CAREER: Investigation of bubble dynamics in microscale geometries, with applications in bioengineering and microfluidics

Suny At Stony Brook, Stony Brook NY

Investigators

Abstract

ABSTRACT 0449269 Investigation of bubble dynamics in microscale geometries, with applications in bioengineering and microfluidics Dynamics phenomena involving microbubbles are aesthetic, complex, and important in industrial applications such as bubble-jet printing. If the dynamics of a bubble in an unbounded liquid is well understood, a lot a basic scientific work needs to be done to understand the dynamics of a bubble in contact with a solid surface, in a bounded microscale geometry. This problem of fundamental and practical interest will be addressed through two research initiatives. The first initiative concerns the dynamic motion of a bubble in a microchannel. The channel geometry, and the dynamic wetting at the gas-liquid-wall interface, control the pressure needed to move the bubble in the channel. This issue is critical in microfluidics devices, where bubbles can clog microchannels with narrow restrictions. This problem will be studied theoretically and experimentally with a MEMS-based setup and high-speed visualization. The second initiative studies how a microbubble attached to a solid surface reacts to ultrasound. Recent investigations have shown that ultrasound drives bubbles oscillations, which produce a tiny, donut-shape vortex in the vicinity of the bubble, a phenomenon called microstreaming. Our theoretical and experimental research will involve simulations of microstreaming in the presence of solid boundaries and Particle-Image-Velocimetry (PIV). This microstreaming field and the associated shear stress will be used to deform biological cells and bring drugs through their membranes, as well as to build a microengine. A general-purpose micro- PIV system will be acquired for this research, with a camera that also allows high-speed imaging. The intellectual merit is the development of a science base for the dynamic behavior of microbubbles in contact with a solid geometry. This first study on the motion of a bubble in a microchannel will be supported on the theoretical side by a collaboration with Henrik Bruus.s research group in Denmark, and on the experimental side (nanocoatings) with Oleg Gang, from the Center for Functional Nanomaterials at Brookhaven National Laboratory. Significant advances are expected on the understanding of the motion of the wetting angle, its hysteresis and relaxation time scale. Our second study will investigate how microstreaming depends on the bubble wetting angle and the nearby solid surfaces. Theoretical and experimental investigations will be performed, involving (for the theoretical side) coupled solid-fluid interactions acoustic calculations, simulations of acoustic microstreaming in the presence of solid boundaries, and (for the experimental side) high-speed visualization together with micro Particle Image Velocimetry. This second study involve collaboration with Dr. Citovski.s biology group at Stony Brook, as well as Dr. Moraga from the Center for Multiphase Research at Rensselaer Polytechnic Institute. The broader impact will be the development in collaborations with Seyonic SA and Micronics Inc- of more reliable microfluidic devices, solving the issue of undesired bubbles through self-cleaning channel geometries or bubble traps. Also, novel ways to interact with biological cells through microstreaming will be investigated, with the development of a novel sonoporation device to control drug transfection through cell membranes and manipulate them. The microstreaming flow field will also be used to power a novel type of microengine that fits in a human hair, to be developed in collaboration with Oleg Gang, from the Center for Functional Nanomaterials at Brookhaven National Laboratory. Finally, we are convinced that visualization of bubble-related phenomena provide an attractive path from everyday experience to current scientific challenges involving micro- and nanoscale phenomena. This will be used to interest local high school and elementary school students from the Bronx to engineering, and to generate interest for research in the Stony Brook student community.