Now there really is nowhere for dirt to hide. Scientists have created the world's smallest cleaning tool to remove the slightest imperfection on a microchip or tidy up flaws in DNA structures, writes Steve Farrar.

The nanonozzle is smaller than one-thousandth of the diameter of a human hair and can be precisely controlled.

It has been created by Ivo Rangelow's team at the Institute for Microstructural Technology and Analysis at Kassel University in Germany. The group has already devised an array of miniaturised implements to help advance nanotechnology. The nanonozzle will sit in the nano-toolbox alongside a set of pliers so small that they can pick up objects the size of red blood cells.

The tool will direct a tiny plasma jet of highly reactive molecules, known as radicals, onto the surface or structure that needs cleaning.

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These can be used to smooth out atomic defects on silicon surfaces, for example, when flaws occur during the fabrication of a microchip.

Scratches and craters can also be removed by laying down polymer layers.

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The nozzle itself is linked to a single-nanometre-resolution sensor and controlling microchip to enable it to work on problems rapidly and efficiently.

The flow of radicals comes from an external microwave generator that is connected to the three-component device.