Controlling the force and the position of acoustic traps with a tunable acoustofluic chip: application to spheroid manipulations
Résumé
In this study, we present a multi-node acoustofluidic chip working over a large range of frequencies. This approach opens the path to a multitude of acoustophoretic manipulations including the accurate control of the force applied onto cells and cell spheroids, but also the ability to move the levitation nodal planes, the merging and the assembly of spheroids. The design of a transparent cavity and the use of a broadband ultrasonic transducer allow the characterization of the acoustic energy and the comparison with a simple 1D model. The acoustic properties of the system were first estimated through the effects of the acoustic radiation force (ARF) on suspension of particles. From the particles velocities induced by the ARF, measured by Particle Image Velocimetry (PIV), we deduce the acoustic energy over a large frequency range. The automation of the setup allowed the acquisition of a large amount of data with the possibility to make parametric and statistic studies. The results show a wide continuous operating range for the acoustic radiation forces. We also show that it is possible to apply a constant amplitude for the ARF even while changing the acoustic frequency. This approach is applied on human Mesenchymal Stem Cells (hMSCs). We show that it is possible to create large hMSC spheroids on each acoustic node, as demonstrated recently in [Jeger-Madiot et al., Scientific Reports, 2021, 11, 8355 ], before moving and merging them while maintained in acoustic levitation.
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