Nature Mater. doi:10.1038/nmat2208 (2008)

Credit: SU EUN CHUNG ET AL.

A network of grooves only a few millimetres long has been used to guide tiny structures around fluid-filled channels. These structures organize themselves into complex arrangements, as illustrated by the Greek temple pictured above.

More than 50 microstructures were slotted into the grooves. Water flow pushed them to the end of the lines, where they latched into place. Then exposure to ultraviolet light fused them together. The microstructures can carry living cells, among other things, suggesting an application in tissue assembly.

Sunghoon Kwon's team at Seoul National University in South Korea say that this improves on other methods of sub-200-micrometre robotic assembly, which are dearer and slower.