Acoustofluidic separation: impact of microfluidic system design and of sample properties

We describe the results of a numerical study about the separation of fluid-suspended microsamples (as microbeads and cells) by acoustophoresis. A microfluidic channel with rectangular cross section is considered, and we investigate the impact on particle separation of many different parameters, dividing them in two groups: sample’s intrinsic factors (own properties of the sample) and extrinsic factors (related to the microfluidic system design and operation). Differently from what is usually done, we include in our study the impact of the initial sample position, which always has a certain variability in real experiments, and we introduce several new parameters allowing to assess system performance and to optimize the microchip separation efficiency. The obtained results show the importance of two design parameters that are generally overlooked: the channel width and the offset between the channel border and the input of the target samples in the microchannel. Additionally, the analysis method we describe and the new parameters we introduce to study the system can be beneficially used in almost any study of acoustophoretic-based separation system.