Highly Stretchable Strain-Insensitive Vertical Serpentine Conductors for Flexible Electronics

Abstract

The stretchable and curved electronics have recently attracted tremendous attention due to their unique advantages and broad application scenarios. Stretchable conductors are the most important units and determine the performance of the whole device. This article focuses on the development of a novel vertical serpentine conductor (VSC) with a high aspect ratio through MEMS-based fabrication technology for stretchable and curved electronics with superior performance. A comprehensive study of various designs for the vertical serpentine structure was conducted to provide a critical basis for subsequent structural design and fabrication. Next, a series of VSCs of different designs were manufactured for comparative experiments, which also confirmed the feasibility of constructing vertical serpentine structures via MEMS-based technology. After that, the mechanical properties of the VSC were investigated experimentally. The VSC with a radius of $30~\mu $ m can be stretched up to 4000% while maintaining structural integrity and electrical performance. Excellent stability can also be obtained, where the electrical properties of VSC were strain insensitive during deformation. In addition, the superior durability of the VSC was verified after 20 000 cycles of stretching and releasing at 3000% applied strain, where the relative resistance only changed within 5%.