How Gas Sensors can Help with Controlling COVID-19

16-11-2020 |   |  By Robin Mitchell

Recently, research firm IDTechX explored the use of CO2 sensors to control COVID-19 transmission better while the world awaits the release of the vaccine. How can the transmission of COVID-19 be minimised, what sensor technologies exist, and how can they be used to help decrease COVID-19 transmission?

How is COVID-19 transmitted?

The current COVID-19 pandemic has shaken the world to its core, and the result of global lockdowns to prevent the spread of the virus has had massive economic consequences including the closure of many thousands of businesses and many tens of millions of people left without jobs. However, even a year on from the first cases of COVID, the exact method in which the virus is transmitted is still unknown. Still, studies suggest that COVID is transmitted by either direct contact with those infected, indirect through surfaces that infected individuals have touched, and in saliva, droplets suspended in their air when coughed or sneezed from an infected individual. While some patients have shown the virus to exist in faecal matter and urine, it is more likely that the virus mostly utilises aerosol transmission as one of the main symptoms of COVID is frequent sneezing (viruses often cause symptoms which improve their transmission rate).  

As a result, many restrictions and rules which have been put in place attempt to minimise COVIDs ability to infect a population. Firstly, lockdowns reduce contact between people which makes it hard for any disease to spread. Secondly, the use of masks prevents infected people from spreading the virus into the surrounding air. Thirdly, the use of gloves prevents infection through contact with infected surfaces, but this is only effective when not touching the face and frequent changing of gloves. 

Metal-Oxide vs NDIR Gas Sensors

Increasingly advanced sensor technology will allow for electronic systems to play a key role in future pandemics as they will be able to track people’s movements, determine the presence of particulates in the air, and monitor key variables in the surrounding atmosphere which may aid the spread of any infection. However, choosing the right sensor technology is critical, so what is the difference between the two main gas sensing technologies Metal-Oxide and NDIR?

Chemiresistors are sensors that utilise a material whose resistance depends on the presence of specific chemicals in the surrounding environment. These sensors are often referred to as metal-oxide gas sensors as the material they utilise is often a metal-oxide (such as Tin oxide). Nondispersive Infrared sensors, or NDIR, are those that utilise a form of spectroscopy whereby light is shone into the environment under test, and the spectrum of that light is received and recorded. It is called nondispersive because it does not use a dispersive element such as a prism for selecting the frequency of light to record. 

One of the biggest differences between metal-oxide and NDIR sensors is that metal-oxide sensors need to interact with their environment chemically and as such, can take long periods of time to provide accurate recordings. NDIR sensors, however, are indirect, which not only provides instant results but also allows for effective isolation between the environment and the sensor. This is especially useful in hazardous environments such as biological or explosive atmospheres. NDIR can also be made to detect most gasses as it relies on spectroscopy, whereas metal-oxide sensors often only react with compounds that have reactivity. This means that CO2 sensors cannot be made using metal-oxide technology, and those that claim they can often use inference by detecting other compounds and thus determining the CO2 concentration from those compounds.


Research Firm IDTechX Explores the Use of Gas Sensors to Reduce COVID-19 Transmission

Recently, the research firm IDTechX have explored how NDIR gas sensors can be used for determining the quality of air in a room, and thus identify areas that may pose COVID transmission risks. The concept of gas detection works on the assumption that a room which is poorly ventilated or has too many individuals, will show an increase in CO2 concertation in the air. From there, smart systems connected to the sensors can then alert individuals to the increased risk of virus transmission, or environmental controls can be activated to replace the air in the room with cleaner, outside air. The use of sensors to monitor air quality is already being put in place in schools across Germany, and these sensors utilise a traffic light colour system to indicate to those nearby the quality of the air. According to IDTechX, it is believed that by 2021, Germany will have installed over 50,000 air quality sensors and that the demand for CO2 sensors will increase to over 1 million units globally.

Of course, the mass installation of such sensors not only provides the ability to fight against COVID but other airborne diseases that will eventually occur in the future. Thus, the next COVID pandemic will not only have better protection methods from the public, but from smart systems installed all around the world, and such technology may be able to better mitigate against the economic effects of lockdowns. The use of such technology also provides a whole wealth of environmental information that could prove beneficial to climate researchers. 

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By Robin Mitchell

Robin Mitchell is an electronic engineer who has been involved in electronics since the age of 13. After completing a BEng at the University of Warwick, Robin moved into the field of online content creation developing articles, news pieces, and projects aimed at professionals and makers alike. Currently, Robin runs a small electronics business, MitchElectronics, which produces educational kits and resources.

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