Validity of Fluctuation Theorem on Self-Propelling Particles

The experimental application of fluctuation theorem (FT) on nanometer to submicrometer sized systems has received thorough attention in the past several years. Nonetheless, the employment of FT on self-propelling objects has seldom been performed due to experimental difficulties. In this paper, we applied FT on a doublet that is comprised of asymmetrically coated self-propelling colloidal particles (Janus particles), which experiences a continuous rotation by applying AC electric field. We found that FT is valid for rotating self-propelling colloids by evaluating the estimated rotary torque to coincide with another form of torque estimation, which considers the rotation speed of the doublet and a simple Stokes equation.