  Hypothesis: Measuring rotational and translational Brownian motion of single
spherical particles reveals dissipations due to the interaction between the
particle and the environment. Experiments: In this article, we show experiments
where the in-plane translational and two rotational drag coefficients of a
single spherical Brownian particle can be measured. These particle drags are
functions of the particle size and the particle-wall distance, and of the
viscous dissipations at play. We measure drag coefficients for Janus particles
close to a solid wall and close to a lipid bilayer membrane. Findings: For a
particle close to wall, we show that according to hydrodynamic models,
particlewall distance and particle size can be determined. For a particle
partially wrapped by lipid membranes, in absence of strong binding
interactions, translational and rotational drags are significantly larger than
the ones of non-wrapped particles. Beside the effect of the membrane viscosity,
we show that dissipations in the deformed membrane cap region strongly
contribute to the drag coefficients.
