Multifunctional Organohydrogel-Based Strain Sensor for Sitting Posture Feedback and Human–Machine Interaction

Flexible strain sensors based on hydrogel materials have attracted considerable interest for their potential in human motion detection, human–machine interaction, and electronic skin. However, traditional hydrogels suffer from limited mechanical performance and severe dehydration, which greatly hinder their practical application in wearable electronics. In this study, a P(DMA-co-AM)/LiCl organohydrogel with exceptional mechanical strength, water retention, and adhesion and sensing properties was developed via one-step ultraviolet (UV)-initiated copolymerization using acrylamide (AM), N,N-dimethylacrylamide (DMA), and lithium chloride (LiCl) in a water–glycerol (Gly) binary solvent system. The introduction of DMA significantly increased the cross-linking density, resulting in a 202% improvement in tensile strength compared to PAM-based organohydrogels. Simultaneously, the incorporation of Gly endowed the organohydrogel with superior water retention, allowing it to maintain excellent flexibility and stretchability even after 8 days of ambient exposure. In addition, the organohydrogel exhibited excellent adhesion (48.61 kPa on copper) and outstanding sensing performance, including high sensitivity (gauge factor (GF) = 3.09), rapid response and recovery (40 and 30 ms), and stable signal output. These features enabled the precise detection of human motion. Furthermore, the organohydrogel-based strain sensor was successfully applied to a sitting posture feedback device and a smart glove for robotic arm control, demonstrating promising prospects for wearable health monitoring devices and human–machine interaction.