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Bioelectronic devices and components made from soft, polymer-based and hybrid electronic materials form natural interfaces with the human body. Advances in the molecular design of stretchable dielectric, conducting and semiconducting polymers, as well as their composites with various metallic and inorganic nanoscale or microscale materials, have led to more unobtrusive and conformal interfaces with tissues and organs. Nonetheless, technical challenges associated with functional performance, stability and reliability of integrated soft bioelectronic systems still remain. This Review discusses recent progress in biomedical applications of soft organic and hybrid electronic materials, device components and integrated systems for addressing these challenges. We first discuss strategies for achieving soft and stretchable devices, highlighting molecular and materials design concepts for incorporating intrinsically stretchable functional materials. We next describe design strategies and considerations on wearable devices for on-skin sensing and prostheses. Moving beneath the skin, we discuss advances in implantable devices enabled by materials and integrated devices with tissue-like mechanical properties. Finally, we summarize strategies used to build standalone integrated systems and whole-body networks to integrate wearable and implantable bioelectronic devices with other essential components, including wireless communication units, power sources, interconnects and encapsulation. 

Cells execute remarkable functions using biopolymers synthesized from natural building blocks. Engineering cells to leverage the vast array of synthesizable abiotic polymers could provide enhanced or entirely new cellular functions. Here we discuss the applications of in situ-synthesized abiotic polymers in three distinct domains: intracellular polymerization, cell-surface polymerization and extracellular polymerization. These advances have led to novel applications in various areas, such as cancer therapy, cell imaging, cellular activity manipulation, cell protection and electrode assembly. Examples of these synthetic approaches can be applied across all domains of life, ranging from microbes and cultured mammalian cells to plants and animals. Finally, we discuss challenges and future opportunities in this emerging field, which could enable new synthetic approaches to influence biological processes and functions. 

Abstract Skin-like field-effect transistors are key elements of bio-integrated devices for future user-interactive electronic-skin applications. Despite recent rapid developments in skin-like stretchable transistors, imparting self-healing ability while maintaining necessary electrical performance to these transistors remains a challenge. Herein, we describe a stretchable polymer transistor capable of autonomous self-healing. The active material consists of a blend of an electrically insulating supramolecular polymer with either semiconducting polymers or vapor-deposited metal nanoclusters. A key feature is to employ the same supramolecular self-healing polymer matrix for all active layers, i.e., conductor/semiconductor/dielectric layers, in the skin-like transistor. This provides adhesion and intimate contact between layers, which facilitates effective charge injection and transport under strain after self-healing. Finally, we fabricate skin-like self-healing circuits, including NAND and NOR gates and inverters, both of which are critical components of arithmetic logic units. This work greatly advances practical self-healing skin electronics. 

Cell type-specific interfaces within living animals will be invaluable for achieving communication with identifiable cells over the long term, enabling applications across many scientific and medical fields. However, biological tissues exhibit complex and dynamic organization properties that pose serious challenges for chronic cell-specific interfacing. A new technology, combining chemistry and molecular biology, has emerged to address this challenge: genetically targeted chemical assembly (GTCA), in which specific cells are genetically programmed (even in wild-type or non-transgenic animals, including mammals) to chemically construct non-biological structures. Here, we discuss recent progress in genetically targeted construction of materials and outline opportunities that may expand the GTCA toolbox, including specific chemical processes involving novel monomers, catalysts and reaction regimes both de cellula (from the cell) and ad cellula (towards the cell); different GTCA-compatible reaction conditions with a focus on light-based patterning; and potential applications of GTCA in research and clinical settings. 

Genetically engineered neurons express membrane-bound enzymes that can catalyze oxidative polymerization on the cell surface. 

Self-healing soft electronic and robotic devices can, like human skin, recover autonomously from damage. While current devices use a single type of dynamic polymer for all functional layers to ensure strong interlayer adhesion, this approach requires manual layer alignment. In this study, we used two dynamic polymers, which have immiscible backbones but identical dynamic bonds, to maintain interlayer adhesion while enabling autonomous realignment during healing. These dynamic polymers exhibit a weakly interpenetrating and adhesive interface, whose width is tunable. When multilayered polymer films are misaligned after damage, these structures autonomously realign during healing to minimize interfacial free energy. We fabricated devices with conductive, dielectric, and magnetic particles that functionally heal after damage, enabling thin-film pressure sensors, magnetically assembled soft robots, and underwater circuit assembly.