Electrodewetting

作为一种处理液滴的简单技术，电使液体在非润湿表面上润湿，即，自进入世纪以来，电润湿，特别是电介质上电润湿（EWOD）技术已经显示出显著的进步。虽然主要的商业产品已经开始出现，但众所周知的EWOD设备的可靠性问题正在阻碍其持续增长。来自工程和医学院的UCLA团队提出探索一种与电润湿相反的现象，因此命名为电去湿，在发现它具有类似于EWOD的液滴操作能力而没有可靠性问题之后。注意到基于电极去湿的设备的高可靠性和易于制造，该团队建议研究电极去湿的起源，表征机制，并建立有助于设计应用设备的基础知识。拟议的电去湿研究预计将显着增加数字（液滴）微流体的用户群，目前由EWOD技术提供动力。吸引所有级别和不同目标的用户，无论他们的专业知识和兴趣如何，由于其简单性和可靠性，预计电极去湿设备将服务于学术和工业研究人员以及一些业余爱好者。拟议的工作需要在研究和培训方面采取跨学科的方法，涉及从基础电气工程、表面科学和微加工到光学和生物化学应用等问题。研究生将从这一跨学科的研究中获得第一手经验，并为成为未来的领导者做好充分准备。本科生和高中生将在一个垂直的研究团队中执行任务。研究结果将丰富工程课程，包括加州大学洛杉矶分校的MEMS/纳米博士课程。 在提供EWOD的所有基本数字微流体功能的同时，电去湿避免了EWOD的关键问题。首先，电去湿使用既不具有介电层也不具有疏水性顶涂层的亲水性基底。EWOD所需的这些涂层是其可靠性问题和高制造成本的主要罪魁祸首。亲水性表面，如玻璃，在生物医学、光学、化学和其他领域的许多不同应用中是常见的。重要的是，这种简单性还将使电极去湿装置的设计和制造容易且便宜。其次，电极去湿通常仅使用~ 3V用于致动。这种低电压允许使用现成的集成电路，因此开发人员可以快速构建紧凑的系统，这对于移动的应用特别有用。第三，液滴可以在没有盖板的开放配置中分裂成更小的液滴，从而允许设备设计的更大灵活性。在拟议的研究中，基于从初步实验和观察中精心构建的假设，加州大学洛杉矶分校的团队将阐明电极去湿机制如何工作，了解它如何响应设备参数，建立设备设计的基础工程知识，并通过开发电子显示设备来探索应用。其基本目标是开发知识基础，帮助其他研究人员和开发人员将这种优雅简单的液体处理技术应用于自己的应用。

As a simple technology for handling liquid droplets, electrically making a liquid wetting on a non-wettable surface, i.e., electrowetting, especially electrowetting-on-dielectric (EWOD) technology, has shown significant progress since the turn of the century. While major commercial products have started to emerge, the well-known reliability problem of EWOD devices is hampering the continued growth. A UCLA team from the engineering and medical school proposes to explore a phenomenon opposite to electrowetting, thus named electrodewetting, after finding it has a droplet manipulation capability similar to EWOD without the reliability problem. Noting the high reliability and easy manufacturing of electrodewetting-based devices, the team proposes to study the origin of electrodewetting, characterize the mechanism, and build the fundamental knowledge that will help design application devices. The proposed electrodewetting study is expected to significantly increase the user base of digital (droplet) microfluidics, which is powered by EWOD technology currently. Attractive to users of all levels and different goals regardless of their expertise and interests, electrodewetting devices are expected to serve both academic and industrial researchers as well as some hobbyists because of their simplicity and reliability. The proposed work requires an interdisciplinary approach in research and training on issues ranging from basic electrical engineering, surface science, and microfabrication, all the way to optical and biochemical applications. Graduate students will gain first-hand experience from this interdisciplinary research and be well prepared to be future leaders. Undergraduate and high school students will carry out tasks in a vertical team of researchers. The results will enrich the engineering curricula, including the MEMS/Nano PhD program at UCLA. While providing all the basic digital microfluidic functions of EWOD, electrodewetting avoids the key problems of EWOD. First, electrodewetting uses a hydrophilic substrate with neither the dielectric layer nor the hydrophobic topcoat. These coated layers needed for EWOD are the main culprits to its reliability problem and high manufacturing cost. Hydrophilic surfaces, such as glass, are common to many diverse applications spanning biomedical, optical, chemical, and other fields. Importantly, this simplicity would also make the design and manufacturing of electrodewetting devices easy and cheap. Second, electrodewetting typically uses only ~3 V for actuation. This low voltage allows the use off-the-shelf integrated circuits so the developers can quickly build a compact system, which is especially useful for mobile applications. Third, droplets can be split into smaller ones in an open configuration with no cover plate, allowing more flexibility in device design. In the proposed study, based on hypotheses carefully constructed from preliminary experiments and observations, the UCLA team will elucidate how the electrodewetting mechanism works, understand how it responds to device parameters, build the fundamental engineering knowledge for device design, and explore applications by developing an electronic display device. The underlying goal is to develop knowledge foundation that will assist other researchers and developers who would like to adopt this elegantly simple liquid handling technology for their own applications.