An optically driven pump for microfluidics.

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 that the pump is able to displace fluid in microchannels, with flow rates of up to 200 microm(3) 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.

[1]  S. Quake,et al.  Monolithic microfabricated valves and pumps by multilayer soft lithography. , 2000, Science.

[2]  Miles J. Padgett,et al.  Lights, action: Optical tweezers , 2002 .

[3]  Jennifer E. Curtis,et al.  Dynamic holographic optical tweezers , 2002 .

[4]  Johannes Courtial,et al.  3D manipulation of particles into crystal structures using holographic optical tweezers. , 2004, Optics express.

[5]  Halina Rubinsztein-Dunlop,et al.  Optical microrheology using rotating laser-trapped particles. , 2004, Physical review letters.

[6]  M J Padgett,et al.  Intrinsic and extrinsic nature of the orbital angular momentum of a light beam. , 2002, Physical review letters.

[7]  H. Rubinsztein-Dunlop,et al.  Characterization of optically driven fluid stress fields with optical tweezers. , 2005, Physical review. E, Statistical, nonlinear, and soft matter physics.

[8]  D. Grier,et al.  Microoptomechanical pumps assembled and driven by holographic optical vortex arrays. , 2004, Optics express.

[9]  S. Quake,et al.  Microfluidics: Fluid physics at the nanoliter scale , 2005 .

[10]  S. Chu,et al.  Observation of a single-beam gradient force optical trap for dielectric particles. , 1986, Optics letters.

[11]  S. Neale,et al.  All-optical control of microfluidic components using form birefringence , 2005, Nature materials.

[12]  Alex Terray,et al.  Microfluidic Control Using Colloidal Devices , 2002, Science.

[13]  J. Cooper,et al.  Multipoint holographic optical velocimetry in microfluidic systems. , 2006 .

[14]  Miles J. Padgett,et al.  IV The Orbital Angular Momentum of Light , 1999 .

[15]  Johannes Courtial,et al.  Assembly of 3-dimensional structures using programmable holographic optical tweezers. , 2004, Optics express.

[16]  H. Rubinsztein-Dunlop,et al.  Optical alignment and spinning of laser-trapped microscopic particles , 1998, Nature.

[17]  Mattias Goksör,et al.  Creating permanent 3D arrangements of isolated cells using holographic optical tweezers. , 2005, Lab on a chip.

[18]  Kenneth J. Weible,et al.  Rectangular channels for lab-on-a-chip applications , 2003 .