A high-density flexible tactile sensor array for fingertip sensing

A capacitive flexible tactile sensor with high-density array and high sensitivity is proposed for robot fingertip sensing. This tactile sensor consists of contact layer, transmission layer, pressure-sensitive layer and driving layer from top to bottom. To simulate human fingers, the contact layer is designed as hemispherical button structure. For high sensitivity, the micro-needle array is used as the pressure-sensitive layer and the density of micro-needle is about 2400 dots/cm ² . Furthermore, driving layer is designed as flower structure which density is 25 dots/cm ² with one main detection and 24 sub-detection units. The area of sensor is 1 cm ² . To ensure safe human-robot interaction, the contact layer and pressure-sensitive layer is made of polydimethylsiloxane (PDMS), driving layer is made of FPCB and transmission layer is made of conductive fabric. According to tests, the sensitivity of sensor's main detection unit is 62.5%N, the sub-detection units are 79.6%N in the range of 0 to 30N. When the manipulator assembled with the tactile sensor grasps different material objects, sensors' outputs are different, it can clearly distinguish different materials according to the hardness of objects. It also can detect three-dimensional force and get complete tactile information when manipulator grasps but object slides. Because of the high-density array and high sensitivity, the proposed tactile sensor can be used to help robot complete fingertip sensing and perform fine operations.