Fabrication of microscale silver conductive structures by electric field-driven direct writing

The electrohydrodynamic (EHD) printing technology has great potential in micro/nano manufacturing. However, due to the electrostatic repulsion between conductive particles, the EHD cannot form a jet stably using conductive materials. Herein, an improved electric field-driven direct writing (EDW) method is proposed, which utilizes the Taylor cone in contact with substrates to print directly but not form a jet. This strategy avoids the unstable electric jet printing with conductive ink and enables the fabrication of micro-scale, large-area conductive structures. In this study, the effects of printing speed on the line width, resistance of the Ag nanoparticles (AgNPs) and Ag nanowires (AgNWs) conductive structures were investigated. The mechanism of AgNWs arrangement and the relationship between arrangement and resistivity was also deeply analyzed. The final fabricated AgNPs and AgNWs conductive structures were with minimum line widths of 81.0 μm and 78.6 μm, the resistivities of 8.40 × 10-7 Ω·m and 7.78 × 10-7 Ω·m separately. Furthermore, interdigital electrodes with a line width of 380 μm were fabricated using AgNPs ink, and flexible electrodes which can maintain stable resistance when bent at 180° were printed with AgNWs ink. This demonstrated the good applicability of EDW printing in the fabrication of microscale silver conductive structures.