Facile microfluidic channels for acoustophoresis on a budget

Acoustophoresis is a powerful yet gentle technique for manipulating cells and particles that has quickly earned a place in the lab-on-a-chip toolkit. However, traditional construction techniques for acoustophoretic resonators have typically required prohibitively expensive and laborious processing methods. Here, we propose a highly cost-effective and cleanroom-free construction technique for transversal acoustophoretic resonators. Channels with two different widths of 750 and 300 μm were constructed using a simple glass and polyimide sandwiching technique. Half and full wavelength resonators were then established using 1 and 5 MHz ultrasound respectively and polystyrene beads were successfully manipulated in both types of resonators. This construction technique was then utilized to demonstrate a bifurcation and trifurcation microchannel with 600 μm widths and 2.5 MHz ultrasound. Our approach addresses some of the key drawbacks of acoustophoretic devices by drastically simplifying the fabrication and prototyping of transversal resonators and will assist in expanding this technology from laboratory benches and into the broader market.