METHODS AND SYSTEMS FOR DETECTING THE HYDRATION OF SENSORS

• US 20110048941A1
• Filed: 09/21/2010
• Published: 03/03/2011
• Est. Priority Date: 12/30/2005
• Status: Active Grant

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: MORGAN, WAYNE A., SHAH, RAJIV, REGHABI, BAHAR, SCHULTZ, PETER, HOSS, UDO, CHOY, DAVID Y., HENKE, JAMES L., SOUNDARARAJAN, GOPIKRISHNAN
• Granted Patent: US 8,532,732 B2
• Time in Patent Office: Days
• US Class Current: 204/406
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 2562/02 Details of sensors specially adapted for in-vivo measurements
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/1473 invasive, e.g. introduced into the body by a catheter A61B5/1482 takes precedence
• CPC Class Codes: C12Q 1/006 for glucose
• CPC Class Codes: G01N 27/327 Biochemical electrodes , e.g. electrical or mechanical details for in vitro measurements
• CPC Class Codes: G01N 27/403 Cells and electrode assemblies
• CPC Class Codes: G01N 27/416 Systems G01N27/27 takes precedence

Abstract

A sensor system includes a sensor and a sensor electronics device. The sensor includes a plurality of electrodes. The sensor electronics device includes a connection detection device, a power source, and a delay circuit. The connection detection device determines if the sensor electronics device is connected to the sensor and transmits a connection signal. The delay circuit receives the connection signal, waits a preset hydration time, and couples the regulated voltage from the power source to an electrode in the sensor after the preset hydration time has elapsed. Alternatively, the sensor electronics device may include an electrical detection circuit and a microcontroller. The electrical detection circuit determines if the plurality of electrodes are hydrated and generates an interrupt if the electrodes are hydrated. A microcontroller receives the interrupt and transmits a signal representative of a voltage to an electrode of the plurality of electrodes.

Claims

1. A program code storage device, comprising:

a computer-readable medium; and

computer-readable program code, stored on the computer-readable medium, the computer-readable program code having instructions, which when executed cause a microcontroller to;

receive an interrupt from a detection circuit, the interrupt being representative of the detection circuit detecting hydration of a sensor by detecting a high level of attenuation of an AC signal that had been applied to the sensor; and

transmit a signal to a digital-to-analog converter (DAC), in response to the interrupt, the signal being representative of a voltage that the DAC is to apply to the sensor to provide power to the sensor.

2. The program code storage device of claim 1, the computer-readable program code including instructions, which when executed cause the microcontroller to receive a sensor signal from the sensor and to extract a parameter of a physiological condition of a patient.

3. A sensor system, comprising:

a sensor, the sensor including a plurality of electrodes; and

a sensor electronics device that is coupled to the sensor and includes;

an electrical detection circuit that determines whether the plurality of electrodes in the sensor are hydrated and, if said plurality of electrodes are hydrated, generates an interrupt; and

a microcontroller that receives the interrupt from the electrical detection circuit and transmits a signal representative of a voltage to the sensor, wherein an electrode of the plurality of electrodes receives the voltage derived from the transmitted signal.

4. The sensor system of claim 3, wherein the sensor electronics device further includes a digital-to-analog converter (DAC) that receives the signal from the microcontroller and converts the signal into the voltage to be applied to said an electrode of the plurality of electrodes.

5. The sensor system of claim 3, wherein the sensor electronics device further includes a measurement detection circuit that detects a reading of a physiological condition of a patient at a second electrode of the sensor.

6. The sensor system of claim 5, wherein the measurement detection circuit is a current-to-frequency converter that measures a current reading at said second electrode, converts the current reading of the physiological condition to a frequency reading indicative of the physiological condition, and transmits the frequency reading to the microcontroller.

7. The sensor system of claim 3, wherein the sensor electronics device further includes an AC voltage source that is coupled to a second electrode of the plurality of electrodes to supply an AC voltage signal to said second electrode.

8. The sensor system of claim 7, wherein the electrical detection circuit includes a comparator to detect a level of the AC signal present at an input of the comparator, and wherein, if a low level AC signal is present at the input of the comparator, the electrical detection circuit generates the interrupt that is transmitted to the microcontroller.

9. The sensor system of claim 3, wherein:

the plurality of electrodes includes a counter electrode, a reference electrode, and a working electrode;

an AC source is coupled to the reference electrode and supplies an AC signal to the reference electrode;

the electrical detection circuit includes a comparator to detect a level of the AC signal present at the input of the comparator and generate the interrupt that is transmitted to the microcontroller if a low level AC signal is present at the input of the comparator; and

the voltage derived from the signal that is transmitted by the microcontroller is to be applied to the counter electrode.

10. The sensor system of claim 9, wherein a measurement detection circuit detects a measurement of a physiological characteristic at the working electrode and transmits said measurements to the microcontroller.

11. The sensor system of claim 9, wherein the low level AC signal is present at the input of the comparator because of effective sensor capacitance between the working electrode and the reference electrode, and effective sensor capacitance between the reference electrode and the counter electrode.

12. A sensor system, comprising:

a sensor including a plurality of electrodes; and

a sensor electronics device that is coupled to the sensor and includes;

an electrical detection circuit to determine whether the plurality of electrodes in the sensor are hydrated, to generate a first interrupt if the plurality of electrodes are hydrated, and to generate a second interrupt if the electrical detection circuit determines that the sensor has been disconnected from the sensor electronics device; and

a microcontroller to receive the second interrupt and to generate a signal to turn off power to one or more components or circuits within the sensor electronics device in response to the second interrupt.

13. The sensor system of claim 12, wherein the sensor electronics device includes a digital-to-analog converter that is powered down in response to said second interrupt.

14. The sensor system of claim 12, the sensor electronics device further including an AC source coupled to a first electrode of the plurality of electrodes and supplying an AC signal to said first electrode, wherein the electrical detection circuit includes a comparator to detect a level of the AC signal present at the input of the comparator, to generate the first interrupt that is transmitted to the microcontroller if a low level AC signal is present at said input, and to generate the second interrupt if a high level AC signal is present at said input after the generation of the first interrupt.