A flexible three-dimensional force sensor based on PI piezoresistive film

In this paper, a flexible three-dimensional (3D) force sensor utilizing the piezoresistive principle has been manufactured. The proposed sensor is designed as four pressure sensing resistors embedded in a flexible substrate. The piezoresistive PI film is used to be sensing material, as its effective pressure sensitivity, good linearity, and low hysteresis. The bump built on top of the sensor convert an applied force to the mechanical stress, and changes the resistances of the four sensing cells. The normal and shear forces can be therefore detected by the resistance responses. Calibration and test experiments have been conducted to characterize the 3D force sensor. The results demonstrate that the sensor is capable of 3D force measurement with good linear responses and sensitivity. The proposed 3D force sensor could be suitable for tactile sensing in intelligent robots, and other applications requiring three-dimensional force detection.