EHD Equipment and Applications

Abstract

Electrohydrodynamic (EHD) printing, which adopts electrical force to pull the jet from nozzle, is a hotspot of printing techniques, due to its unique advantages of high-resolution (50 nm) and compatibility with wide range of inks (1–10,000 cps). EHD printing is rooted in the traditional electrospinning, which is an effective method for micro/nano fibers generation, but has difficulties in orientation and controllability. Recently, considerable improvements have been made to realize electrohydrodynamic direct writing for micro/nano manufacturing, e.g. MES and HE-Printing techniques to enhance the controllability on the positioning and morphology of fibers, various functional inks adopted to widespread its applications, design and fabrication of nozzles to improve printing efficiency and accuracy, and control methods of EHD printing to achieve online modulating. High precision EHD printing equipment that integrates the latest technology is the core to realize practical micro/nano manufacturing, however, most of the apparatuses are in the laboratory level with limited functionality and accuracy. This chapter first summarizes the necessary features of EHD equipment with a multifunction of three printing modes (drop on demand, electrospinning and electrospray) for various viscosity inks in Sect. 7.1. Basic comprising modules of the EHD printer are also introduced in this section, as well as its extension modules including printing environment control, roll to roll, and nozzle array. Then some specific applications of stretchable generator, gas sensor and flexible small-channel thin-film transistors that generated based on high resolution EHD printing equipment are demonstrated in Sects. 7.2, 7.3 and 7.4 respectively.