When microcantilever bending becomes cooperative.

Microcantilever sensors can measure adsorption in two ways. Resonance frequency mainly follows total mass uptake, whereas static bending follows surface stress. These two signals do not always change smoothly together. In many bending measurements, sharp jumps, plateaus, and burst-like features appear on top of a smooth adsorption or recovery curve, and these features are often treated as noise or drift. Here, we show that they can contain useful physical information. We separate the smooth bending response from the residual signal and use detrended fluctuation analysis to measure how persistent the residual activity is through a scaling exponent, α. The experiments show strongly persistent residual fluctuations. A minimal kinetic Ising model, with the Hamiltonian unchanged but the transition rule made locally cooperative, shows that such burst-like activity and persistent scaling can arise from local pathway selection alone. The results reveal a residual route to cooperative surface-stress dynamics and suggest how local transition rules can generate abrupt collective switching.