Liquid metal flexible multifunctional sensors with ultra-high conductivity for use as wearable sensors, joule heaters and electromagnetic shielding materials

With the improvement of living standards and the growing concern for health issues, wearable strain sensors are receiving more and more extensive attention from researchers in the field of health monitoring due to their excellent flexibility. Gallium-based liquid metals (GLMs) have shown superiority in the field of wearable electronics due to their high conductivity and fluidity, however, GLMs droplets are highly susceptible to oxidation, which leads to performance degradation. Here, Polyvinyl alcohol, okra polysaccharide and citric acid (PVA/OP/CA) have rich oxygen-containing functional groups and can encapsulate GLMs through non-covalent interactions. It is conducive to avoid the further oxidation of GLMs. And through the “one-pot method” and solution casting method, the PVA/OP/CA/GLMs (POCG) flexible multifunctional sensor was successfully prepared with a conductivity of up to 2155.17 S/m, a maximum gauge factor (GF) of 10.38, a strain response range of 5 %–270 %. In addition, the POCG can monitor small strains and large strain movements, quickly generate up to 42.2–181.3 °C quantity of heat at a low voltage of 1.0 V–3.5 V, and has an electromagnetic interference shielding efficiency (EMI SE) of up to 30–40 dB, which meets the needs of multifunctional sensing. Therefore, the designed POCG multifunctional sensor has a wide range of application potential in the field of wearable health monitoring and mother and baby wearable.