Reducing the contact time of droplet impact by active control of substrate motion

We report a method to reduce the contact time of a droplet impacting a superhydrophobic surface by typically 50%, which is achieved by controlling the substrate motion. In our method, the substrate motion is sinusoidal and triggered by a detection of the moment of impact with a piezoresistive force sensor which is fabricated on the substrate. This force sensor allows us to precisely move the substrate as the droplet comes into contact with it. We investigated the effect of the period of the substrate motion on the contact time and found that the most efficient reduction of the contact time was reached when moving the substrate with a period that is comparable to the spreading time of the droplet.