Soft, Flexible, and Stretchable Platforms for Tissue-Interfaced Bioelectronics.

Seamless integration of electronic systems with living tissues requires not only biocompatibility but also careful matching of mechanical properties across heterogeneous organs. This review clarifies the often-conflated notions of "soft," "flexible," and "stretchable" electronics, and links these definitions to a tissue-mechanics framework spanning brain, nerve, skin, myocardium, and visceral organs. Based on this framework, we outline general mechanical design principles-ultrathin structures, stretchable architectures, and bioadhesive interfaces-that enable deformable devices to conform to moving, curved surfaces. Recent advances are then organized into tissue-targeted platforms, including imperceptible skin-mounted nanosheet and nanomesh electrodes, haptic and neural interfaces for bidirectional communication, and wet-organ adhesive systems for cardiac and gastrointestinal applications. We further highlight emerging material systems such as liquid metal-based conductors and biodegradable transient electronics, which respectively extend mechanical adaptability and introduce time-programmed disappearance to reduce surgical burden. Across these topics, the review distills unifying design rules for matching modulus, adhesion, and strain tolerance to specific biological environments, positioning soft, tissue-interfaced bioelectronics as a coherent toolbox that bridges wearable, implantable, and transient formats for future healthcare technologies.