Lens-Less Acoustic Tweezers Based on Spiral-Arm Vortex-Beam Transducers Capable of Levitating, Trapping, and Manipulating Large and Heavy Particles

This paper presents the lens-less acoustic tweezers (18 × 18 × 1 mm
³
in size) based on a spiral-arm vortex-beam acoustic transducer (SVAT) capable of trapping large and heavy particles. Moreover, the tweezers is shown to levitate a particle (with a levitation force of up to 21.3μN) from the tweezers’ surface and trap the particle at a distance determined by the voltage applied to the tweezers. By changing the amplitude of the applied sinusoidal voltage, the tweezers is shown to selectively trap particles of various sizes and densities as well as to change the z-position of the trapped particle. Also, the trapped particle can be (1) manipulated in a 3-dimensional (3D) space by moving the tweezers and (2) pushed to the liquid-air interface by increasing the applied voltage.