Microfluidics and optical trapping integrated for the
first time in new lab-on-a-chip research
Researchers at Cornell University for the first time have integrated
optical functions with microfluidic ones, enabling the sorting of
particles by light.
WASHINGTON � Researchers at
Cornell University for the first time have integrated optical functions
with microfluidic ones, enabling the sorting of particles by light.
Reported in the Oct. 29 issue of Optics Express, due out Monday, the
Cornell team showcases a new design for a "lab-on-a-chip" structure that
provides the ability to move or sort particles using light. In addition
to the advance in telecom and datacom applications this brings, the new
architecture also lends itself to applications in biodetection,
including the sorting of viruses and protein recognition.
Summary
This novel architecture, created by lead researcher Michal Lipson and
her group and David Erickson and his group, is made up of a field of
solid core waveguides. The waveguides are fabricated from SU-8, a
material whose mechanical hardness and chemical resistance make it a
source for use in lab-on-chip analysis systems. The waveguides used in
the device achieve a much more efficient sorting process, which
enables trapping and sorting much smaller spheres with much lower
intensities than what has been previously reported. By integrating
these waveguides on a chip, a massive parallel sorting system may be
created. This sorting system would allow for hundreds of measurements
in parallel on a 1x1 cm chip, introducing a portable system that
provides greater efficiency and lower cost than the current
methodologies.
Key Findings
This is the first demonstration of complete integration of planar
optical waveguides with microfluidic ones.
This integrated system allows researchers to use light to control the
movement of particles in a pressure-driven flow.
The planar optofluidic architecture developed represents a simple yet
functional optical manipulation system for lab-on-chip applications.
The use of planar photonic structures in microfluidic devices removes
the need for table-top free-space optics, potentially reducing costs
and increasing platform portability.
Such a system could find application in high-stability particle
trapping and sorting, but also in biodetection by exploiting the
strong light interaction between the particle and the evanescent field.
Further Information and Source:
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Bradley S. Schmidt, Allen H. Yang, David Erickson, and Michal Lipson: Optofluidic trapping and transport on solid core waveguides
within a microfluidic device.
In: Optics Express;
Vol. 15, Issue 22, pp. 14322-14334; Open
Access Article.
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Abstract:
"In this work we demonstrate an integrated microfluidic/photonic
architecture for performing dynamic optofluidic trapping and
transport of particles in the evanescent field of solid core
waveguides. Our architecture consists of SU-8 polymer waveguides
combined with soft lithography defined poly(dimethylsiloxane) (PDMS)
microfluidic channels. The forces exerted by the evanescent field
result in both the attraction of particles to the waveguide surface
and propulsion in the direction of optical propagation both
perpendicular and opposite to the direction of pressure-driven flow.
Velocities as high as 28 �m/s were achieved for 3 �m diameter
polystyrene spheres with an estimated 53.5 mW of guided optical
power at the trapping location. The particle-size dependence of the
optical forces in such devices is also characterized."