Inkjet printed differential mode touch and humidity sensors on injection molded polymer packages

Abstract

Today's printed electronics are mainly focused on producing sensors on thin, flexible, smooth foils, which limits their use on 2D applications. Within this study we report on the design of inkjet printed capacitive touch and humidity sensors on thermoplastic substrates, to fabricate printed functional structures on injection molded 3D components. Both sensors are based on printed differential interdigital capacitors (IDC) made of silver ink and a printed sensitive layer. Reproducible results and low hysteresis were achieved, proving the concept to be able to improve sensitivity and to reduce drift effects due to temperature as well as moisture absorption by the substrate.