News Image - Prof. Igor Paprotny in his research lab


Dr. Igor Paprotny wants to change the air quality in Chicago. To accomplish this task, he is planning to use the city as his laboratory and gather data with the help of residents as “citizen scientists.” Paprotny, an assistant professor in the Department of Electrical and Computer Engineering at the University of Illinois at Chicago (UIC), is leading the Air-Microfluidics Group (AMFG), which is a research consortium that includes UIC, Lawrence Berkeley National Laboratory, Argonne National Laboratory, University of California, Berkeley, and a researcher from the U.S. Environmental Protection Agency (EPA). The team, which includes UIC students Omid Mahdavipour, Dorsa Fahimi, and John Sabino, is developing the direct-read mass MEMS PM2.5 sensor which is a potentially wearable particulate matter sensor about the size of a memory stick that could be connected to a cell phone, and provide your exposure in real time.

“It is much smaller than the instrumentation currently used by the EPA to measure air pollution, which is about the size of a toaster or a desktop computer,” said Paprotny. “Since our sensor measures the mass of the particulates it has the potential to be very accurate, perhaps approaching EPA’s Federal Reference Method (FRM) for PM2.5, which is currently used as the gold standard for measuring PM2.5 concentration.”

Particulate matter, which is also known as “particle pollution” and “PM,” is a mixture of tiny particles and liquid droplets. Particle pollution consists of a number of components, including acids, organic chemicals, metals, and soil or dust particles. According to the EPA, “the size of particles is directly linked to their potential for causing health problems. The EPA is concerned about particles that are 10 micrometers in diameter or smaller because those are the particles that generally pass through the throat and nose and enter the lungs. Once inhaled, these particles can affect the heart and lungs and cause serious health effects.”

There is particulate matter that is 10 microns or smaller called PM10, and the even smaller one is called PM2.5, which is particulates that are 2.5 microns or smaller. A micron is 1000th of a millimeter.

“When particles get small, such as below 2.5 microns, they are even more dangerous,” said Paprotny. “The get very deep into our lungs, and we really don’t have a natural way to get rid of them. Our immune system cannot handle them because they are too big, but they are still small enough to enter deep into our respiratory system.” That is why PM2.5 is bad. Since EPA started regulating PM2.5 exposure in the 80s, the exposure limit has been revised several times as we learned how bad fine particles really are.

According to Paprotny, other low-cost sensors are not very accurate in detecting particulate matter. These sensors use an optical method, and often miscalculate their actual concentration. Other precise, mass-based (not-optical based) sensors are much more expensive – as much as $10,000 to $50,000.

“What this means is that we need a more accurate low-cost sensor,” said Paprotny. “Our sensor is currently the only sensor that actually weighs the particles and reports the concentration as a mass. We have a resonator that weighs the particles, and we pull in the air and it goes through the channels and the first thing we do is separate the bigger particles from the smaller ones – which means it gives us PM2.5. It’s currently the only technology that fits in a wearable or portable device and is capable of measuring precisely what the EPA is concerned about.” Using the “Direct-Read Mass MEMS PM2.5 Sensor,” Paprotny wants to study the air quality throughout Chicago. Due to the sensor’s small size, it will cost approximately $20 in large quantities to fabricate, while being much more accurate than other low-cost PM2.5 sensors.

“We’re in discussions to potentially work with a Chicago environmental organization to recruit “citizen scientists” to wear the sensors,” said Paprotny. “With mobile sensors across the city, we can build a map of pollution and gather data. This sensor has the potential to make Chicago a healthier city, which has big issues with air pollution and asthma. We are also starting collaboration with the School of Public Health at UIC to investigate the connection between PM exposure and health effects.”

Data from the Respiratory Health Association of Metropolitan Chicago shows that “in Cook County, 317,906 adults and 121,610 children have been diagnosed with asthma,” and “the asthma hospitalization rate in Chicago is nearly double the national average.”

“Our research could help determine quickly if the local air-pollution could cause or promote respiratory problems such as asthma,” said Paprotny. “It could help us target problem areas and implement solutions to combat the pollution in those areas. It could also, for the first time really, provide a precise measurement of personalized PM2.5 exposure in real time. A portable PM sensor attached to a cell-phone could enable all of us to scan the air around us, and determine if it’s safe to go out. This could be especially relevant with all the recent bad air-pollution in Asia. We expect air around us to be clean, and it is not always the case.”

Learn more about UIC’s the Department of Electrical and Computer Engineering and Igor Paprotny’s research here.

EPA’s Two Categories for Particle Pollution

“Inhalable coarse particles,” such as those found near roadways and dusty industries, are larger than 2.5 micrometers and smaller than 10 micrometers in diameter.

“Fine particles,” such as those found in smoke and haze, are 2.5 micrometers in diameter and smaller. These particles can be directly emitted from sources such as forest fires, or they can form when gases emitted from power plants, industries and automobiles react in the air.

By David Staudacher, UIC

Source: U.S. Environmental Protection Agency.


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