Bulk Acoustic Wave Based Mocrfluidic Particle Sorting with Capacitive Micromachined Ultrasonic Transducers

Abstract

The main limitation of acoustic particle separation for microfluidic application is its low sorting efficiency. This is due to the weak coupling of surface acoustic waves (SAWs) into the microchannel. In this work, we demonstrate bulk acoustic wave (BAW) particle sorting using capacitive micromachined ultrasonic transducers (CMUTs) for the first time.A collapsed mode CMUT was driven in air to generate acoustic pressure within the silicon substrate in the in-plane direction of the silicon die. This acoustic pressure was coupled into a water droplet, positioned at the side of the CMUT die, and measured with an optical hydrophone. By using a beam steering approach, the ultrasound generated from 32 CMUT elements were added in-phase to generate a maximum peak-to-peak pressure of 0.9 MPa. Using this pressure, 10 µm latex beads were sorted almost instantaneously.

Measuring and Simulating the Transient Packing Density During Ultrasound Directed Self‐Assembly and Vat Polymerization Manufacturing of Engineered Materials

“…Ultrasound-directed self-assembly (DSA) uses the acoustic radiation force associated with a standing ultrasound wave field to organize and orient spherical [1] or high aspect ratio particles [2] dispersed in a fluid medium into specific patterns. It finds application in a broad spectrum of engineering applications, such DOI: 10.1002/admt.202301950 as noncontact manipulation of particles and objects for precise handling or quality control, [3][4][5] levitated displays, [6][7][8] and organizing [9][10][11] and separating particles and cells, e.g., in lab-on-a-chip devices. [12][13][14] Ultrasound DSA is also useful to manufacture engineered composite materials with tailored properties.…”