A rotational magnetic-bearing rheometer for soft-materials characterization

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A state-of-the-art rotational rheometer with magnetically floating bearings is sought to furnish rheological data for characterizing the microstructure of hydrogels, dispersions, solutions, and nano-composites. The instrument subjects these delicate materials to precise shear deformations, furnishing the shear viscosity and elastic modulus under steady and oscillatory forcing, over a wide range of controlled strain rate and strain amplitudes, at a precisely controlled temperature. The data will be used to advance fundamental theoretical models of nanoparticle transport in hydrogels; e.g., from the measured shear modulus, we learn the cross-link density, which controls porosity and draining properties. The visco-elastic characteristics are also required as input data and parameters for theoretical models of hydrogel dynamics, which are important in biosensors. The instrument will be used to test and validate in-house microrheological instrumentation, and to furnish data to interpret novel electroacoustic and optical-tweezers microelectrophoresis experiments on hydrogel-colloid composites. Finally, the instrument will be used to ascertain the shear modulus of waste-water sludge, providing critical information with which to build a predictive theoretical model of electroosmotic dewatering; in turn, this model will help place an energy-efficient Canadian dewatering treatment technology in the global water-treatment market. The rheometer will benefit the Canadian research enterprise by strengthening a fundamental and applied research program that advances energy, environmental, and human health applications, including molecular separations, drying and disinfection, micro-fluidic actuation, drug delivery, nanoparticle characterization, and biosensing.