Methods and systems for detecting the hydration of sensors

• US 9,759,678 B2
• Filed: 09/21/2010
• Issued: 09/12/2017
• Est. Priority Date: 12/30/2005
• Status: Expired due to Fees

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: Shah, Rajiv, Morgan, Wayne A., Choy, David Y., Henke, James L., Reghabi, Bahar, Soundararajan, Gopikrishnan, Schultz, Peter, Hoss, Udo
• Primary Examiner(s): Mallari, Patricia
• Assistant Examiner(s): TOTH, KAREN E
• Application Number:
  US12/887,460
• Publication Number:
  US 20110010105A1
• Time in Patent Office: 2,548 Days
• Field of Search: 600345, 600347, 600365, 600309
• 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 glucose sensor system, comprising:

a subcutaneous or implantable glucose sensor, the sensor including a plurality of electrodes configured to be inserted into a body of a human subject; and

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

a power source to apply a voltage signal to the sensor after said electrodes are inserted into the human subject'"'"'s body and prior to any measurement of a glucose level of the human subject;

an electrical characteristic measuring device that, prior to any measurement of said glucose level of the human subject, measures a resistance of the sensor and transmits a signal to indicate hydration of the sensor if the resistance is below a set criterion;

a detection circuit that receives the signal transmitted from the electrical characteristic measuring device and generates an interrupt after receipt thereof; and

a microcontroller that receives the interrupt from the detection circuit and transmits a signal representative of a voltage to the sensor to a digital-to-analog converter (DAC) which transmits a sequence of voltages to the sensor including application of a first voltage for a first time and a second voltage for a second time for a total timeframe of 10, 15, or 20 minutes, wherein, after receipt of the interrupt from the detection circuit and after completion of the sequence of voltages, the sensor performs a first measurement of said glucose level of said human subject, such that no measurement of the glucose level is performed by the sensor prior to completion of said hydration and said sequence of voltages.

2. The sensor system of claim 1, wherein the power source is a DC power source.

3. The sensor system of claim 1, wherein one of said plurality of electrodes is a counter electrode, and the DAC transmits the sequence of voltages to the counter electrode through an operational amplifier.

4. The sensor system of claim 1, wherein the DAC applies the sequence of voltages directly to an electrode of the plurality of electrodes in the sensor.

5. The sensor system of claim 1, wherein the set criterion is a threshold measurement.

6. A glucose sensor system, comprising:

a subcutaneous or implantable glucose sensor, the sensor including a plurality of electrodes configured to be inserted into a body of a human subject; and

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

a power source to apply a voltage signal to the sensor after said electrodes are inserted into the human subject'"'"'s body and prior to any measurement of a glucose level of the human subject;

an electrical characteristic measuring device that, prior to any measurement of said glucose level of the human subject, measures an impedance of the sensor and transmits a signal to indicate hydration of the sensor if the impedance is below a set criterion;

a detection circuit that receives the signal transmitted from the electrical characteristic measuring device and generates an interrupt after receipt thereof; and

a microcontroller that receives the interrupt from the detection circuit and transmits a signal representative of a voltage to the sensor to a digital-to-analog converter (DAC) which transmits a sequence of voltages to the sensor including application of a first voltage for a first time and a second voltage for a second time for a total timeframe of 10, 15, or 20 minutes, wherein, after receipt of the interrupt from the detection circuit and after completion of the sequence of voltages, the sensor performs a first measurement of said glucose level of said human subject, such that no measurement of the glucose level is performed by the sensor prior to completion of said hydration and said sequence of voltages.

7. The sensor system of claim 6, wherein the power source is an AC power source.

8. The sensor system of claim 6, wherein one of said plurality of electrodes is a counter electrode, and the DAC transmits the sequence of voltages to the counter electrode through an operational amplifier.

9. The sensor system of claim 6, wherein the DAC applies the sequence of voltages directly to an electrode of the plurality of electrodes in the sensor.

10. The sensor system of claim 6, wherein the set criterion is a threshold measurement.