A highly conductive hydrogel driven by phytic acid towards a wearable sensor with freezing and dehydration resistance-Qin Zhang

Conductive hydrogels with anti-freezing and moisturizing properties have sparked huge attention in flexible electronics, which can work stably in harsh environments. However, it is challenging and urgent to enhance the environmental adaptability of hydrogels while maintaining high conductivity. Here, a highly conductive hydrogel featuring remarkable freezing resistance and moisture-holding ability is fabricated via incorporating phytic acid (PA) into the polyacrylamide/chitosan hydrogels. The addition of PA not only endows the hydrogels with marvelous conductivity of 0.105 S/cm due to the ionization of PA, but also promotes the antibacterial property against Gram-negative bacteria and Gram-positive bacteria. Besides,

based on the strong hydrogen bonding between PA and water molecules, the hydrogels exhibit excellent flexibility and great conductivity (0.041 S/cm) at -20 °C and could function well after storage of 15 days at ambient conditions. More importantly, the hydrogels can serve as reliable electrodes for electrocardiography (ECG) signals detection. Meanwhile, with the imperceptible strain perceive ability (0.1% of strain) and a high gauge factor of 10.87, the hydrogel wearable sensors are capable of precisely monitoring and recognizing both drastic and subtle human motions under diverse working environments. This work provides a novel and promising method for developing flexible wearable electronics with environmental stability.

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