A Fully Additive Low-Temperature All-Air Low-Variation Printed/Flexible Electronics With Self-Compensation for Bending: Codesign From Materials, Design, Fabrication, and Applications

Abstract

Sensing and its electronics based on printed/flexible electronics offer unique attributes of mechanical flexibility of its substrate, hence the unique applications. Nevertheless, one of the ensuing key challenges of flexible-electronics-based sensing is the issues associated with consistency and repeatability of its parameters of the flexible electronics elements/sensors due to their variations, which are sometimes intractable. These may be due to manufacturing variations, aging, when the substrate is bent, and so on. In this article, we describe our codesign between the different chains of the flexible electronics supply chain to derive practically flexible electronics and sensors for applications where the substrate is expected to bend, e.g., in an augmented sensing e-skin smart glove application. This effort includes our fully additive low-temperature all-air low-cost screen printing process, and how we obtain consistency and repeatability. To improve the matching of thin-film transistors—a critical consideration for conditioning sensor outputs—we describe layout techniques where relatively good matching can be achieved, but with area overheads. We describe how we accommodate the variations of printed elements and circuits embodying printed elements when the substrate is bent—a self-compensating means—and propose the application of the same for printed sensors. The cost of our self-compensation means is without power or area overheads, albeit more (uncomplicated) printing steps. We finally describe our process development kit (PDK) encompassing all of the aforesaid to predict the performance of the printed circuits and sensors, including the effects of bending and our proposed self-compensation thereto. We demonstrate the efficacy of our methods based on measurements on printed elements and circuits.