High Sensitivity Pressure Sensor Using Tandem Wheatstone Bridge for Low Pressures

A tandem Wheatstone bridge low-pressure (TWBLP) sensor with high sensitivity which can be widely used in medical and industrial fields has been designed and fabricated. Compared with the conventional low-pressure (CLP) sensor, the TWBLP sensor membrane is arranged with eight piezoresistors, which are formed into two Wheatstone bridges. They achieved the detection of membrane stress with different positions and different directions. The output ports of the two Wheatstone bridges are connected in tandem to realize the non-interference superposition of the output electric potential, thus improving the sensitivity of the sensor. The structure of the sensor membrane and the position of the piezoresistors are optimized using the finite element analysis (FEA). The TWBLP sensor is simple in structure design and easy to produce in large quantities, with the advantage of high sensitivity, which can provide tiny pressure measurement results for pressure measurement in related fields. In the laboratory environment, the local atmospheric pressure is used as the reference zero point to calibrate the sensor. The test results show that the sensitivity of the TWBLP sensor is 26.20% higher than that of the CLP sensor. For the measurement range from -10 to 10 kPa, the fabricated sensor achieves a high sensitivity of 23.07 mV/kPa and an accuracy of 0.19%F.S.