Flexible Strain Sensors Based on Direct-Writing VO<sub>2</sub> Nanobelts Inks for Monitoring Human Motions and Human–Machine Interaction
Hanzhi Han, Youliang Cheng, Changqing Fang, Taifei Zhao, Jie Liu, Haochen Du
Abstract
Flexible strain sensors have attracted extensive attention due to their promising applications in wearable electronics and artificial intelligence, and VO 2 smart materials have been applied in this field due to their sole stimuli-response. In addition, the direct writing method is very facile for the preparation of flexible sensors. Herein, the VO 2 (B) nanobelts with the width ranging from 100 to 200 nm were synthesized by the hydrothermal method in this work. Subsequently, VO 2 (B)-based flexible sensors were prepared via the direct-writing strategy, where the conductive ink containing synthesized VO 2 (B) powders was patterned on the different substrates by pen or brush. The sensors exhibited high sensitivity (GF = 470) and excellent stability (stretch–release cycles more than 1000) and can accurately monitor varieties of human health signals (respiration, pulse, muscle state, etc.). As-prepared smart integrated glove associating with LEDs and power supply can effectively achieve gesture recognition and a primary human–computer interaction model. Furthermore, the sensing signals of joint movements were collected by VO 2 (B)-based flexible sensors and then remotely transmitted to the smart terminal through a wireless local-area network, which achieved real-time monitoring of human movement. Therefore, this work demonstrated the potential application of a VO 2 (B)-based conductive ink in wearable electronic devices and human–computer interaction systems.