Figure 10.7
207
Bacterial Nanocellulose Biomaterials with Controlled Architecture
Electrodes
PDMS mold
BC media
BC layers
Figure 10.7
(See color insert.).Three.schematics.illustrating.the.concept.of.depressing.the.curved.portion.of.
the.silastic.meniscus.form.overlaying.the.bacteria-rich.media.with.the.thin.PDMS.nanoconduit.
mold..Eventually.enough.media.and.growth.will.occur.to.be.fully.covered.by.the.overlay.
nanoconduit.mold,.and.the.silastic.meniscus.form.was.mechanically.raised.
in.concert.with.a.slow.infusion.of.media.for.approximately.5.days,.reaching.
a.height.of.8.mm.along.the.lateral.wall.
Design of a Mask and the Production of a PDMS Conduit Mold
The.microfluidic.features.and.channels.were.designed.using.AutoCAD.and.
COMSOL.Multiphysics.numerical.modeling..Designs.for.a.meniscal.shape.
(semicircle). and. for. a. full. circle,. generated. using. AutoCAD,. were. used. to.
produce. masks. for. our. lithography. fabrication. process.. Silicon. master.
stamps.of.the.conduit.mask.design.were.fabricated.using.deep.reactive.ion.
etching.(photolithography.fabrication).followed.by.Teflon.deposition.based.
on.techniques.developed.by.Davalos.et.al..(2008)..PDMS.monomers.and.the.
curing.agent.were.mixed.in.a.10:1.ratio.(Sylgard.184,.Dow.Corning,.USA)..
Liquid.PDMS.was.poured.onto.the.silicon.master.and.cured.at.room.temperature. or. for. 15. min. at. 115°C. (Figure 10.8).. Test. cultures. were. set. up. to.
confirm.that.the.PDMS.conduit.mold.would.produce.the.desired.pattern.in.
the.bacteria.cellulose.
Testing PDMS Conduits Using Charged
Fluorescent Beads or Fluorescent Stained Bacteria
The.objective.of.the.first.set.of.experiments.was.to.evaluate.the.movement.
of.charged.beads.and.bacteria.along.the.PDMS.conduits..The.purpose.was.
to.determine.if.the.beads/bacteria.moved.smoothly.along.the.track.and.to.
establish.an.ideal.voltage.and.frequency.range.for.bacteria.movement.
207
Bacterial Nanocellulose Biomaterials with Controlled Architecture
Electrodes
PDMS mold
BC media
BC layers
Figure 10.7
(See color insert.).Three.schematics.illustrating.the.concept.of.depressing.the.curved.portion.of.
the.silastic.meniscus.form.overlaying.the.bacteria-rich.media.with.the.thin.PDMS.nanoconduit.
mold..Eventually.enough.media.and.growth.will.occur.to.be.fully.covered.by.the.overlay.
nanoconduit.mold,.and.the.silastic.meniscus.form.was.mechanically.raised.
in.concert.with.a.slow.infusion.of.media.for.approximately.5.days,.reaching.
a.height.of.8.mm.along.the.lateral.wall.
Design of a Mask and the Production of a PDMS Conduit Mold
The.microfluidic.features.and.channels.were.designed.using.AutoCAD.and.
COMSOL.Multiphysics.numerical.modeling..Designs.for.a.meniscal.shape.
(semicircle). and. for. a. full. circle,. generated. using. AutoCAD,. were. used. to.
produce. masks. for. our. lithography. fabrication. process.. Silicon. master.
stamps.of.the.conduit.mask.design.were.fabricated.using.deep.reactive.ion.
etching.(photolithography.fabrication).followed.by.Teflon.deposition.based.
on.techniques.developed.by.Davalos.et.al..(2008)..PDMS.monomers.and.the.
curing.agent.were.mixed.in.a.10:1.ratio.(Sylgard.184,.Dow.Corning,.USA)..
Liquid.PDMS.was.poured.onto.the.silicon.master.and.cured.at.room.temperature. or. for. 15. min. at. 115°C. (Figure 10.8).. Test. cultures. were. set. up. to.
confirm.that.the.PDMS.conduit.mold.would.produce.the.desired.pattern.in.
the.bacteria.cellulose.
Testing PDMS Conduits Using Charged
Fluorescent Beads or Fluorescent Stained Bacteria
The.objective.of.the.first.set.of.experiments.was.to.evaluate.the.movement.
of.charged.beads.and.bacteria.along.the.PDMS.conduits..The.purpose.was.
to.determine.if.the.beads/bacteria.moved.smoothly.along.the.track.and.to.
establish.an.ideal.voltage.and.frequency.range.for.bacteria.movement.