URBANA — Brett Walker seemingly can't stop creating stuff.
The 27-year-old doctoral student at the University of Illinois started a gun-parts business in high school.
He turned his attention to fuels in college, converting waste grease into biodiesel and "slop oil" into pipeline-grade oil.
Now, completing his doctoral degree, he's launching a business around reactive silver inks — used in printed electronics.
"I'm a tinkerer," Walker said. "I can't sit still. I like creating new things and exploring problems I want to explore."
Last year, his work to develop a cheaper, easier-to-make ink than those already on the market earned him runner-up honors in the National Collegiate Inventors Competition — and a $12,500 award.
Walker, who was born in Killeen, Texas, and grew up in Oklahoma City, comes from a family of physicians.
His father, mother and older brother are all emergency-room doctors, but Walker chose a different route.
"I always liked working with my hands and making things," he said. "Engineering seemed to be the more natural choice for me."
Walker started his newest company — Electroninks Inc. — on Jan. 2. The name sounds a lot like "electronics," and that's no accident, since the ink is used in printed electronics.
His co-founder in the venture, Jennifer Lewis, is a former UI materials science professor who recently joined Harvard University's School of Engineering and Applied Sciences.
The reactive silver ink is superior in several respects to colloidal inks conventionally used for printed electronics, Walker said.
Those particle-based inks are "relatively expensive and difficult to make," he said. Plus, they require high annealing temperatures that can distort plastic printing surfaces, he added.
Walker said the reactive silver ink is "simple to make," and small batches of it cost about $2.50 per gram, compared with prices of $10 to $15 a gram for small quantities of colloidal inks.
Walker said he has already approached several large customers in the biomedical and electronic circuitry fields about using the ink.
The biggest market for the ink, he said, is thought to be the printed electronics market, which uses about $1.5 billion in materials a year.
But the biomedical industry can also use the ink in producing electrodes for pacemakers and diagnostic glucose sensors.
Plus, the ink can be used in printing barcode labels and producing high-end decorative signs.
The UI's Office of Technology Management has international and U.S. patents pending on the invention, Walker said.
Lisa Dhar, the office's assistant director for life sciences and strategic initiatives, said the ink has several attractive attributes.
It has a "conductivity that approaches that of bulk silver" and doesn't require high annealing temperatures, she said.
Plus, it's compatible with a wide range of "deposition schemes," ranging from ink-jet printers to spray applications, she said.
When scientific publications about the ink appeared, the Office of Technology Management was "inundated" with interest and requests from researchers and industry, Dhar said.
Lewis, the co-founder of Electroninks, said she knows of only one other supplier of particle-free silver inks, and that's South Korea's InkTek.
She credited Walker as the lead in developing the ink.
"Much of these advances come out of his ingenuity and hard work," she said, adding that Walker is working with 10 to 20 companies in developing inks for their applications.
"He's an excellent chemist as well as a material scientist," she said.
Lewis also credited Dhar and OTM Director Lesley Millar for supporting the technology and UI Research Park Director Laura Frerichs for helping to secure seed funding for the company through EnterpriseWorks' I-Start program for entrepreneurs.
Walker's first brush with entrepreneurship came in high school when he founded Walker Tactical Systems, a business that catered to competitive shooters.
He designed parts for guns — particularly failure-prone parts, ranging from magazine funnels to firing pins. He still has the business today.
While getting his undergraduate degree in mechanical engineering at Oklahoma State University, he developed a business that converted waste greases — the kind collected in grease traps of sinks in commercial restaurants — into biodiesel.
The business, Biotek, sold the biodiesel to small trucking firms that blended it with diesel to save fuel costs. Later, the business ventured into slop oil reclamation, converting it to pipeline-grade fuel.
Walker left that business when he started graduate school, and it's no longer around, he said.
Walker said he chose materials science as his focus in graduate school because it's at "the intersection of a lot of interesting engineering fields."
He initially worked on colloidal inks before concentrating on silver inks.
Now he's working on new applications for silver inks.
"I'm currently working on other variations of reactive silver inks from screen printing to ink-jet formulations into (conductive) textiles," he said.
Walker recently returned from Harvard, where he served as a visiting fellow. He said he was glad to return to Urbana, partly because "I don't like being crowded or cramped."