Ionic Double‐Network Hydrogels for Integrated Electromagnetic Shielding and Self‐Powered Sensing in Wearable Electronics

Cardiovascular implantable electronic devices (CIEDs) face dual challenges of high-frequency electromagnetic interference and functional integration. This work reports a multifunctional material constructed via a double-network ionic hydrogel strategy, enabling the integrated realization of efficient electromagnetic shielding and self-powered physiological monitoring. An interpenetrating network skeleton is formed through physical crosslinking of sodium alginate (SA) with Ca²⁺ and in situ polymerization of acrylamide (AM). By regulating the specific coordination of ions to induce directional channels and synergistically regulating salt concentration with hydration, an absorption-dominated shielding mechanism centered on ion polarization-interface relaxation is established. The optimized h-CA-PAM-Li⁺-1.0 hydrogel exhibits an electromagnetic interference (EMI) shielding effectiveness (SE_T) of 63.75 dB in the X-band, with absorption loss accounting for over 93%. Leveraging the excellent ionic conductivity of the hydrogel, a self-powered sensor encapsulated in PDMS films and integrated with wireless modules is fabricated, capable of real-time capture of physiological signals such as heartbeat while maintaining high sensitivity and anti-interference capability in dynamic environments. Free of traditional conductive fillers, this material combines biocompatibility, low cost, and designability, providing a material-device-system integrated solution for electromagnetic protection and intelligent monitoring of implantable electronic devices and opening a new research paradigm for multifunctional shielding materials.