H. Chang, S. Kim, S. Jin, S-W Lee, K-Y Lee, H. Yi
Korea Institute of Science and Technology,
Keywords: CNT nanomesh, piezoresistive pressure sensors, wearable
Summary:Wearable pressure sensors that can detect pressure changes induced by human body have been attracting drastically increasing interest in various applications such as wearable health condition monitoring systems, human-machine interfaces, and artificial intelligence. In particular, for the health monitoring applications, the wide pressure range produced by human body needs to be considered. For example, the pressure range of arterial pulse is ~ 10 kPa and the range by body weight and accordingly by walking can exceed ~ 90 kPa. A variety of pressure sensors employing different materials systems have been proposed to show ultrasensitive response and/or tunable operation ranges. However, an approach to tune the operation range of flexible pressures covering from sub kPa to hundreds of kPa by tuning materials properties has been elusive. Here we report that a biologically assembled conductive nanomesh of single-walled carbon nanotubes can be successfully employed for the fabrication of wearable pressure sensors with high sensitivity and wide operation range. We show that the tunable electrical properties and the nanostructures of the conductive nanomesh synergistically change the operation range of the pressure sensors. In addition, a very large sensitivity of 6.2 kPa-1 at lower pressure range, ~ 5 kPa, and a wide detection range, up to 100 kPa, with relatively high sensitivity could be successfully obtained using our scheme. Furthermore, the device shows excellent cycle stability at 100 kPa and consumes a relatively low power, < 25 μW. We envision that out approach would not only enable the development of high-performance wearable health-monitoring devices but also benefit other fields involving human-machine interface.