Biomedical Engineering Reference
In-Depth Information
FIGURE 1.14
Laser-cut. laminated. devices. for. diagnostics.. Image. contributed. by. the. author..
(Disclaimer:. The. author. has. collaborated. with. Micronics,. however,. the. image. is. not. meant. to.
endorse.Micronics'.devices..Micronics.and.the.laboratory.of.its.founder.Paul.Yager,.at.the.University.
of.Washington's.Bioengineering.Department,.are.early.developers.of.laser-cut.laminate.technology.)
lamination approach, in combination with
laser cutting
, has been used successfully by various
companies to make low-cost microluidic devices for medical diagnostics (
Figure 1.14
).
1.4.5 Multiphoton Lithography
Multiphoton lithography
, also called
direct laser writing
, allows for the fabrication of arbi-
trary 3-D structures (
Figure 1.15
) and is based on multiphoton polymerization of an adequate
photoresist. he center wavelength of the laser is chosen to coincide with the transparent spec-
trum of the photoresist, and it takes two or more photons (absorbed simultaneously on the same
tightly focused spot) to expose the photoresist. he beam spot is moved relative to the sample by
displacing the sample with a programmable piezoelectric XYZ sample stage. Once the exposure
is inished, the unexposed photoresist is dissolved away in a developer solution. Unfortunately,
the price of these systems is still in the range of hundreds of thousands of dollars.
Jason Shear's group (from the University of Texas at Austin) has extended the concept of
direct laser writing to the use of photo-cross-linkable biomolecules in aqueous environments
Piezoelectric
3-D scanning stage
10 µm
Microscope objective
100×, NA = 1.4
Inverted
microscope
CCD-
camera
Beam expansion
Polarizer
AOM
Laser-
controlling
interface
2 µm
Fiber laser
FIGURE 1.15
Direct.laser.writing..(Courtesy.of.Nanoscribe.GmbH.Germany.).(Note:.the.igure.is.not.
meant.to.endorse.Nanoscribe's.technology.over.other.direct.laser.writing.systems.)
