Two methods for producing stretchable materials have emerged in recent years. One is remote epitaxy, or the “peel and stack” method. Developed by engineers at the Massachusetts Institute of Technology (MIT), remote epitaxy involves growing thin films of semiconducting material on a large, thick wafer of the same material. This is covered in an intermediate layer of graphene, which is 200-times stronger than steel and thought to be one of the most promising semimetals on Earth.
Any number of thin, flexible semiconducting films can then be peeled away from the graphene-covered wafer. Crucially, it’s possible to stack films made from different materials to produce flexible, multifunctional electronic devices. The essence of the technology — that MIT says is cost-effective — depends on polarity, or charges between the atoms flowing over graphene and the atoms in the underlying wafer.
Meanwhile, researchers in China have developed an alternative to MIT’s “peel and stack” method. This fashioned material is called a metal-polymer conductor (MPC). However, the metals are not typical conductive solids — copper, silver, or gold — but, instead, gallium and indium that exist as a syrupy liquid through which electricity can flow. In simple terms, the MPC has been described as islands of round liquid metal floating in a sea of silicone-based polymer.
The polymer network itself yields mechanically resilient materials with enough conductivity to support functioning circuits. MIT’s engineers have tested different MPC formulations in a range of applications including wearable keyboard gloves.
Whatever exciting applications are in the pipeline for stretchable electronics, materials scientists and design engineers can make use of a comprehensive materials database like Matmatch to keep up-to-date with the latest applications, materials choices and fabrication strategies behind this fascinating new evolution in electronics. While the days of the rigid computer chip are not over, we can at least look forward to the expanded possibilities of a more flexible future.
About the author:
Samir Jaber, content writer at materials database Matmatch - www.matmatch.com