CMOS micromachined low power microlamp vacuum sensor

A CMOS micromachined thermally sensitive polysilicon resistor is used as the radiating element of a microlamp light source. The device is operated with constant electrical power input and heated to an elevated temperature. A detection method of monitoring the response of the device to its surrounding pressure with a photodiode is used instead of conventional thermal conductivity measurements. Micromachining technology helps to lower the power consumption of the sensor to the 10 mW range. An automatic power-switching scheme is discussed to increase the sensitivity of the measurement and lifetime of the device, over the pressure range from 10^-3 Pa to 10⁵ Pa