Electroacoustic particle analyzer for ultrasound micro-rheology of hydrogel-colloid composites

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A commercially available electroacoustic particle analyzer will be adopted to characterize the microstructure of a novel class of hydrogels termed hydrogel-colloid composites. Such instruments are routinely used to apply a high-frequency oscillatory electric field to a colloidal dispersion and sense the resulting pressure fluctuations. This response accesses the colloidal stability of optically opaque (dense) fluids, such a paints, foods, and cosmetics, by furnishing the so-called zeta-potential, which is a measure of particle charge. In this research, however, the instrument will be used as an innovative, non-invasive, quantitative tool for probing the mechanical and electrical characteristics hydrogel-colloid composites. This is a rapidly emerging class of nanocomposites with widespread applications as responsive biomaterials and sensors, for example. We have recently published theoretical predictions linking the elastroscoustic signal to important microstructural characteristics, such as the particle and hydrogel charge, and viscoelasticity. Accordingly, the instrument will allow us to test the theory and, thus, pave the way toward widespread use of electroacoustic technologies for microrheological analysis.