Wearable PANI@CoFe<sub>2</sub>O<sub>4</sub> organohydroges for strain sensing, EMI shielding and thermal insulation

With the rapid escalation of electromagnetic pollution and electromagnetic interference, conventional EMI shielding materials can no longer satisfy the integrated requirements of next-generation flexible electronic devices and information terminals for mechanical deformability, wearable adaptability, and real-time signal monitoring. In this work, a multifunctional polyacrylamide/glycerol (PG)/P@CoFe (PAM/Gly/PANI@CoFe₂O₄) composite organohydrogel sensor with synergistic electromagnetic dissipation was fabricated through a hydrothermal-assisted one-pot strategy. CoFe₂O₄ magnetic nanoparticles were first synthesized via an ethylene glycol-assisted solvothermal route. Subsequently, the surface-active sites of CoFe₂O₄ were utilized to induce aniline polymerization, yielding conductive-magnetic polyaniline (PANI)@CoFe₂O₄ composite nanoparticles. Mechanical characterization demonstrated that the resulting organohydrogel exhibited excellent compressive properties, while the incorporation of glycerol effectively suppressed water evaporation and enhanced water-retention capability. Electromagnetic measurements revealed that, at a PANI@CoFe₂O₄ loading of 4 wt.%, the 4 mm-thick hydrogel achieved an electrical conductivity of 0.55 ± 0.01 S/m and an average electromagnetic interference shielding effectiveness (EMI SE) of 50.27 ± 2.51 dB in the X-band. In addition, the hydrogel exhibited excellent thermal iInsulation performance. More importantly, its outstanding adhesion and rapid stimuli-responsive behavior enabled favorable human–machine interactive strain-sensing performance with good compatibility. This work provides an effective strategy for the development of integrated, robust multifunctional materials that simultaneously combine flexible sensing, electromagnetic shielding, and thermal insulation.