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The effect of surface conductivity and adhesivity on the electrostatic manipulation condition for dielectric microparticles using a single probe

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Journal of Micromechanics and Microengineering
Authors:
  • National Institute of Technology, Hakodate College
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By clarifying the effect of surface conductivity and adhesivity on the electrostatic manipulation condition, a dielectric particle made of any material can be manipulated with surface conductivity. The manipulation system consists of three elements: a conductive probe as a manipulator, a conductive plate as a substrate, and a dielectric particle as the target object for manipulation. The particle can be successfully picked up/placed if a rectangular pulse voltage is applied between the probe and the plate. Four kinds of particle materials are used in the experiment: silica, soda-lime glass, polymethyl methacrylate coated by conductive polymer, and polystyrene coated by surfactant. The radius of each particle is 15 μm. A first-order resistor-capacitor (RC) circuit model is adopted to describe the effect of surface conductivity and adhesivity on the manipulation condition. The manipulation system is modeled as a series circuit consisting of a resistor and a capacitor by considering the surface conductivity. A detachment voltage is defined as the capacitance voltage to detach the particle adhered to the plate or probe. Parameters of the RC model, surface resistance, surface capacitance and detachment voltage are identified by a simulation and measurements. To verify the RC model, the particle’s behavior is observed by a high-speed camera, and the electrical current is measured by an electrometer. A manipulation experiment is demonstrated to show the effectiveness of the model. The particle reaction is observed for each duration and magnitude of the pulse voltage for the manipulation. The optimum pulse voltage for successful manipulation is determined by the parameters of the RC model as the standard. This knowledge is expected to expand the possibility of micro-fabrication technology.
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1 © 2016 IOP Publishing Ltd Printed in the UK
1. Introduction
A micro-manipulation technique is in high demand in the
eld of biology [1] and micro-fabrication technology. For
example, these techniques can be applied to the deposition
of a micro-optical element and the assembly of micro-optical
devices such as microlenses [2], microLEDs [3], microsphere
lasers [4, 5], photonic crystals [6, 7], and photonic memory
[8]. In micro-manipulation, adhesional force is dominant since
it is proportional to the rst power of the object size, whereas
Journal of Micromechanics and Microengineering
The effect of surface conductivity and
adhesivity on the electrostatic manipulation
condition for dielectric microparticles using
a single probe
RyoFujiwara1, PasomphoneHemthavy2, KunioTakahashi2
and ShigekiSaito1
1 Department of Mechanical and Aerospace Engineering, Graduate School of Engineering, Tokyo Institute
of Technology 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552, Japan
2 Department of International Development Engineering, Graduate School of Engineering, Tokyo Institute
of Technology 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552, Japan
E-mail: fujiwara.r.ab@m.titech.ac.jp and saitos@mep.titech.ac.jp
Received 12 February 2016
Accepted for publication 26 February 2016
Published 13 April 2016
Abstract
By clarifying the effect of surface conductivity and adhesivity on the electrostatic
manipulation condition, a dielectric particle made of any material can be manipulated with
surface conductivity. The manipulation system consists of three elements: a conductive probe
as a manipulator, a conductive plate as a substrate, and a dielectric particle as the target object
for manipulation. The particle can be successfully picked up/placed if a rectangular pulse
voltage is applied between the probe and the plate. Four kinds of particle materials are used
in the experiment: silica, soda-lime glass, polymethyl methacrylate coated by conductive
polymer, and polystyrene coated by surfactant. The radius of each particle is 15 μm.
A rst-order resistor-capacitor (RC) circuit model is adopted to describe the effect of
surface conductivity and adhesivity on the manipulation condition. The manipulation system
is modeled as a series circuit consisting of a resistor and a capacitor by considering the
surface conductivity. A detachment voltage is dened as the capacitance voltage to detach
the particle adhered to the plate or probe. Parameters of the RC model, surface resistance,
surface capacitance and detachment voltage are identied by a simulation and measurements.
To verify the RC model, the particles behavior is observed by a high-speed camera, and the
electrical current is measured by an electrometer. A manipulation experiment is demonstrated
to show the effectiveness of the model. The particle reaction is observed for each duration
and magnitude of the pulse voltage for the manipulation. The optimum pulse voltage for
successful manipulation is determined by the parameters of the RC model as the standard.
This knowledge is expected to expand the possibility of micro-fabrication technology.
Keywords: electrostatics, micromanipulation, dielectric, surface conductivity, adhesivity
(Some guresmay appear in colour only in the online journal)
R Fujiwara etal
Printed in the UK
055010
JMMIEZ
© 2016 IOP Publishing Ltd
2016
26
J. Micromech. Microeng.
JMM
0960-1317
10.1088/0960-1317/26/5/055010
Paper
5
Journal of Micromechanics and Microengineering
IOP
0960-1317/16/055010+10$33.00
doi:10.1088/0960-1317/26/5/055010
J. Micromech. Microeng. 26 (2016) 055010 (10pp)
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... When the contact angles are 90°, the force curve almost fits the JKR theory because the capillary force is relatively small under this condition [see Eqs. (28), (32)]. When the contact angles are smaller or larger than 90°, another characteristic is shown with respect to the JKR theory in which the force curves of the same contact angles have different paths between the loading and unloading processes. ...
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