Transcutaneous electrotherapy of facial nerve injuries based on dissolvable conductive microneedles

Local electrical stimulation (LES) is a widely used clinical method to treat peripheral nerve injury. However, existing plate electrodes (PE) usually suffer from low electronic transport efficiency, whereas acupuncture electrical stimulation may cause damage to normal tissues. There is an urgent need to develop an innovative LES technique with efficient electronic transport, minimal tissue injury and enhanced biosafety. Here, we present a new stretchable transcutaneous electrical stimulation system (STESS) that integrates dissolvable conductive microneedles (DCMN) for optimal skin penetration and electronic transport, along with snake-like electrodes that offer superior flexibility, which can effectively penetrate the stratum corneum, enabling deep tissue electrostimulation with minimal injury. In vitro studies and 3D finite-element analysis demonstrate that the DCMN-based electrotherapy significantly enhances subcutaneous nerve stimulation compared to the conventional PE-based technique. By diminishing the electrical resistance of the stratum corneum, the DCMN-based electrotherapy has shown remarkable in vivo therapeutic efficacy in a rat facial nerve crush injury model. This will pave the way for innovative physiotherapeutic methodologies in the realm of neurological rehabilitation.