A novel integrated transparent flexible tactile sensor

In this work, we propose a novel capacitance tactile sensor with flexibility and transparency using polydimethylsiloxane (PDMS), polyethylene terephthalate (PET), and indium tin oxide (ITO) for based materials. This sensor can measure normal force and shear force simultaneously. Each capacitance sensor cell consists six layers and includes four capacitors. When a normal force is applied on the bump, the capacitance of four capacitors all increase. Nevertheless, when a sheer force is applied on the bump, the capacitance of two capacitors increase but the others decrease. Therefore, we consider the relationship of capacitance changed in the sensor cell to determine the magnitude and direction of the applied force. The readout sensing circuit is also designed and implemented. The sensitivity is 30.37%/N or 1.622 pF/N and the transparency is over 88%. This is the first publication for the combination of high transmittance and flexibility for detecting the normal and shear forces simultaneously. The proposed tactile sensor can be applied to the touch penal and display devices.