Microvibration-Enhanced Adhesion in Soft Contacts:

High-frequency, micrometrical vibrations can dramatically enhance the adhesive performance of soft interfaces, providing a simple and rapid strategy to achieve reversible and tunable adhesion, a phenomenon referred to as vibroadhesion. Despite increasing interest in vibroadhesion, a comprehensive understanding of the mechanisms governing this phenomenon and their quantitative description has remained elusive. Here, we combine systematic experiments and theoretical modeling to investigate the adhesive behavior of vibrating viscoelastic PDMS–glass contacts during unloading. Adhesion tests were performed using borosilicate glass spherical indenters of different radii on PDMS substrates subjected to high-frequency vibrations, while varying substrate thickness, elastic modulus, thermodynamic work of adhesion, unloading rate, and preload. In all cases, vibration activation induced an abrupt expansion of the contact area, followed during unloading by an evolution closely resembling the classical JKR solution, but with a substantially increased effective work of adhesion. The pull-off force increased with vibration amplitude until reaching a saturation level, consistently associated with the onset of interfacial instabilities (wrinkling). Although the absolute pull-off force strongly depended on geometry and material properties, the maximum adhesion enhancement relative to static conditions remained remarkably constant at approximately 13-fold. Unloading rate exhibited only a weak influence on adhesion enhancement, whereas preload was found to be nearly irrelevant. A lumped mechanical model incorporating independently measured rate-dependent interfacial adhesion accurately reproduced the experimental observations without adjustable parameters, providing both qualitative and quantitative agreement. These findings establish a unified framework for understanding vibroadhesion and offer practical design guidelines for vibration-modulated adhesive interfaces with rapidly switchable and controllable adhesion.