Rapid and dynamic cell assessments in dielectrophoresis-based microfluidic devices

1336160 Lapizco-Encinas食品和水安全、环境监测和临床筛查是微流控技术可以做出重大贡献的领域，因为在这些领域，快速取得成果至关重要。使用微流控装置具有重要的优势：样品需求小、分辨率和灵敏度高、处理时间更短(~分钟)。智能介电(DEP)是一种电动(EK)传输机制，是用于分析细胞的微型设备中最流行的技术之一。基于绝缘体的DEP(IDEP)提供了一种采用位于两个外部电极之间的三维绝缘结构的介电模式。这些系统已经被广泛地研究，使用直流电位和高频交流电位。然而，在具有低频(1 KHz)交流电势的IDEP系统中，关于粒子行为的知识存在着显著的差距。本提案的重点是在IDEP系统中使用低频交流电势。为了在IDEP系统中固定和浓缩颗粒，DEP必须克服电渗流(EOF)。EOF作为通过微通道泵送液体和细胞的手段是必要的，但DEP克服EOF的成本很高，因为需要非常高的电位，这会损害细胞的活力并产生热量。该方案旨在通过改变施加的交流电势的特性来动态控制EOF。这比取消EOF更有优势，因为它允许“动态”控制EOF，从而降低电压要求。在IDEP系统中使用交流电势具有很大的灵活性和新颖性，因为可以使用一组新的参数来微调粒子和细胞操作。通过使用这些参数(信号形状、频率、幅度、偏移量)，可以动态地控制EOF，以在较低的所需电位下产生更有效的细胞操作。这项工作还将采用数学建模，这将有助于理解IDEP背后的基本原理。还将评估应用交流和直流电位序列的集成系统和包括流动DEP和捕获DEP的部分的多部分设备，目标是在单个设备上实现包含各种细胞类型的样本的分类、浓缩和分离。广泛影响科学影响：IDEP的潜力尚未得到充分开发；需要能够在单个设备上执行几个过程的系统，而低频交流电位可以满足这一需求。该项目将促进IDEP应用的最新水平，解决低频区域(1 KHz)的缺口。本课程还将增进关于IDEP系统的数学建模知识和员额几何学的基础知识。通过将一个过程的几个步骤整合到一个设备上，将设计细胞分选、分离和浓缩的方案。一种可以在几分钟内处理包含几种类型细胞的样本的微型方法的可能应用是众多的。这项研究可以在许多其他领域产生影响，在这些领域，对含有细胞的样本的快速反应是至关重要的。社会影响：该项目将为本科生和研究生提供一个重要的研究机会。它还将通过女性工程学计划，帮助为女性学生以及少数族裔和代表性不足的群体提供研究机会，包括RIT Ronald E.McNair毕业后成就计划的学生，该计划致力于低收入的第一代少数族裔学生，以确保他们进入研究生教育。

1336160Lapizco-EncinasFood and water safety, environmental monitoring and clinical screening are examples of fields where microfluidics can make a significant contribution, since in these areas it is critical to obtain rapid results. Working with microfluidic devices offers important advantages: small sample requirements, higher resolution and sensitivity, and shorter processing times (~minutes). Intellectual Merit Dielectrophoresis (DEP), an electrokinetic (EK) transport mechanism, is one of the most popular techniques used in microdevices for analyzing cells. Insulator-based DEP (iDEP) offers a dielectrophoretic mode that employs 3-dimensional insulating structures located between two external electrodes. These systems have been extensively studied employing DC potentials and high frequency AC potentials. There is, however, a significant gap in knowledge for particle behavior in iDEP systems with low frequency ( 1 kHz) AC electric potentials. The present proposal is focused on the use of low frequency AC potentials in iDEP systems. In order to immobilize and concentrate particles in iDEP systems, DEP has to overcome electroosmotic flow (EOF). EOF is necessary as means to pump the liquid and cells through a microchannel, but it is costly for DEP to overcome EOF, since very high potentials are required, which compromises cell viability and produces heat. This proposal aims to dynamically control EOF by modifying the characteristics of an applied AC potential. This is more advantageous than eliminating EOF, since it allows controlling EOF "on the fly," leading to lower voltage requirements. There is great flexibility and novelty on the use of AC electric potentials with iDEP systems, since a new set of parameters can be used to fine tune particle and cell manipulation. By using these parameters (signal shape, frequency, amplitude, offset), EOF can be dynamically controlled to produce more effective cell manipulation at lower required potentials. This work will also employ mathematical modeling that will aid on the understanding of the fundamentals behind iDEP. Integrated systems with the application of sequences of AC and DC potentials and multipart devices comprising sections for streaming DEP and trapping DEP will also be evaluated, with the objective of achieving sorting, concentration and separation of a sample containing various cell types on a single device.Broader Impacts Scientific impact: The potential of iDEP has not been fully explored; there is a need for systems able to perform several processes on a single device, and low frequency AC potentials can answer this need.This project will advance the state of the art in the applications of iDEP, addressing the gap in the low frequency regime (1kHz). It will also advance on the knowledge of mathematical modeling of iDEP systems and fundamentals on post geometry. Schemes for cell sorting, separation and concentration will be designed, by integrating several steps of a process on a single device. The possible applications of a microscale method that can process a sample containing several types of cells in a matter of minutes are numerous. This research can make an impact in many other fields, where a rapid response of samples containing cells is critical.Societal impact: This project will provide a premier research opportunity for undergraduate and graduate students. It will also assist in providing research opportunities for female students through the Women in Engineering program, and for minorities and underrepresented groups, including those students in the RIT Ronald E. McNair Post-Baccalaureate Achievement Program, a program dedicated to low income, first generation minority students to ensure they enter graduate education.