Creases gate and steer droplets via elastocapillary repulsion.

Creases enable strain-tunable, size-dependent gating and steering of droplets through elastocapillary repulsion, with critical radius thresholds up to several times larger near instability.

• Why it matters: Understanding how elastic instabilities influence droplet behavior is crucial for developing reconfigurable fluidic systems and passive control mechanisms in soft materials.
• What they did: The study combines experiments and modeling to investigate how creases impose a sharp, strain-dependent threshold for droplet movement, revealing two distinct size-based repulsion regimes and force laws.
• The result: This work enables programmable droplet manipulation, including filtration, path guidance, and logic operations, by harnessing reversible substrate deformation, positioning creases as versatile regulators of fluid transport.