Mechanical and Electrical Principles for Separation of Rare Cells

Early detection of disease has long been a goal of many research projects and public health initiatives, as prevention from disease advancement is one of the most effective cures. Many diseases that are difficult to treat in late stage such as melanoma, pancreatic cancer, and highly metastatic tumors are treatable with a much better prognosis in early stage. One method of interest in early cancer detection has been the isolation of circulating tumor cells (CTCs) from the blood. By isolating CTCs, we can determine the presence of cancer from only a blood sample rather than requiring multiple screening modalities be performed on a patient. In addition, cancers without effective screening modalities, such as pancreatic cancer, may produce CTCs while the patient is asymptomatic, allowing for a much earlier start to treatment and improved prognosis [1]. In this chapter, we present several approaches that employ microfluidics to separate rare cells of interest. We start with a basic overview of fluid dynamics that includes scaling analysis and several solutions to the Navier-Stokes equations. We then introduce mechanical and electrical separation techniques along with an overview of their respective theories and several examples of each.