CMDITR Review of Undergraduate Research - Pluto - University of ...

would begin. A marker was created using
AutoCAD 2004, exported as a “.stl” file,
converted into a “.3dml” file using python, and
then fabricated onto the substrate using
LabVIEW (“fabricate solid GPIB.vi”, “fabricate
solid GPIB 7.vi”). The marker is necessary to
locate the voxels that are being created for the
experiment. Next, the voxels were created by
opening and closing the shutter using LabVIEW
(“expose for interval.vi”). The voxels were
separated by five microns, and they were spaced
by using the piezoelectric Nanocube software,
which allows for 100 microns of movement in
three dimensions. The vertical movement was
not used while spacing the voxels. The
measurement of the voxels was originally taken
with an Atomic Force Microscope (AFM) and
the later measurements were taken with a
Scanning Electron Microscope (SEM).
The secondary objective of support
manufacturing for others required designs and
instructions for the desired object to be
fabricated. Once these designs were provided,
the object was created in AutoCAD 2004, again
exported as a “.stl” file, converted into a “.3dml”
file using python, and then fabricated onto the
substrate provided by the researcher who desires
the fabrication using LabVIEW (“fabricate solid
GPIB.vi”, “fabricate solid GPIB 7.vi”, “fabricate
solid GPIB v2_1 no_display.vi”). The substrates
provided were poly-di-methyl silane (PDMS),
quartz and optical fiber, and 40 micron deep
chambers on quartz. Preparation and cleaning of
the substrates was the same as before. The area
of fabrication was much more difficult to find
under the objective lens in comparison to the
voxel volume-filling rate experiment.
Results/Intended Results
The voxel volume-filling rate experiment
was designed to determine whether or not there
was a limiting volume with respect to the
exposure time. The plot in Table 1 shows data
that has a fairly linear trend. This is the only true
data that was extracted from the samples thus far.
The support manufacturing with Dr. Deirdre
Meldrum and her graduate student Pahnit
Seriburi yielded unfortunate results. First,
fabrication had to occur in a channel carved in
PDMS that was 10 microns deep, 100 microns
across, and 25 millimeters across. The vowels
created were longer than originally thought, so as
fabrication continued within the channel, the
final structure that should have been 10 microns
tall was closer to 12 microns tall, which
defeated the purpose of fabricating in the
channel. By fabricating the funnel 12 microns
tall, the experiment that Pahnit Seriburi was
attempting to run could not be started simply
because the structure fabricated protruded over
the top of the PDMS, which was going to be
placed on top of a glass substrate. Also, when
attempting to fabricate filters for the PDMS
channel, the filters would not remain vertical, or
were not sturdy enough to withstand the amount
of fluid being forced through them. Continuing
with this experiment, it was then decided to
attempt to fabricate a mold of the funnel.
However, the PDMS will not backfill within the
resolution of the mold desired and created.
Support manufacturing with Dr. Antao Chen
and his graduate student Travis Sherwood did
not produce the desired results from the
fabrication aspect, but did present results
involving the resilience of the polymer and the
ability to remove the polymer from the substrate
to place it on another. The fabrication of the
micro-ring was difficult to produce because the
desired location was to have the edge of the
circle tangent to the edge of the core. The microrings
were then moved on the substrate, removed
from the substrate and placed on another
substrate, and stretched like elastic bands, all
with a micromanipulator.
Conclusions
Through the voxel volume-filling rate
experiment, support manufacturing, and free
exploration it has been determined that the power
of the laser can be reduced and the resolution of
the objects fabricated has been refined by
defining finer resolution in the program python.
Other ways to help refine the resolution of the
final product is to slow the translation speed of
the Nanocube, optimizing the shutter reaction
speed during all scans rather than some of the
scans, post-bake the product once the fabrication
has completed, and attempt to lower the power
even further as long as it does not fall below the
polymerization threshold. The voxel volumefilling
rate has so far not returned any conclusive
results.
Being able to remove the micro-rings from
the substrate shows that the polymer is not
actually adhering to the substrate, rather there are
weak bonds between the substrate and the
created polymer. Also, the resilience of the
polymer was tested and shows that it is fairly
strong on the micro scale, and very elastic.
62 CMDITR Review of Undergraduate Research Vol. 1 No. 1 Summer 2004