Late-Stage Zebrafish Embryo Manipulation and Imaging with Acoustic Tweezers Based on Bessel Beam Trapping

This paper presents trapping, manipulation, and imaging of late-stage zebrafish embryo under Light Sheet Microscope™ with an underwater acoustic tweezers, in a completely-liquid environment (for the first time) without any embryo-growth-limiting gel (such as agarose) commonly required to suspend the embryo. This new method of trapping can provide a more favorable optical environment for imaging compared to gel. Trapping and manipulating a large living organism in liquid require acoustic wavelength comparable to particle size, and thus a tweezers which operates at a low frequency of 524 kHz has been designed and fabricated. As the waves are reflected from the liquid-air and liquid-solid interfaces, low acoustic loss at such a low frequency induces significant standing waves within the liquid, which turn out to prevent accurate tweezing. Precise and stable acoustic manipulation of zebrafish embryo within the limited space under the microscope is obtained through integrating acoustic absorbers (with openings to allow light to pass through) at the reflection-inducing interfaces in the microscope.