Methods and systems for detecting the hydration of sensors

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.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

A detailed description of embodiments of the invention will be made with reference to the accompanying drawings, wherein like numerals designate corresponding parts in the figures.

FIG. 1 is a perspective view of a subcutaneous sensor insertion set and block diagram of a sensor electronics device according to an embodiment of the invention;

FIG. 2( a) illustrates a substrate having two sides, a first side which contains an electrode configuration and a second side which contains electronic circuitry;

FIG. 2( b) illustrates a general block diagram of an electronic circuit for sensing an output of a sensor;

FIG. 3 illustrates a block diagram of a sensor electronics device and a sensor including a plurality of electrodes according to an embodiment of the invention;

FIG. 4 illustrates an alternative embodiment of the invention including a sensor and a sensor electronics device according to an embodiment of the present invention;

FIG. 5 illustrates an electronic block diagram of the sensor electrodes and a voltage being applied to the sensor electrodes according to an embodiment of the present invention;

FIG. 6( a) illustrates a method of applying pulses during stabilization timeframe in order to reduce the stabilization timeframe according to an embodiment of the present invention;

FIG. 6( b) illustrates a method of stabilizing sensors according to an embodiment of the present invention;

FIG. 6( c) illustrates utilization of feedback in stabilizing the sensors according to an embodiment of the present invention;

FIG. 7 illustrates an effect of stabilizing a sensor according to an embodiment of the invention;

FIG. 8 illustrates a block diagram of a sensor electronics device and a sensor including a voltage generation device according to an embodiment of the invention;

FIG. 8( b) illustrates a voltage generation device to implement this embodiment of the invention;

FIG. 8( c) illustrates a voltage generation device to generate two voltage values according in a sensor electronics device according to implement this embodiment of the invention;

FIG. 9 illustrates a sensor electronics device including a microcontroller for generating voltage pulses according to an embodiment of the present invention;

FIG. 9( b) illustrates a sensor electronics device including an analyzation module according to an embodiment of the present invention;

FIG. 10 illustrates a block diagram of a sensor system including hydration electronics according to an embodiment of the present invention;

FIG. 11 illustrates an embodiment of the invention including a mechanical switch to assist in determining a hydration time;

FIG. 12 illustrates an electrical detection of detecting hydration according to an embodiment of the invention;

FIG. 13( a) illustrates a method of hydrating a sensor according to an embodiment of the present invention;

FIG. 13( b) illustrates an additional method for verifying hydration of a sensor according to an embodiment of the present invention;

FIGS. 14( a) and (b) illustrate methods of combining hydrating of a sensor with stabilizing a sensor according to an embodiment of the present invention; and

FIG. 14( c) illustrates an alternative embodiment of the invention where the stabilization method and hydration method are combined.

Claims

1. A method of hydrating a sensor having a plurality of electrodes, comprising: coupling a sensor electronics device to the sensor;counting down a hydration time utilizing a counter in the sensor electronics device; andapplying power to the sensor after the hydration time has elapsed.

2. The method of claim 1, wherein the hydration time is five minutes.

3. A method of hydrating a sensor assembly having a plurality of electrodes, comprising: inserting a sensor system into a subject, the sensor system including the long-term sensor assembly;initiating a timer to start counting a hydration time; andapplying a voltage to the long-term sensor assembly after an elapsing of the hydration time.

4. The method of claim 3, wherein the hydration time is ten minutes.

5. A program code storage device, comprising: a computer-readable medium;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 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; andtransmit 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.

6. The program code storage device of claim 5, 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.

7. The program code storage device of claim 5, wherein the signal to the DAC instructs the DAC to apply a stabilization series of voltages, the stabilization series of voltages being a first voltage applied for a first time period, a second voltage applied for a second time period, and a cycling of the application of the first voltage for the first time period and the second voltage for the second time period for a number of iterations.

8. The program code storage device of claim 5, including instructions which when executed, causes the microcontroller to only receive a sensor signal from the sensor after a stabilization series of voltage pulses have been applied.

9. A sensor system, comprising: a sensor, the sensor including a plurality of electrodes; anda sensor electronics device, the sensor electronics device capable of being connected to the sensor, and the sensor electronics device including: a connection detection device to determine if the sensor electronics device is connected to the sensor and to transmit a connection signal;a power source to supply a regulated voltage; anda delay circuit to receive the connection signal, to wait a preset hydration time, and to couple the regulated voltage to an electrode of the plurality of electrodes.

10. The sensor system of claim 9, wherein the connection detection device is a mechanical switch.

11. The sensor system of claim 9, wherein the power source includes a DC power supply and a regulator.

12. The sensor system of claim 9, wherein the delay circuit includes a counter to count the preset hydration time and supplies a signal to a switch to couple the regulated voltage to the electrode of the plurality of electrodes.

13. A sensor system, comprising: a sensor, the sensor including a plurality of electrodes;a sensor electronics device, the sensor electronics device coupled to the sensor, the sensor electronics device including,an electrical detection circuit to determine whether the plurality of electrodes in the sensor are hydrated and to generate an interrupt; anda microcontroller to receive the interrupt from the electrical detection circuit and to transmit a signal representative of a voltage to the sensor, wherein an electrode receives the voltage derived from the transmitted signal.

14. The sensor system of claim 13, wherein a digital-to-analog converter (DAC) receives the signal from the microcontroller and converts the signal into the voltage to be applied to the electrode of the plurality of electrodes.

15. The sensor system of clam 13, wherein a measurement detection circuit detects a reading of a physiological condition of a patient at a second electrode of the sensor.

16. The sensor system of claim 15, wherein the measurement detection circuit is a current-to-frequency converter that measures a current reading at the second electrode of the sensor, converts the current reading of the physiological condition to a frequency reading indicative of the physiological condition of the patient, and the frequency reading is transmitted to a microcontroller.

17. The sensor system of claim 13, further including an AC voltage source, the AC voltage source being coupled to a second electrode to supply a AC voltage signal to the second electrode.

18. The sensor system of claim 17, wherein the detection circuit includes a comparator to detect a level of the AC signal present at an input of the comparator and if a low level AC signal is present at the comparator, representing the AC signal has been attenuated by parasitic capacitance, the detection circuit generates the interrupt that is transmitted to the microcontroller.

19. The sensor system of claim 13, 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 detection circuit includes a comparator to detect a level of the AC signal present at the input of the comparator and to generate the interrupt that is transmitted to the microcontroller if a low level AC signal is present at the input to the comparator, andthe microcontroller receives the interrupt and generates the signal representative of the voltage that is to be applied to the counter electrode.

20. The sensor system of claim 19, wherein a measurement detection circuit measures a measurement of a physiological characteristic at the working electrode and transmits the measurements of the physiological characteristic to the microcontroller.

21. The sensor system of claim 19, wherein if 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.

22. The sensor system of claim 13, the sensor electronics device further including an AC source, the AC source being coupled to a first electrode in the plurality of electrodes and supplying an AC signal to the first electrode, and also including an impedance measuring device to measure an impedance within the sensor and to transmit a hydration signal if the impedance decreases below a threshold impedance, wherein the detection circuit receives the hydration signal and generates the interrupt that is transmitted to the microcontroller if the hydration signal is received at the detection circuit, andthe microcontroller receives the interrupt and generates the signal representative of the voltage that is to be applied to a second electrode of the plurality of electrodes.

23. The sensor system of claim 13, the sensor electronics device further including a DC source, the DC source being coupled to a first electrode in the plurality of electrodes and supplying a DC signal to the first electrode, and also including a resistance measuring device to measure a resistance within the sensor and to transmit a hydration signal if the resistance decreases below a threshold resistance, wherein the detection circuit receives the hydration signal and generates the interrupt that is transmitted to the microcontroller if the hydration signal is received at the detection circuit, andthe microcontroller receives the interrupt and instructs a digital-to-analog converter to apply a voltage to the sensor.

24. A sensor system, comprising: a sensor, the sensor including a plurality of electrodes; anda sensor electronics device, the sensor electronics device connected to the sensor, the sensor electronics device including,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; anda microcontroller to receive the second interrupt and to generate a signal to turn off power to circuits within the sensor electronics device in response to the second interrupt.

25. The sensor system of claim 24, wherein the circuits that are powered down include the digital-to-analog converter.

26. The sensor system of claim 24, 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 the first electrode of the plurality of electrodes, wherein the detection circuit includes a comparator to detect when what level of AC signal is 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 the input to the comparator, and to generate the second interrupt if a high level AC signal is present at the input of the comparator after the generation of the first interrupt, andthe microcontroller receives the second interrupt and generates a power signal to turn off the circuits of the sensor electronics device in response to receiving the second interrupt.

27. The sensor system of claim 24, further including an AC source coupled to the first electrode of the plurality of electrodes and supplying an AC signal to the first electrode of the plurality of electrodes, and an impedance measuring device to measure an impedance within the sensor and to transmit a non-hydration signal if the impedance is above a threshold impedance, whereinthe detection circuit receives the non-hydration signal and generates the second interrupt that is transmitted to the microcontroller if the non-hydration signal is received at the detection circuit, and the microcontroller receives the second interrupt and turns off the circuits of the sensor electronics device.

28. The sensor system of claim 24, further including a DC source coupled to an electrode of the plurality of electrodes and supplying a DC signal to the electrode of the plurality of electrodes, and a resistance measuring device to measure a resistance within the sensor and to transmit a non-hydration signal if the resistance is above a threshold resistance, whereinthe detection circuit receives the non-hydration signal, generates the second interrupt that is transmitted to the microcontroller if the non-hydration signal is received at the detection circuit, and the microcontroller receives the second interrupt and turns off components of the circuits of the sensor electronics device.

29. A program code storage device, comprising: a computer-readable medium;computer-readable program code, stored on the computer-readable medium, the computer-readable program code having instructions, which when executed cause a controller to:transmit a stabilization initiation signal to a digital-to-analog converter (DAC) representative of a stabilization series of pulses to be applied to the sensor;receive an interrupt from a detection circuit indicating that a sensor is hydrated;set a first indicator that the interrupt has been received from the detection circuit; andset a second indicator once the stabilization series of pulses have been applied to the sensor.

30. The program codes storage device of claim 29, including instructions, which when executed causes the controller to: utilize a sensor signal received from the sensor once the first indicator has been set and the second indicator has been set to measure a physiological characteristic of a patient.

31. A program code storage device, comprising: a computer-readable medium;computer-readable program code, stored on the computer-readable medium, the computer-readable program code having instructions, which when executed cause a controller to:receive an interrupt from a detection circuit indicating a sensor has been hydrated;transmit a signal to a sensor indicating a stabilization sequence of voltages are to be applied to a sensor; andreceive a sensor signal from the sensor indicating a physiological characteristic of a subject into which the sensor is inserted.

32. The program code storage device of claim 31, wherein the signal indicating the stabilization sequence is transmitted to a digital-to-analog converter.

33. A program code storage device of claim 31, including instructions, which when executed cause the controller to: transmit a hydration assist signal to the sensor to assist in the hydration of the sensor if the controller does not receive the interrupt from the detection circuit indicating the sensor has been hydrated within a hydration time threshold.

34. A sensor system, comprising: a sensor, the sensor including a plurality of electrodes; anda sensor electronics device, the sensor electronics device coupled to the sensor, the sensor electronics device including,a power source to apply a voltage signal to the sensor;an electrical characteristic measuring device to measure an electrical characteristic of the sensor and to transmit a hydration signal if the electrical characteristic is below a set criteria;a detection circuit to receive the hydration signal and to generate an interrupt after receipt of the hydration signal; anda microcontroller to receive the interrupt from the detection circuit and to transmit a signal representative of a voltage to the sensor, wherein one electrode of the plurality of electrodes receives the voltage derived from the transmitted signal.

35. The sensor system of claim 34, wherein the power source is an AC power source and the electrical characteristic that the electrical characteristic measurement device is measuring is an impedance.

36. The sensor system of claim 34, wherein the power source is a DC power source and the electrical characteristic the electrical characteristic measurement device is measuring is a resistance.

37. The sensor system of claim 34, wherein the microcontroller receives a sensor signal from the sensor indicative of a measurement of a physiological characteristic of a subject into which the sensor is inserted.

38. The sensor system of claim 34, the microcontroller transmits the signal representative of the voltage to the sensor to a digital-to-analog converter (DAC) which transmits a stabilization of sequence of voltages to the sensor.

39. The sensor system of claim 38, wherein DAC transmits the stabilization sequence of voltages to a counter electrode through an operational amplifier.

40. The sensor system of claim 38, wherein the DAC applies the stabilization sequence of voltages directly to the electrode of the plurality of electrodes in the sensor.

41. The sensor system of claim 34, wherein the set criteria is a threshold measurement.

42. A sensor system, comprising: a sensor, the sensor including a plurality of electrodes; anda sensor electronics device, the sensor electronics device coupled to the sensor, the sensor electronics device including,a detection circuit to receive a hydration signal and to generate a first interrupt after receipt of the hydration signal; anda microcontroller to transmit a stabilization signal to the sensor, the stabilization signal representative of a voltage to be applied to the sensor, and to set a second indicator after the stabilization signal has been applied to the sensor, wherein the microcontroller receives the first interrupt indicating the sensor is hydrated and sets a first indicator identifying the sensor is hydrated, and if the first indicator is set and the second indicator is set, the microcontroller receives the sensor signal from the sensor to identify a physiological characteristic of the sensor.

43. The sensor system of claim 42, the sensor electronics device further including an AC source coupled to an electrode of the plurality of electrodes and supplying the electrode with an AC signal, wherein if the detection circuit detects a high level of attenuation in the AC signal, the detection circuit generates the first interrupt.

44. The sensor system of claim 42, further including a DC source coupled to an electrode of the plurality of electrodes and supplying a DC signal to the electrode, wherein if the detection circuit detects a high level of attenuation in the DC signal, the detection circuit generates the first interrupt.