Design, fabrication, testing and mechanical analysis of bulk-micromachined flowmeters

Micromachined piezoresistive flowmeters with four different types of sensing structures have been designed, fabricated and tested. Piezoresistors were defined at the end of the sensors through p-diffusion, and their values were about 3.5kOmega. Wheatstone bridge was configured with the piezoresistors in order to measure the output response. The output voltage increases with increasing flow rate of air, obeying determined relationships. The testing results show that the sensors that are designed for measuring 10L/M in full operational range have desired sensitivities. The sensor chip is manufactured with bulk-micromachining technologies, requiring a set of seven masks.