Electrokinetic Microfluidics

动电微流控

• 批准号: RGPIN-2016-03622
• 负责人: Li, Dongqing
• 金额: $ 3.35万
• 依托单位: University of Waterloo
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=708822
• 关键词: Electrokinetic; Microfluidics

The proposed research program is to investigate several new electrokinetic microfluidic phenomena critical to the development of lab-on-a-chip devices for applications in medical diagnosis and food safety. The proposed research program will: (1) Develop a novel micro-pump based on induced charge electroosmotic flow. This new pump is realized by embedding a pair of small metal plates on microchannel walls, and applying a small electrical potential difference via two electrodes placed close to the metal plates. The applied local electrical field will induce a strong electroosmotic flow over the metal plates and hence pump the liquid. Such a pump can be installed at any position in a microchannel, and does not require large electrical potential difference along the whole channel (thus avoiding Joule heating and damage to biological cells). Extensive theoretical and experimental studies will be carried out to examine and verify the proposed method, and working prototypes of such pumps will be developed. (2) Study effects of dielectric polarizability on induced charge electroosmotic flow (ICEOF) in microchannels. So far, almost all studies of ICEOF are limited to fully polarizable (i.e., metal) materials due to simplicity. However, most materials involved in microfluidic applications are not fully polarizable; they are dielectric materials such as glass and polymers. The induced surface potential of dielectrics is critical to the ICEOF. The objective of this research is to find the correlation of the induced charge surface potential to the applied electrical field, the polarizability of the solid and its surrounding liquid. Extensive numerical simulations and experimental verifications will be conducted. This proposed fundamental research is the first in this field, will provide new understanding and develop new methods to control the motion of dielectric particles and to separate different types of dielectric particles in microfluidic chips. (3) Study the flow field and motion of electrically induced Janus droplets (EIJD). As the surface charges of the droplet are mobile, the surface charges can be pulled to one side of the droplet surface due to the attraction to the applied electrical field. This will result in an electrically induced Janus droplet (EIJD), a droplet with electrostatic charges on one side of the droplet surface; the other side of the droplet surface has no or little electrostatic charges. The proposed research work will study (a) the redistribution of mobile surface charges of liquid-fluid interfaces under the influence of electrical field; (b) the flow field around an EIJD and the motion of EIJD in an electric field. With the fundamental understandings developed from this study, we will further study how to control of EIJD motion for at least two applications: a microfluidic valve controlled by EIJD, and separation of different EIJDs.

拟议的研究计划旨在研究几种新的电动微流体现象，这些现象对于开发用于医疗诊断和食品安全的芯片实验室设备至关重要。拟议的研究计划将： (1)开发一种基于感应电荷电渗流的新型微型泵。这种新型泵是通过在微通道壁上嵌入一对小金属板，并通过靠近金属板放置的两个电极施加小的电势差来实现的。施加的局部电场将在金属板上感应出强烈的电渗流，从而泵送液体。这种泵可以安装在微通道中的任何位置，并且不需要沿整个通道产生很大的电势差（从而避免焦耳热和对生物细胞的损害）。将进行广泛的理论和实验研究来检验和验证所提出的方法，并开发此类泵的工作原型。 (2)研究介电极化率对微通道中感应电荷电渗流(ICEOF)的影响。到目前为止，由于简单，几乎所有 ICEOF 的研究都仅限于完全可极化（即金属）材料。然而，微流体应用中涉及的大多数材料并不是完全可极化的；它们是介电材料，例如玻璃和聚合物。电介质的感应表面电势对于 ICEOF 至关重要。 本研究的目的是找到感应电荷表面电势与所施加的电场、固体及其周围液体的极化率的相关性。将进行广泛的数值模拟和实验验证。这项基础研究是该领域的首次，将为控制介电粒子的运动以及分离微流控芯片中不同类型的介电粒子提供新的理解并开发新的方法。 (3)研究电诱导Janus液滴(EIJD)的流场和运动。由于液滴的表面电荷是可移动的，因此由于施加的电场的吸引力，表面电荷可以被拉到液滴表面的一侧。这将产生电感应 Janus 液滴 (EIJD)，这是一种在液滴表面一侧带有静电荷的液滴；液滴表面的另一面没有或很少有静电荷。拟议的研究工作将研究（a）在电场影响下液体-流体界面的移动表面电荷的重新分布； (b) EIJD 周围的流场以及 EIJD 在电场中的运动。 根据本研究的基本理解，我们将进一步研究如何控制至少两种应用的 EIJD 运动：由 EIJD 控制的微流体阀，以及不同 EIJD 的分离。