Sensors And Sensibility: This Breakthrough Could Lead To Better Ways For Spotting Dangerous Gases

Radislav Potyrailo, a principal scientist at GE Research in Niskayuna, New York, has a saying he picked up from one of his mentors: “A day in the library is worth a year in the lab.” So, while other scientists might spend their free time hiking or fishing, Potyrailo likes to pore over the footnotes of scientific journal articles looking for details about how others have tried and failed — or succeeded — and the nuances of their experiments.

The Ukraine native, who came to the U.S. in 1993 to study analytical chemistry at Indiana University in Bloomington, has visited scientific libraries from Moscow to Manhattan and corresponded with scientists all over the world, all in the name of curiosity. “It’s all about finding the knowledge that is out there and then building a bridge to the future,” he says.

Potyrailo also gains inspiration from the natural world. In an earlier project, he and his research team created a toxic chemicals-detecting film for homeland security modeled after structures on the wings of iridescent Morpho butterflies. Potyrailo, whose background is in optoelectronic engineering, had studied the scales on the butterfly wings to understand how they absorb and bend light. The development was just one example of his creative, interdisciplinary approach to designing new technologies.

His most recent achievement is an improvement on gas sensors, which alert people to the presence of dangerous chemicals for industrial safety. Small as a grain of rice and impervious to changes in temperature, these new gas sensors might be used someday in drones or in wearable applications to help keep workplaces and people safe. In May, the discovery made the cover of the journal Nature Electronics.

His latest project led him to question the fundamental assumptions of conventional gas sensors. When exposed to a gas, the activated sensor shows a dramatic change in its resistance. That change can indicate a high level of a highly flammable gas. Used widely, they have helped people avert many fires or other accidents.

But these conventional gas sensors perform only within a certain range. Temperature and humidity affect their results. And they only have one output such as resistance, so if you want to test different gases, you need to incorporate them into a complex array, which quickly becomes large, expensive and power-hungry.

Rather than trying to push the conventional technology further, Potyrailo sought a different perspective. “It boils down to understanding the relations between the things that are involved in different measurements, and once you understand them at some deeper level and see how they’re related, you can come up with solutions as an industrial scientist,” he says.

From the ideas he gathered through his exhaustive reading, he decided to run an alternating current electric field through a material over its dielectric relaxation region. To explain how it works, Potyrailo uses the analogy of looking at a famous painting: Leonardo da Vinci’s “Mona Lisa." Examine this painting turned on its edge, he says, and you see a single line. That represents the single output of a traditional sensor. But turn this painting perpendicular to show its surface, and all the crucial details suddenly appear.

That’s similar to what happened when Potyrailo’s team used a principle called dielectric excitation, which is driven by an alternating current to activate the sensors. “If you have the right variable when you turn, you see multiple colors in the painting,” he says. Or, in the case of the gas sensor, multiple outputs that tell users much more about the atmospheric conditions they are trying to measure.

As a result of this breakthrough, the sensors developed by Potyrailo and his team are much smaller, use less power, and are more reliable, accurate and functional than the traditional models. The research was partly funded by the Centers for Disease Control and Prevention’s National Institute for Occupational Safety and Health. 

The research team demonstrated the effectiveness of its approach with wireless sensors that it tested under increasingly harsh conditions: first in their research center, then eventually in the field in states such as North Dakota and Texas. It wanted to see how well the sensors detected greenhouse gas pollutants such as methane under more-extreme temperature and humidity conditions. The team has also tested these new sensors for the detection of a broad range of volatiles of environmental and industrial importance: benzene, toluene, hydrogen sulfide, hydrogen, carbon monoxide, ethane, propane, acetylene, methanol, ethanol, acetone and formaldehyde. In the years ahead, this design could be used for sensors that detect gas leaks at businesses and homes, survey environmental pollutants or hazardous industrial areas, or monitor indoor air quality.

Potyrailo, meanwhile, is already in pursuit of his next discovery. His upcoming project, he says, is “a little crazier than this one.” He wants to design sensors that he describes as “not afraid of anything” in terms of interferences from temperature, humidity or other environmental conditions that would normally harm their performance. They would be used in applications where you don’t have an opportunity to calibrate the devices. That next breakthrough, he says, “is another painting that we are working on to unveil soon.”