The researchers made sensors from porous thin films of organic conductive plastics with the goal of portable, disposable devices for medical and environmental monitoring. The results of the study, led by professor Ying Diao, were published in the journal Advanced Functional Materials. Diao’s group collaborated with Purdue University professor Jianguo Mei on this work.
“In the clinical setting, physicians use bulky instruments, basically the size of a big table, to detect and analyze these compounds. We want to hand out a cheap sensor chip to patients so they can use it and throw it away,” said Diao, a professor of chemical and biomolecular engineering at Illinois, in ap press release.
Not sensitive enough
So far, most researchers have tried using organic semiconductors for gas sensing, but the materials were not sensitive enough to detect trace levels of disease markers in breath. Diao’s group realized that the reactive sites were not on the surface of the plastic film, but buried inside it. Diao: “We developed this method to directly print tiny pores into the device itself so we can expose these highly reactive sites. By doing so, we increased the reactivity by ten times and can sense down to one part per billion.”For their first device demonstration, the researchers focused on ammonia as a marker for kidney failure. Monitoring the change in ammonia concentration could give a patient an early warning sign to call their doctor for a kidney function test.
The material they used is highly reactive to ammonia but not to other compounds in breath, according to Diao. But by changing the composition of the sensor, they could create devices that are tuned to other compounds. For example, the researchers have created an ultrasensitive environmental monitor for formaldehyde, a common indoor pollutant in new or refurbished buildings.