Fabrication of microstructured CNT/PDMS-based tactile sensor for flexible and stretchable electronic skin

Abstract

Research on tactile sensors that can detect various human motions by applying to flexible and stretchable electronic skin is emerging. By mimicking the way the real skin converts mechanical signals to electrical signals through the receptors, the tactile sensor uses a change of resistance, capacitance and voltage by pressure or stretching. In this paper, piezoresistive tactile sensor was fabricated with microstructure using carbon nanotubes (CNT) and polydimethylsiloxane (PDMS). The problems with conventional tactile sensors are that multi-functional tactile sensors have difficulty in distinguishing between different senses and subtle-pressure sensors have low sensitivity. So, we have developed a 2 type tactile sensor that were pressure-insensitive strain sensor and pressure sensor with high sensitivity in subtle-pressure region to solve this difficulty. In the case of pressure-insensitive strain sensor, the sensor was fabricated by emulsion process and the concentration of CNT and the volume of the CNT-based aqueous solution are controlled to characterize with various electrical properties. In the pressure sensor with a high sensitivity at subtle-pressures, we fabricated pressure sensor with porous pyramid using PS microsphere. Therefore, it had high sensitivity ($251 kPa^{-1}$) and little hysteresis. Finally, fabrication process of these sensors was simple and then it was useful for application of electronic skin.