10.1021/la063075a.s004
Masato Suzuki
Masato
Suzuki
Tomoyuki Yasukawa
Tomoyuki
Yasukawa
Hitoshi Shiku
Hitoshi
Shiku
Tomokazu Matsue
Tomokazu
Matsue
Negative Dielectrophoretic Patterning with Colloidal Particles and
Encapsulation into a Hydrogel
American Chemical Society
2007
template IDA electrode
block UV transmission
SMPB
conductive ITO support
glass substrate
bottom support
ITO support
particle patterns
nonconductive glass substrate
field gradient regions
ITO interdigitated microband array
conductive indium tin oxide
photoreactive hydrogel polymer
Negative Dielectrophoretic Patterning
polymerized hydrogel sheet
2007-03-27 00:00:00
Figure
https://acs.figshare.com/articles/figure/Negative_Dielectrophoretic_Patterning_with_Colloidal_Particles_and_Encapsulation_into_a_Hydrogel/3017053
Microparticle patterns have been fabricated on a nonconductive glass substrate and a conductive indium tin oxide
(ITO) substrate using negative dielectrophoresis (n-DEP). The patterned microparticles on the substrate were immobilized
by covalent bonding or embedded into polymer sheets or strings. The patterning device consisted of an ITO interdigitated
microband array (IDA) electrode as the template, a glass or ITO substrate, and a polyester film (10-μm thickness)
as the spacer. A suspension of 2-μm-diameter polystyrene particles was introduced into the device between the upper
IDA and the bottom glass or ITO support. An ac electrical signal (typically 20 Vpp, 3 MHz) was then applied to the
IDA, resulting in the formation of line patterns with low electric field gradient regions on the bottom support. When
the glass substrate was used as the bottom support, the particles aligned under the microband electrodes of the IDA
within 5 s because the aligned areas on the support were regions with the weakest electric field; however, for the ITO
support, the particles were directed to the regions under the electrode gap and aligned on the support because these
regions had the weakest electric field. The width of the particle lines could be roughly controlled by regulating the
initial concentration of the suspended particles. The particles forming the line and grid patterns with single-particle
widths were immobilized by using a cross-linking reaction between the amino groups on the aligned particles and
<i>N</i>-hydroxysuccinimide-activated ester on the glass substrate activated by succinimidyl 4-(<i>p</i>-maleimidophenyl)-butyrate
(SMPB). The patterned particles were also embedded in a photoreactive hydrogel polymer. A prepolymer solution
of poly(ethylene glycol) diacrylate (PEG-DA) was used as the suspension medium to maintain the particle patterns
in the polymerized hydrogel sheet and string following photopolymerization. The hydrogel sheets with particle patterns
were fabricated by ultraviolet (UV) irradiation through the ITO-IDA template for 120 s. Hydrogel strings with the
aligned particles were fabricated by using a conductive ITO support and a Pt-IDA template. Pt-IDA was used as a
template as well as a photomask to block UV transmission. The present procedure affords extremely simple, rapid,
and highly reproducible fabrication of particle arrays. The reusability of the template IDA electrode is also a substantial
advantage over previous methods.