Extraction and manipulation of hydrocarbon droplets by ultrasound radiation

Abstract

Acoustic tweezers are a method of using sound radiation forces to trap and manipulate objects. Previously, we demonstrated an acoustic tweezer capable of first creating the objects, droplets of CCl4 from a reservoir, before trapping and manipulating them. We achieved this using a single transducer whose field was modified by a low-profile fraxicon (Fresnel axicon) lens exhibiting specific near-field trapping zones and far-field Bessel beam behavior which enable the trapping process. Here, we extend the method to include another class of fluids, complex hydrocarbons, using conventional SAE30 motor oil in water. Furthermore, with the higher power levels used in this study we demonstrate the discovery of a second trapping region in the field generated by our transducer. The non-contact extraction and manipulation of organic and hydrocarbon fluid samples could have significant biological and environmental applications where a container would contaminate, destroy, or otherwise change the samples under investigation.