Static and dynamic behaviour of gas bubbles in T-shaped non-clogging micro-channels |
| |
Authors: | C Litterst T Metz R Zengerle P Koltay |
| |
Affiliation: | (1) Laboratory for MEMS Applications, Department of Microsystems Engineering (IMTEK), University of Freiburg, Georges-Koehler-Allee 106, 79110 Freiburg, Germany |
| |
Abstract: | Preventing micro-channels from clogging is a major issue in most micro and nanofluidic systems (Gravesen et al., J Micromech
Microeng 3(4):168–182, 1993; Jensen et al., In: Proc. of MicroTAS 2002, Nara, Japan, pp 733–735, 2002; Wong et al., J Fluid Mech 292:71–94, 1995). The T-shaped channel first reported by Kohnle et al. (In: IEEE MEMS, the 15th international IEEE micro electro mechanical
conference (ed), Las Vegas, pp 77–80, 2002) prevents micro-channels from clogging by the aid of the equilibrium bubble position in such a geometry. This work is concerned
with the static and dynamic behaviour of bubbles in such T-shaped micro-channels. The aspect ratio of a rectangle enclosing
the T-shaped channel and the contact angle of the walls are the main parameters influencing the static and dynamic bubble
behaviour. It is investigated in this article how these parameters relate to the equilibrium bubble shape and how optimum
bubble velocities can be achieved inside the channel. An analytical model depending on the contact angle and the channel geometry
is presented that allows to determine the bubble configuration inside the channel by minimizing the bubble’s surface energy.
A second model is derived to predict the velocity of gas bubbles driven by buoyancy in vertical T-shaped channels. The model
is applied to design T-shaped channels with a maximum mobility of gas bubbles. Experiments with MEMS fabricated devices and
CFD simulations are used to verify the models. Furthermore design rules for an optimum non-clogging channel geometry which
provides the highest gas bubble mobility are given. |
| |
Keywords: | Gas bubble Micro-channel Clogging Interfacial energy |
本文献已被 SpringerLink 等数据库收录! |
|