314:
81:
628:. Pressure would then be released on demand, for the fluid to flow through micro-channels. When water travels, or streams over a surface, the ions in the water "rub" against the solid, leaving the surface slightly charged. Kinetic energy from the moving ions would thus be converted to electrical energy. Although the power generated from a single channel is extremely small, millions of parallel micro-channels can be used to increase the power output. This
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95:
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or can cause undesirable dispersion in sample injection, separation and stacking. These instabilities are caused by a coupling of electric fields and ionic conductivity gradients that results in an electric body force. This coupling results in an electric body force in the bulk liquid, outside the
297:{\displaystyle F_{e}=\rho _{e}{\overrightarrow {E}}-{1 \over 2}\varepsilon _{0}{\overrightarrow {E}}^{2}\triangledown \varepsilon _{r}+{1 \over 2}\varepsilon _{0}\triangledown {\Bigl (}{\overrightarrow {E}}^{2}\rho _{f}\left({\frac {\partial \varepsilon _{r}}{\partial \rho _{f}}}\right){\Bigr )}}
624:, by pumping fluid through tiny micro-channels with a pressure difference. This technology could lead to a practical and clean energy storage device, replacing batteries for devices such as mobile phones or calculators which would be charged up by simply compressing water to high
89:
The electric forces acting on particles consist of electrostatic (Coulomb) and electrophoresis force (first term in the following equation)., dielectrophoretic force (second term in the following equation), and electrostrictive force (third term in the following equation):
61:. EHD, in its simplest form, involves the application of an electric field to a fluid medium, resulting in fluid flow, form, or properties manipulation. These mechanisms arise from the interaction between the
603:
has also been observed in biology, where it was found to cause physical damage to neurons by inciting movement in their membranes. It is discussed in R. J. Elul's "Fixed charge in the cell membrane" (1967).
597:
If the electrodes are free to move within the fluid, while keeping their distance fixed from each other, then such a force will actually propel the electrodes with respect to the fluid.
504:
999:
Yang, Jun; Lu, Fuzhi; Kostiuk, Larry W.; Kwok, Daniel Y. (1 January 2003). "Electrokinetic microchannel battery by means of electrokinetic and microfluidic phenomena".
411:
In the second instance, the converse takes place. A powered flow of medium within a shaped electrostatic field adds energy to the system which is picked up as a
592:
572:
548:
524:
441:
transport produced by an electric field acting on a fluid having a net mobile charge. (See -kinesis for explanation and further uses of the -kinesis suffix.)
672:
instabilities. The particular case of a flat plane geometry with homogeneous ions injection in the bottom side leads to a mathematical frame identical to the
1057:
Ferraro, P.; Coppola, S.; Grilli, S.; Paturzo, M.; Vespini, V. (2010). "Dispensing nano–pico droplets and liquid patterning by pyroelectrodynamic shooting".
660:. Conductivity gradients are prevalent in on-chip electrokinetic processes such as preconcentration methods (e.g. field amplified sample stacking and
688:, that can generate temporal, convective, and absolute flow instabilities. Electrokinetic flows with conductivity gradients become unstable when the
1103:
457:, although he seems to have misidentified it as an electric field acting on gravity. The flow rate in such a mechanism is linear in the
834:
Wall, Staffan. "The history of electrokinetic phenomena." Current
Opinion in Colloid & Interface Science 15.3 (2010): 119-124.
695:
Since these flows are characterized by low velocities and small length scales, the
Reynolds number is below 0.01 and the flow is
685:
898:
751:
465:, because it offers a way to manipulate and convey fluids in microsystems using only electric fields, with no moving parts.
664:), multidimensional assays, and systems with poorly specified sample chemistry. The dynamics and periodic morphology of
726:
471:
960:
888:
673:
692:
stretching and folding of conductivity interfaces grows faster than the dissipative effect of molecular diffusion.
669:
57:
fluids. Electrohydrodynamics (EHD) is a joint domain of electrodynamics and fluid dynamics mainly focused on the
17:
405:
307:
652:
of order unity or smaller). However, heterogeneous ionic conductivity fields in the presence of applied
1136:
870:
746:
716:
428:
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in a fluid subjected to an electric field are the underlying physics of all EHD-based technologies.
1131:
771:
736:
454:
1141:
1109:
933:
845:
689:
699:. The onset of instability in these flows is best described as an electric "Rayleigh number".
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633:
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450:
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797:
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661:
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412:
369:
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50:
8:
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In
October 2003, Dr. Daniel Kwok, Dr. Larry Kostiuk and two graduate students from the
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1020:
981:
956:
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648:
and nanofluidic devices are often stable and strongly damped by viscous forces (with
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350:
338:
1115:
798:"Electrohydrodynamics and its applications: Recent advances and future perspectives"
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1016:
815:
805:
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373:
396:, generally to move the electrodes. In such case, the moving structure acts as an
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by exploiting the natural electrokinetic properties of a liquid such as ordinary
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427:"Electrokinesis" redirects here. For the ability to manipulate electricity, see
952:
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is the ion mobility coefficient of the dielectric fluid, measured in m/(V·s).
449:
of clay particles The effect was also noticed and publicized in the 1920s by
1125:
527:
462:
313:
1086:
731:
645:
329:
EHD covers the following types of particle and fluid transport mechanisms:
80:
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985:
27:
Study of electrically conducting fluids in the presence of electric fields
401:
904:
656:
can, under certain conditions, generate an unstable flow field owing to
890:
Micro- and
Nanoscale Fluid Mechanics: Transport in Microfluidic Devices
621:
393:
632:, water-flow phenomenon was discovered in 1859 by German physicist
625:
445:
was first observed by
Ferdinand Frederic Reuss during 1808, in the
84:
Electrohydrodynamics employed for drying applications (EHD Drying).
551:
385:
349:. In general, the phenomena relate to the direct conversion of
438:
392:, no flow is produced. Such flow can be directed against the
389:
377:
574:
is the distance between electrodes, measured in metres, and
461:. Electrokinesis is of considerable practical importance in
1056:
946:
867:
468:
The force acting on the fluid, is given by the equation
415:
by electrodes. In such case, the structure acts as an
580:
560:
536:
512:
474:
400:. Practical fields of interest of EHD are the common
98:
864:
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542:
518:
498:
296:
998:
795:
707:Liquids can be printed at nanoscale by pyro-EHD.
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213:
73:within the fluid. The generation and movement of
1123:
802:International Journal of Heat and Mass Transfer
770:
639:
1001:Journal of Micromechanics and Microengineering
616:discussed a method to convert hydrodynamic to
1041:
947:Patterson, Michael; Kesner, Raymond (1981).
886:
796:Iranshahi, Kamran; Defraeye, Thijs (2024).
949:Electrical Stimulation Research Techniques
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306:This electrical force is then inserted in
1110:Science-daily article about the discovery
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809:
843:
811:10.1016/j.ijheatmasstransfer.2024.125895
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310:equation, as a body (volumetric) force.
59:fluid motion induced by electric fields
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752:List of textbooks in electromagnetism
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858:
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526:is the resulting force, measured in
384:is produced. If the dielectric is a
24:
727:Electrodynamic droplet deformation
668:are similar to other systems with
658:electrokinetic instabilities (EKI)
317:Electrohydrodynamics employed for
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252:
25:
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1097:
978:Fixed charge in the cell membrane
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679:EKI's can be leveraged for rapid
499:{\displaystyle F={\frac {Id}{k}}}
422:
208:
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992:
844:Thompson, Clive (August 2003).
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893:. Cambridge University Press.
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364:In the first instance, shaped
13:
1:
1044:Physicochemical Hydrodynamics
865:Chang, H.C.; Yeo, L. (2009).
846:"The Antigravity Underground"
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406:electrohydrodynamic thrusters
666:electrokinetic instabilities
640:Electrokinetic instabilities
550:is the current, measured in
7:
1104:Dr. Larry Kostiuk's website
710:
10:
1158:
1021:10.1088/0960-1317/13/6/320
871:Cambridge University Press
747:Electrostatic precipitator
674:Rayleigh–Bénard convection
426:
1116:BBC article with graphics
930:Theoretical Microfluidics
717:Magnetohydrodynamic drive
429:List of psychic abilities
408:and EHD cooling systems.
737:Electrokinetic phenomena
934:Oxford University Press
702:
588:
568:
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500:
376:. When such media are
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75:charge carriers (ions)
49:, is the study of the
39:electro-fluid-dynamics
1079:10.1038/nnano.2010.82
1059:Nature Nanotechnology
1042:Levich, V.I. (1962).
686:electric double layer
634:Georg Hermann Quincke
614:University of Alberta
608:Water electrokinetics
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521:
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451:Thomas Townsend Brown
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887:Kirby, B.J. (2010).
776:Electrohydrodynamics
722:Magnetohydrodynamics
662:isoelectric focusing
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510:
472:
455:Biefeld–Brown effect
453:which he called the
417:electrical generator
413:potential difference
372:(HSP, or motion) in
370:hydrostatic pressure
366:electrostatic fields
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71:polarization effects
55:electrically charged
31:Electrohydrodynamics
1071:2010NatNa...5..429F
1013:2003JMiMi..13..963Y
976:Elul, R.J. (1967).
821:20.500.11850/683872
742:Optoelectrofluidics
644:The fluid flows in
630:streaming potential
437:is the particle or
928:Bruus, H. (2007).
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1137:Energy conversion
900:978-0-521-11903-0
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587:{\displaystyle k}
567:{\displaystyle d}
543:{\displaystyle I}
519:{\displaystyle F}
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351:electrical energy
339:dielectrophoresis
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67:charged particles
37:), also known as
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402:air ioniser
1126:Categories
911:2010-02-13
758:References
394:electrodes
359:vice versa
1029:250922353
622:tap water
272:ρ
268:∂
257:ε
253:∂
237:ρ
225:→
209:▽
200:ε
177:ε
173:▽
162:→
147:ε
133:−
128:→
114:ρ
1087:20453855
774:(1998).
711:See also
626:pressure
51:dynamics
1067:Bibcode
1009:Bibcode
986:6040152
697:laminar
552:amperes
528:newtons
506:where,
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681:mixing
386:vacuum
378:fluids
357:, and
345:, and
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390:solid
388:or a
353:into
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1083:PMID
982:PMID
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382:flow
380:, a
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