WP1 – Acoustically Packed Blood:
This work package focused on understanding the behavior of blood under acoustic forces. Experiments on acoustically packed red blood cells revealed distinct streaming patterns, with four rolls forming inside the packed RBC bed and four additional rolls in the surrounding plasma. Neighboring rolls rotated in the same direction, likely due to viscosity contrasts, and RBC streaming was slower and flatter than plasma streaming. These observations provide fundamental insight into the physics of dense cell suspensions under acoustic fields, forming the basis for later work on single-cell behavior and separation. We demonstrated that the effect can be applied to cell separation of rare cells in a flow-through configuration. These results have been published in Analytical Chemistry, highlighting both mechanistic understanding and practical applications of this phenomenon.
WP2 – Single-Cell Measurements and Cell Separation:
In this work package we developed novel methods for quantitative characterization of individual cells and exploited these properties for cell separation. A key achievement was a technique to measure the density of single cells, linking mechanical cell properties to their response in acoustic fields. Using this knowledge, several studies demonstrated label-free acoustic separation of blood cells and other cell types, including peripheral blood mononuclear cells and circulating tumor cells. These results have been published in Physical Review Applied, Scientific Reports, and Analytical Chemistry, highlighting both mechanistic understanding and practical applications in cell sorting and enrichment.
WP3 – Thermoacoustic Streaming:
In this work package we explored the interplay between acoustic and thermal fields in microfluidic channels. By using laser-induced local temperature gradients, experiments demonstrated configurable microscale streaming, with velocities far exceeding conventional acoustic streaming. The relative orientation of sound and thermal fields was critical: perpendicular configurations increased streaming velocities over 100-fold compared to parallel ones, due to directional differences in the induced body force. Time-resolved studies quantified the build-up and decay of streaming flows, and observations were in qualitative agreement with finite-element simulations. These insights are foundational for precise microfluidic manipulation using thermoacoustic effects and have been published in Physical Review Letters, Physical Review Applied, and Physical Review E.
Dissemination and exploitation: The results have been published in journal papers and presented at Acoustofluidics 2021-2024 and MicroTAS 2023. Beyond fundamental understanding, the project outcomes provide a strong basis for developing acoustofluidic devices for rare-cell isolation, label-free cell sorting, and programmable microfluidic manipulation.
