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University of Missouri

The Incredible Shrinking X‐ray

A small X‐ray machine developed by MU engineers is proving to be a big hit.

mini x-ray technology

The piezoelectric properties of lithium niobate crystal mean this small transformer can power big results. Photo by Rob Hill.

Big, high‐performance computers are perfect for graphic design or data modeling, but no one would use them to check email while in line at the grocery store. That’s what smartphones are for.

Similarly, in the world of X‐rays, big machines that do fine work in hospitals and airports are ill‐suited for use in remote villages in developing countries.

But Scott Kovaleski, professor in the College of Engineering’s electrical and computer engineering department, and his team of researchers have developed a smartphone‐scale X‐ray, and they’ve been surprised how big the demand for the small device is.

Their accomplishment was somewhat unintentional. Kovaleski started by designing a neutron generator, but he needed a way to measure its energy output. Traditional methods weren’t working, but he thought X‐rays might. After a lot of tinkering, he and graduate assistant Brady Gall produced a portable, low‐cost X‐ray machine that did the job. Kovaleski says he had a hunch people might be excited about the X‐ray technology itself, so he wrote a journal article about the work and MU issued a press release.

The year since “has been a pretty crazy ride,” he says. People have bombarded him with ideas about how they could apply the technology to their field.

Global health organizations are interested in it for low‐cost medical imaging in places where electricity is unreliable. Industry is interested in it as a factory‐floor quality‐control tool, spotting product flaws in minutes that might take a week to discover with laboratory testing. And the security industry likes it as a possible mobile bomb detection tool for searching suspicious packages.

The FBI called to talk to us about security‐related stuff,” Kovaleski says. “We got to meet the bomb technicians in [Missouri] to see how they do their thing, which was one of the highlights of my career. I had a good time doing that.”

The “secret sauce” behind the technology is the transformer, a standard piece of electrical technology that is used to increase or decrease voltage in an electrical circuit. But rather than use traditional magnetic transformers that involve large, coated coils of wire submerged in oil that weigh 50 pounds and cost about $50,000, Kovaleski used a tabletop‐sized piezoelectric transformer made from lithium niobate that costs about $200. By exploiting the unusual properties of the lithium niobate crystal, his team was able to get 100,000 volts of energy output from a 10‐volt energy input — a 10,000-to-one ratio.

Kovaleski says people have known piezoelectric transformers had great potential, but he doesn’t know of anyone who has achieved a transformation ratio that big. Typically the crystals shake themselves apart at energies that high, a problem Kovaleski’s team also encountered. “We had models that told us we should be able to get the voltages we were intending to get, but we just had to very carefully eliminate all the little things that could keep us from getting where we wanted to go,” he says.

Kovaleski will apply for a full patent before June. He’s also thinking about forming his own company, licensing the technology from Mizzou and pursuing a joint venture with a manufacturer.