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.
“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.”
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.
The device could also be used as a radiation source for oil well drilling that would do without the need for radioisotopes.
“It’s this mechanism for producing energetic charged particles that just hasn’t been explored at all, so we’re really just having a fun time hunting and pecking in the dark on this thing, trying to figure out what we can do with it,” he said.
In its current form, however, the device likely won’t produce enough energy for the high-resolution imaging required in medicine, but it’s stackable. You can add several devices together to reach the throughput you need, while still remaining far smaller or more compact than most X-ray units. “If you need additional current, add more devices to get additional current,” Kovaleski said.
Kovaleski said his team hasn’t looked into commercialization prospects, but they expect they could have a finished device ready in about three years. As for cost, he said the crystals themselves are the most expensive part of the system, and they only run a couple of hundred dollars each.
“The rest of the device is fairly common off-the-shelf electronics on a circuit board, and so there are great efficiencies there if you’re mass producing,” he said. “The expense could be fairly low.”
Kovaleski’s study, “Investigation of the Piezoelectric Effect as a Means to Generate X-Rays,” was published this month in IEEE Transactions on Plasma Science.