Rheology of fluids measured by correlation force spectroscopy

TR Number
Journal Title
Journal ISSN
Volume Title
AIP Publishing

We describe a method, correlation force spectrometry (CFS), which characterizes fluids through measurement of the correlations between the thermally stimulated vibrations of two closely spaced micrometer-scale cantilevers in fluid. We discuss a major application: measurement of the rheological properties of fluids at high frequency and high spatial resolution. Use of CFS as a rheometer is validated by comparison between experimental data and finite element modeling of the deterministic ring-down of cantilevers using the known viscosity of fluids. The data can also be accurately fitted using a harmonic oscillator model, which can be used for rapid rheometric measurements after calibration. The method is non-invasive, uses a very small amount of fluid, and has no actively moving parts. It can also be used to analyze the rheology of complex fluids. We use CFS to show that (non-Newtonian) aqueous polyethylene oxide solution can be modeled approximately by incorporating an elastic spring between the cantilevers. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4704085]

Microscopic viscoelasticity, 2-point microrheology, Thermal fluctuations, Stochastic dynamics, Frequency-response, Micelle solutions, Microcantilevers, Viscous fluids, Complex fluids, Soft materials
Radiom, Milad; Robbins, Brian; Honig, Christopher D. F.; et al., " Rheology of fluids measured by correlation force spectroscopy," Rev. Sci. Instrum. 83, 043908 (2012); http://dx.doi.org/10.1063/1.4704085