Biomedical Engineering Reference
In-Depth Information
Sample input
PMT
Filter (525/40)
Buffer
Buffer
488 nm laser
Sheath
reservoir
Analysis region
IR laser
AOM
Optical switch
Microfluidic
cartridge
Output
wells
Sample
input
Photodiode
Filter
(488/10)
(b)
(a)
Waste
Collection
Brightfield
Fluorescence
Brightfield
Fluorescence
(c)
Collection well
Waste well
Figure 19.9
(See companion CD for color igure.)
.Schematic.of.a.microluidic.cell.sorting/separation.apparatus.with.opti-
cal.trap.technology..(a).The.layout..(b).The.instrument.setup..(c).The.cell.sorting.results..A.near-infrared.laser.
and. 488.nm. laser. are. focused. through. the. same. lens. onto. the. microluidic. sorting. junction.. The. presence. of.
all. cells. is. measured. by. a. photodiode. while. the. luorescence. signal.of. some. cells. is. measured. with. a. photon.
multiple.tubes.(PMT)..Based.on.a.gating.of.the.luorescence.signal.from.the.passing.cell,.the.optical.tweezers.
equipped.with.AOD.is.triggered.to.optically.delect.some.cells.(those.illuminate.luorescence.signal).to.the.col-
lection.well.while.the.rest.of.cells.go.to.the.waste.cell..In.(c),.both.brightield.and.luorescence.images.of.HeLa.
cells. in. both. the. collection. well. (left. images). and. waste. well. (right. images). are. shown. after. optical. sorting..
(Reprinted.by.permission.from.Macmillan.Publishers.Ltd..
Nat. Biotechnol
.,.Wang,.M.M.,.Tu,.E.,.Raymond,.D.E.,.
Yang,.J.M.,.Zhang,.H.,.Hagen,.N.,.Dees,.B..et.al.,.Microluidic.sorting.of.mammalian.cells.by.optical.force.switch-
ing,.23,.83-87,.Copyright.2005.)
processes.. Such. “optical. chromatography”. had. been. successfully. used. to. separate. blood.
cells.(Kaneta.et.al..1997),.bacteria.(Hart.et.al..2006),.and.pollens.(Terray.et.al..2005).
The. most. valuable. optical. cell. sorting. examples. came. from. microluidic. luorescence-
activated.cell.sorting.(FACS,.Herzenberg.et.al..2002)..In.early.optical.tweezers.based.separation,.
only.a.few.cells.could.be.sorted.(Ozkan.et.al..2003b;.Enger.et.al..2004).until.the.appearance.
of.high-throughput.microluidic.FACS.(Wang.et.al..2005)..In.this.microluidic.FACS.system,.
two.laser.beams.were.used:.a.visible.laser.(λ.=.488.nm).was.used.to.detect.target.cells.while.
a. near-infrared. laser. (λ.=.1070.nm). was. used. to. attain. optical. sorting.. A. hydrodynamics.
focusing.low.(a.center.low.stream.carrying.the.cell.suspension.is.sandwiched.by.two.side.
low. streams. containing. buffer. solutions). was. maintained. to. guide. cells. into. the. middle.
detection.zone.where.the.visible.laser.was.used.in.order.to.identify.the.luorescence-tagged.
target.cells..The.detection.signal.was.then.transferred.to.the.downstream.separation.region.
to.trigger.an.AOD.modulator.to.grab.the.wanted.cells.and.delect.them.into.the.receiving.
channel. while. allowing. the. rest. of. the. cells. to. low. to. the. waste. channel.. Such. optical.
