A temperature responsive adhesive hydrogel for fabrication of flexible electronic sensors

Flexible electronics are playing an increasingly important role in human health monitoring and healthcare diagnosis. Strong adhesion on human tissue would be ideal for reducing interface resistance and motion artifacts, but arising problems such as skin irritation, rubefaction, and pain upon device removal have hampered their utility. Here, inspired by the temperature reversibility of hydrogen bonding, a skin-friendly conductive hydrogel with multiple-hydrogen bonds was designed by using biocompatible poly(vinyl alcohol) (PVA), phytic acid (PA), and gelatin (Gel). The obtained PVA/PA/Gel (PPG) hydrogel with temperature-triggered tunable mechanic could reliably adhere to skin and detect electrophysiological signals under a hot compress while be readily removed under a cool compress. Furthermore, the additional advantages of transparency, breathability, and antimicrobial activity of the PPG hydrogel ensure its long-time wearable value on the skin. It is both environmentally friendly and cost saving for the waste PPG hydrogel during production can be recycled based on their reversible physical bonding. The PPG hydrogel sensor is expected to have good application prospects to record electrophysiological signals in human health monitoring.