High-sensitivity flexible tri-axial capacitive tactile sensor for object grab sensing

•Photocured 3D printer was used to fabricate the sensor dielectric layer and bump structure.•The sensitivity of the sensor is enhanced by Mold Max 25 silica gel material with low compression modulus.•The sensor with pyramidal dielectric layer shows high sensitivity and wide dynamic range.•The sensor applied to the manipulator can realize the function of tri-axial force detection. In this paper, a high sensitivity, flexible capacitive tri-axial tactile sensor is constructed by pyramid-shaped microarray dielectric layer. The tactile sensor consists of a staggered 2 × 2 capacitive sensor array. Through the measure and analysis of the three-dimensional force, which was applied on the sensor, it could decompose into normal and shear force components. The sensor exhibits high sensitivity due to the pyramidal-shaped microarray and low modulus of the dielectric layer. The sensitivity of the sensor in the x,y and z-axis are 56.47, 53.45 and 90.39 %/N in the ranges of 0 ∼ 0.8, 0 ∼ 0.8 and 0 ∼ 0.6 N, respectively. In addition, the sensor also exhibits fast response and recovery times (60 ms), and longtime cycling stability. The low average test error (about 10.4 %) of the tri-axial tactile sensor provides the technical basis for the application of robotics and wearable devices.