A POLYSILICON FLOW SENSOR FOR GAS-FLOW METERS

We have developed a one-wire-type thermal flow sensor that has a polys ilicon microheater. It has a very wide flow-measurement range of 0.005 -35 m s(-1) and very short response time of 0.14 ms (90%), The size of the flow-sensor chip is 1 mm x 1 mm x 0.3 mm. The sensitivity is abov e 22 mV (ms(-1))(-1/2) when it is operated in constant-resistance mode . The electric power consumed to keep the temperature rise of the micr oheater at 80 K in windless air at 22 degrees C under atmospheric pres sure is about 6 mW. To minimize the power consumption the shape oi the microheater should be a straight line and its length should be a spec ific value. As polysilicon has large resistivity, large output signals can be obtained without amplifiers, it can be applied to household ga s Row meters and other systems.