The low temperature liquid metal pressure sensors

Pressure measurement of geotechnical constructions subjected to low temperature plays significant roles in the safety and stability of geotechnical engineering activities. However, the research of pressure sensors in low temperature environment is lacked. In this work, a Galinstan liquid metal pressure sensor under low temperature condition is developed to detect pressure in geotechnical engineering. The elastomer PDMS (polydimethylsiloxane) is employed as the base material. Micro-channels are carved using microfluidic soft lithography technology. The liquid metal is filled as a conductor, and a spring steel case is used for encapsulation. The theoretical relationship between the resistance and pressure is derived, and the theoretical resistance values are compared with experimental resistance values to verify the accuracy of theoretical derivations. The key performance indexes of the designed sensor, such as the compliance, repeatability and hysteresis, are experimentally investigated. The numerical results show that the applied pressure can be uniformly transmitted to the internal PDMS chip with the help of the liquid buffer layer. The experimental results imply that this developed sensor with liquid buffer layer has high curve compliance, good repeatability and low hysteresis in low temperature environment, which provides effective tools for the pressure monitoring of geotechnical constructions subjected to low temperature.