Bruus H. – TechConnect Briefs

Capillary filling speed in silicon dioxide nano-channels

Jarlgaard S.E., Mikkelsen M.B.L., Skafte-Pedersen P., Bruus H., Kristensen A., Technical University of Denmark, DK

We present a simple silicon-based fabrication technique for nanocapillaries based on controlled growth of silicon-dioxide, UV lithography, etching with etch-stop, and glass wafer bonding. Our approach improves state-of-the-art with respect to the obtained cross-wafer homogeneity [...]

On the Motion of a Bubble through Microchannel Contractions

Chio H., Jensen M.J., Wang X., Bruus H., Attinger D., Columbia University, US

We present the first transient pressure measurements and high-speed visualizations of a gas bubble passing through liquid-filled microchannel contractions. Results are compared with a simple theoretical model taking into account the Young-Laplace pressure drop, the [...]

Applications of Topology Optimization in the Design of Micro- and Nanofluidic Systems

Okkels F., Olesen L.H., Bruus H., Technical University of Denmark, DK

The material distribution method in topology optimization was developed in the late 1980ies for stiffness design of mechanical structures, and only recently the first steps have been taken towards implementing the method in fluidics. Topology [...]

Clogging Pressures of Bubbles in Microchannel Contractions: Theory and Experiments

Jensen M.J., Wang X., Attinger D., Bruus H., Mikroelektronik Centret, DTU, DK

We present a theoretical, numerical, and experimental study of bubbles passing through a microchannel contraction. A certain pressure, the so-called clogging pressure, is needed to push a bubble through a microchannel contraction. We present the [...]

Quasi-static Motion of Bubbles in Microchannel Contractions

Jensen M.J., Goranovic G., Bruus H., Technical University of Denmark, DK

We present a thorough theoretical and computational study of bubble dynamics in icrofluidic channels with contractions. We investigate the effects of geometry and surface physics (friction and contact angle) on the behavior of incompressible bubbles, [...]

Electroosmotic Pumping of Nonconducting Liquids by Viscous Drag from a Secondary Conducting Liquid

Brask A., Goranovic G., Bruus H., Technical University of Denmark, DK

A novel electroosmotic pump design relying on two-liquid viscous drag to pump nonconducting liquids is presented and analyzed theoretically. A conducting pumping liquid driven by electroosmotic flow (EOF) drags a nonconducting working liquid by viscous [...]