Optimizing the quality of acoustophoretic separation by the in-flow mobility-ratio method

Achieving good acoustic particle or cell separation performance requires skilled operators, who must carefully fine-tune the input parameters (actuation voltages, flow rates, and flow split ratios). Often the fine-tuning is done by time-consuming parameter sweeps, which are tedious and expensive. Here, we present a straightforward model-based approach to determining input parameters that yield optimal separation performance. The optimal parameters are a function of the device performance, the material properties of the separation species (compressibility, density, size), and the properties of the buffer (compressibility and density). The device performance is assessed by a calibration step, while the material properties are combined into the mobility ratio and measured by the in-flow mobility-ratio method, which is introduced in this work. The optimal separation settings are validated by separating green fluorescent 7.8-μm particles from red fluorescent 4.9-μm particles.