Analysis of biological particles using dielectrophoresis and impedance measurement

A novel electrical technique for detecting the collection of particles by dielectrophoresis (DEP) is described. The method is based on the impedance changes resulting from this collection in a microfabricated, integrated dual-channel electrode structure. The results show good agreement with measurements of DEP collection by optical method for suspensions of bacterial species B. subtilis, E. coli and abiotic latex beads, but with substantially reduced experimental uncertainties. The technique overcomes the restriction on particle size of optical techniques and can potentially be used to investigate highly sub-micron sized particles like viruses and DNA fragments. The dual-channel electrode cells can be integrated with other structures for analysing sub-micron scale particles, for example chip-based capillary electrophoresis.