Abstract:
Researchers from the University of California at Davis have built compass needles as small as 20 by 200 nanometers, which is 3,000 times narrower than a human hair and 50 times narrower than an E. coli bacterium. The researchers' compass needles are just under half the size of the previously smallest known compasses, which occur naturally in magnetotactic bacteria that orient themselves using the earth's geomagnetic field.