Low power consumption thermal gas-flow sensor based on thermopiles of highly effective thermoelectric materials

A thermal gas-flow sensor based on thermopiles made of thin films of Bi0.87Sb0.13 for the n-type legs and Sb for the p-type legs with a high thermoelectric figure of merit is presented. The micromachined sensor chip is mounted within a package, which is kept at a constant temperature of 22 degrees C. Experimental data and the results of finite-element analysis calculations concerning the response of the signal voltage to variations of the flow velocity at constant gas temperature as well as to variations of the gas temperature at constant flow velocity are given. A high sensitivity of 5.9 V W-1 m(-1) s at low flows is achieved, which makes the sensor suitable for battery-powered devices where a low power consumption is desirable.