Electrodewetting

作为一种简单的处理液滴的技术，在不可润湿的表面上进行电润湿，即电润湿，特别是电介质润湿(EWOD)技术，自本世纪初以来得到了显著的发展。虽然主要的商业产品已经开始出现，但众所周知的EWOD设备的可靠性问题正在阻碍其持续增长。加州大学洛杉矶分校工程医学院的一个团队建议探索一种与电润湿相反的现象，因此被称为电除湿，因为他们发现它具有类似于EWOD的液滴操纵能力，而不存在可靠性问题。注意到基于电除湿的设备具有高可靠性和易于制造的特点，该团队建议研究电除湿的起源，表征其机理，并建立有助于设计应用设备的基础知识。拟议的电脱湿研究预计将显著增加目前由EWOD技术提供动力的数字(液滴)微流体的用户基础。电除湿设备吸引了所有层次和不同目标的用户，无论他们的专业知识和兴趣如何，由于其简单和可靠，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。拟议的工作需要在研究和培训方面采取跨学科的方法，问题范围从基础电气工程、表面科学和微制造，一直到光学和生物化学应用。研究生将从这项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执行任务。这一成果将丰富工程课程，包括加州大学洛杉矶分校的MEMS/Nano博士项目。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，电除湿使用的是既没有电介质层也没有疏水面层的亲水性衬底。这些涂层是造成EWOD可靠性问题和制造成本高的主要原因。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都是常见的。重要的是，这种简单性还将使电除湿设备的设计和制造变得容易和廉价。其次，电除湿通常只使用~3V的驱动电压。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，这对移动应用特别有用。第三，液滴可以在没有盖板的开放式配置中拆分成更小的液滴，从而在设备设计中提供更大的灵活性。在这项拟议的研究中，加州大学洛杉矶分校的团队将基于根据初步实验和观察精心构建的假设，阐明电除湿机制是如何工作的，了解它如何响应设备参数，为设备设计建立基本的工程知识，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，以帮助其他希望在自己的应用中采用这种优雅简单的液体处理技术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.