Machines that take x rays need a lot of power and as a result are generally large, cumbersome contraptions. Anything that needs to be x rayed has to brought to the machine. But there are plenty of reasons develop a portable x-ray machine. A mobile device could be carried into the sports field or battlefield to diagnose injured people or it could be used by security personnel to analyze packages at airports or check concealed shipments at seaports for illegal contents.
Scott Kovaleski, an associate professor of electrical and computer engineering, and some of his graduate students, found a way to make a lower-power x-ray machine that's only about the size of a stick of gum. That means instead of bringing objects to an x-ray lab for analyze, technicians can bring the x rays to the field.
The key to the small machine is a crystal of lithium niobate, which exhibits a particular property known piezoelectricity. Piezoelectric crystals generate a small electrical current when put under mechanical stress, such as being squeezed. The effect also works in reverse. Running a current through a piezoelectric crystal generates a mechanical action, like a vibration.