Emerging Soft Bioelectronics

Bioelectronics can transduce signals across the tissue and device interface to measure and regulate biological activities for healthcare monitoring and diseases treatment.Currently, a variety of bioelectronic devices are widely used, such as glucose sensors, cardiac pacemakers, and electrocorticalgrams.However, due to the diverse mechanical strains and complex biofluids within the body, conventional rigid electronics cannot effectively meet the requirements of long-term comfort, precision, and stability.Over the last few years, there has been growing interest in flexible and stretchable bioelectronics in the form of wearable textiles, attachable to skin and implantable inside the body, that aim to comply with nonplanar and dynamic tissues.It is thus our great pleasure to organize this special issue on bioelectronics for Advanced Functional Materials.We here highlight materials, structures, functions, and interfaces for soft bioelectronics with a collection of 6 reviews, 1 progress report, and 11 articles from this exciting field.Traditional electronic devices are typically rigid, planar, dry, and static, while biological tissues are soft, curvilinear, ionic, and dynamic, so new materials should be designed to reduce these differences to establish effective and reliable interfaces.Pooi See Lee and co-workers (article number 1907184), Xiaodong Chen and co-workers (article number 1909540), and Moumita Kotal and Ilkwon Oh and co-workers (article number 1910326) discuss the basic requirements and material designs for both epidermal and implantable bioelectronic interfaces, ranging from metallic and carbonaceous nanomaterials, to conductive polymers and hydrogels.The challenges involving long-term stability of the bioelectronics in vivo are also addressed.Besides materials, device structures and implementation techniques are widely studied to reduce tissue damage and provide longterm signal stability, and the main advances and representative examples are carefully highlighted by Fei Pei and Bozhi Tian (article number 1906210) and Kyung-In Jang and Taeyoon Lee and co-workers (article number 1910026).Sensors are one type of the most explored bioelectronic devices.For tactile sensors, Darren J. Lipomi and co-workers (article number 1906850) report the development of stimuliresponsive organic materials for haptic devices.Zhenan Bao and co-workers (article number 1903100) present an effective method for tunable, consistent, and reproducible capacitive pressure sensors by using a pyramid microstructured design.