(Keynote) Dielectrophoresis: Exploring the ‘2nd Frontier’ of Its Application in the Biomedical Sciences

Dielectrophoresis (DEP) has been widely studied for its potential as a biomarker-free method of sorting cells based on their intrinsic dielectric properties [1-4]. Under appropriate experimental conditions the DEP frequency spectrum typically exhibited by a viable mammalian cell in suspension is characterized by two frequencies, f_xo1 and f_xo2. At these two characteristic frequencies the effective conductance and capacitance values of the cell exactly match those of the fluid it has displaced, and are commonly known as the DEP cross-over frequencies.

At low frequencies (<10 kHz) viable cells typically exhibit negative DEP and move away from electrodes, with the transition to positive DEP occurring at f_xo1 - where the cells move towards high field regions at the electrodes. The investigation, understanding (in terms of cell biology) and biomedical exploitation of this phenomenon can be considered to represent exploration of the ‘1^st frontier of dielectrophoresis’. The results of this work, extending over more than 25 years, are now exploited in the form of various commercial devices for clinical and biomedical applications.  The status of this activity will be reviewed.

A transition back to negative DEP occurs at f_xo2 (~150 MHz). The factors that control the high frequency DEP cross-over at f_xo2 have only recently been explored, and the status and implications of this ‘2^nd frontier of dielectrophoresis’ will also be reviewed in this presentation.

1. Pethig, R. Review Article - Dielectrophoresis: Status of the theory, technology, and applications. Biomicrofluidics  4, 022811 (2010).

2. Gagnon, Z.R. Cellular dielectrophoresis: Applications to the characterization, manipulation, separation and patterning of cells. Electrophoresis 32: 2466-2487 (2011).

3. Pethig, R. Dielectrophoresis: An assessment of its potential to aid the research and practice of drug discovery and delivery. Adv. Drug Deliv. Rev. 65: 1589-1599 (2013).

4. Gascoyne, P.R.C. and Shim, S. Isolation of circulating tumor cells by dielectrophoresis, Cancers 6: 545-579 (2014).

5. Chung, C., et al. Dielectrophoretic characterisation of mammalian cells above 100 MHz, J. Elec. Bioimpedance 2: 64-71 (2011)