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Manipulation of cells by dielectrophoresis – the effect of EHDBy Lionel Broche

With the help of Kai Hoettges

Biomedical Engineering Group

Supervisors: M.P.Hughes, S.Ogin, G.E.N.Kass

Summary

Principles of experimentation with dielectrophoretic forces

Observations at low-frequency: the EHD effect

Presentation of the theory of EHD

Manipulation of cells by dielectrophoresis – the effect of EHD

Principles of experimentation with dielectrophoretic forces

Principles of experimentation with dielectrophoretic forces

Suspension medium

Membrane

Cytoplasmc, c

d, d

m, m

Principles of experimentation with dielectrophoretic forces

E

Principles of experimentation with dielectrophoretic forces

E

Principles of experimentation with dielectrophoretic forces

E

Principles of experimentation with dielectrophoretic forces

E

Principles of experimentation with dielectrophoretic forces

E

FDEP

Principles of experimentation with dielectrophoretic forces

E

FDEP

Principles of experimentation with dielectrophoretic forces

Suspension medium

Membrane

Cytoplasmc, c

d, d

m, m

E

FDEP

Principles of experimentation with dielectrophoretic forces

Suspension mediumm, m

E

2.r

Q -Q

Principles of experimentation with dielectrophoretic forces

DEP theory for spherical particles:

FDEP = 4r3.m0.Re(K(

DEP force

Cell radiusDipole-related

factor

Principles of experimentation with dielectrophoretic forces

1kHz 7kHz 50kHz 350kHz 2MHz 14MHz

Principles of experimentation with dielectrophoretic forces

The DEP spectrum:

Frequency (Hz)

FDEP

Principles of experimentation with dielectrophoretic forces

Electrode 1

Electrode 2

Gap

Principles of experimentation with dielectrophoretic forces

The experiments give a measure of the DEP force for different frequencies of the signal

The result can be used in several ways (detection, measure…)

Manipulation of cells by dielectrophoresis – the effect of EHD

Observations at low-frequency: the EHD effect

Observations at low-frequency: the EHD effect

Low-frequency is <40kHz

Observation of parasitic flows

Observations at low-frequency: the EHD effect

Electrode 1

Electrode 2

Gap

Observations at low-frequency: the EHD effect

Electrode 1

Electrode 2

Gap

Observations at low-frequency: the EHD effect

Electro-HydroDynamics: EHD

Caused by the electronic double-layer

Manipulation of cells by dielectrophoresis – the effect of EHD

Presentation of the theory of EHD

Presentation of the theory of EHD Navier-Stokes equation:

gfvPvvtv

mEm

2.

Negligible since Re<<1

Pressure

Visquous forces

Electric forces

Gravitation

Presentation of the theory of EHD The electric force equation:

** .41Re21 EEEf qE

Coulomb forces Dielectric forces

Presentation of the theory of EHD The electric force equation:

** .41Re21 EEEf qE

Coulomb forces Dielectric forces

>>

EHD

Presentation of the theory of EHD The electric force equation:

** .41Re21 EEEf qE

Coulomb forces Dielectric forces

<<

Electro-thermal forces

Presentation of the theory of EHD

ElectrodeSubstrate

Water

~nm

Presentation of the theory of EHD

Presentation of the theory of EHD

Presentation of the theory of EHD

Enhanced DEP trapping

Fluid pumping

Others…

Presentation of the theory of EHD

Thank you for your attention

References

Castellanos, Ramos et al. (2003), “Electrohydrodynamics and dielectrophoresis in microsystems: Scaling laws”, Journal of Physics D: Applied Physics, 36(20): 2584

Hoettges, McDonnell et al. (2003), “Use of combined dielectrophoresis / electrohydrodynamics forces for biosensor enhancement”, Journal of Physics D: Applied Physics, 36(20): 101-104