Stretchable, transparent and multifunctional PVC-gel heater: a novel approach to skin-mountable, wearable thermal devices

Electric heaters based on functional materials and innovative designs have been developed for various applications. In this paper, we propose a soft dielectric heater (SDH) using polyvinyl chloride-gel (PVC-gel) as the dielectric heater and hydrogel as stretchable electrodes. Under an AC voltage, the leakage current in the PVC-gel leads to continuous injection and discharge of charges, causing the polarized plasticizers and flexible PVC chains to vibrate and collide, thereby generating heat through dielectric heating. Furthermore, the SDH generates a uniform temperature distribution even under strains up to 400%. Besides, high transmittance over 86% across the visible range renders it suitable for wearable or skin-mountable heaters from an esthetic viewpoint. Its capacitor-like structure achieves a scalable design, enabling extension from a singular cell to a row/column addressable and pixelated array of heaters. The 5 × 5 SDH array can deliver varied thermal information and sensations while maintaining performance even when stretched.