Microfluidic sorting, concentration and patterning with Surface Acoustic Waves

Lab-on-a-chip microfluidic systems hold substantial promise for a wide range of diagnostic and therapeutic applications. By shrinking down conventional laboratory processes and replicating their functions on-chip, the size, cost, required time, and amount of reagent and sample needed can be drastically reduced. However, because these devices operate at length scales orders of magnitude smaller than conventional fluid processes different physical phenomena become dominant, meaning new forces and techniques must be developed to perform them. Acoustic forces have the potential to be useful at small length scales, where a developing technology relying on the application of surface acoustic waves (SAW) is especially promising due to the high frequencies (~0.01-1GHz) and small wavelengths (~1-100 µm) that can be generated. In the studies presented here, the use of SAW is demonstrated for individual droplet production in two-phase systems, the deterministic sorting of particles with fractional differences in size, the active concentration and release of particles and the creation of 2D cell/particle array patterns.