by Brendon Nafziger
, DOTmed News Associate Editor | January 10, 2013
Scientists at the University of Missouri say they have developed a battery-powered device a little smaller than an iPad mini that can generate X-rays and could one day be used to take dental scans or search for dangerous contraband in ports.
The 6-inch long device uses the vibration and expansion of a small crystal to magnify by a thousand-fold the input of small amounts of electricity, to generate the energy required to create X-rays.
Like many inventions, the project began somewhat serendipitously, and was an offshoot of space propulsion research. Scott Kovaleski, a developer of the device and assistant professor of electrical and computer engineering at the University of Missouri, told DOTmed News that a graduate student on his team was experimenting with a nickel-shaped piece of crystal to create plasma when they discovered that applying an A/C current at a certain frequency made it much easier to produce the stuff.
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"We started looking into it, and we were taking advantage of this piezoelectric transformer-type property in the crystal," Kovaleski said, referring to a physical phenomenon where energy is created by putting certain materials under mechanical stress. He said he then thought: "If we can make 10,000 volts for space propulsion, I wonder if we can make 100,000 for X-rays."
The prototype X-ray source.
At the heart of the system is a crystal of lithium niobate, 10 centimeters long and one and a half millimeters thick, giving it about the size, and shape, of a stick of gum, according to Kovaleski.
To make the device work, scientists apply 10 volts of alternating current to the one and a half-millimeter side of the crystal, "squeezing" it and causing it to expand and contract lengthwise. The voltage is applied at a certain frequency (40,000 hertz) that makes the crystal resonate or ring as it swells and shrinks, turning it into a piezoelectric transformer and generating a 100,000 volt electron beam. That beam in turn interacts with a target to produce X-rays.
But Kovaleski said they could create other energetic particles, such as neutrons. These could be useful for "homeland security type" applications. In this, investigators could use the device as a neutron source to hunt for radiological weapons in, say, a shipping container at a port. As explained by Kovaleski, when neutrons emitted by the device interact with nuclear material in the container, the material undergoes radioactive decay, which could then be detected.