【Shanghai Jiao Tong University: Research on a flexible PDMS pressure sensor based on micro pyramid structure and embedded silver nanowires and its application in urine flow measurement】

1. Working principle of flexible pressure sensors

This study introduced micro cone structures on the surface of flexible PDMS and uniformly embedded silver nanowires inside these micro cones. The introduction of micro vertebral structures enhances the sensitivity response of sensors to small pressure signals; At the same time, silver nanowires, as conductive components, not only achieve the acquisition and conversion of pressure resistance signals, but also effectively reduce the inherent hysteresis phenomenon of PDMS, an elastic material, due to the inherent rigidity of its metal material.Under no load conditions, due to the small contact area between the micro cone and the electrode, the resistance value of the sensor is relatively high. When pressure is applied, the compression deformation of PDMS causes more conductive connections between the silver nanowires embedded on the surface of the micro cone, and the contact area between the micro cone and the electrode also increases accordingly.Therefore, there is a negative correlation between the applied pressure and the resistance of the sensor. By applying a constant voltage to the sensor, a current response that is positively correlated with the pressure signal will be obtained. Therefore, measuring current can provide a more intuitive indication of pressure changes than directly measuring the resistance of the sensor.