Intense cavitation in microfluidics for bio-technology applications

Abstract

This study reports the use of intense ultrasonic cavitation in the confinement of a microfluidics channel [1], and the applications that has been developed for the past 4 years [2]–[5]. The cavitation bubbles are created at the gas-water interface due to strong capillary waves which are generated when the system is driven at its natural frequency (around 100 kHz) [1]. These bubbles oscillate and collapse within the channel. The bubbles are useful for sonochemistry and the generation of sonoluminescence [2]. When we add bacteria (Escherichia coli), and yeasts (Pichia pastoris) into the microfluidics channels, the oscillating and collapsing bubbles stretch and lyse these cells [3]. In another application, human red blood cells are added to a microchamber. Cell stretching and rapture are observed when a laser generated cavitation bubble expands and collapses next to the cell [4]. A numerical model of a liquid pocket surrounded by a membrane with surface tension which was placed next to an oscillating bubble was developed using the Boundary Element Method. Lastly, new results on gene transfection [5], lysing of bacterial spores, and emulsification by ultrasonic bubbles will be presented.