Single Cell Impedance Spectroscopy

Impedance spectroscopy is a label-free method of analysis which has the potential to allow quantitative measurements of cell characteristics, for example changes in properties of the membrane, cytoskeleton or nucleus elicited by chemical compounds. Dielectrophoresis is a increasingly common technique used for the manipulation and sorting of particles in micro-chips. The forces responsible for these phenomena are linked to the intrinsic dielectric properties of the biological particles. However, impedance analysis of cells in micro-systems is not yet part of the µTAS and lab-on-chip toolkit.

I am collaborating with Daniele Malleo and Hywel Morgan at the University of Southampton to build a platform for perfoming impedance spectroscopic studies of arrays of single cells. The platform we are building combines the advantages offered by impedance analysis, as used in micro-flow cytometry, with the ability to capture and monitor large numbers of single cells on a single device, so that long-term transient and steady state analysis can be performed. Cells are captured using the arrayed hydrodynamic single cell principle developed by Di Carlo in our lab. The cells are held between two microelectrodes which are used to measure the impedance signal. The system enables the analysis of multiple single cells, allowing the detection of rare events and the identification of unique events. Temporal averaging is avoided because single cells are individually probed, individual responses and fast kinetic events can be recorded.

References:

1. D Malleo, JT Nevill, D Di Carlo, LP Lee, and H Morgan, “Examining Cytotoxic Effects on Single Cells using an Impedance Spectroscopic Platform,” Proc. MicroTAS, Paris, France, pp. 1083-1085, 2007.
2. D. Malleo, D. Di Carlo, J. T. Nevill, D. Holmes, L. P. Lee, H. Morgan, Single Cell Differential Impedance Spectroscopy Analysis Using High Density Hydrodynamic Cell Trapping Arrays, Proceedings of Micro Total Analysis Systems 2006, pp.1292-1294, Tokyo, Japan, November 5-9, 2006.