  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.
