Acoustophoresis in polymer-based microfluidic devices: Modeling and experimental validation

A finite-element model is presented for numerical simulation in three dimensions of acoustophoresis of suspended microparticles in a microchannel embedded in a polymer chip and driven by an attached piezoelectric transducer at MHz frequencies. In accordance with the recently introduced principle of whole-system ultrasound resonances, an optimal resonance mode is identified that is related to an acoustic resonance of the combined transducer-chip-channel system and not to the conventional pressure half-wave resonance of the microchannel. The acoustophoretic action in the microchannel is of comparable quality and strength to conventional silicon-glass or pure glass devices. The numerical predictions are validated by acoustic focusing experiments on 5-mu m-diameter polystyrene particles suspended inside a microchannel, which was milled into a polymethylmethacrylate chip. The system was driven anti-symmetrically by a piezoelectric transducer, driven by a 30-V peak-to-peak alternating voltage in the range from 0.5 to 2.5MHz, leading to acoustic energy densities of 13 J/m(3) and particle focusing times of 6.6s.

Automated summary

The study introduces a finite-element model for simulating acoustic focusing of microparticles in a microchannel embedded in a polymer chip and driven by a piezoelectric transducer. The optimal resonance mode identified is related to an acoustic resonance of the combined system, rather than the conventional pressure half-wave resonance of the microchannel. Experimental results validate the numerical predictions, demonstrating comparable quality and strength to traditional silicon-glass or pure glass devices.