Prototype dispenser photocathode: Demonstration and comparison to theory
A method to significantly extend the operational lifetime of alkali-based photocathodes by diffusing cesium to the surface at moderate temperature is presented and shown to restore the quantum efficie...
A method to significantly extend the operational lifetime of alkali-based photocathodes by diffusing cesium to the surface at moderate temperature is presented and shown to restore the quantum efficie...
Microcantilever mechanics in flowing viscous fluids
Microcantilevers are often deployed in flowing fluids to measure local flow velocities or to detect rapidly the nanomechanical binding of trace quantities of target analytes. The authors investigate t...
Microcantilevers are often deployed in flowing fluids to measure local flow velocities or to detect rapidly the nanomechanical binding of trace quantities of target analytes. The authors investigate t...
Scaling of interface displacement in a microfluidic comparator
Appl. Phys. Lett. 90, 114109 (2007); doi:10.1063/1.2713800
Published 15 March 2007
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The authors quantify both experimentally and theoretically the scaling behavior between interface displacement and excess pressure drop in a microfluidic comparator. Unlike previous studies, the authors measure the interface displacement in the outlet channel of the comparator that yields a unique power-law scaling. For an outlet channel width to depth ratio r=3, the authors experimentally determine the scaling exponent to be 0.60±0.01, which is in excellent agreement with theory. In general, the authors find the scaling exponent to increase from 0.51 for square channels (r=1) to 0.93 for very wide channels (r>100). This geometry dependent scaling exponent offers greater sensitivity and flexibility in measurement of hydrodynamic resistance of soft objects.
©2007 American Institute of Physics
| History: | Received 20 November 2006; accepted 10 February 2007; published 15 March 2007 |
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http://link.aip.org/link/?APPLAB/90/114109/1 |
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REFERENCES (17)
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- For each channel aspect ratio,
was determined by fitting a power law to the numerically generated data of 
Y/W vs P/Pi in the range 0.01
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- We estimate the diffusion-limited Y as
, where D is the diffusion coefficient of the dye and
is the residence time. In our experiments, D![[approximate]](http://scitation.aip.org/stockgif3/ap.gif)
10−9 m2/s and 0.01 s, which gives Y4.5 µm and is comparable to the smallest measurable Y of 5.4 µm. - The hydrostatic head at the inlet of the reference channel was fixed at 548.8 mm and the pressure in the test channel varied until backflow was observed. The pressure for backflow was found to be 172.5±10.7 mm yielding P/Pi=2.2–2.4. The minor deviation from theory is due to rapid smearing of the interface during backflow.
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