This invention provides a solution to the problem of controlling fluid flow in micro/nanofluidic circuits on chips, and specifically for chemical, biochemical and optofluidic applications. Fluid motion is controlled when entering, propagating and exiting the channel circuit by an original and very effective pumping system based on surface-acoustic-waves (SAW) generated by interdigitated electrode transducers (IDTs) on a piezoelectric substrate, e.g. lithium niobate, to which the fluidic circuit is bonded.

The fluid is pumped by the pressure gradient induced by the SAW (of suitable wavelength compared to the channel cross section) in a direction opposite to its propagation direction, and is immediately stopped when the SAW is turned off (valve effect) if the channel material is hydrophobic. A single transducer is sufficient to control motion in the whole circuit, while combining a plurality of IDTs allows mixing, splitting or routing operations on the fluid in complex circuits, as sketched in the figure.

The fluid circuit can be preferably manufactured in polydimethylsiloxane PDMS by a low cost replica molding technique, and bonded (reversibly or permanently) to the piezoelectric substrate, which can be coated by a thin film with convenient biochemical properties. This allows independent choice and optimization of the piezoelectric micropump and of the microfluidic circuit according to specific requirements for a wide range of applications.
Patent Application No. PCT/IB2008/052925

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