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Capillary flow in sacrificially etched nanochannels
Mark N Hamblin1, Aaron R Hawkins, Dallin Murray
1Department of Electrical and Computer Engineering, Brigham Young University, Provo, Utah 84602, USA.
Biomicrofluidics
|July 21, 2011
Summary
Nanochannel filling is slower than predicted by classical theory. The dynamic contact angle increases significantly in smaller channels, deviating from macroscopic measurements.
Area of Science:
- Materials Science
- Fluid Dynamics
- Nanotechnology
Background:
- Classical continuum theory, like the Washburn equation, describes fluid filling in porous media.
- Understanding fluid behavior at the nanoscale is crucial for developing advanced materials and devices.
Purpose of the Study:
- To investigate transient fluid filling in planar nanochannels.
- To compare experimental results with the Washburn equation and analyze deviations.
Main Methods:
- Fabrication of planar nanochannels using sacrificial etching with aluminum, chromium, and germanium cores.
- Measurement of transient filling via capillary action in nanochannels with heights from 18 to 98 nm.
- Comparison of experimental filling speeds with predictions from the Washburn equation.
Main Results:
- Experimental filling speeds were significantly lower than predicted by the Washburn equation.
- A varying dynamic contact angle was observed, reaching up to 83° in 18 nm channels.
- The dynamic contact angle increased with decreasing channel dimensions, deviating notably from macroscopic values.
Conclusions:
- Classical continuum theory inadequately describes fluid filling in nanoscale channels.
- Dynamic contact angle is a critical parameter that varies with channel size at the nanoscale.
- Further theoretical and experimental studies are needed to accurately model nanoscale fluid transport.
