Vertically Aligned Laser Patterned Carbon Nanotube based Strain-less Sensor for Motion Detection

Carbon nanotubes (CNTs) have paved the way as a functional material in wearable motion sensors. Most of these flexible motion sensors are strain based with their output response being electrical. This paper reports the fabrication and implementation of laser-patterned vertically aligned CNT (VACNT)-based motion sensors that operate on the change in intensity of the transmitted light with angular displacement, and is based on the concept of shadowing effect by the VACNTs. The sensing mechanism does not involve straining the sensor, ensuring its longevity. The sensor also exhibits versatility in sensor parameter tuning with a highest sensitivity of 25 μm and a sensing range of ± 40° with negligible hysteresis being recorded for the sensors reported in this study. The sensor offers high accuracy, reliability, and precision. The influence of the design parameters, like the height of the VACNT film and the dimension of the pattern, has been explored in this study. A prototype device has been 3D printed for the VACNT-based sensor to monitor minute human wrist movements of speed as high as 160°/s. The proposed sensor is suitable for real-time tracking of high-speed, small- and large-scale movements with good reproducibility.