Particle Handling by Electric Field



Particle Handling by Electric Field[1]
Keywords: Electrostatic force, Particle, Particle conveyance,
Micro-parts handling


1. IntroductionTraveling electric fields have been applied
in mass transportation of powder by an electric curtain[2], where fine particles
are levitated against the gravity. In order to provide such devices which can
convey particles more precisely and with more flexibility of manipulation like
sorting, several devices have been developed. The characteristic of the drive
methods is that particles are not levitated but conveyed along or very close to
the surface of cover film which insulates the electrodes.


2. Principle of conveyanceBalanced, multi-phase high
voltages are supplied to a series of encased, parallel electrodes which are
covered and protected against electric sparkovers by a thin insulating film.
Upon the activation, a traveling electric field is created around the
electrodes. Particles on the film-surface become charged, and when the dynamic
forces of the electric field overcome adhesion and gravitational forces,
particles move with the traveling field in a direction perpendicular to the
electrodes as shown in the structure of the electric panel in Figure 1 and 2. By
this transportation process, particles proceed stepwise from electrode to
electrode, producing an overall conveyance velocity in direct proportion to the
frequency and the electrode gap.
A multi-channel, PC-controlled, high voltage supply is linked to the panel,
where every sixth electrode belongs to the same phase state: a, b, c, d, e, or
f. Particle motion depends on the property of particles, effective gap from
activated electrodes and patterns of applied voltages.
Various particle materials with a 5µm to 400µm diameter range have been
examined in experiments; Fe, Al, glass, and plastic spheres showed the best
performances.










Figure 1: Electric panel
device






Figure 2: Intersection of electric panel
device


3. Various devices for handlingThree structurally novel
devices were developed: the electric panel, the electric tube and the electric
dots. Each incorporates the same principle for particle handling, but serves a
different purpose.
ELECTRIC PANEL DEVICE



As shown in Fig.1, the device is composed of parallel electrodes
encased in epoxy resin, an insulating thin cover-film, a supporting panel.
Due to the simple electrode design, the panel can be fabricated with
various features.
An approach to achieving two-dimensional particle handling is shown in
Figure 3. A mesh electric panel, which interweaves the insulated electrode
wires for X drive with those for Y drive, can convey groups of particles
in X and (or) Y direction.






Figure 3: Electric panel for XY manipulation

ELECTRIC TUBE DEVICE



The cross section of an electric tube device with 6 phases is shown in
Figure 4. This structure is very easy to fabricate. To make a tube of a
number of phases, the same number of insulated wires are spooled as shown
in Figure 4.
The particles can be transported along the inside surface of the tube.
By this device, small aluminum balls with 0.2mm diameter could be easily
conveyed upward against the gravity. This device is also suitable for long
distance transportation of particles.






Figure 4: Electric tube device

ELECTRIC DOTS DEVICE



Fig.5 illustrates the concept of the electric dots device. The
manipulation electrodes appear as a matrix of dots in the handling
surface. The device incorporates a bundle of insulated conductive wires,
embedded in a supporting body. The surface has been ground in a plane
normal to the wires to form the handling surface which is subsequently
covered by a thin film. The particles are manipulated on the film-surface
along the dot electrodes. Particles are handled precisely from dot to dot.







Figure 5: Electric dots device



See also

High-power
electrostatic motor

Pulse
driven electrostatic induction motor
Dual
excitation multiphase electrostatic drive
Electrostatic
paper feeder
Electrostatic
non-contact suspension of thin plate


References[1]F.Moesner and T.Higuchi, "Devices for particle
handling by an AC electric field", Proc. of IEEE Workshop on Micro Electro
Mechanical Systems, pp.66-71 (1995)
[2]S.Masuda and T.Kamimura, "Approximate methods for calculating a
non-uniform traveling electric field", Journal of Electrostatics, Vol.1,
pp.351-370 (1975)



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