Fabrication of self-testable pressure sensors based on phase change

A novel self-testable method, thermo-pneumatic actuation, which is based on phase change, is presented. It can be used in large-scale self-testable pressure sensors. The phase change material (PCM) fills the cavity of the sensor. Applying voltage to the heating resistor, the PCM will be brought to boil. The vapor inside the cavity of the pressure sensor produces a significant pressure on the diaphragm, so a self-test is implemented by means of a thermal actuator based on the phase change. By the magnitude of the PCM that fills the cavity and the power of the heating resistor, the self-testing of the pressure sensors with different measurement range can be achieved. Based on this principles novel large-scale self-testable pressure sensor is fabricated. The sensor is built in a silicon-glass-silicon sandwich structure by anodic bonding. The self-testing output of the sensor is 6.8% of the full-scale output, and the accuracy is 2.1‰.