Microhotplate for Low Power and Ultra Dense Gaseous Sensor Arrays using Recessed Silica Aerogel for Heat Insulation

In the operation of an air pitted gaseous sensors, the microhotplate (microHP) consumes almost all the power used by the sensor. The required area to micromachine the air pit for the microHP of a single sensor is several times more than the actual area required by the sensor itself. The feasibility of implementing low power and ultra-dense gaseous sensor array is investigated by developing a new microHP structure using recessed silica aerogel. In comparison with the conventional microHP structure, the recessed aerogel not only has decreased the utilized area of the chip almost tenfold (181 x 181 microm2 vs. 573 x 573 microm2) but also has decreased the power consumed by each microHP more than two fold (54 nW vs. 30 nW) to maintain the temperature of 360ºC. Using the new structure, as the number of sensors increases in a sensor array, the saved area of the chip increases quadratic. Moreover, the power consumed by the new designed structure reduces drastically.