Special issue on advanced flexible electronics for sensing applications [Scanning the Issue]

This articles in this special issue on flexible hybrid electronics provides insight into the technical problems that must be overcome as well as the new capabilities they will provide. The term, 'flexible hybrid electronics' means different things based on the context in which it is being discussed. It could mean adaptable for multiple applications, but, here the term refers to mechanical properties, although not necessarily precisely defined. Mechanically flexible might mean anything from conformable (nonlinear shape) to bendable or rollable (around a defined radius of curvature), or even foldable and stretchable. Although not well defined, the intent is to differentiate from the rectangular, rigid form factor of conventional semiconductor electronics. Hybrid means heterogeneous integration of conventional electronics with other electronic components (passive devices, sensors, etc.) that could be fabricated using conventional thin-film transistor (TFT) process technology by additive printing (ink jet, gravure, etc.). The purpose is to provide an electronics solution that has adequate performance, but in a low cost, novel form factor because printing offers the ability to inexpensively fabricate structures over large areas on mechanically flexible substrates (plastics, metal sheets, bendable glass). However, integration with conventional electronics such as silicon CMOS is necessary to achieve required performance because TFT and printed devices are significantly inferior to conventionally fabricated devices.