedure for one or more of said plurality of independent working electrodes to generate impedance-related data for said one or more working electrodes;

a programmable sequencer configured to provide a start stimulus and a stop stimulus for performing said EIS procedure; and

a microcontroller interface configured to operably couple the sensor electronics to a microcontroller.

2. The system of claim 1, wherein the sensor electronics further includes sensor-connection sensing circuitry configured to detect connection of the sensor to, and disconnection of the sensor from, the sensor electronics.

3. The system of claim 2, wherein the sensor-connection sensing circuitry includes an analog switched capacitor circuit that is configured to monitor an impedance of the reference electrode to determine whether the sensor is connected to, or disconnected from, the sensor electronics.

4. The system of claim 3, wherein the sensor-connection sensing circuitry is configured to generate an interrupt when the sensor is connected to, or disconnected from, the sensor electronics.

5. The system of claim 2, wherein the sensor-connection sensing circuitry is configured to generate a microcontroller-startup signal to activate the microcontroller when the sensor is detected to be connected to the sensor electronics.

6. The system of claim 1, wherein said plurality of independent working electrodes are of the same shape, size, and configuration.

7. The system of claim 1, wherein two or more of said plurality of independent working electrodes are of different shapes, sizes, or configurations.

8. The system of claim 1, wherein at least one of said plurality of independent working electrodes is configured to detect hypoglycemia, and at least another one of said independent working electrodes is configured to detect hyperglycemia.

9. The system of claim 1, wherein the sensor electronics further include a buffer memory to store said impedance-related data.

10. The system of claim 9, wherein the buffer is 64 measurements deep.

11. The system of claim 1, wherein the sensor electronics further include an electrode multiplexer operatively connected to said counter electrode, reference electrode, and plurality of independent working electrodes.

12. The system of claim 11, wherein said electrode multiplexer is configured to allow said counter electrode and said reference electrode to be connected to any one of said plurality of working electrodes.

13. The system of claim 1, wherein the sensor includes five redundant working electrodes.

14. The system of claim 1, wherein at least one of said plurality of working electrodes is an oxygen sensor, and at least another one of said plurality of working electrodes is a peroxide sensor.

15. The system of claim 1, wherein the respective voltage level of each of the plurality of working electrodes is independently programmable.

16. The system of claim 15, wherein each said respective voltage is independently programmable in amplitude and sign with respect to the reference electrode.