Acoustic Tweezers Based on Linear Fresnel Lens with Air Cavities for Large Volume Particle Trapping

This paper reports a novel acoustic tweezers with multi-foci linear Fresnel lens that was designed to create a large Bessel beam zone for contactless, non-invasive object trapping in liquid. The tweezers was built on a 1-mm-thick lead zirconate titanate (PZT) substrate with rectangular air-cavity Fresnel lens having multiple focal lengths. With 25 Vpp continuous 2.32 MHz sinusoidal drive, the acoustic tweezers is capable of trapping a silicon chip of $5.30\times 0.67\times 0.51\ \text{mm}^{3}$ in size and 3.98 mg in mass along with two $500-\mu\mathrm{m}$-diameter Polyethylene microspheres.