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

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.