Portable X-ray device has exciting potential
French physicist and Nobel laureate Henri Becquerel’s accidental discovery of radioactivity in 1896 occurred as he worked to uncover the secrets of X-rays. One hundred and seventeen years later, serendipity and X-rays again joined forces for an unexpected consequence and an exciting discovery in the lab of Scott Kovaleski, an MU associate professor of electrical and computer engineering and interim department chair.
One of Kovaleski’s research emphases is the development of space propulsion thrusters. As he and his team conducted experiments toward the development of an ion thruster, they realized the output energy — in the form of an electron beam — produced X-rays. The researchers immediately recognized the potential of their discovery to produce an inexpensive, portable X-ray system that would also have other advantages such as limiting dosage of radiation via previously impossible configurations.
“Rather than having the film in your mouth and the X-ray source exposing your head for dental X-rays, for instance, such a device would shoot outward, limiting your exposure,” Kovaleski said.
The device operates using what is known as the piezoelectric effect: non-conducting crystals that are subjected to mechanical stress — in this case exposing a man-made crystalline ceramic material, lithium niobate (LiNbO3), to a low-voltage electrical signal — store energy in a vibrating mechanical wave that can be extracted and accelerated as a high-voltage electron beam.
The AC electrical energy used in the experiments cause the crystal to vibrate and “ring” like a bell. “You can hear it chirping,” Kovaleski said of the chewing gum-sized crystal.
“Piezoelectricity is used in a lot of neon signs, LCD monitors, laptops and AC/DC converters,” said Brady Gall, an electrical engineering graduate student working with Kovaleski. “They produce at most, 300 volts.”
But, Gall said, repeated experiments have produced 120,000 volts with statistical certainty.
“All the simulations said that it was possible, but no one got it. We were the first to try it,” Gall said.
The researchers said there was nothing “magic” about the project. It has taken three years of tinkering, testing and new configurations to get them to this point, and they continue to work to optimize the output of the crystal. They estimate it will be three to five years before an actual portable X-ray prototype is developed.
“Currently, most X-ray machines are huge and require tremendous amounts of electricity. A cell-phone-sized device could improve medical services in remote and impoverished regions and reduce health care expenses,” Kovaleski said of the device’s potential. “And it can run on batteries.”
He said that in addition to being a used as a low-cost scanner to detect contraband and playing a role in other security devices, the technology has implications for everything from space exploration to its use in oil drilling.
It also has potential to replace dangerous radioisotopes in a variety of applications.
“Our device is perfectly harmless until energized, and even then it causes relatively low exposure to radiation,” Kovaleski said. “It has never before been possible to develop radioisotope devices with an on-off switch.
“More applications will develop over time,” he said. “The potential for innovation is very exciting.”
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