Design and Fabrication of a High-Sensitivity Mems Pirani Vacuum Sensor with Three-Mode Switching

This paper reports a three-mode switching operation method to extend the detection sensitivity of the MEMS Pirani vacuum sensor in low and medium vacuum. The MEMS chip is designed with a suspended membrane, and the output characteristics of the three driving states, including constant-current, constant-voltage, and constant-temperature-difference, are investigated deeply. The results show that the constant-current drive is suitable for measuring medium vacuum (above 0.5 torr). The constant temperature difference drive has high sensitivity in the range of 0.5 Torr and 1.12 Torr. And the constant voltage drive is suitable for measuring low vacuum (vacuum below 1.12 torr). With three driving modes switching, the sensitivity of the sensor is improved by 1.7 times, 1.4 times, and 2.4 times in the ranges of less than 0.5 torr, $0.5 \sim 1.12$ torr, and more than 1.12 torr, respectively. The proposed method can effectively improve the vacuum detection sensitivity of the MEMS Pirani vacuum sensor.