Development of Electrostatic Inkjet Head by Integrating Metallic and Silica Capillaries for Stable Meniscus

This article discusses the stability and analysis of meniscus for electrohydrodynamic printing (EHDP) system and printed results on flexible substrate. Conventionally, an electrode is inserted vertically into the fluid for generating electric field to induce charges that move towards the surface of the liquid. Disturbances and vibrations in the inkjet head, caused by the application of high electric potential is the main problem affecting the stability of the meniscus. Centralization, obstruction to the fluid flow, and the fixed position of vertically inserted electrode in the inkjet head adds to the complexity of the system design. In order to overcome all these limitations, a new technique has been developed and verified experimentally. A metallic capillary enclosed by tapered glass capillary results in removing obstructions to the fluid flow caused by inserting electrodes from top into the capillary head. The voltage applied in new setup for extraction is reduced around 1.2 kV, analyzed by simulation, and also verified by experiments. Electrode within the fluid channel remains at fixed point eliminating the positioning problems for repeatable parameters. With this head design, uniformity of the patterned lines is enhanced by obtaining a stable meniscus. Resolution of the printed patterns on flexible polyimide substrate is minimized. Ink having properties of 39.68 wt% of Ag nanoparticles, viscosity of 39 cps, and 5 dyn/cm of surface tension is used. All experiments are performed in ambient environment.