Lubricant is not only a support, but also an escort runner for an electrically-driven droplet

What is it about?

Electrowetting-on-dielectric (EWOD) is a technique to manipulate small droplets using electricity. However, it requires high voltage to drive the droplets fast. This paper demonstrates that the droplet velocity increases more than 10 times by installing a free-flowing lubricant. Unlike a conventional understanding that the lubricant works as a static-friction reduction agent, which supports starting of the droplet motion, we show that the lubricant also works as an assistant during the motion.

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Photo by Nithya Ramanujam on Unsplash

Photo by Nithya Ramanujam on Unsplash

Why is it important?

The driving force depends on a square of the applied voltage. Which means the force (and resulting droplet velocity) rapidly decreases if the applied voltage is reduced. By drastically increasing the droplet velocity, the proposed technique opens a door for low-voltage manipulation. It is also effective to protect droplets from contamination as the lubricant spontaneously covers the droplets.