Armando R. Tovar

Microfluidic Air-Liquid Cavity Acoustic Transducers for On-Chip Integration of Sample Preparation and Sample Detection

A simple low-cost yet versatile microtechnology platform is demonstrated as capable of performing a variety of microfluidic actuation functions including on-chip pumping, mixing, cell/particle sorting, and sample extraction. This technology termed air-liquid cavity acoustic transducers (ALCATs) uses trapped air bubbles as the functional elements. When an external acoustic energy source is applied to the device, the trapped bubbles oscillate, generating acoustic streaming within the fluid. By controlling their relative position and angle with the liquid channel/chamber, the ALCAT can push away or pull in the surrounding liquid contents and its contained particulates. In this report, we provide a general introduction of the ALCAT microtechnology platform and its application to enhancing biomolecular assays.

Acoustic cavity transducers for the manipulation of cells and biomolecules

A novel fluidic actuator that is simple to fabricate, integrate, and operate is demonstrated for use within microfluidic systems. The actuator is designed around the use of trapped air bubbles in lateral cavities and the resultant acoustic streaming generated from an outside acoustic energy source. The orientation of the lateral cavities to the main microchannel is used to control the bulk fluid motion within the device. The first order flow generated by the oscillating bubble is used to develop a pumping platform that is capable of driving fluid within a chip. This pump is integrated into a recirculation immunoassay device for enhanced biomolecule binding through fluid flow for convection limited transport. The recirculation system showed an increase in binding site concentration when compared with traditional passive and flow-through methods. The acoustic cavity transducer has also been demonstrated for application in particle switching. Bursts of acoustic energy are used to generate a second order streaming pattern near the cavity interface to drive particles away or towards the cavity. The use of this switching mechanism is being extended to the application of sorting cells and other particles within a microfluidic system.