Electronic nose detects SARS-CoV-2 from breath

Early diagnosis of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of the coronavirus disease 2019 (COVID-19) pandemic, is important to limit its transmission. In this context, a reliable point-of-care screening system is urgently needed. Some of the characteristics needed for mass testing of COVID-19 include short detection time, inexpensive procedure, and simple sample collection method.

Study: Detection of COVID-19 from exhaled breath – Clinical studies. Image Credit: Danilina Olga / Shutterstock.com

Background

The reverse transcription-polymerase chain reaction (RT-PCR) test is the gold standard for detecting COVID-19. However, this technique cannot be used for rapid and mass testing, as RT-PCR requires trained personnel to take test samples from the infected person and perform this test.

Thus, the development of an exhaled breath analysis device for the rapid detection of COVID-19 could be extremely practical. This type of device could be very beneficial due to its simple sample collection method, non-invasive nature, reusability and ability to provide results in a short interval.

Interestingly, previous studies have reported an odor distinct from COVID-19 patients that was easily detected by dogs. The compound that was detected by the dog was then analyzed by gas chromatography-ion mobility spectrometry.

Breath samples can be used to detect SARS-CoV-2 infection by determining the presence of volatile organic compounds (VOCs) in the sample. The exhaled breath of a COVID-19 patient contains specific VOCs that arise due to altered metabolic reactions or changes in the microbiota of the lungs during infection.

Exhaled breath, which contains various gases including VOCs, can be acquired through an electronic nasal device. Unlike RT-PCR tests, an electronic nasal device can easily detect SARS-CoV-2 infection during its various stages of development.

Several studies have reported the development of nanoparticle gas sensors, carbon nanotube sensors, and metal oxide gas sensors for the selective detection of VOCs. Previous studies have also shown that exhaled breath analysis techniques can detect viruses, such as influenza and human rhinoviruses, through analysis of exhaled VOCs using an electronic nasal device.

There are several concerns regarding the detection of COVID-19 by an electrical nasal breath analyzer, such as the limited repeatability of detecting infections by this approach. Moreover, these devices cannot be applied in various environmental conditions for the collection and analysis of breath samples.

About the study

In a recent study under review in the journal Scientific Reports and published on the preprint server Research Square*, researchers discuss the development of an electronic nose device for VOC detection using commercial gas sensors, which require little power to operate at high temperatures. Here, researchers conducted clinical studies in the northern part of Poland to assess the effectiveness of the device.

In the current study, the scientists carried out the experimental studies in hospital wards dedicated to the treatment of patients infected with SARS-CoV-2 during the third wave of COVID-19 in Poland, which took place between March and July 2021. Breath samples were obtained from the university. Center for Maritime and Tropical Medicine, Poland, then analyzed by the new electronic nasal device.

A total of 56 breath samples, which consisted of 33 samples obtained from severely infected COVID-19 patients, 17 from healthy controls and six from ambient air, were used for the current study. All samples were taken in the morning after study participants had brushed their teeth but before breakfast. This measure was taken to reduce the sampling of contaminated breath.

Approximately 130 mL of breath sample was collected by a BioVOC™ breath sampler from all study participants breathing in the same hospital ward atmosphere.

Developed electronic nose analyzing the exhaled breath sample using the end-expiratory portion of the final wave, and (b) illustration of breath sample collection with the BioVOCTM.

Developed electronic nose analyzing the exhaled breath sample using the final tidal part of the final wave, and (b) illustration of breath sample collection with the BioVOCMT.

Study results

Breath samples obtained from COVID-19 patients showed higher moisture levels than controls. Notably, the electronic nose device used here provided a better detection rate of COVID-19 for the elderly group than for younger patients. In fact, the device provided detection accuracy as low as 80% in some younger patients.

The device described here could be used to assess the effectiveness of a particular medical treatment or for mass pre-screening. One of the challenges associated with this device is its limited accuracy when used outdoors; thus, future studies should focus on improving its accuracy and improving its resistance to fluctuating environmental factors.

Future research

Taken together, the results of the present study strongly suggest that the use of commercial gas sensors is favorable for the identification of VOCs in breath samples. Therefore, the device and methodology used in the present study could be practically applied for the detection of COVID-19.

In the future, further research is needed to determine why repeated calibration of the device should be performed during operation. In addition, a more efficient and faster procedure for cleaning the gas sensor is needed.

*Important Notice

Research Square publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be considered conclusive, guide clinical practice/health-related behaviors, or treated as established information.

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