Translational thermophoresis and rotational movement of peanut-like colloids under temperature gradient

Thermophoresis can be used for particle manipulation and separation in microfluidics. This work reports an experimental investigation on thermophoresis and the associated rotational patterns of dilute peanut-like colloids in DI water and SDS surfactant solutions. A microfluidic device is utilized for generating a linear temperature gradient and for directly visualizing the thermophoretic motion and rotation of peanut-like particles. Thermophilic behavior was observed for the peanut-like particles, and their thermophoretic mobilities were found smaller than those of the spherical particles of similar sizes. The peanut-like particles' rotation characterized by the rotational diffusion coefficient is found to be free diffusive dominated. A very small orientation order toward a preferred direction is distinguished along with the random Brownian rotation.