It’s hard to imagine that a human heartbeat can create a local disturbance in the Earth’s magnetic field, but, of course, it does.  Now, engineers at the National Institute of Standards and Technology have created a min-sensor that can measure the heartbeat’s magnetic disturbance.  The sensor itself is a capsule holding about 100 billion rubidium atoms with a low-power IR laser and optics.  It measures in trillionths of a tesla.  One medical application the developers envision is localized detection of drug-carrying nanoparticles in targeted tissue.       MORE