A micromachined, silicon mass-air-flow sensor for automotive applications

A micromachined, monolithic silicon mass-air-flow sensor has been developed for measuring engine intake air flows in the range of 1-60 m/s. It has a response time of under 1 ms and can be temperature compensated to a deviation of +or-3.5% error or less in indicated flow over a temperature range of -30 degrees C to +40 degrees C. The device can withstand bombardment by particles up to 50- mu m in size in the air stream, or larger ones if elements with reduced accuracy are used. A more rugged design, using larger silicon beams but retaining good temperature compensation capability, can be achieved by modifying the beam ends and their support to increase the thermal isolation between the beams and the rest of the silicon chip.<>