(250h) Electrohydrodynamic Scaling Laws Analysis in a Microfluidic Isodep Device

Electrohydrodynamic scaling
laws analysis in a microfluidic IsoDEP device

M.Z. Rashed¹, K.C. Grome¹, S.P.
Hendricks², S.J. Williams¹

1. University of Louisville, Louisville, Kentucky USA

2. Murray State University, Murray, Kentucky USA

Dielectrophoresis (DEP) is the phenomenon in which a particle, such as
a living cell, is moved by the interaction between a non-uniform electric field
and its induced polarization. Isomotive dielectrophoresis (isoDEP)
is a cell analysis and characterization technique that uniquely utilizes a
constant gradient field-squared (∇Erms2)
 resulting in a uniform DEP force. The resultant constant (isomotive) particle translational velocity that
can be tracked using particle tracking
velocimetry (PIV) software to extract the cell/particle dielectric properties. Inspired by initial
analysis by Herbert Pohl, we have developed modified electrode geometry for isoDEP. Fabrication of extruded electrodes is
straightforward via microfabrication methods (DRIE of conductive wafers) or
sub-millimeter machining. A sample is injected and flow is halted before field
activation. Digital images will extract particle size and, due a constant ∇Erms2
, the only unknown for each particle is Re[f_CM]
The field is applied and Re[f_CM]
is extracted through particle tracking. The particle’s velocity will change as
the AC frequency is swept over a specified range to obtain a comprehensive Re[f_CM]
 spectrum. Through simultaneous particle
tracking such spectra are obtained for every particle in the imaging area,
enabling parallel analysis of cells. IsoDEP can extract the dielectric
properties of each cell (ex: membrane capacitance) –
these properties directly correlate to the cell physiology. Any unwanted flow
will disrupt the trajectory of the particles and compromise their analysis. To
that end, we have conducted an electrohydrodynamic study and scaling law
analysis to reduce electrothermal hydrodynamics in an
isoDEP device. Numerical simulations (COMSOL
Multiphysics) are in good agreement with experimental measurements via
micro-PIV. In addition to experimental results, current and future IsoDEP platform
designs will be shared.

References

[1] H.A. Pohl, Dielectrophoresis:
The Behavior of Neutral Matter in Nonuniform Electric Fields, Cambridge;
New York: Cambridge University Press (1978).

[2] Allen, D. J., Accolla, R.
P. and Williams, S. J. (2017), Isomotive dielectrophoresis for parallel
analysis of individual particles. ELECTROPHORESIS.
doi:10.1002/elps.201600517.