Universiteit Leiden

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Vidi research grant for physicist Daniela Kraft

The image of the Leiden microboat traveled all over the world, from the BBC up to Arab shipping blogs. But Daniela Kraft's research group has quite a few more different 3D printed microswimmers up their sleeves. Kraft receives a Vidi research grant for research into these variously shaped active particles.

'Our boat can propel itself, too', says Kraft. After printing the micro boat in a 3D printer that can print on micrometer scales, they covered the stern section with a thin layer of platina. In a dilute solution of hydrogen peroxide, this causes a chemical reaction that propels the boat like a miniature outboard engine. Kraft: 'We filmed it while it was going around in circles.' (see: 3D printed micro boat)

Such 'active particles'  and their behaviour are the subject of the Vidi proposal that research funder NWO awarded  with 800 thousand euros. Most of this is intended for a PhD student and a postdoc, also a part will be used for Krafts position. 'With natural microswimmers, such as bacteria, shape and flexibility play large roles, which we would like to reserach using our active microparticles', says Kraft.

Daniela Kraft


Active microparticles can be made in various shapes now. For instance, Kraft’s group also printed small spirals, which look like small Archimedes wheels on electron microscopy images. Propelled by a catalytic reaction at a platinum layer, they swim through the water, which also induces a rotation.

Depending on the direction of this rotation, the spirals' path bends either to the left, or the right. 'We don't know exactly what causes this, it's possible that this has to do with the substrate over which they move', says Kraft.

The physicists also printed flexible rods. Possibly, the research can provide new insights into the behavior of natural microswimmers like bacteria or certain types of cells. Eventually, the researchers would like to study their collective behaviour. 'Microswimmers can organise themselves into ordered, but dynamic crystals, which dissolve subsequently', says Kraft. 'There are several theories as to how this works for microswimmers of different shapes and elasticity, and we hope to test these.'

Microswimmer Gallery

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