(388c) Automated High-Throughput Microrheology for Material Formulation

Brownian probe microrheology has become a popular method for characterizing viscoelasticity on small fluid samples, and holds significant potential for informing rheological design over a wide formulation space with limited material. Realizing this potential will require automated, high-throughput data acquisition and analysis. Here, we report a new method for extracting microrheology information using differential dynamic microscopy (DDM). Using Fourier-domain analysis of video images, DDM can extract the mean-squared displacement in systems that would otherwise be difficult to measure using conventional particle tracking. Combining DDM with downsampling by Gaussian process regression, we demonstrate that DDM microrheology can be performed in real time. This rapid acceleration is leveraged to integrate fully automated sample preparation, data acquisition and analysis to demonstrate autonomous, high-throughput microrheology characterization. We illustrate the utility of high-throughput microrheology through two examples – in situ characterization of viscosity during polyelectrolyte coacervation, and kinetic profiling of gelation in protein solutions. The results highlight the considerable promise of automated microrheology to aid the design of complex fluids and soft solids.