Animal tissue and elaborate structures for microelectronics could be engineered by generating tiny swells in a dish of saline solution
THESE are waves worth catching. Generating tiny swells in a dish of saline solution prompts beads, copper powder and even cells to assemble into a panoply of intricate patterns. The technique could offer a simple way to build elaborate microelectronics and make human tissue.
Many attempts at small-scale construction build structures piece by piece, which can be time-consuming for complex products. Other methods can only use specific building blocks, such as magnetic materials. Now a team led by Utkan Demirci at Stanford University in California has found a way to quickly build structures a few millimetres across from almost anything, using a "liquid template".
The team started by making acrylic containers, each roughly 1 centimetre across, but sculpted in various shapes. They filled the containers with saline solution and connected them to a vibration generator and amplifier.
After adding a handful of starter pieces, such as silicon chips or plastic beads, the researchers tuned the generator to various frequencies to create waves in the solution. Depending on their surface chemistry, the added particles spontaneously collected in either the crests or the valleys. Retuning the generator let the team switch between patterns (Advanced Materials, doi.org/f2smkc).
The researchers also cajoled cells into forming delicate structures. When they put cultured mouse cells in the liquid template, the cells collected into little spheres that became the building blocks of larger geometric patterns. Adding blood-clotting proteins to the saline solution locked the cells in place, an approach the team is now investigating for growing liver tissue.
The diverse array of patterns generated by the technique and the ability to switch from one pattern to another in real time is impressive, says David Gracias at Johns Hopkins University in Baltimore, Maryland. And there's nothing fancy about the required equipment, so researchers could easily take advantage of the approach for all kinds of uses, he says.
This article appeared in print under the headline "Miniature structures appear with a wave"
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