Salipante, P.
, Kuei, S.
and Hudson, S.
(2022),
A small-volume microcapillary rheometer, Rheologica Acta, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=931127
(Accessed January 19, 2026)
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A small-volume microcapillary rheometer
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Abstract
We demonstrate a capillary device used to measure the shear rate dependent viscosity of microliter scale volumes. Liquid samples are driven pneumatically to fill a microcapillary and partially fill a larger glass capillary. The glass capillary is mounted on an optical linear sensor array to track the air-liquid meniscus in real time. The pressure differential driving the flow is reversed by switching a pneumatic valve. Each transit is used to measure the volumetric flow rate, which in combination with the pressure drop, is used to determine viscosity as a function of shear rate. A given sample of at least 50 $\mu$L can typically be measured over 2 to 3 decades in shear rate, in the range of 10 s$^-1$ to 10$^5$ s$^-1$, and be essentially fully recovered. Validation is performed using samples of Newtonian and non- Newtonian fluid and compared to reference measurements. An analysis of the range of operation and uncertainty arising from instrumentation, interfacial pressure, meniscus effects, and inertial effects.Citation
Rheologica Acta
Volume
61
Pub Type
Journals
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Created March 30, 2022, Updated September 29, 2025