A team led by Johns Hopkins materials scientists has developed a new type of potentially wearable sensor with specially designed plastic-like materials that can be used for environmental monitoring to detect harmful chemicals in the air, including detecting acetone in human breath, which when produced in excess amounts can be a marker for diabetes. Their research appears in the Journal of Materials Chemistry C.
“This technology could change the game in how we monitor our health and the environment,” says lead author Howard Katz, a professor of materials science and engineering. “Imagine having a small wearable device that could sniff out diabetes through your breath or alert you to dangerous air pollution in real time.”
ACETONE CONCENTRATIONS TESTED: 5-50 PPM
SENSOR RESPONSE TIME: 3 MINUTES
CHEMICALS TESTED FOR COMPARISON: 3
(ACETONE, VINEGAR, BATTERY FLUID)
DPP POLYMER VARIANTS SYNTHESIZED: 7
Katz’s team set out to modify existing organic field-effect transistors, or OFETs (electronic switches made from carbon-based materials that can change their electrical properties when exposed to chemicals) to elicit heightened electrical responses to volatile organic compounds, including formaldehyde, dimethyl carbonate, and acetone.
“We wanted to create a semiconductor, which is a tiny switch that controls the flow of electricity in these devices, using a polymer we had experimented with before. We adjusted the polymer’s molecular composition by attaching aniline, a substance commonly used in dyes, because we thought that it would detect gaseous acetone,” he says.
The researchers already knew that diketopyrrolopyrrole (DPP) polymers were good conductors of electricity and that aniline is reactive with acetone. They combined the two to make the device especially sensitive to acetone, creating three polymers with varied concentrations of aniline.
Through controlled experiments in an airtight chamber, the team found that when acetone was introduced at 50 parts per million, the current running through the device decreased—indicating the transistors had recognized and responded to the gas. To ensure specificity, they tested other molecularly similar substances like acetic acid and dimethyl carbonate, confirming the device remained selective to acetone.
“This technology could change the game in how we monitor our health and the environment.” — Howard Katz
“We wanted to make the best combination to allow the most possible current to run through the device while maintaining its high selectivity to detect gaseous acetone,” says Katz.
Having fine-tuned their device to achieve maximum sensitivity to acetone, the team is now working to bring their technology to market as a potential wearable or flexible device for health monitoring. This work was funded by the National Science Foundation’s Partnerships for Innovation program.
— CONNER ALLEN