Rupture noise of a moving contact line*

Many disordered systems exhibit crackling noise when driven by an external force or filed, such as Barkhausen noise in magnetization of ferromagnetic materials, acoustic emission in plastic deformation and seismic activity in earthquakes. Here, we report the avalanche statistics of a moving contact line (CL) pulled by an AFM-based hanging glass fiber through a liquid-air interface. The measured capillary force acting on the circular CL between the liquid-air interface and fiber surface exhibits zig-zag fluctuations, resulting from stick-slip motion of the CL. In the stick state, the measured capillary force increases linearly with CL displacement. Once it reaches a critical value, the CL slips quickly in the form of avalanches, accompanied by a loss of capillary force δf. We found that the measured δf follows a power-law distribution and the power-law exponent agrees with the predicted value by the ABBM model. The experimental results reveal novel features of the stick-slip dynamics and can help to understand other stick-slip phenomena.