Nanoscale sintering of zinc micropowders for high conductivity and sensing applications of transient electronics

Abstract

In the face of new social and environmental challenges, there is a need for an alternative approach to the fabrication of electronics. Increasing demand for smart healthcare applications or the growing e-waste problems inspired the work on new adaptations and materials for biodegradable, bioresorbable or even edible electronics. Such a trend is called transient electronics, which is a response to the mentioned problems, yet efficient and affordable fabrication of such elements is challenging. We report a broader approach to the application of zinc inks for printed electronics and a nanochemical sintering approach with several types of organic acids. Selectively spray-printed fine zinc microparticles subjected to acetic, lactic, malonic, ethylmalonic and citric acids were evaluated for obtaining the lowest electrical resistivity and its variations induced by the amount of applied acids. Resulting sintered Zn patterns exhibited sheet resistivity values as low as 15·10-2Ω/sq. Not all acids are suitable for fabricating stable, conductive paths, as in the case of citric and ethylmalonic acids. On the other hand, with malonic acid, there was a wide range of resistance changes in the function of applied acid doses (from one to fifteen), suggesting application as a chemical sensor for acid concentration. Such results suggest that with a low-cost zinc powder, absorbable by living organisms and disintegrating in the natural environment, using common organic acids, we can efficiently fabricate printed electronic circuits and sensors for transient electronics applications.