Current-modulated Electrohydrodynamic (EHD) Jet Printing with Dual-channel Nozzles for Micro/Nano-Fabrication

用于微/纳米制造的双通道喷嘴电流调制电流体动力 (EHD) 喷射打印

基本信息

批准号：
1726627
负责人：
Daren Chen
金额：
$ 30万
依托单位：
Virginia Commonwealth University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2017
资助国家：
美国
起止时间：
2017-07-01 至 2021-06-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1726627&HistoricalAwards=false
关键词：
Current modulated Electrohydrodynamic EHD Jet

项目摘要

Inkjet printing as an additive fabrication method has been used in the manufacturing of printed electronics, 3-D object prototypes, solar cells, and light-emitting devices, as well as applications in tissue engineering and other biological and pharmaceutical fields. Unlike the more common method of piezo inkjet printing, which typically generates individual droplets of 10-50 micrometers in diameter, voltage-modulated electrohydrodynamic (EHD) jet printing has a demonstrated ability to produce sub-micrometer-sized droplets/fibers for the fabrication of patterns or features at nanometer scales. However, EHD jet printing has not been considered as a viable manufacturing tool because of the issues of nozzle clogging, ink accumulation at the nozzle exit, and low printing frequencies (resulting in a limited production rate). This project conducts fundamental research on a new form of EHD jet printing, using novel dual-channel printing nozzles and electrical current (instead of voltage) modulation. It is hypothesized that the circulation of liquid ink in the dual channels will eliminate nozzle clogging due to evaporation of carrier fluids or polymerization of ink, and the current modulation/control will enable high-speed, drop-on-demand EHD jet printing. This research could also lead to further improvements on current inkjet printing processes or devices in both industrial and household settings. Furthermore, the technique will be used in education and outreach activities geared toward students (at all levels) and workers in advanced manufacturing.This project will investigate the fundamental science involved in a new current-modulated, drop-on-demand EHD printing method with novel dual-channel nozzles for the fabrication of high-resolution micro/nano patterns at high jetting frequencies (on the level of MHz). The proposed dual-channel printing nozzles use two concentric tubes, providing an annular channel around the inner tube. In the proposed nozzle configuration, one channel provides new ink and the other for extracts ink from the nozzle, thereby achieving fluid circulation within the dual tube nozzle. It is hypothesized that this fluid circulation will eliminate or greatly reduce the issues of nozzle clogging and ink accumulation associated with polymerization or carrier fluid evaporation at the nozzle outlet. This project further hypothesizes that the ejection rate of droplets can be increased through current control, instead of the voltage control commonly used. Scientific understanding of fluid meniscus dynamics and droplet generation in the proposed EHD printing will be required to achieve robust current control, and needs to incorporate effects of fluid recirculaiton. The novelties of the proposed EHD jet printing technique are i) the proposed dual-channel nozzles that will resolve the technical issues often encountered in single-capillary inkjet printing; and ii) the modulation of frequencies with current rather than voltage in order to achieve reliable EHD jet printing at high jetting frequencies. The specific aims of this project are to: i) develop the fundamental science involved in liquid meniscus formation, jetting, and droplet ejection in a voltage-modulated EHD jet printing process with the dual-channel nozzles; ii) investigate the fundamental jetting mechanisms in current-modulated EHD jet printing process (particularly at high frequencies); iii) numerically model the jetting characteristics in the EHD jet printing technique to develop the underlying fundamental science and aide control strategies; and iv) provide a proof-of-concept of the proposed approach and validate the numerical models through parametric investigations of the quality (i.e. the size, uniformity, and resolution) of micro/nano-sized patterns created.

与更常见的技术不同，喷墨打印作为一种增材制造方法，已用于印刷电子产品、3D 物体原型、太阳能电池和发光器件的制造，以及组织工程和其他生物和制药领域的应用。压电喷墨打印方法通常会产生直径为 10-50 微米的单个液滴，电压调制电流体动力 (EHD) 喷射打印已被证明能够产生亚微米尺寸的液滴然而，由于喷嘴堵塞、喷嘴出口处的墨水积聚以及打印频率低等问题，EHD 喷射打印尚未被认为是一种可行的制造工具。该项目对一种新型 EHD 喷射打印进行基础研究，使用新型双通道打印喷嘴和电流（而不是电压）调制来捕获液体的循环。双通道中的墨水将消除由于载液蒸发或墨水聚合而导致的喷嘴堵塞，并且当前的调制/控制将实现高速、按需滴 EHD 喷射打印。此外，该技术将用于针对先进制造领域的学生（各级）和工人的教育和推广活动。该项目将研究一项新的基础科学。电流调制、按需滴 EHD 打印方法，采用新型双通道喷嘴，用于在高喷射频率（MHz 级）下制造高分辨率微/纳米图案。所提出的双通道打印喷嘴使用两个同心管，在内管周围提供环形通道。在所提出的喷嘴构造中，一个通道提供新墨水，另一个通道用于从喷嘴提取墨水，从而实现双管喷嘴内的流体循环。人们再次认识到，这种流体循环将消除或大大减少与喷嘴出口处的聚合或载体流体蒸发相关的喷嘴堵塞和墨水积累问题。该项目进一步利用了可以通过电流控制来提高液滴的喷射率。要实现强大的电流控制，需要对所提出的 EHD 打印中的流体弯月面动力学和液滴生成进行科学理解，并且需要考虑流体再循环的影响。所提出的 EHD 喷射打印技术的新颖之处在于：i）所提出的双通道喷嘴将解决单毛细管喷墨打印中经常遇到的技术问题；ii）用电流而不是电压调制频率，以实现可靠的 EHD。该项目的具体目标是：i) 开发电压调制 EHD 喷射打印过程中液体弯月面形成、喷射和液滴喷射的基础科学。双通道喷嘴；ii) 研究电流调制 EHD 喷射打印过程中的基本喷射机制（特别是在高频下）；iii) 对 EHD 喷射打印技术中的喷射特性进行数值模拟，以开发基础科学和辅助控制策略；以及 iv) 提供所提出方法的概念验证，并通过微米/纳米尺寸图案的质量（即尺寸、均匀性和分辨率）参数研究来验证数值模型创建的。