Influence of material and geometrical parameters on the adhesive performance of vibration-modulated soft contacts

Vibroadhesion, the modulation of interfacial adhesion by superimposing small-amplitude, high-frequency vibrations on an adhesive contact, offers a simple and fast strategy to rapidly tune contact forces. A systematic understanding of how key geometrical and material parameters govern this behavior is still lacking. Here, we present a comprehensive experimental investigation of vibroadhesion in viscoelastic PDMS–glass Hertzian contacts, examining the influence of substrate thickness t, radius of the indenter R, material properties like modulus and thermodynamic surface energy, unloading rate r and preload Fc0 on the stickiness performance of vibration-modulated interfaces such as: pull-off force FPO, contact radius a, mean stress at pull-off σPO, maximum enhancement with respect to the static adhesion test, range of vibration amplitudes that sustain adhesion enhancement. We find that across all tests, vibration activation triggers an abrupt expansion of the contact area, which upon unloading, results in a substantial increase of the pull-off force up to a saturation level always coinciding with the vibration level causing interfacial instabilities at the interface (wrinkles). Although the absolute value of the pull-off force may be strongly influenced by geometrical and material parameters, the maximum adhesion enhancement with respect to the reference static test remained consistently close to a 13-fold increase. We obtained the maximum mean stress at pull-off of 186 kPa when indenting with the smallest sphere. The unloading rate r weakly affects the adhesive performance and the preload Fc0 is nearly irrelevant in determining the pull-off force FPO. Taken together, these results provide both physical insights and practical guidelines for designing vibration-modulated adhesive interfaces for rapid, reversible, and tunable adhesion.