Electrodewetting

电润湿，特别是介电润湿（EWOD）技术，是一种在不可润湿表面上进行液体润湿的简单技术，自世纪之交以来取得了重大进展。虽然主要的商业产品已经开始出现，但众所周知的EWOD设备的可靠性问题阻碍了其持续增长。加州大学洛杉矶分校（UCLA）工程与医学院的一个研究小组发现，电润湿具有与EWOD类似的液滴操纵能力，但没有可靠性问题，他们提议探索一种与电润湿相反的现象，因此被命名为电润湿。注意到基于电除湿的设备的高可靠性和易于制造，该团队建议研究电除湿的起源，表征其机制，并建立有助于设计应用设备的基础知识。提出的电除湿研究有望显著增加数字（液滴）微流体的用户基础，目前由EWOD技术提供动力。无论其专业知识和兴趣如何，电除湿设备都吸引着各个层次和不同目标的用户，由于其简单可靠，预计将为学术和工业研究人员以及一些业余爱好者提供服务。拟议的工作需要跨学科的研究和培训方法，涉及的问题包括基础电气工程，表面科学，微加工，一直到光学和生化应用。研究生将从这一跨学科研究中获得第一手经验，并为成为未来的领导者做好准备。本科生和高中生将在一个垂直的研究团队中进行任务。研究结果将丰富工程课程，包括加州大学洛杉矶分校的MEMS/Nano博士课程。在提供EWOD的所有基本数字微流控功能的同时，电除湿避免了EWOD的关键问题。首先，电除湿使用既没有介电层也没有疏水面漆的亲水性衬底。EWOD所需的这些涂层是其可靠性问题和高制造成本的主要原因。亲水表面，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都很常见。重要的是，这种简单性也将使电除湿装置的设计和制造变得容易和便宜。其次，电除湿通常只使用~ 3v作为驱动。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一个紧凑的系统，这对移动应用程序特别有用。第三，液滴可以在没有盖板的开放式配置中分裂成更小的液滴，从而使设备设计更具灵活性。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除湿机制是如何工作的，了解它如何响应设备参数，为设备设计建立基础工程知识，并通过开发电子显示设备探索应用。潜在的目标是开发知识基础，以帮助其他希望将这种优雅简单的液体处理技术用于自己应用的研究人员和开发人员。

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.