High-Pressure Sensor With High Sensitivity and High Accuracy for Full Ocean Depth Measurements

Ocean depth measurement is very important for ocean observation, prediction and development. In this work, an absolute piezoresistive pressure sensor with high sensitivity and high accuracy for full ocean depth measurement is designed and fabricated through theoretical calculations and simulations. The shape and dimension of the diaphragm are designed through finite element simulation. A thick circular C-type diaphragm is used and the stress distribution on the diaphragm is simulated. The influence of the shape, dimension and position of the piezoresistors on the sensitivity and nonlinearity is calculated and analyzed, and the performance of sensors with single-bar-shaped piezoresistors and sensors with meander-shaped piezoresistors with different spacing is further compared. A tri-meanders-shaped piezoresistor with a large ratio of piezoresistance to connecting layer resistance is designed, and the piezoresistor position with high linearity is determined through simulation. Non-glue oil-filled isolation package is used to improve the repeatability and hysteresis of the sensor. The pressure sensor has a range of 0–120 MPa, a sensitivity of 0.425 mV/V/MPa, and an accuracy of 0.0182 %FS.