Central to the success of microfluidic systems has been the development of innovative methods for the
manipulation of fluids within microchannels. We demonstrate a method for generating flow within a
microfluidic channel using an optically driven pump. The pump consists of two counter rotating birefringent
vaterite particles trapped within a microfluidic channel and driven using optical tweezers. The transfer of spin
angular momentum from a circularly polarised laser beam rotates the particles at up to 10 Hz. We show the
that the pump is able to displace fluid in microchannels, with flow rates of up to 200 μm3 s-1 (200 fL s-1). The direction of fluid pumping can be reversed by altering the sense of the rotation of the vaterite beads. We also
incorporate a novel optical sensing method, based upon an additional probe particle, trapped within separate
optical tweezers, enabling us to map the magnitude and direction of fluid flow within the channel. The
techniques described in the paper have potential to be extended to drive an integrated lab-on-chip device,
where pumping, flow measurement and optical sensing could all be achieved by structuring a single laser
beam.
We demonstrate a technique for the multi-point measurement of fluid flow in microscopic geometries. The
technique consists of an array of microprobes can be simultaneously trapped and used to map out the fluid flow
in a microfluidic device. The optical traps are alternately turned on and off such that the probe particles are
displaced by the flow of the surrounding fluid and then re-trapped. The particles' displacements are monitored by
digital video microscopy and directly converted into velocity field values. The techniques described have potential
to be extended to drive an integrated lab-on-chip device, where pumping, flow measurement and optical sensing
could all be achieved by structuring a single laser beam.
We use holographic optical tweezers to create and monitor the liquid flow within a micro-fluidic device. Using the tweezers to both trap and spin micron-sized beads within a 10-20 micron wide channel creates a fluid flow of the order of 200 cubic microns/sec. We also use the optical tweezers to measure the fluid flow by trapping and releasing probe particles that are imaged with high temporal and spatial resolution. Using the multi-trap capability of the holographic optical tweezers we measure the transverse fluid velocity at many positions simultaneously with an accuracy of better than 1 micron/sec. Such studies are highly pertinent to lab-on-chip systems for various applications and studies within the biosciences.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.