Dynamics and rheology of active biomaterials and gels quantified with optical microscopy tools

How can we quantify the microscale dynamics and mechanics of soft materials that are quickly restructuring in time, exhibit spatial and temporal heterogeneities, and move in all three dimensions? Here, I will discuss optical microscopy techniques that can capture such complex dynamics observed in, e.g., active soft materials. I will highlight the image analysis technique of differential dynamic microscopy and recently developed microscopy modalities and their applications to cytoskeleton networks driven by molecular motors and to suspensions and gels of colloidal rod-shaped particles. Through optical tweezers microrheology and bulk rheology used in combination with video microscopy, we robustly connect observed microscale dynamics with a material's mechanical properties. I will present new methods we are developing to extend differential dynamic microscopy to achieve finer temporal resolution and improved detection of 3D motion.