Cells are usually studied in bulk quantities: they are suspended in a cell culture mixture and this suspension is usually analyzed. However, uncertainties and difficulties arise from the study of mixtures and volume fractions: for example it is extremely difficult if not impossible to discover a single cancerous cell in a population of healthy cells. It is immediately obvious that the study of individually-addressed cells can enhance our understanding of their structure and behavior. Here we present a device that allows the trapping, manipulation and simultaneous electrical/optical analysis of single polyelectrolyte microcapsules which we use as model for cells. Individually addressable electrodes and micrometer-sized traps are integrated in a microfluidic platform to provide a non-invasive, label-free tool for single cell analysis. Among its applications we envision the study of cell response due to ligand-receptor interactions and the observation of structural changes in the cell due to the introduction of drug compounds. The device consists of an array of traps aligned to individually addressable pairs of electrodes for the differential impedance spectroscopy analysis of single cells. The use of a transparent substrate allows simultaneous optical analysis ( i.e. epifluorescence), although ultimately the device can be used as an all-electrical measurement tool. Upon interrogation of the traps, cells are expected to exhibit different impedance responses depending on their state. This will allow the development of an all-electrical assay, or the detailed study of kinetic response of each trapped cell to the introduction of specific cell-altering compounds, e.g. drugs and or/toxins.
Project end date: 08/13/08