A wire thinner than a human hair designed to navigate tiny blood vessels in the brain has been built by scientists. The tool will allow doctors to access parts of the body that existing methods can not reach as the capillaries are too narrow. Swiss researchers developed the tool which uses the flow of a patient's blood to create a smooth path through winding vessels, reducing pressure on the walls and lowering the risk of perforation. It is hoped the technique could usher in a new frontier in neurological therapeutics as doctors can get deeper into the brain and nervous system than ever before.