Comunicazione
Optical calibration of standing wave acoustic levitator.
Marrara S., Ferretti S., Bronte Ciriza D., Magazzù A., Caruso R., Saija R., Foti A., Gucciardi P.G., Musolino A., Folco L., Della Corte V., Rotundi A., Mandanici A., Maragò O.M., Donato M.G.
Acoustic levitation uses the forces arising from acoustic radiation pressure to counteract gravity and suspend both solid and liquid objects in the air. In this work, we use a standing acoustic wave levitator to trap multiple particles in the nodes of the acoustic wave. The calibration of the trapping forces is done by video microscopy, tracking the particle position fluctuations. Power spectra of the tracking signals can be used to calculate the spring constants. After the calibration using spherical particles and liquid drops, we present the results obtained by acoustically levitating sub-millimetric particles of extraterrestrial origin ($i.e.$, micrometeorite) and cometary dust analogues. The contactless manipulation shows the usefulness of acoustic tweezers for sample-return missions, for which contamination of the samples is still a key problem. The agreement between Agenzia Spaziale Italiana (ASI) and Istituto Nazionale di Astrofisica (INAF) n. 2018-16-HH.0, project "SPACE Tweezers" is acknowledged. This work has been also partially funded by European Union (NextGeneration EU), through the MUR-PNRR project SAMOTHRACE (ECS00000022) and PNRR MUR project PE0000023-NQSTI.