Wet-Adhesive, Swelling-Resistant Hydrogels for Human-Machine Interaction and Underwater Physiological Signal Monitoring

With the advancement of flexible electronics, there has been a growing focus on monitoring physiological activity and health status. However, flexible electronic devices are prone to detaching under dynamic conditions or underwater environments, resulting in inaccurate and delayed signal transmission. This work employed a "one-pot method" to prepare a hydrogel (named DPE) with a three-dimensional network structure composed of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (DMAPS), polyacrylic acid solution (PAA), and ethylene glycol dimethacrylate (EDMA). It demonstrates excellent wet-adhesion properties, superior swelling-resistant (swelling rate of 5.82%), water retention capacity (88.53%), self-healing properties, biocompatibility, and reliable detection of physiological signals both in air and underwater. Additionally, the hydrogel possesses a low modulus (7.62 kPa) and a good linear operating range (gauge factor = 4.41). Given these advantages, hydrogels are highly sensitive and reliable for monitoring human motion signals, transmitting Morse code, and acquiring bioelectric signals. At the same time, based on the electrical signals generated by the hydrogel bending at different angles, the hydrogel can also drive the robotic hand to perform actions. In addition, hydrogels are capable of capturing electromyographic (EMG) signals underwater and achieving 98.75% gesture recognition accuracy using deep learning algorithms. This multifunctional hydrogel opens up possibilities for the application of flexible wearable sensors in various environments and holds great potential for next-generation bioelectronic devices.