Gas sensor

1. A gas sensing device comprising:

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

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

a heater located within the dielectric layer;

a material configured to sense a gas; and

one or more polysilicon electrodes coupled and in direct contact with the material configured to sense the gas,

wherein the one or more polysilicon electrodes comprise a first pair of electrodes comprising interdigitated electrodes and a second pair of electrodes interleaving between the first pair of electrodes, and

wherein the polysilicon electrodes comprises two connections configured for current flow through the material configured to sense the gas and two further connections configured for resistance or voltage measurement of the material configured to sense the gas.

2. The gas sensing device according to claim 1 , wherein the one or more polysilicon electrodes are highly doped.

3. The gas sensing device according to claim 1 , wherein a width of at least some of a plurality of interdigitated structures and/or a distance between adjacent interdigitated structures within the plurality of interdigitated structures have sub-micrometer dimensions.

4. The gas sensing device according to claim 1 , wherein the one or more polysilicon electrodes are formed in a CMOS compatible process.

5. The gas sensing device according to claim 1 , wherein the gas sensing device comprises a flip-chip configuration.

6. The gas sensing device according to claim 1 , wherein the heater comprises a CMOS material, and optionally wherein the CMOS material is any of polysilicon, platinum, titanium, tungsten, or a combination of these.

7. The gas sensing device according to claim 1 , wherein the heater is formed underneath the one or more polysilicon electrodes.

8. The gas sensing device according to claim 1 ,

wherein the dielectric membrane comprises an etched recess portion, and

wherein the material configured to sense the gas is located within the etched recess portion of the dielectric membrane.

9. The gas sensing device according to claim 1 , wherein the one or more polysilicon electrodes comprise a first polysilicon layer, and wherein the heater comprises a second polysilicon layer.

10. The gas sensing device according to claim 1 , wherein the one or more polysilicon electrodes comprise a first polysilicon layer and a second polysilicon layer.

11. A gas sensor array assembly comprising:

an array of a plurality of gas sensing devices according to claim 1 ,

wherein the plurality of devices is formed on a single chip.