LOW-POWER CONSUMPTION THERMAL GAS-FLOW SENSOR-BASED ON THERMOPILES OFHIGHLY EFFECTIVE THERMOELECTRIC-MATERIALS

A thermal gas-flow sensor based on thermopiles made of thin films of B i0.87Sb0.13 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 tempera ture of 22 degrees C. Experimental data and the results of finite-elem ent analysis calculations concerning the response of the signal voltag e to variations of the flow velocity at constant gas temperature as we ll as to variations of the gas temperature at constant flow velocity a re given. A high sensitivity of 5.9 V W-1 m(-1) s at low flows is achi eved, which makes the sensor suitable for battery-powered devices wher e a low power consumption is desirable.