Differential Dynamic Microscopy in soft matter research*

Studying the dynamics of nanoparticles inside polymers provide important information about the mechanical and viscoelastic properties which are useful in various medical and technological fields. We focus on studying the diffusion of different sized particles in various polymer solutions using a new optical technique known as Dynamic differential microscopy (DDM). DDM is based upon analyzing the motion of particles in Fourier space that can extract useful information about their wave-vector dependent dynamics. This technique had been developed recently and was used to study a wide range of problems, including active motion of particles inside cells, bacterial motility, fluctuations in non-equilibrium systems, etc. We have implemented DDM in our own research to characterize the dynamics of nanometer sized particles within concentrated polymer solutions, and thus extended its capability at nanoscale.