Materials

Colloidal diamonds self-assembled in breakthrough for photonics

Colloidal diamonds self-assemb...
Diamond colloids, held together with DNA glue
Diamond colloids, held together with DNA glue
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3D models of colloids linking together in different shapes
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3D models of colloids linking together in different shapes
Colloids link together thanks to DNA strands
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Colloids link together thanks to DNA strands
Micrograph images of diamond colloids
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Micrograph images of diamond colloids
Diamond colloids, held together with DNA glue
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Diamond colloids, held together with DNA glue
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Engineers have developed a simple way to make colloidal diamonds that self-assemble. These structures have traditionally been tricky to manufacture in bulk, but with this new method they could be used to help make better photonic devices.

Colloids are mixtures of particles suspended in a fluid, but unlike a solution they don’t dissolve, instead remaining in two separate phases. In some cases those particles can be induced to link up into various crystalline structures, which can in turn be used to make optical devices.

These colloids link up thanks to strands of DNA attached to each particle. As they float around in the liquid, the DNA hook up in specific ways and hold the particles together in a particular structure. By changing where on the particle the DNA is attached, colloidal cubes, strings and pyramids can be made, but diamonds have remained elusive.

The problem is that to form a diamond shape, the particles need to stick together in a staggered orientation – but they aren’t usually that selective. Instead, their DNA strands just stick to whatever they find.

3D models of colloids linking together in different shapes
3D models of colloids linking together in different shapes

On the new study, researchers at New York University (NYU), CNRS and Sungkyunkwan University found a way to get them to form diamond shapes. The trick seems to be to start with pyramids, which can then interlock with each other in a staggered formation to create diamonds. These crystal structures remain stable after the liquid phase is drained out, which is important for using them in practical applications.

So what’s the big deal about colloidal diamonds? The team says that this particular arrangement can be useful in the field of photonics, where light is used instead of electrons to make circuits, computers and other devices that would normally be “electronic.” Colloidal diamonds would be especially useful for making optical waveguides, filters and laser resonators.

Having these structures self-assemble makes them easier to produce in bulk, which could speed along the development of photonic technology that relies on them.

The research was published in the journal Nature.

Source: New York University

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So what element was used?