Acoustically driven programmable liquid motion using resonance cavities

Abstract

Performance and utility of microfluidic systems are often overshadowed by the difficulties and costs associated with operation and control. As a step toward the development of a more efficient platform for microfluidic control, we present a distributed pressure generation scheme whereby independently tunable pressure sources can be simultaneously controlled by using a single acoustic source. We demonstrate how this scheme can be used to perform precise droplet positioning as well as merging, splitting, and sorting within open microfluidic networks. We further show how this scheme can be implemented for control of continuous-flow systems, specifically for generation of acoustically tunable liquid gradients. Device operation hinges on a resonance-decoding and rectification mechanism by which the frequency content in a composite acoustic input is decomposed into multiple independently buffered output pressures.

Microscale acoustofluidics: Microfluidics driven via acoustics and ultrasonics

“…The possible applications for acoustic pumping technology extend into medical applications, for example, the insulin pump reported by Ma et al (2006), where the PZT was used in a Helmholtz cavity arrangement to deliver insulin into a silicon patch with surface machined hollow microneedles designed to painlessly puncture the skin. By applying this idea at far lower frequencies, well into the audible range at around 100 Hz, but in a set of resonance cavities external to the microfluidics device, each holding fluids to be delivered, Langelier et al (2009) were able to selectively pump these fluids through the device as shown in Fig. 11.…”

Magnetic Artificial Cilia for Microfluidic Propulsion

“…The fluid propulsion in microfluidic systems is performed using three different approaches: (i) mechanical methods -such as external syringe pumps, peristaltic pumps [74,64,30,86,58,31] and membrane pumps, (ii) using the electrokinetic properties of the fluids -such as in electro-osmotic pumps [97,67] and magnetohydrodynamic pumps [63,37,42,93] -and (iii) acoustic methods [60,73,96,95]. These fluid propulsion mechanisms have been developed only in recent years.…”

Chapter 24. Using Microfluidics, Real-time Imaging and Mathematical Modelling to study GPCR Signalling

“…The most common pumping methods employed in microfluidics are gravity-driven and syringe-mediated pumping, of which the latter is more reliable. More elaborate pumping systems include 'Quake valves', 32 Braille actuation, 33,34 acoustics, 35 and most recently autonomous pumping regulation by embedded components. 36 The reproducibility and versatility of generation of temporal patterns is in large part determined by the pumping mechanisms implemented for conveying fluids through the microfluidic channels.…”