Using a cellphone compass to measure tiny concentrations of compounds important for human health

Nearly every modern cellphone has a built-in compass, or magnetometer, that detects the direction of Earth's magnetic field, providing critical information for navigation. Now a team of researchers at the National Institute of Standards and Technology (NIST) has developed a technique that uses an ordinary cellphone magnetometer for an entirely different purpose—to measure the concentration of glucose, a marker for diabetes, to high accuracy.