A One-Sided Acoustic Trap for Cell Immobilization Using 30-MHz Array Transducer.

Biological studies often involve the investigation of immobilized (or trapped) particles and cells. Various trapping methods without touching, such as optical, magnetic, and acoustic tweezers, have been developed to trap small particles. Here, we present the manipulation of a single cell or multiple cells using ultrasound-array-based single-beam acoustic tweezers (UA-SBATs). In SBATs, only a one-sided tightly focused acoustic beam produces a high acoustic gradient force-a mechanism that mirrors that of optical tweezers. As a result, targeted cells can be attracted to the beam center and immobilized within its trapping zone. Since an array transducer allows acoustic beam steering and scanning electronically instead of mechanical translation, it can manipulate cells more simply and quickly compared with single-element transducers, especially in biocompatible setup. In this experiment, a customized 30-MHz array transducer with an interdigitally bonded (IB) 2-2 piezocomposite was employed to immobilize MCF-12F cells. Cells were attracted to the center of the beam and laterally displaced with the array transducer without any damages to the cells. These findings suggest that UA-SBAT can be a promising tool for cell manipulation and may pave the way for exploring new biological applications.