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体可以做出重大贡献的领域的例子，因为在这些领域，获得快速结果至关重要。使用微流体装置具有重要的优势：小样品要求，更高的分辨率和灵敏度，以及更短的处理时间（~分钟）。智能品质电泳（DEP）是一种电动（EK）传输机制，是用于分析细胞的微设备中最常用的技术之一。基于绝缘体的DEP （iDEP）提供了一种介电模式，采用位于两个外部电极之间的三维绝缘结构。利用直流电位和高频交流电位对这些系统进行了广泛的研究。然而，在低频（1khz）交流电势的iDEP系统中，粒子行为的知识有很大的差距。本提案的重点是低频交流电势在iDEP系统中的应用。为了在iDEP系统中固定和浓缩颗粒，DEP必须克服电渗透流（EOF）。EOF是通过微通道泵送液体和细胞的必要手段，但DEP克服EOF的成本很高，因为需要非常高的电位，这会损害细胞活力并产生热量。该方案旨在通过改变外加交流电势的特性来动态控制EOF。这比消除EOF更有利，因为它允许“动态”控制EOF，从而降低电压要求。在iDEP系统中使用交流电位具有很大的灵活性和新捷性，因为一组新的参数可用于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。应用交流和直流电位序列的集成系统以及包括流DEP和捕获DEP部分的多部分设备也将进行评估，其目标是在单个设备上实现包含各种细胞类型的样品的分选，浓缩和分离。更广泛的影响科学影响：非洲发展规划的潜力尚未得到充分探索；需要能够在单个设备上执行多个过程的系统，而低频交流电势可以满足这一需求。该项目将推进iDEP应用的最新技术，解决低频（1kHz）的差距。它还将推进iDEP系统的数学建模知识和后期几何基础。通过在单个设备上集成一个过程的几个步骤，将设计细胞分选、分离和浓缩方案。可以在几分钟内处理含有几种细胞的样品的微尺度方法的可能应用是很多的。这项研究可以在许多其他领域产生影响，在这些领域，对含有细胞的样品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“工程领域的女性”项目为女学生以及少数族裔和代表性不足的群体提供研究机会，其中包括皇家理工学院罗纳德·e·麦克奈尔后学士学位成就项目（Ronald E. McNair Post-Baccalaureate Achievement program）的学生，该项目专门面向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.