Staff Photo by Matt Hamilton / Ben Romines demonstrates a pick and place machine at Variable in Chattanooga on Thursday, April 15, 2021.

When George Yu graduated with a Ph.D. from Georgia Tech in 2008, there were few jobs in his field as the Great Recession took hold of the economy.

The young electrical engineering graduate followed his wife to Chattanooga where she became a professor of computer science at the University of Tennessee at Chattanooga and Yu managed to get a contract with NASA's Ames Research Center. With funding from the Department of Homeland Security, Yu worked remotely in Chattanooga to develop a device that enabled smartphones to detect harmful gases using the agency's nanosensor technology. Yu ultimately produced a successful prototype for NASA to help detect a potential chemical terrorist attack.

When his technical development contract with NASA ended, Yu decided to try to capitalize on his development with his own business, which he began in 2012 known as Variable.

Aided by the Company Lab and housed until 2019 in the Hamilton County Business Development Center, Yu's company developed everything from the Node to detect differences in temperatures and volatile gases to a Color Muse to identify color variations.

True to its name, the business has adapted the sensor technology to variable uses, including a new product that might help detect whether someone has the COVID-19 virus.

Yu, who has built his Chattanooga business into a 32-employee business selling to a variety of business and government customers over the past decade, got a call last spring from some of his old friends at NASA's Ames center where researchers were eager to find new ways to quickly determine who might be carrying the COVID-19 virus.

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Staff Photo by Matt Hamilton / Variable CEO George Yu speaks during a meeting at Variable in Chattanooga on Thursday, April 15, 2021.

Inside Variable's 7,230-square-foot offices and factory on Clay Street in Chattanooga, Yu and his engineering team began working last year on a prototype COVID-19 detection device called the E-Nose. The device, which can be connected with any smart phone for a digital read out, can detect the volatile organic compounds or VOCS in a person's breath and with the right assessment determine if the person is carrying the COVID-19 virus.

The E-Nose device uses a gas sensor to look at different gases from your breath.

"Based on that, we can tell if you have COVID-19 and if you are infected or not infected as a way of rapid testing of people," Yu said."The breath coming out of your body can have a lot of tell signs of what kind of disease you have. It's a national emergency so every technology that is potentially available has to be put together and this is one of them."

Most detection instruments for sensing harmful gases are bulky and designed for laboratory use, but the E-Nose device can be held in your hand and connected to any smart phone. The E-Nose device is still being perfected, but the prototype is showing promise for detecting viruses that may arise in future pandemics.

"At this point it's difficult to say if it will make a difference in the COVID struggle but the technology that's being developed here is going to be used for other diseases and potentially for future threats down the road," Yu said.

Variable's expert engineering staff, experience with a range of hand-held devices and its ability to respond to changing needs made the Chattanooga firm uniquely qualified to undertake the NASA contract, Yu said.

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Staff Photo by Matt Hamilton / Variable director of operations Ian Gilliam puts a prototype together at Variable in Chattanooga on Thursday, April 15, 2021.

Variable first created the NODE Bluetooth sensor platform allowing interchangeable sensor modules to work wirelessly with smartphones. In 2012 when his first daughter was born, Yu discovered the difficulty of choosing a color for her room and decided to make digital color matching technology available to aid everyone from paint companies and contractors to fashion designers and artists. The NODE Chroma color sensing technology formed the Color Muse which accurately measures the color of paint, plastics, and textiles.

Over the past nine year, Variable has built and shipped thousands of products and created numerous sensor driven apps for enterprise applications. But Yu said he is thrilled to be working with NASA again on a potentially life-saving device such as the E-Nose.

"We are incredibly honored to have this opportunity to work with NASA and feel strongly about this project because our nation and the world is in need," he said. "If we are able to be of any help, we want to do our part with the abilities we can offer our country."

Contact Dave Flessner at or at 423-757-6340.