Nanorobots. Illustration of nanorobots destroying diseased tissue inside a human blood vessel. The robot on the left is using its three spinning blades to destroy a tumour. On the right another robot is attacking a blood clot (thrombus). This is one of the possible applications nanotechnology might bring to medicine in the future. Driven by engines invisible to the human eye, these robots would roam through the body in search of abnormal tissue to destroy. Also seen here are red blood cells (red discs), antibody-covered white blood cells (yellow spheres) and fat droplets. The robots, made from a neutral material, are left unharmed by the white blood cells.