A novel system for measuring liquid flow rates with nanoliter per minute resolution
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An experimental system for liquid flow-rate measurements of pressure-driven flow through microchannels is described. The displacement of a meniscus is tracked in a precision borehole using a laser distance meter mounted on a feed-back controlled traversing stage. Successful measurements of flow rates as small as 30 pl/s are reported when using non-evaporative hexadecane, and evaporative fluids such as ethanol are measured at flow rates of 0.1 nl/s. The set-up can also be used for measurements in time-dependent flows. Finally, a discussion of the influence of dissolved nitrogen on the measured flow rates is given.
KeywordsPressure Drop Hexadecane Channel Height Test Fluid Measure Flow Rate
This work was supported by DARPA. The authors wish to thank Zhiqiang Cao for the numerical estimates of the channel entrance effects. Peter Huang and Professors Bruce Caswell, Peter D. Richardson, Merwin Sibulkin and Tayhas Palmore are acknowledged for valuable suggestions during the project.
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