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Updated: May 19, 2026

Measuring the Interaction Force Between a Droplet and a Super-hydrophobic Substrate by the Optical Lever Method
Published on: June 14, 2019
Rebounding droplet-droplet collisions on superhydrophobic surfaces: from the phenomenon to droplet logic
Henrikki Mertaniemi1, Robert Forchheimer, Olli Ikkala
1Department of Applied Physics, Aalto University, Espoo, Finland.
Abstract:
When water droplets impact each other while traveling on a superhydrophobic surface, we demonstrate that they are able to rebound like billiard balls. We present elementary Boolean logic operations and a flip-flop memory based on these rebounding water droplet collisions. Furthermore, bouncing or coalescence can be easily controlled by process parameters. Thus by the controlled coalescence of reactive droplets, here using the quenching of fluorescent metal nanoclusters as a model reaction, we also demonstrate an elementary operation for programmable chemistry.
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