Fabrication of High-Resolution Flexible Circuits and Sensors Based on Liquid Metal Inks by Spraying and Wiping...

Owing to the development of soft electronics enabled from liquid metal, flexible and wearable sensors have been attracting more and more interest recently. So far, several types of liquid metal sensors based on soft substrate have been gradually developed. However, there is still too much space to explore regarding fabrication efficiency including resolution etc. which in fact determines further development and applications of liquid-metal flexible sensors. In this article, we proposed and demonstrated a novel method to fabricate liquid-metal circuits on PDMS (Polydimethylsiloxane) by spraying and wiping processing, which simultaneously offers simpler manufacturing process and smaller feature size as compared with existing approaches. According to various desired needs, the PDMS substrate can be prepared with specifically designed micro-channels in advance and then liquid metal entity can be patterned via subsequent spraying and wiping. As experiments indicate, the whole process is quite implementable and convenient. Except for PDMS, we further showed that PDMS mixed up with Ecoflex can also serve as a benign substrate. In order to illustrate the applications of this technique, we successfully produced several typical functional circuits and tested their working performances. Their roles to develop further electrical or thermal resistive sensors were discussed. Overall, the feature size with high reliability has reached 50 μm. The present method is expected to contribute to the development of liquid-metal sensors with high resolution and sensitivity.