Chih-hung Chang: Nanotechnology on a T-shirt

Chih-hung Chang standing in front of an array of photovoltaic panels.
Chih-hung Chang, professor of chemical engineering, works with nanostructured thin films and printable electronics, with applications from solar panels to smart textiles.

In the near future, you might be able to charge your smartphone using solar panels printed directly onto your T-shirt, says Oregon State chemical engineering professor Chih-hung Chang.

Perhaps that same shirt will contain sensors that take your temperature or monitor your health by sampling your sweat. Or maybe the fabric will change color to alert you to environmental threats.

“I love coming up with new ideas,” Chang said. “It’s always exciting to try new things.”

Chang is optimistic about the potential for “smart textile” applications like these. An expert in printable electronics, Chang is currently working on a project supported by the Walmart Manufacturing Innovation Foundation that aims to print functional electronic devices directly onto fabrics.

“Right now we’re at the stage where we want to be able to fabricate components onto the fabric, including transistors or solar cells,” Chang said.

The way printable electronics are fabricated is similar to inkjet printing, Chang says. A silicon microfluidic chip dispenses microscopic droplets of different inks with a very high degree of accuracy. Only with this printer, instead of different colored pigment inks, molecular and nanoparticle “inks” function as conductors, semiconductors, and insulators.

“We are working to develop the inks that will be used to print electronics using print-additive techniques,” Chang said. “And we’re looking at energy-efficient curing processes, like microwaves, to make smart textiles.”

Printable electronics are just part of what Chang spends his days on. The majority of Chang’s work, largely funded by the National Science Foundation, focuses on using microchemical reactors in the creation of nanomaterials, nanostructures, and thin films.

“We use microreactors as a tool for manufacturing and also for fundamental study,” Chang said. “In the reactor, we generate all sorts of reactive species, including nanoparticles. We send these to a surface, and then they reorganize themselves on the surface to create nanostructured thin films.”

These thin films are used in a variety of applications, including photovoltaic cells, heat-transfer surfaces for electronic devices, and a variety of chemical sensors.

Some of Chang’s recent projects, supported by the Department of Energy’s National Energy Technology Laboratory, have potential applications in carbon sequestration. Chang’s work focused on using organic/inorganic hybrid nanomaterials to capture carbon dioxide, and also using nanomaterials to enhance near-infrared signals for monitoring carbon dioxide.

Chang’s own spinoff company, CSD Nano, developed a process to retrofit solar cells with a nanostructured coating that increases the output from existing solar farms. Chang founded the company in 2007. He currently advises the firm, sits on its board, and serves as its chief science officer.

Another Oregon company, Abom, turned to Chang to help develop its next-generation patented self-defogging ski goggles. Supported by ONAMI, Chang worked with his collaborator, Dr. Rajiv Malhotra, to develop innovative processes used in the defogging technology as well as a proprietary lens coating material.

Developing sustainable processes, by reducing energy consumption and achieving higher material utilization, is a guiding principle in Chang’s work. One major emphasis is developing a scalable manufacturing process for nanomaterials.

“The hope is that by making these processes more efficient, devices will be more cost-effective so they can be commercialized,” Chang said. “We want to get them into the market.”

Chang says he derives great personal satisfaction from his work, and working with students is one of the job’s major perks.

“It keeps your mind fresh, as you get older,” he says. “I think it’s very gratifying to see a student get excited about a project. Once they are motivated, they just do it themselves. In the research area, that’s the part that I like the most. To come up with new ideas and try them out in the lab and working with students.”

When he was himself a student, Chang says he was first drawn to study art, but he ultimately decided on chemical engineering. However, he doesn’t see the two as being mutually exclusive.

“I feel like I still get to do art,” he says. “Lots of people are using smart textiles for artistic expression in T-shirts. For example, you can have lighting or other interesting effects — for fashion, not necessarily for function. As engineers, of course, we care a lot more about function.”

Chang recently found creative inspiration in a collaboration with Sara Robinson, professor of wood science and engineering in College of Forestry. Their project, another Walmart-funded venture, aims to turn biopigments from fungi that grow on wood into printable inks for textiles.

“I actually bought a T-shirt printer, just to play around with,” Chang said. “My idea is that once I have the ink, I can design T-shirts and print them myself.”

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