Gas Sensors

1 . A gas sensor comprising:

a catalyst material;

a temperature detector configured to measure a change in temperature of the catalyst material; and

a plurality of electrodes configured to measure the current and/or resistance of the catalytic material.

2 . A gas sensor according to claim 1 , wherein the plurality of electrodes forms an interdigitated electrode array.

3 . A gas sensor according to claim 2 , wherein the interdigitated array is in contact with the catalytic material.

4 . A gas sensor according to claim 1 , wherein the temperature detector is a thermopile, or wherein the temperature detector is a temperature diode.

5 . A gas sensor according to claim 1 , wherein the gas sensor is configured to provide a calorimetric output, and a resistive or capacitive output.

6 . A gas sensor according to claim 5 , wherein the gas sensor is configured such that the temperature detector provides the calorimetric output and the plurality of electrodes provide the resistive or capacitive output.

7 . A gas sensor according to claim 5 , wherein the calorimetric output is provided at a first temperature, and the resistive or capacitive output is provided at a second temperature.

8 . A gas sensor according to claim 5 , wherein the calorimetric output and the resistive output are provided at the same temperature.

9 . A gas sensor according to claim 1 , further comprising a heater.

10 . A gas sensor according to claim 9 , wherein the heater is a microheater.

11 . A gas sensor according to claim 9 , wherein the heater comprises a Peltier heater switchable between two configurations.

12 . A gas sensor according to claim 11 , wherein in a first configuration a current of a first polarity through the heater produces a heating effect, and wherein in a second configuration a current of a second polarity through the heater produces a cooling effect, and wherein the first polarity and the second polarity are opposite polarities.

13 . A gas sensor according to claim 9 , wherein the gas sensor is configured to operate the heater such that at least two different gases are detected at different temperatures.

14 . A gas sensor according to claim 13 , wherein the catalyst material is formed on the dielectric layer and wherein the area of the catalyst material extends throughout the entire dielectric membrane area.

15 . A gas sensor according to claim 1 , further comprising:

a semiconductor substrate comprising a substrate portion and an etched cavity portion;

a dielectric layer disposed on the substrate, wherein the dielectric layer comprises a dielectric membrane area, wherein the dielectric membrane area is adjacent to the etched cavity portion of the substrate.

16 . A gas sensor according to claim 15 , wherein the temperature detector comprises a thermopile which comprises a plurality of thermocouples coupled in series, and wherein at least one thermocouple comprises first and second thermal junctions, and wherein the first thermal junction is a hot junction and the second thermal junction is a cold junction, and wherein the hot junction is located within the dielectric membrane area and wherein the cold junction is located outside the dielectric membrane area.

17 . A gas sensor according to claim 1 , wherein the gas sensor further comprises:

a reference material, wherein the reference material has substantially similar thermo-conductivity properties as the catalytic material, but is configured to not act as a catalyst for a specified gas reaction;

a second temperature detector configured to measure a change in temperature of the reference material; and

a plurality of electrodes configured to measure the current and/or resistance of the reference material.

18 . A gas sensor according to claim 1 , wherein the gas sensor further comprises:

a second catalytic material, wherein the second catalytic material is a different material to the catalytic material;

a second temperature detector configured to measure a change in temperature of the second catalytic material; and

a plurality of electrodes configured to measure the current and/or resistance of the second catalytic material.

19 . A gas sensor according to claim 1 , wherein the gas sensor further comprises a second temperature detector, and wherein the second temperature is configured to measure a change in the ambient temperature.

20 . A method of manufacturing a gas sensor, the method comprising:

forming a plurality of electrodes;

forming a temperature detector; and

depositing a catalytic material coupled with the plurality of electrodes.