A new single-molecule, nanoscale sensor -- more than 1,000 times smaller than the width of a human hair -- stands to play a big part in what some scientists see as a revolution in diagnostics. Creation of the microtool, by physicists at the University of California, Los Angeles, could pave the way for early detection of cancer and other genetic diseases. It also could lead to timely identification of anthrax and other biowarfare agents and prompt determination of the potential power of a new drug.