Buckling analysis in stretchable electronics

Abstract

In the last decade, stretchable electronics evolved as a class of novel systems that have electronic performances equal to established semiconductor technologies, but can be stretched, compressed, and twisted like a rubber band. The compliance and stretchability of these electronics allow them to conform and mount to soft, elastic biological organs and tissues, thereby providing attractive opportunities in health care and bio-sensing. Majority of stretchable electronic systems use an elastomeric substrate to carry an ultrathin circuit mesh that consists of sparsely distributed stiff, thin-film electronic components interconnected by various forms of stretchable metal strips or low-dimension materials. During the fabrication processes and application of stretchable electronics, the thin-film components or nanomaterials undergo different kinds of in-plane deformation that often leads to out-ofplane or lateral buckling, in-surface buckling, or a combination of all. A lot of creative concepts and ideas have been developed to control and harness buckling behaviors, commonly regarded as pervasive occurrences in structural designs, to facilitate fabrication of stretchable structures, or to enhance stretchability. This paper provides a brief review of recent progresses on buckling analysis in stretchable electronics. Detailed buckling mechanics reveals important correlations between the geometric/material properties and system performance (e.g., mechanical robustness, deformability, structural architecture, and control). These mechanics models and analysis provide insights to design and optimize stretchable electronics for a wide range of important applications.

Materials and Structures toward Soft Electronics

“…Kinetic growth of the wave/wrinkle includes three stages: initial growth, coursing, and equilibrium, which can be quantitatively understood by the combination of liner perturbation analysis and energy minimization . Both single‐ and multiwave patterns can occur ( Figure a), corresponding to the global and local buckling modes of the hybrid system, respectively . Critical factors that separate these two modes are the modulus and thickness ratio between the substrate and the inorganic thin film .…”

Surface Instability of Composite Thin Films on Compliant Substrates: Direct Simulation Approach

“…In the case of "hard" PV and/or conducting layers such as silicon, perovskite, and indium tin oxide, various ways of fabricating them onto an instability-driven wrinkled base structure, for the purpose of enhancing light trapping (Ram et al, 2017;Bush et al, 2018;Schauer et al, 2018;Zhang et al, 2018) or scattering (Wang C. et al, 2017), have been reported. An added benefit of the wrinkled structure is the possible improvement in deformability in stretchable electronics (Wang B. et al, 2017); thus enabling their potential deployment in fabrics and on curved or uneven surfaces. Some recent studies have demonstrated the mechanical robustness upon stretching, bending, and cyclic deformation while retaining reasonable optoelectronic performances (Kaltenbrunner et al, 2012;Hsieh et al, 2018;Ryu and Mongare, 2018).…”

Buckled Structures: Fabrication and Applications in Wearable Electronics

“…The thickness of the substrate also affects the buckling structures in practical applications, which is not considered in the above theory . More complicated buckling theories are reviewed elsewhere for interested readers …”