GAS SENSOR WITH A CONFIGURABLE HEATING ELEMENT, AND METHODS EXPLOITING THE CONFIGURABILITY

• US 20190310216A1
• Filed: 04/04/2019
• Published: 10/10/2019
• Est. Priority Date: 04/05/2018
• Status: Active Grant

• Current Assignee: Alpha M.O.S.
• Original Assignee: Alpha M.O.S.
• Inventors: SHIM, Chang Hyun, PELLETIER, Sebastien
• Granted Patent: US 11,402,347 B2
• Time in Patent Office: Days
• CPC Class Codes: G01N 27/123 for controlling the temperature temperature control per se G05D23/00
• CPC Class Codes: G01N 27/125 Composition of the body, e.g. the composition of its sensitive layer
• CPC Class Codes: H05B 2203/003 using serpentine layout
• CPC Class Codes: H05B 2203/037 Heaters with zones of different power density
• CPC Class Codes: H05B 3/20 Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater H05B3/62, H05B3/68, H05B3/78, H05B3/84 take precedence

Abstract

In a gas sensor having a gas-sensitive layer and a heating element to heat the gas-sensitive layer, the heating element comprises a heater track having first and second outer electric terminals and at least one inner electric terminal located between the outer electric terminals. The gas sensor includes a control unit configured to control the electric potentials that are applied to the electric terminals during use, and the control unit is configured to be capable of varying the set of electric potentials applied to the electric terminals. In certain applications the control unit may select the terminals to which power is applied, in order to assure the gas-sensitive layer is heated to a specified temperature. In certain applications the gas sensor has multiple measurement electrodes and the control unit selects the set of electric potentials so that different temperatures are attained at locations where different measurement electrodes are located.

Claims

1. A gas sensor, comprising:

a gas-sensitive layer; and

a heating element to heat the gas-sensitive layer, the heating element comprising a heater track having first and second outer electric terminals;

wherein;

the heater track has at least one inner electric terminal located between the outer electric terminals;

the heating element is configurable to set a temperature profile produced by the heating track; and

there is provided a control unit to configure the heating element by controlling the pattern of electric potentials applied to the inner and outer electric terminals of the heater track during use.

2. A gas sensor according to claim 1, wherein:

the control unit is configured to select a pattern of electric potentials for application to the terminals of the heater track which, when applied, heat the gas-sensitive layer to a predetermined target temperature.

3. A gas sensor according to claim 2, wherein the control unit is configured:

to select, from among the outer and inner electric terminals, a pair of terminals between which to apply power, and

to select, as said pair of terminals, the two terminals which, when power is applied therebetween, heat the gas-sensitive layer to a temperature having a deviation from the predetermined target temperature which is the smallest out of the deviations produced when power is applied between the different possible pairs of terminals.

4. A gas sensor according to claim 3, wherein the control unit is configured to select said pair of terminals dependent on test data, said test data comprising information indicative of a temperature that is reached by the gas-sensitive layer when power is applied between two candidate terminals chosen from among the outer and inner terminals.

5. A gas sensor according to claim 1, wherein the control unit is configured to select a pattern of electric potentials which, when applied to the terminals of the heater track, produce a temperature profile along the heater track, said temperature profile comprising regions at different temperatures.

6. A gas sensor according to claim 1, comprising plural measurement electrodes to measure an electrical characteristic of the gas-sensitive layer at different locations,

wherein the control unit is configured to select a pattern of potentials which, when applied to the electric terminals of the heater track, produce a temperature profile having regions at the same temperature coinciding, respectively, with said different locations where the measurement electrodes take measurements.

7. A gas sensor according to claim 6, and comprising a biasing unit configured to apply bias voltages to the measurement electrodes,

wherein the biasing unit is configured to apply different bias voltages to measurement electrodes taking measurements in regions at the same temperature.

8. A gas sensor according to claim 5, comprising plural measurement electrodes to measure an electrical characteristic of the gas-sensitive layer at different locations,

wherein the control unit is configured to select a pattern of potentials which, when applied to the electric terminals of the heater track, produce a temperature profile having different-temperature regions coinciding, respectively, with said different locations where the measurement electrodes take measurements.

9. A gas sensor according to claim 8, wherein:

the heater track has a meandering shape comprising plural bends and the inner terminals are located on the outside of bends in the heater track; and

measurement electrodes are disposed inside bends of the heater track.

10. A gas sensor according to claim 1, wherein the control unit is configured to clean a selected part of the length of the heater track by applying power between an inner terminal of the heating track and another electric terminal of the heater track, the selected part of the length of the heater track being the part between the inner electric terminal and the other electric terminal.

11. A method of calibrating a gas sensor comprising a gas-sensitive layer, a heating element to heat the gas-sensitive layer, the heating element comprising a heater track having first and second outer electric terminals and at least one inner electric terminal located between the outer electric terminals, and a control unit to control a pattern of electric potentials applied to the electric terminals, the method comprising:

applying power between a pair of candidate electric terminals selected among the inner and outer electric terminals of the heater track;

determining the temperature attained by the gas-sensitive layer when power is applied between the candidate electric terminals;

comparing the determined temperature with a predetermined target temperature; and

calibrating the control unit, based on the result of the comparing, to select a pair of terminals between which to apply power to heat the gas-sensitive layer to the predetermined target temperature.

12. A method of operating a gas sensor comprising a gas-sensitive layer, a heating element to heat the gas-sensitive layer, the heating element comprising a heater track having first and second outer electric terminals and at least one inner electric terminal located between the outer electric terminals, a control unit to control a pattern of electric potentials applied to the electric terminals, and plural measurement electrodes disposed at different locations relative to the electric terminals of the heater track, the method comprising:

controlling, by the control unit, electric potentials applied to the terminals of the heater track, to produce along the heater track a temperature profile heating different ones of said plural measurement electrodes to different temperatures; and

determining the electrical characteristics of the gas-sensing layer at said different temperatures by measuring the set of signals produced by said different ones of the measurement electrodes during heating of the measurement electrodes by said temperature profile.