Acoustic microstreaming for biological sample mixing enhancement

Abstract

A mixing technique based on bubble-induced acoustic microstreaming principle was developed. A mixer consists of a piezoelectric disk that is attached to a reaction chamber, which has a set of air bubbles with desirable size trapped in the solution. Fluidic experiments showed that air bubbles resting on a solid surface and set into vibration by the sound field generated circulatory flows, resulting in global convection flows and thus rapid mixing. The time to fully mix a 100 chamber is significantly reduced from hours (diffusiononly) to tens of seconds. CFD modeling showed that the induced flowfield and thus degree of mixing strongly depends on bubble positions. Immuno-magnetic cell capture experiments showed acoustic microstreaming provided efficient mixing of bacterial cell (E. coli K12) matrix suspendedin blood with magnetic capture beads, resulting highly effective immuno-magnetic cell capture. Bacterial viability assay experiments showed that acoustic microstreaming has a relatively low shear strain field since the blood cells and bacteria remained intact after mixing. Acoustic microstreaming has many advantages over most existing chamber micromixing techniques, including simple apparatus, ease of implementation, low power consumption (2 mW), and low cost.

Optimization of a Microfluidic Mixing Process for Gene Expression–Based Bio-Dosimetry

“…Gene expression-based biosignatures (Paul S. and S.A. Amundson, 2008) were identified and an enzymatic assay was developed to provide rapid detection of biological exposure to low dose radiations. The quantitative Nuclease Protection (qNPA) chemistry (Martel, R., Botros, I., Rounseville, M., et al, 2002) was developed to be integrated into a microfluidic platform (Liu, R. H., Lenigk, R., Grodzinski, P., 2003) for enhancing its reaction kinetics by using several mixing steps for efficient nucleic acid hybridization (Liu, R. H., Yang, J., Pindera, M. Z., Athavale, M., Grodzinski, P., 2002). The development of a fully integrated microfluidic system suitable for automating all the laboratory operations necessary to perform the qNPA measurement requires great control of small volume of fluids in a series of microfluidic components.…”

A fast passive and planar liquid sample micromixer

“…1 More specifically, fast and efficient mixing of small volumes of reactants is important in areas such as DNA hybridization, cell activation, enzyme reactions, chemical synthesis and protein folding. 2 For example, the key steps in chemical synthesis include mixing, heating, and cooling. In large reaction vessels, mixing often creates large concentration gradients resulting in formation of byproducts, which lead to overheated areas (i.e.…”