Research Article Alternating Current Electrohydrodynamic Printing of Microdroplets Gao-Feng Zheng, 1 Hai-Yan Liu, 1 Rong Xu, 1 Xiang Wang, 1 Juan Liu, 1 Han Wang, 2 and Dao-Heng Sun 1 1 Department of Mechanical and Electrical Engineering, Xiamen University, Xiamen 361005, China 2 Guangdong Provincial Key Laboratory of Micro/Nano Manufacturing Technology and Equipment, Guangdong University of Technology, Guangzhou 510006, China Correspondence should be addressed to Juan Liu; cecyliu@xmu.edu.cn Received 9 February 2014; Revised 3 May 2014; Accepted 5 May 2014; Published 26 May 2014 Academic Editor: Huarong Nie Copyright © 2014 Gao-Feng Zheng et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Tis paper discusses the technology of orderly printing of microdroplets by means of electrohydrodynamic print (EHDP) with alternating current (AC). Te AC electric feld induces charges to reciprocate in the electrohydrodynamic charged jet and generates periodic alternation of electric feld force, which facilitates the breakup of charged jets and injection of microdroplets. Microdroplets with a diameter of 100∼300 m can be printed with a frequency of 5∼25Hz via AC EHDP. Efects of process parameters on the microdroplet injection behaviors were investigated. A higher frequency of applied AC voltage led to a higher deposition frequency, but smaller diameters of printed droplets. Deposition frequency and droplet diameters increased with the increase of duty cycle and solution supply rate. AC pulse voltage has provided a novel way to study the control technology in EHDP, which would accelerate the application of inkjet printing in the feld of micro/nanosystem production. 1. Introduction Owing to advantages of bendableness, low cost, robustness, and lower power consumption [1], fexible electronics have great potential application in the felds of information [2, 3], energy [4–6], lithium-ion [7, 8], health [9], and micro/nano system [10, 11], among others. Utilization of organic func- tional materials and fexible substrates are the trademarks for fexible electronics which, however, are incompatible with conventional IC fabrication technology [12] and call for novel fabrication methods [13, 14]. As a high efciency, low- cost, low-waste, and noncontact fabrication process, inkjet printing has been regarded as one of the most potential technologies for large scale manufacturing of fexible and organic electronics [15, 16]. Inkjet printing does not need stencil-plate and etching process; therefore, electronic devices with complex patterns or three-dimensional structures can be printed directly and quickly [17, 18]. Conventional inkjet printing technologies, which rely on inner pressure generated by thermal bubbles or the piezo- electric pump, have limitations in reducing the droplet size and line width of printed patterns [19]. Electrohydrodynamic print (EHDP) utilizes external electric feld force to stretch viscoelastic solution. EHDP jet was ejected from the tip of Taylor cone under the spinneret [20–22]. Te diameter of the EHDP jet is independent of the inner diameter of the spinneret, which is a great advantage to reduce the size of printed micro/nanostructures. Near feld electro- spinning [23] (NFES) takes the advantage of stable straight jet outside the spinneret to produce precise deposition of printed micro/nanostructures. According to NFES theory, micro/nanodroplets [24] can be deposited accurately on the collector through the EHDP technology, the same as nanofbers [25, 26]. Not only direct current (DC) high voltage sources, but also multistep pulse voltage sources [27] and alternating Hindawi Publishing Corporation Journal of Nanomaterials Volume 2014, Article ID 596263, 7 pages http://dx.doi.org/10.1155/2014/596263