Impedimetric Cell Detection using Microfluidic Viscoelastic Focusing

Abstract

Identification and successive separation of cell populations have a vast number of applications in both clinical research and basic sciences. In the last few decades several custom-made microfluidic systems have been developed to address the differentiation needs of the researchers. For all these systems there is a need for focusing the cells of interest in the interrogation zone during the flow. In this article, a new method of viscoelastic focusing was used for this purpose. By adding polymeric materials into the carrying fluid, elastic lift force was generated on the cells that allows passive particle focusing. Once the cells are aligned with the sensor, detection and identification was achieved using impedance characterization. The carrier fluid properties were investigated to achieve successful viscoelastic focusing and impedimetric detection. Two blood cell types, red blood cells and white blood cells, were differentiated based on their impedance signal. In addition to its capability as a microfluidic cell counter, this work reveals the possibility of using viscoelastic focusing for flow through impedance based particle characterization.