Bonnie Gray Discusses Her Latest Work on Sensors

Bonnie Gray

Bonnie Gray, professor at Simon Fraser University.

Editors’ Choice—Development of Screen-Printed Flexible Multi-Level Microfluidic Devices with Integrated Conductive Nanocomposite Polymer Electrodes on Textiles

Bonnie Gray, a professor at Simon Fraser University’s school of engineering science, was inspired by the city of Vancouver in British Columbia in her latest work.

“Vancouver is well-known for its technical clothing, and I have a lot of friends in the film industry who work in costume design. A combination of these influences and my own engineering background caused me to look further into integrating clothing with technology. That’s how I went on to become involved in developing screen-printed flexible multi-level microfluidic devices on textiles,” said Gray, which led to the fruition of her and lead author Daehan Chung‘s research paper, “Development of Screen-Printed Flexible Multi-Level Microfluidic Devices with Integrated Conductive Nanocomposite Polymer Electrodes on Textiles.”

In their open access paper, published in the Journal of The Electrochemical Society, the pair “present a flexible plastisol-based microfluidic process integrated with conductive nanoparticle composite polymer (C-NCP) electrodes for flexible active microfluidic devices on textile substrates.”

According to Gray, flexible and wearable microfluidic devices are among the newest wearable devices for applications in health monitoring, drug delivery systems, and bio-signal sensing.

And while many researchers are working on developing wearable biofluid sensors, what makes Gray and Chung’s work unique is that the sensors are directly integrated onto clothing fabric, which offers many advantages.

“They can conform to the body’s curved surfaces and enable stable sensing monitoring due to firm contact to skin, without impeding motion. They’re lightweight, there are no attachment procedures needed, and they offer real-time monitoring as well,” said Gray, adding, “Clothing is something that people wear every day. You don’t have to remember to put on a separate device, or wear it all the time like a “tattoo” sensor. And, while machine washing may damage other flexible devices, our devices are quite robust because we base them on materials that are well established for screen-printing on textiles.”

Ajit Khosla

Ajit Khosla, technical editor of the Journal of The Electrochemical Society.

Ajit Khosla, technical editor of the Journal of The Electrochemical Society, says Gray’s approach is a “very interesting and an economical process used to make microfluidic channels on the fabric itself.”

“They’re using screen printing to fabricate microchannels and embed flexible sensors on the fabrics. Materials being used and developed by Dr. Gray’s group can under hundreds of wash cycles and still maintain its reliability,” explained Khosla. “This is a significant step towards realizing wearable textile-based sensor technology, to reach to a level of commercialization where the garment industry/textile manufacturers can easily integrate and work with the developed technology.”

He adds that the possibilities are endless.

“It’s shown sodium as one of the biomarkers it can detect, but I’m sure with the integration of few other sensors they’ll be able to detect biomarkers found sweat such as chloride, potassium, ammonium, alcohol, peptides, proteins and lactate. Dr. Gray’s research work is interesting in the sense that it employs a very low-cost fabrication process. Some of the base materials which are being used by her research group are already a standard in the textile industry, this makes integration of microchannels along with different types of sensors feasible, leading towards commercialization,” said Khosla, who can see the technology eventually being used by military personnel, athletes, fitness-pros, senior citizens or even health enthusiasts who are looking to perform to the best of their ability.

Gray agrees.

“This kind of technology can potentially sample salt, lactic content, and pH. For someone who is elderly, it could potentially measure dehydration and fatigue. It can be applied to many other items of clothing as well, like sweatbands or safety vests. What we’ve published is an enabling technology for all these things,” said Gray.

Gray and Chung aren’t the only ones working with textile technologies. The Otherlab team presented a demo of their work in “Adaptive Apparel for Personalized Thermal Comfort” at the 2019 ARPA-E Energy Innovation Summit. The team’s temperature-sensitive, adaptive textile structure offers a large insulation change in response to small differences in temperature. They believe that by coupling advanced production techniques with standard materials creates, it will create an opportunity in the market for thermally responsive textiles with a low barrier for adoption. Learn more here.

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This editors’ choice paper is available to read for free, online in the Journal of The Electrochemical Society.

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