Controlled Actuation of Self-Propelled Droplets

In this paper we present controlled self-propelled actuation of droplets employing Laplace pressure gradients between two non-parallel superhydrophobic plates. For small angles (cos β ≈ 1) a simplification of available energy-based models can accurately predict the droplets initial acceleration. By adjusting the plates’ spacing and angle (from 0.2° to 1.5°), the value of the droplets initial acceleration can be varied from 0.28 m s^-2 to 3.9 m s^-2 hence showing significant promise for precise controlled actuation. Such an actuation principle could find applications within droplet-based lab-on-a-chip systems where superhydrophobic surfaces could help address the challenges of transporting biomaterial laden droplets.