Biomedical Engineering Reference
In-Depth Information
energy.is.optimally.effective.when.it.is.just.below.the.limit.absorbed.by.the.target.which.
would.damage.the.transfer.material.(Hopp.et.al..2004;.Smausz.et.al..2006).
13.2.1.2 BioLP
BioLP.is.a.renamed.version.of.AFA-LIFT.coupled.with.motorized.receiving.stages,.and.a.
CCD.camera.oriented.orthogonally.to.the.path.of.the.laser.at.the.ribbon-substrate.gap.and.
used.to.study.the.transfer.process..This.technique.also.utilizes.a.metal.absorption.layer..
The.metal.experiences.rapid.thermal.expansion,.which.propels.a.local.volume.of.cell.sus-
pension.to.the.receiving.substrate.(Barron.et.al..2005a,b).
13.2.2 MAPLe DW
MAPLE. DW. uses. a. sacriicial. biological. or. polymeric. target. matrix. that. functions. to.
absorb.the.laser.energy.and.propel.the.transfer.material,.which.can.be.biological.or.inor-
ganic.(Figure.13.2)..This.sacriicial.target.layer,.often.gelatin.or.Matrigel,.is.thicker.than.
the.metal.ilm.used.in.AFA-LIFT.based.on.the.difference.in.the.attenuation.length..It.is.
desirable.that.the.laser.pulse.width.be.∼10.to.8.ns.and.that.the.wavelength.be.one.that.is.
strongly.absorbed.by.the.target.material.such.as.UV.(≤248.nm)..The.print.ribbon.substrate.
should.be.UV.transparent.(>90%).so.that.the.laser.pulse.will.not.interact.with.the.ribbon..
The. matrix. material. should. be. highly. absorptive. in. the. wavelength. of. the. laser,. so. the.
laser.pulse.will.not.penetrate.far.into.the.transfer.material,.avoiding.photolytic.effects.in.
the.target..Rapid.and.complete.absorption.keeps.the.laser.energy.focused.in.a.small.area,.
lowering.the.total.amount.of.energy/pulse.necessary.for.transfer..The.thicker.layer,.low.
200 μm
(a)
(b)
Figure 13.2
Cell.or.protein.patterns.printed.with.MAPLE.DW:.(a).polystyrene.microbeads;.(b).cell.colonies.
