Aligned Ion Transport Design Advances High-Performance Moisture-Enabled Energy Harvesting and Multidirectional Sensing
Moisture-enabled energy harvesting technologies offer a promising route for self-powered strain sensing, yet conventional generators suffer from slow response, poor recovery, and limited multidirectional resolution. Here, we report a stretchable thermoplastic polyurethane (TPU) nanofiber moisture-enabled electric generator (MEG) with highly aligned ion channels. A carbon black/sodium dodecylbenzene sulfonate (CB/SDBS) layer is coated on the TPU membrane, while carboxymethyl cellulose (CMC) and acidified poly(sodium 4-styrenesulfonate) (HPSS) are applied on opposite sides, establishing lateral hydrophilicity and ion gradients to drive directional ion migration. The planar MEG is lightweight, flexible, and requires no fully covered electrodes, enabling conformity to complex deformations. The aligned channels reduce ion migration tortuosity, enhancing ion transport efficiency and flux. As a result, the aligned MEG (ATMEG) delivers 0.2 V and 0.51 μA cm−2 at ~90% relative humidity, corresponding to 400% and 287% enhancements compared with the unaligned MEG (UATMEG). The ATMEG also exhibits ultrafast response (0.16 s) and recovery (0.08 s). Utilizing its anisotropic characteristics, a multidirectional self-powered strain sensor is developed, capable of distinguishing both the amplitude and direction of human motion, demonstrating strong potential for adaptive wearable electronics and intelligent motion monitoring.