Drop Trampoline

TL;DR

This paper investigates how deformable PDMS membranes affect water drop rebound dynamics, revealing that membrane softness can significantly reduce contact time and alter bounce behavior compared to rigid surfaces.

Contribution

It introduces a novel experimental setup to study impact on deformable superhydrophobic membranes and demonstrates control over rebound dynamics by tuning membrane properties.

Findings

Membrane deformability alters rebound mechanics.

Contact time can be reduced by up to 70%.

Drop and membrane dynamics interplay controls bouncing behavior.

Abstract

Rigid superhydrophobic materials have the ability to repel millimetric water drops, in typically 10 ms. Yet, most natural water-repellent materials can be deformed by impacting drops. To test the effect of deformability, we perform impacts of non-wetting drops onto thin ($\sim$ 10 \micro m), circular PDMS membranes. The bouncing mechanism is markedly modified compared to that on a rigid material: the liquid leaves the substrate as it is kicked upwards by the membrane. We show that the rebound is controlled by an interplay between the dynamics of the drop and that of the soft substrate, so that we can continuously vary the contact time by playing on the membrane's characteristics and reduce it up to 70\%.