Part gimmick, part interesting photo experiment, photographer Robin de Puy's latest creation is truly impressive. By combining the science of fluid dynamics, electricity and optics, she was able to take a set of professional portraits using a water droplet as a lens.

De Puy embarked on this project for SPA, a Belgian bottled water company that wanted to illustrate how pure its water was by creating the so-called 'purest picture' for its latest online marketing campaign. But marketing dream only became photographic reality with help from a group of scientists who custom-built the special 'water drop' camera you see below, and came up with a way to 'focus' water.

The custom-built 'camera' used to take these portraits. It consists of a mirror, a diaphragm, a drop of water (the 'lens'), and a sensor mounted on top of each other.

The 'camera' consists of a glass plate with a water-repellent coating, sitting atop a diaphragm, which is in turn sitting atop an image sensor.

The water-repellent coating ensures the droplet stays spherical. Then, by electrifying the plate, de Puy is able to take advantage of the Electrowetting effect to shape the drop and, by adjusting the voltage, bring her subject into focus.

You can watch the whole ad below:

And here is a technical breakdown that explains how they were able to control the water drop lens:

The results are surprisingly good – slightly soft, black and white portraits that ooze a Fine Art character, if you're into that sort of thing.

'Taking the portraits was a big challenge for me. I have to admit I had gotten quite spoiled working with the newest cameras, being used to the speed and convenience. For this project I had to start at the base again: a mirror, a diaphragm, a lens (the Spa droplet) and a sensor mounted on top of each other,' says de Puy. 'After that I tried to find interesting characters to portray. It was a challenge but I think I managed to capture them.'

We think so too. Check out the full gallery for yourself at the top of this article.