Self-supporting 3D printed flexible liquid metal electrodes for electrostatically microfluidic valves

Abstract

The growing demand for portable and wearable electronics has led to an increased interest in flexible electrodes. The 3D flexible electrode structure is the key to realising the wide application of diversified flexible electronic devices. However, most of the existing flexible electrode manufacturing methods is restricted to fabricating 1D and 2D electrode structures, and it is difficult to simultaneously complete the preparation of the substrate-electrode double-flexible structure in one device. Here, we propose a dual-mode 3D printing system that can realise the one-step integrated manufacturing of flexible 3D electronic devices with nanofiber membrane substrates and liquid metal electrodes. Nanofiber membranes and liquid metal materials have a double flexible structure that increases the compliance performance of the electrode. As a proof of concept, we demonstrated the application of 3D flexible electrodes in electrostatically driven microfluidic valves. The 8 kV driving voltage can make the displacement of the movable membrane more than 40 μm, and realise the on–off control of the microvalve. This technology has the advantages of low cost and integration, demonstrating the promising potential of such printed 3D electrodes to enable 3D flexible electrode devices to be used in microfluidics, software robots and wearable electronic devices.