Portable Breath Sensor Detects Pneumonia Biomarkers in Minutes

Breath-based diagnostics promise faster answers but typically rely on bulky instruments unavailable at most points of care. Detecting trace disease biomarkers in exhaled breath has therefore been challenging outside specialized labs. Researchers now report a portable sensor that captures and reads synthetic pneumonia biomarkers from breath within minutes.

At the Massachusetts Institute of Technology (MIT), engineers have developed a chip-scale breath sensor designed for rapid, point-of-care detection of pneumonia and other lung conditions. The system pairs inhalable nanoparticles carrying synthetic biomarkers with a surface engineered to trap and read those biomarkers after disease-specific cleavage. The team plans to incorporate the sensor into a handheld instrument for use in clinical or at-home settings.

The device, called PlasmoSniff, operates by leveraging plasmonics and Raman spectroscopy. Patients would inhale nanoparticles tagged with synthetic biomarkers that cleave only in the presence of disease-related enzymes, such as those associated with pneumonia. Cleaved biomarkers are exhaled and pass through a nanogap formed between a thin gold film and gold nanoparticles coated with a porous silica shell. Water-mediated hydrogen bonding within this 5-nanometer gap captures the target molecules, while plasmonic resonance amplifies their Raman scattering, enabling identification by their vibrational “fingerprints.”

For the study, researchers evaluated the sensor using samples of lung fluid from healthy mice spiked with pneumonia biomarkers previously developed by the team. The samples were evaporated to simulate exhaled breath, the sensor was mounted on the vial cap, and a Raman spectrometer measured scattered light as vapor passed through the device. The sensor quickly detected pneumonia biomarkers at extremely low, clinically relevant concentrations. Earlier work reported in 2020 showed these biomarkers appear in infected mice at about 10 parts per billion using mass spectrometry.

The study is published online in Nano Letters. Several characterization and fabrication steps were conducted at MIT.nano. The team notes the platform can detect diseases beyond pneumonia, as well as non-disease biomarkers, provided the target has a known vibrational fingerprint.

“Our next goal is to have a breath collection system, like a mask you can breathe into. A patient would first use something like an asthma inhaler to inhale the nanoparticles. They could then breathe through the mask sensor for five minutes. We could then integrate a handheld Raman spectrometer to detect whatever biomarker is breathed out, within minutes,” said Aditya Garg, a postdoc in MIT’s Department of Mechanical Engineering.

“It’s not just limited to these biomarkers or even diagnostic applications. It can sniff out industrial chemicals or airborne pollutants as well. If a molecule can form hydrogen bonds with water, we can use its vibrational fingerprint to detect it. It’s a pretty universal platform,” said Loza Tadesse, assistant professor of mechanical engineering at MIT, who is leading the project.

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MIT Department of Mechanical Engineering