A Strain Sensor for Multidirectional Deformation Detection Realized by Rolling Patterned Vertically Aligned Carbon Nanotubes

Flexible and stretchable sensors have garnered significant attention in the fields of human-computer interaction, motion capture, and health monitoring. Presently, most sensors are limited to capturing motion in a single direction and lack the capability to analyze multidirectional deformations in real world. A single device capable of detecting multidirectional deformations has always been a high expectation and a daunting challenge. In this work, we realize the idea of using a single sensor for multidirectional sensing by adopting a "one-step" rolling process to transfer vertically aligned carbon nanotubes grown on a silicon wafer onto a flexible Ecoflex substrate. The entire preparation process is simple and efficient. Distinct conductive paths form along different directions controlled by the rolling process and the pattern design of carbon nanotubes, thus resulting in a sensitive directional dependence. The sensor exhibits remarkable performance, including a wide operating range (0-120%), high sensitivity (GF = 126.6), short response time (64 ms), and good stability (over 4000 cycles under strain 40%). The sensors are demonstrated for detecting motion signals and monitoring human health, ranging from subtle motion signals to large deformation. These sensor characteristics fulfill the requirements of various practical scenarios and have an immense potential for applications in human-computer interaction interfaces, intelligent robots, and in situ health monitoring.