Abstract

Many diseases such as cancer are initiated in single cells which modify their functions and amplify certain biological activities of the normal cells. These changes affect and permanently change the mechanical properties of normal cells. The significant difference between mechanical properties of different malignant cell lines could be used as a label free biomarker to distinguish between invasive and non-invasive carcinoma cells whose shapes and sizes are roughly the same. Among recent experimental methods for single cell assessments, dielectrophoresis (DEP) based devices have been introduced as novel techniques to direct deformation measurement of the living cell. In this work the application of microdevices for trapping and stretching of two human breast carcinoma cell lines based on dielectrophoresis phenomena, is presented.
The results of electro-deformation process of two malignant cell lines, MDA-MB-231 (highly metastatic human breast carcinoma cell line) and MCF-7 (weakly metastatic human breast carcinoma cell line) using a positive DEP micro-device is presented in this work. The elastic constants of cells are measured by comparing the results of finite element simulation using COMSOL multiphysics with those of experimental studies. Concurring with the previous works, the results of this study show that highly metastatic breast cancer cells (MDA-MB-231) are much softer than weakly metastatic breast cancer cells (MCF-7), such that they could squeeze easier and migrate into human tissue through capillary blood vessels.
An improved design to trap the suspended living cells in the middle of electrodes is presented and experimentally tested in the thesis. Inducing symmetric elongation on cells could improve the accuracy of calculated elastic constant of cells. Also, as the cells are positioning between electrodes (in the transparent zone) the visibility of captured images and accuracy of calibrated images could be improved.