Sept. 18, 2023 –The race is on to “sniff out” diseases in human breath.
Hundreds of breath analyzers that sense odorous compounds linked to cancers are under development, but only a handful have reached the market or are in clinical trials. Some, known casually as artificial or electronic “noses,” mimic biological systems.
The latest platform, from researchers at Seoul National University in South Korea, features a microchip that can let a computer “smell” spoiled food. Unlike previous artificial noses, this one is more compact and energy efficient.
“The main improvement is they have implemented some computation on the chip. This is extremely useful,” said Debajit Saha, PhD, an assistant professor of biomedical engineering at Michigan State University, who was not involved in the study. The design eliminates the need for a separate computing device, saving energy.
“For applications like food safety, where you need to make recurring measurements, less energy consumption is good,” Saha said.
How Scientists Make Tech That Can Smell
Known as artificial olfactory systems, or AOSs, this technology first emerged in the 1980s. In a typical AOS, sensors gather analog data that must be converted into digital data by separate computing devices, before being delivered to a processor that calculates gas concentration levels. But this process is time- and energy-intensive, and data can get lost in transit.
The researchers created a chip, or sensing unit, that gathers information and converts only the essential data, without a separate computing device. The platform could eventually be coupled with smartphones, delivering results wirelessly.
“In order for the AOS to be applied to various non-plugged devices such as mobile phones, small size and excellent energy efficiency are essential,” said study co-author Jong-Ho Lee, PhD, a professor of electrical and computer engineering at Seoul National University.
Fueled by low-power microheaters, the sensors feature thin zinc oxide films that can detect trace amounts of hydrogen sulfide and ammonia gases, the telltale signs of spoilage in high-protein foods.
To test the platform, the researchers placed chicken in a container, which they connected to eight sensors. Next, they injected dry air into the container of meat. The system continually tracked emissions, calculating gas concentration levels to indicate spoilage.
The platform is “highly customizable,” said Lee, who envisions future health care applications including “disease monitoring through human breath.”
Smell-o-Meters: The Future of Cancer Diagnosis?
Cancer cells release volatile organic compounds, chemicals that smell and can serve as biomarkers for diagnosis. Despite the artificial nose’s potential for targeting these compounds, more work is needed to make that reality.
At this stage, the platform can recognize only two chemicals and measure gases in parts per million. To detect cancer and other diseases, it would need to respond to “many” different chemicals and calculate gas concentrations in parts per billion, Saha said.
Very few electronic noses are that sensitive. “The biological olfactory system is still superior,” Saha said. “That's why at the airport, you still see dogs, not devices, to test for explosives and drugs.”
His lab is taking a different approach, using live insect brains and antennae, which provide an “all-in-one device” for gas sensing and computing.
“There’s an open question of how to make chemical sensing more robust, reliable, and sensitive. Our approach is to hijack the biological brain to do the job for us,” Saha said.
His lab has detected oral cancer using locusts. And lately, they’ve been using honeybee neural signals to detect lung cancer, research that could be published soon.
So far, this research has used cell cultures with cancer biomarkers -- but the lab plans to test their approach using human breath.
Lee and his collaborators also hope to expand their research by “combining a neuromorphic system that mimics the human brain with an artificial olfactory system.” Ultimately, it could detect a wide array of gases, aiding numerous fields.