Figure 10.11
210
Bacterial Cellulose
Voltage vs. Frequency
11
9
7
5
Frequency (Hz)
3
1
0
0.1
0.2
0.3
0.4
Voltage (V)
Figure 10.11
Graphic. illustration. of. voltage. versus. minimum. frequency. required. to. achieve. control. over.
bacteria.movement.within.the.PDMS.conduit.mold.
These.experiments.demonstrated.that.a.sine.wave.with.the.AC.generator.is.
superior.to.the.square.wave,.which.caused.sudden.changes.in.the.. bacteria’s.
direction,. causing. collisions. within. the. channels.. The. sine. wave. allows. a.
smoother.flow.since.it.gradually.rises.to.the.maximum.voltage..The.lower.
amount.of.stress.on.the.bacteria.may.prove.useful.for.better.cellulose.production.. We. also. determined. that. 0.60. Hz. with. a. sine. wave. and. a. voltage.
range.between.4.and.6.Vac.is.optimum.when.using.AC.to.control.bacteria.
movement..Based.on.these.results,.we.concluded.that.our.design.would.be.
more.successful.using.the.full.circle.design.rather.than.the.semicircle.that.
mimics.the.shape.of.the.native.meniscus.
Description of a Prototype BNC Meniscus Microweaver
The.meniscus.microweaver.is.a.bioreactor.designed.to.biofabricate.meniscus. .
implants.(see.Figures 10.12a–f)..It.is.placed.in.a.closed.plexiglass.. system.that.
maintains. a. sterile. environment. and. minimizes. water. loss.. Parts. include.
a. circular. silastic. meniscus. mold,. a. PDMS. conduit. mold. attached. to. a.
. gasket.to.keep.the.PDMS.mold.in.place.with.holes.to.guide.the.electrodes.
(see Figure 10.12a),.and.a.central.perforated.cylinder.connected.to.a.stepping.
motor. through. which. medium. is. delivered. (see. Figure 10.12b).. Production.
tion,.held.in.place.by.a.cylinder..Once.a.pellicle.of.bacteria.cellulose.is.established.(static.incubation.of.3.days),.the.microweaver.operation.switches.to.a.
dynamic. mode. (Figures 10.12c–f).. The.stepping. motor.gradually. draws. up.
the.cylinder.(1.mm/24.h),.eventually.allowing.the.meniscus.mold.to.recover.
its.original.shape.(Figures 10.12c.and.10.12e)..As.this.is.happening,.fresh.culture.medium.is.dispensed.through.the.center.of.the.cylinder.using.a.syringe.
210
Bacterial Cellulose
Voltage vs. Frequency
11
9
7
5
Frequency (Hz)
3
1
0
0.1
0.2
0.3
0.4
Voltage (V)
Figure 10.11
Graphic. illustration. of. voltage. versus. minimum. frequency. required. to. achieve. control. over.
bacteria.movement.within.the.PDMS.conduit.mold.
These.experiments.demonstrated.that.a.sine.wave.with.the.AC.generator.is.
superior.to.the.square.wave,.which.caused.sudden.changes.in.the.. bacteria’s.
direction,. causing. collisions. within. the. channels.. The. sine. wave. allows. a.
smoother.flow.since.it.gradually.rises.to.the.maximum.voltage..The.lower.
amount.of.stress.on.the.bacteria.may.prove.useful.for.better.cellulose.production.. We. also. determined. that. 0.60. Hz. with. a. sine. wave. and. a. voltage.
range.between.4.and.6.Vac.is.optimum.when.using.AC.to.control.bacteria.
movement..Based.on.these.results,.we.concluded.that.our.design.would.be.
more.successful.using.the.full.circle.design.rather.than.the.semicircle.that.
mimics.the.shape.of.the.native.meniscus.
Description of a Prototype BNC Meniscus Microweaver
The.meniscus.microweaver.is.a.bioreactor.designed.to.biofabricate.meniscus. .
implants.(see.Figures 10.12a–f)..It.is.placed.in.a.closed.plexiglass.. system.that.
maintains. a. sterile. environment. and. minimizes. water. loss.. Parts. include.
a. circular. silastic. meniscus. mold,. a. PDMS. conduit. mold. attached. to. a.
. gasket.to.keep.the.PDMS.mold.in.place.with.holes.to.guide.the.electrodes.
(see Figure 10.12a),.and.a.central.perforated.cylinder.connected.to.a.stepping.
motor. through. which. medium. is. delivered. (see. Figure 10.12b).. Production.
tion,.held.in.place.by.a.cylinder..Once.a.pellicle.of.bacteria.cellulose.is.established.(static.incubation.of.3.days),.the.microweaver.operation.switches.to.a.
dynamic. mode. (Figures 10.12c–f).. The.stepping. motor.gradually. draws. up.
the.cylinder.(1.mm/24.h),.eventually.allowing.the.meniscus.mold.to.recover.
its.original.shape.(Figures 10.12c.and.10.12e)..As.this.is.happening,.fresh.culture.medium.is.dispensed.through.the.center.of.the.cylinder.using.a.syringe.