Inkjet-Fabricated Capacitors on Paper and Textile Fabrics

In recent years, much attention has been given to various printing techniques to produce low-cost electronic ingredients and equipment. Inkjet printing is one of the most promising methods for printing circuit ingredients in one step almost on any substrates. In this study, the inkjet printing technique was employed for chemical deposition of silver nanoparticles by ejecting aqueous solutions of silver nitrate as metal salt and ascorbic acid as reducing agent on flexible substrates such as paper and fabric. Inkjet-deposited silver patterns were used as capacitors in electrical circuits and their performance was tested. Different values of capacitance were gained by a simple change in the size and shape of the printed capacitor. The highest capacitance values gained on an inkjet-deposited capacitor (a parallel plate capacitor with ۱ cm۲ overlapped area) on paper and fabric were ۸۵.۱ and ۱۳۷۰ pF, respectively. Inkjet-printed capacitors (interdigital capacitors with six fingers) could display a capacitance around ۲۰ and ۶ pF on paper and fabric, respectively. Levels of capacitance achieved by the new inkjet deposition technique can successfully match and exceed the capacitance levels of conventional capacitors produced using current multi-step fabricating methods.