Characteristics of a silicon monolithic pressure-flow sensor for air-mass flow measurements

A monolithic pressure-flow sensor combining a silicon piezoresistive pressure sensor and a thermal type silicon flow sensor was fabricated and its characteristics in air were investigated. At 0-1 kg/cm 2 and 0-75°C, the pressure measurement characteristics such as sensitivity, thermal sensitivity shift, nonlinearity and thermal zero shift were the same as those of a conventional piezoresistive pressure sensor. Reproducible low output hysteresis was obtained at 0-1050 g/s. It was clarified from the flow visualization experiment that a bend observed in the flow calibration curve at the flow of 15-80 gs was due to a separation bubble formed at the front of the chip. The flow output showed large measurement error during the transient change of air temperature and it also decreased with increasing the sensor support temperature