Japanese firm Alps Alpine has developed an ambient air sensor module that can help prevent the spread of Covid-19.

The module can perform high-accuracy sensing of CO₂ concentrations, temperature and humidity in the immediate surrounds. It could be used in restaurants and entertainment facilities to monitor indoor ventilation, temperature and humidity indoors as part of Covid-19 prevention measures.

Other sensors can be included for detection of PM2.5, volatile organic compounds (VOCs) and alcohol.

Alps Alpine says it will proceed with market research with a view to deploying the module for diverse applications, such as energy-saving functionality in major appliances to help combat global warming and automotive features to stop drivers falling asleep at the wheel. Mass production is scheduled to begin next year.

Despite progress made in the development of vaccines, there is still no end in sight for the global Covid-19 pandemic. Japan’s Ministry of Health, Labour & Welfare has suggested three characteristics common among places where clusters of infections emerge: closed spaces with poor ventilation; crowded areas with many people; and people talking with each other within arm’s reach.

Various strategies have been introduced to prevent infections. For example, businesses operating spaces where people gather in close quarters, such as restaurants and entertainment facilities, have limited entry, shortened hours, implemented hand sanitising and temperature taking, and ensured ventilation.

Ensuring constant ventilation with windows or doors open the whole time can affect the temperature and humidity inside, making it difficult to maintain a pleasant environment. The other option is routine ventilation, with priority placed on regulation of temperature and humidity. The problem here is it is hard to tell whether the level of ventilation is effective in preventing virus transmission.

This has heightened the need for high-accuracy CO₂ sensors – for determining optimal ventilation timing – and high-accuracy temperature and humidity sensors to help restore comfortable conditions after the disruption caused by ventilation.

Alps Alpine has developed sensors to measure changes of a wide range of parameters besides CO₂, temperature and humidity, including air pressure, load and electric current. These sensors have been integrated into diverse products, such as automobiles, consumer electronics, smartphones and industrial equipment. Using this expertise, it developed the ambient air sensor module.

This was developed through a partnership with Swiss company Sensirion Holding. The module detects ambient CO₂ concentrations and temperature and humidity levels with high accuracy and can help prevent Covid-19 transmission while maintaining a comfortable indoor environment.

For CO₂ sensing, many existing products use non-dispersive infra-red (NDIR) spectroscopy. The CO₂ concentration is determined from the change in the amount of infra-red light absorbed by CO₂ molecules between an IR emitter and receiver. The large size of sensors is an issue given that detection accuracy corresponds to the distance the infra-red light has to travel. Another concern with NDIR is the potential for the axis of the emitted infra-red light to shift during end-product design or transportation, leading to detection errors.

The CO₂ sensor inside the Alps module uses photoacoustic spectroscopy. Here the CO₂ concentration is ascertained from the sound of CO₂ molecules captured by a microphone as they vibrate on contact with emitted infra-red light.

Because detection accuracy is not dependent on the distance travelled by the infra-red light, Alps managed to maintain high accuracy while realising a sensor measuring 10.1 by 10.1 by 6.5mm. And because there is no longer a need to place a detector opposite the IR emitter, as is the case with an NDIR sensor, external impacts will not have an effect, enabling stable performance.

Expertise in module creation built up through many years of sensor development was also used to offer the option of including VOC and alcohol sensors in addition to the CO₂, temperature and humidity sensors.

Besides monitoring ventilation in restaurants and entertainment facilities, it could be effective in applications such as energy-saving in major appliances and automotive features to stop drivers falling asleep at the wheel. Market research will be conducted in Japan and globally with the aim of achieving sales in excess of ¥1bn during fiscal 2023.

Market deployment of the module can help fight Covid-19 transmission and global warming, and

contribute to safe mobility.