Recent Progress on Flexible Electronic Devices Based on Buckled Structures with Polymeric Substrates.

Recently, flexible electronics have attracted widespread attention in personalized health monitoring, soft robotics, and smart human-machine interactions due to intrinsic high stretchability. Among them, constructing buckled structures in flexible devices is one of the most effective strategies to achieve flexibility and stretchability. Flexible electronic devices based on buckled structure (FEDB) have gained significant research progress, owing to their outstanding advantages such as simple fabrication processes, excellent structural stability, and broad applicability. Furthermore, its application areas are expanding to emerging scenarios, including the human body, underwater environments, the oceans, and space. However, there are few systematic reviews concerning their progresses, although researchers show increasing interest in the emerging applications of FEDB. This review summarizes recent research progress in FEDB. First, this review explains the buckled instability mechanism, listing the common conductive and substrate materials. The polymeric substrates discussed mainly include PDMS, TPU, SBS, PC, and hydrogel, which provide the flexibility and deformability required for FEDB. In addition, this review summarizes several methods for constructing buckled structures, including prestretch-release, solvent swelling, thermal, mold, and 3D printing as well as techniques for controlling morphology. Second, this review summarizes the applications of FEDB, such as flexible electrodes, strain and pressure sensors, and energy devices. Particularly, it provides a detailed introduction to the expansion of emerging scenarios, involving underwater monitoring, in vitro and in vivo physiological signal detection, human-machine interactions, and portable capsule devices. Finally, this review points out the current challenges of FEDB, including long-term service stability, adaptability to extreme environments, conformal attachment to complex curved surfaces, and large-scale manufacturing.