Reversible Thermoactuation Unlocks Minimally Invasive Implantation and Retrieval of Soft Bioelectronics

Minimally invasive delivery of bioelectronics is currently limited by the irreversibility of deployment, rendering device retrieval traumatic and hindering clinical translation. Here, for the first time, we introduce a novel thermoresponsive, reversible-actuating polymer (Trap) that enables both minimally invasive implantation and retrieval. Trap exhibits a mechanistically unique dual-crystalline competition between (110)-oriented low-entropy crystals and (100)-oriented high-entropy crystals. The competitive crystallization governs bidirectional, stress-free shape memory within a human-compatible window (10°C-37°C), enabling rapid (<3 s), fatigue-resistant, and large reversible strain (∼30.17%). The solid-solid switching between two nanocrystalline states provides a robust and tunable actuation mode, allowing Trap to transition reversibly between compact 1D and functional 2D/3D geometries without mechanical loading. This materials' innovation directly enables microinvasive deployment and retraction of Trap-based neural electrodes through the same small incision (∼5 mm), as well as autonomous helical self-assembly and thermal detachment on peripheral nerves, achieving stable electrophysiological interfacing over weeks to months. This work establishes a material-centered framework for reversible biointerfaces, resolving the conflict between surgical invasiveness and device retrievability.