A Critical Review of Janus Electrospun Nanofiber: Triboelectric Nanogenerators for Next‐Generation Wearable Systems

Abstract

This review explores the rapidly emerging, promising domain of Janus nanofiber‐based triboelectric nanogenerators (TENGs). We focus on Janus nanofibers with anisotropic, dual‐faced chemical or physical properties, due to their exceptional potential for engineering high‐performance wearable electronics and self‐powered sensors. The review systematically examines how the inherent structural and functional asymmetry of Janus nanofibers, such as differential conductivity, tailored surface energy on opposing sides, and gradient porosity, enables superior control over triboelectric charge generation, retention, and collection. The discussion is anchored by summarizing state‐of‐the‐art device performances, where Janus nanofiber TENGs have demonstrated exceptional outputs (e.g., >140 V, power densities in the mW range) and remarkable robustness over thousands of cycles. Furthermore, this article critically evaluates the application horizon unlocked by Janus designs. Their multifunctional nature enables dual‐mode operation as sensitive, self‐powered sensors that detect physiological signals (e.g., pulse, swallowing) and biomechanical motions (e.g., joint bending with angle‐specific electrical responses) with high signal distinguishability. This focus is motivated by a significant gap in the literature; despite their transformative advantages, Janus nanofiber TENGs have not been the subject of a dedicated, in‐depth review, leaving their unique design principles and synergistic benefits underexplored.