Development of Highly Sensitive Flexible Sensor Using Area-Arrayed Bundle Structures of Multi-Walled Carbon Nanotubes

Abstract

In order to assure the safety and reliability of next generation robots such as surgical assisting robots and nursing care robots, a highly sensitive flexible sensor for detecting pressure distribution with a high spatial resolution is demanded. The expected specifications of this sensor are spatial resolution of less than 1 mm, and the pressure sensitivity of less than 10 kPa, respectively. The authors have focused on MWCNT (Multi-Walled Carbon Nanotube) because of its large deformability and large change of electrical resistance under uniaxial compressive strain in order to develop a tactile sensor that satisfies the required specifications above. In this study, two types of tactile sensors consisted by MWCNT film and area-arrayed MWCNT bundle were fabricated by synthesizing high quality MWCNT by thermal CVD method. After the synthesis of MWCNT film and MWCNT bundle, PDMS was chosen to coat around the MWCNT as flexible substrate to fabricate highly sensitive flexible sensor. After the fabrication of the tactile sensor, a compressive loading test was performed to evaluate the sensitivity of the sensor. It was found out that the electrical resistance of the MWCNT increased almost linearly with the applied compressive load indicating that the fabricated sensor succeeded in detecting compressive load. The load sensitivity of the sensor fabricated by MWCNT bundle was about 1 mN, and the obtained gauge factor was about 3.5.