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The Flexure-based Microgap Rheometer (FMR)

Research and Teaching Output of the MIT Community

Show simple item record Clasen, Christian Gearing, Brian P. McKinley, Gareth H. 2007-01-23T12:07:15Z 2007-01-23T12:07:15Z 2007-01-23T12:07:15Z
dc.description Submitted to J. Rheol. en
dc.description.abstract We describe the design and construction of a new microrheometer designed to facilitate the viscometric study of complex fluids with very small sample volumes (1-10 μl)and gaps of micrometer dimensions. The Flexure-based Microgap Rheometer (FMR) is a shear-rate-controlled device capable of measuring the shear stress in a plane Couette configuration with directly-controlled gaps between 1 μm and 200 μm. White light interferometry and a three-point nanopositioning stage using piezo-stepping motors are used to control the parallelism of the upper and lower shearing surfaces which are constructed from glass optical flats. A compound flexure system is used to hold the fluid sample testing unit between a drive spring connected to an ‘inchworm’ motor and an independent sensor spring. Displacements in the sensing flexure are detected using an inductive proximity sensor. Ready optical access to the transparent shearing surfaces enables monitoring of the structural evolution in the gap with a long working-distance video-microscope. This configuration then allows us to determine the microgap-dependent flow behavior of complex fluids over 5 decades of shear rate. We demonstrate the capability of the FMR by characterizing the complex stress and gap dependent flow behavior of a typical microstructured food product (mayonnaise) over the range of gaps from 8 to 100 μm and stresses from 10 to 1500 Pa. We correlate the gap-dependent rheological response to the microstructure of the emulsion and changes induced in the material by prolonged shearing. en
dc.description.sponsorship Dupont MIT Alliance en
dc.format.extent 1137850 bytes
dc.format.mimetype application/pdf
dc.language.iso en_US en
dc.relation.ispartofseries 06-P-10 en
dc.subject Shear rheometry en
dc.subject Yield stress en
dc.subject Emulsion en
dc.subject Microrheometry en
dc.subject Microrheology en
dc.subject Wall slip en
dc.subject Mayonnaise en
dc.subject Complex fluid en
dc.subject Gap-dependent rheology en
dc.title The Flexure-based Microgap Rheometer (FMR) en
dc.type Preprint en

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