The marching velocity of the capillary meniscus in a microchannel
In this paper we describe an experimental method and an analytical model for characterizing the surface energy inside a microchannel of micrometer size by measuring the marching velocity or position of a capillary meniscus. This method is based on the fact that the force summation of the meniscus surface tension and the filling reservoir gravitation might produce a pressure to pull liquid into the channel, and the marching velocity or the instantaneous position of the meniscus is related to the surface energy. Both parylene and silicon-nitride microchannels with different surface conditions were fabricated to perform the fill-in experiments subject to different liquids. It is shown that our model agrees well with the experimental data and is a valid method.
Additional Information© Institute of Physics and IOP Publishing Limited 2004. Received 19 March 2003, in final form 27 August 2003. Published 17 November 2003. Print publication: Issue 2 (February 2004). The authors want to thank Mr Ken Walsh, Dr Xing Yang and Dr Yong Xu of Caltech Micromachining Laboratory for technical support. Help from Mr Yu-Lin Huang, Mr Jiun-Min Wang, Miss Hung-Yin Chen, Mr Shin-Shong Wang and Mr Po-Chiang Yang of Tamkang University is also highly appreciated. This project is financially supported by the NSF Engineering Research Center for Neuromorphic Systems Engineering (CNSE) at Caltech and the National Science Council of Taiwan ROC with the project number of NSC-89-2217-E-032-001.
Published - YANjmm04.pdf