The remarkable ability of biological systems to sense and adapt to complex environmental conditions has inspired the design of next-generation electronics with advanced functionalities. This review focuses on emerging bio-inspired strategies for the development of flexible and stretchable electronics that can accommodate mechanical deformations and integrate seamlessly with biological systems. We will provide an overview of the practical considerations in the materials and structure designs of flexible and stretchable electronics. Recent progress in bio-inspired pressure/strain sensors, stretchable electrodes, mesh electronics, and flexible energy devices are then discussed, with an emphasis on their unconventional micro/nanostructure designs and advanced functionalities. Finally, current challenges and future perspectives are identified and discussed.

Advances in neural electrode technologies can have a significant impact on both fundamental and applied neuroscience. Here, we report the development of flexible and biocompatible neural electrode arrays based on a nanopaper substrate. Nanopaper has important advantages with respect to polymers such as hydrophilicity and water wettability, which result in significantly enhanced biocompatibility, as confirmed by both in vitro viability assays and in vivo histological analysis. In addition, nanopaper exhibits high flexibility and good shape stability. Hence, nanopaper-based neural electrode arrays can conform to the convoluted cortical surface of a rat brain and allow stable multisite recording of epileptiform activity in vivo. Our results show that nanopaper-based electrode arrays represent promising candidates for the flexible and biocompatible recording of the neural activity.

Controlled synthesis of hierarchically assembled titanium dioxide (TiO₂) nanostructures is important for practical applications in environmental purification and solar energy conversion. We present here the fabrication of interconnected TiO₂ nanotubes as a macroscopic bulk material by using a porous carbon nanotube (CNT) sponge as a template. The basic idea is to uniformly coat an amorphous titania layer onto the CNT surface by the infiltration of a TiO₂ precursor into the sponge followed by a subsequent hydrolysis process. After calcination, the CNTs are completely removed and the titania is simultaneously crystallized, which results in a porous macrostructure composed of interconnected anatase TiO₂ nanotubes. The TiO₂ nanotube macrostructures show comparable photocatalytic activities to commercial products (AEROXIDE TiO₂ P25) for the degradation of rhodamine B (RhB). Moreover, the TiO₂ nanotube macrostructures can be settled and separated from water within 12 h after photocatalysis, whereas P25 remains suspended in solution after weeks. Thus the TiO₂ nanotube macrostructures offer the advantage of easy catalyst separation and recycle and can be a promising candidate for wastewater treatment.