www.surrey.ac.uk
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 medium
m, 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:
gfvPvvt
vmEm
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