Dual-sided and flexible triboelectric nanogenerator-based hydrogel skin patch for promoting wound healing

Wound healing remains one of the most challenging issues in medicine; thus, innovative approaches are required to enhance this process. Herein, we designed a dual-side and flexible triboelectric nanogenerator (TENG) that could convert mechanical shocks into pulsatile electrical stimulations; these were then applied at the site of the wound with the use of a biocompatible and antibacterial skin patch due to the use of chitosan, polyvinyl alcohol, and zinc oxide nanoparticles (ZnO NPs). The fabricated TENG exhibited an average open-circuit output voltage of 57 ± 5 V and an average short-circuit output current of 2.2 ± 0.3 μA. The in vitro antibacterial activity of the hydrogels was proportional to a higher concentration of ZnO NPs; meanwhile, cell viability showed an inverse relationship. Based on these findings, the most suitable concentration of ZnO NPs used for the skin patch applied to the TENG was determined to be 0.4 % W/V. In vivo experiments on rats demonstrated that slow electrical stimulations from the TENG enhance wound healing more effectively than fast electrical stimulations. Histological analyses further validated these findings. Generally, results show that the electrical stimulation provided by the TENG under the biocompatible skin adhesive is sufficient to protect the wound environment against pathogenic attacks and accelerate wound healing.