Multifunctional PVA/PNIPAM conductive hydrogel sensors enabled Human-Machine interaction intelligent rehabilitation training

Abstract Hydrogels are regarded as an ideal medium for human-machine interaction (HMI) due to their adjustable modulus and flexibility, enabling seamless interaction with smart devices. However, in the field of medical rehabilitation, most of the hydrogel-based sensors are simply used to detect the motion signals of fragments and are rarely applied to help patients with rehabilitation training and improve the efficiency of doctors' diagnosis. This is due to the unstable sensing properties and poor mechanical properties of most hydrogels. The poor durability greatly limits the application of hydrogel-based sensors. Here, a conductive hydrogel sensor with visual temperature sensitivity and good mechanical properties (300% strain, breaking stress 0.19 MPa) is fabricated by introducing polyvinyl alcohol (PVA)-borax system combined with a freeze-thaw physical regulation strategy. The PVA/PNIPAM/PEDOT: PSS (PPP) hydrogels possess a rapid response/recovery time (200 ms/200 ms), a low detection limit of 1% strain, and good stability and durability. Furthermore, by integrating the hydrogels with a LabVIEW circuit program and wireless transmission technology, we have developed an advanced intelligent HMI system capable of monitoring, rehabilitation training, and remote diagnosis.