Photothermally Activated Pyroelectric Enhanced Self-Powered Wound Dressing: Breaking Through the Limitations of Interfacial Impedance to Achieve Efficient Electrical Stimulation for Wound Repair

The mismatch between interfacial impedance at the hydrogel-electrical stimulation layer interface in conventional double-layer self-adhesive electrical stimulation wound dressings remains a critical challenge, limiting charge transfer efficiency, and therapeutic outcomes. Herein, this study introduces a photothermally activated pyroelectric-enhanced self-powered wound dressing designed to overcome this limitation through a synergistic tri-modal mechanism integrating photothermal, pyroelectric, and piezoelectric effects. The wound dressing comprises a dual-layer architecture: an outer layer of hydrophobic poly(vinylidene fluoride) (PVDF)/cotton-based electrostimulation film and an inner hydrophilic self-adhesive hydrogel layer. Upon NIR irradiation, the hydrogel layer undergoes localized photothermal heating, dynamically reducing interfacial impedance (≈10× increase in conductivity) and facilitating efficient charge migration across the interface. Concurrently, the NIR-induced photothermal effect activates pyroelectric polarization in the PVDF layer, which synergistically couples with piezoelectric output to generate an enhanced endogenous electric field (≈1.5× the electric field of piezoelectric-only effects). In vitro and in vivo studies showed that this dressing significantly promoted wound healing. Compared with the control group (on the 7th day), the inflammatory chemokine density reduced by 99.36×, the capillary density increased by 3.85×, resulting in a 2.59× enhancement in the wound healing rate. Consequently, the photothermally activated pyroelectric-enhanced self-powered wound dressing presents a highly sophisticated and effective therapeutic approach for accelerating wound healing.