Structural Innovations in Printed, Flexible, and Stretchable Electronics

Research in stretchable, printed electronics combines multidisciplinary, state-of-the-art developments in material science and structural engineering. In addition to major advances based on developing novel materials and fabrication processes, synergistic structural innovations are of equal importance for enabling stretchability in printed devices and should not be overlooked. Planar printing techniques are preferred, compared to microfabrication or 3D printing processes, owing to their low cost, high throughput, and compatibility with a wide range of materials. Various printing strategies for controlling the substrate, bonding, distribution of strain, and buckling can be used to fabricate a variety of devices featuring wrinkled, textile-embedded, serpentine, island-bridge, or 2D-transformed 3D and 4D structures. Such structural innovations allow the use of ordinary printable materials for creating highly stretchable devices with minimal compromise in device performance and mechanical resiliency. This article provides an overview of the structures used in printed devices and summarizes their corresponding fabrication strategies and distinct features. The challenges of advancing the structural designs in printed devices and the prospects of transforming stretchable structures toward smart, responsive devices are also discussed. Future efforts will greatly expand the possibilities of using planar printing processes for fabricating complex structures with new functionalities.