Conductive Microneedles: From Advanced Fabrication to Multifunctional Biomedical Applications

Microneedles (MNs) have attracted considerable attention as an innovative physical enhancement technology for transdermal drug delivery. In recent years, the incorporation of functional materials such as metals, carbon-based materials, and intrinsically conductive polymers (ICPs) has endowed MNs with excellent electrical properties. This advancement marks a significant functional evolution, transforming MNs from passive drug carriers into actively controllable and multifunctional biomedical platforms. The primary advantage of conductive MNs lies in their capacity to penetrate the stratum corneum and establish a high-quality electrical interface directly with subcutaneous tissues. This capability not only enhances the signal-to-noise ratio of bioelectrical signal acquisition, thereby improving signal fidelity in applications such as physiological monitoring and neural repair, but also enables actively controlled drug release. This review systematically summarizes key research progress in conductive MNs, with emphasis on the types of conductive materials employed and their respective advantages and limitations, strategies for imparting conductivity, corresponding microfabrication techniques, and cutting-edge applications in drug delivery, electrophysiological monitoring, and electrical stimulation therapy. Finally, the challenges associated with clinical translation and future development prospects are discussed, aiming to provide valuable insights for the design and development of novel conductive MNs systems.