Contact Angle Hysteresis: a First Analysis of the Noise of the Creeping Motion of the Contact Line

We study the force exerted on a fiber by a moving liquid interface. We show that the noise of this force should correspond to the pinning-depinning process (or stick and slip) of the contact line on defects (which can be physical defects as roughness or chemical heterogeneities). For fibers with a low concentration of defects, we find experimentally that the contact angle hysteresis γ(cos θr−cos θa) is proportional to −h2/S0, where h is the fluctuation of this force and S0 the average spreading parameter.