# US 8,543,340 B2 · Self-adjusting electrochemical sensor

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- Number: US 8,543,340 B2
- Document ID: US8543340B2
- Status: Granted
- Kind: B2
- Application number: 12/886,251
- Filed: 2010-09-20
- Published: 2011-01-13
- Granted: 2013-09-24
- Earliest claimed: 2004-08-25
- Assignees: Honeywell International Inc.
- Applicants: Lee D. Tice
- Inventors: Lee D. Tice
- Web page: https://patentgrep.com/patent/US8543340B2

## CPC

- G01N 33/0006: {Calibrating gas analysers}
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

A gas detector with a compensated electrochemical sensor exhibits altered sensitivity in response to decreasing stochastic noise in an output thereof. A gain parameter can be adjusted to alter sensitivity. A life-time estimate can be made based on sensitivity.

## Claims

### Claim 1

A method of determining the functionality of an electrochemical sensor in a gas detecting apparatus, comprising:
measuring the electrical noise level in an output signal of an electrochemical gas sensor circuit;
establishing a predetermined threshold;
comparing the electrical noise level to the predetermined threshold;
performing an electronic functionality test of the electrochemical sensor if the electrical noise level is lower than the predetermined threshold; and
indicating a trouble condition if the electrochemical sensor fails the electronic functionality test.

### Claim 2 (depends on 1)

A method as in claim 1 where the electronic functionality test includes applying a test current to the sensor and monitoring the current out of the sensor after the test current has been removed.

### Claim 3 (depends on 1)

A method as in claim 1 where the electronic functionality test includes applying a test current to the electrochemical sensor and monitoring the output of the sensor during the application of the test current.

### Claim 4 (depends on 1)

A method as in claim 1 where the electronic functionality test includes measuring the impedance of the electrochemical sensor and comparing that impedance to predetermined limits.

### Claim 5 (depends on 1)

A method as in claim 1 where the trouble indication is different than an alarm indication.

### Claim 6

A gas detecting apparatus comprising:
an electrochemical sensor;
circuitry including a processor coupled to the electrochemical sensor, the processor receiving signals from the circuitry indicative of noise in the electrical signals from the electrochemical sensor and establishing a noise value associated with the electrochemical sensor;
circuitry for comparing the noise value with a predetermined limit value;
electronic test circuitry for determining a functionality condition of the electrochemical sensor; and
output circuitry coupled to the processor to indicate the functionality condition of the electrochemical sensor.

### Claim 7 (depends on 6)

A gas detecting apparatus as in claim 6 where the output circuitry comprises communication circuitry.

### Claim 8 (depends on 6)

A gas detecting apparatus as in claim 6 where the output circuitry includes a light emitting device.

### Claim 9 (depends on 6)

A gas detecting apparatus as in claim 6 where the output circuitry includes a sound emitting device.