CO₂ sensor

Use Infineon’s XENSIV™ PAS CO2 sensor to track the environment you are in – for improved health, productivity, and overall well-being.

Increasingly efficient building insulation can help to mitigate the effects of climate change, but heavily insulated buildings are not always good for human health. Poor ventilation can result in lower oxygen levels and a build-up of carbon dioxide (CO₂). Even moderate levels of CO₂ can have a negative impact on health and productivity. Already at 1000ppm, people begin to experience drowsiness and have difficulty concentrating. Consequently, CO₂ sensor module manufacturers are facing a growing demand for smart indoor air quality sensors that can “smell” rising levels of CO₂ and either alert the user or trigger a system response. Smart home CO₂ sensors enable real-time CO₂ monitoring for demand-controlled ventilation systems, air purifiers, and thermostats while allowing users to accurately measure and adjust indoor air quality.

With the recent pandemic, awareness of indoor air quality is rising, making accurate, affordable monitoring solutions such as the XENSIV™ PAS CO2 sensor more important than ever. It has been shown that a correlation exists between the concentration of CO₂ and aerosols, one of the transmission pathways of viruses (like COVID-19 or influenza). Therefore, if we can reliably measure the CO₂ level indoors using CO₂ sensing technology, we can actively manage the risk of virus transmission.

Widespread adoption of CO₂ sensors has so far been hampered by size, performance, and cost constraints. The XENSIV™ PAS CO2 sensor from Infineon leverages photoacoustic spectroscopy (PAS) technology to provide an exceptionally small, real CO₂ sensor, overcoming the challenges of existing carbon dioxide gas detectors. Its unprecedentedly small form factor in SMD (Surface Mounted Device) package allows for smooth high-volume assembly and easy system integration. The unique  CO₂ sensor intuitively understands its environment, using disruptive and highly accurate CO₂ sensor technology when measuring carbon dioxide detector levels.

As a global leader in sensor technology, Infineon has developed a CO₂ sensor chip that provides accurate, real-time CO₂ measurement thanks to superior MEMS technology. The MEMS-based CO₂ sensor uses Infineon’s MEMS microphone which acts as a pressure sensor and is optimized for low frequency operation. The XENSIV™ PAS CO2 sensor module integrates a PAS transducer, a microcontroller, and a MOSFET on the PCB.

There are three CO₂ sensor types that are mainly used in the industry. These include PAS (photoacoustic spectroscopy) CO₂ sensors, NDIR (non-dispersive infrared) CO₂ sensors, and EC (electrochemical) CO₂ sensors. Infineon’s XENSIV™ PAS CO2 sensor matches the performance of NDIR and EC CO₂ sensors, while being more affordable and compact, making it the ideal solution for smart home and building automation applications.

Along with size and cost advantages, the sensor delivers superior accuracy, providing a direct readout of the real CO₂ level, not simply a correlation. Infineon’s leading position in MEMS technology is the foundation for this unique and accurate CO₂ detection approach. Reliable CO₂ sensor measurement enables smart CO₂ measurement and monitoring of indoor air quality, allowing users to take control of their environmental conditions and experience improvements in health, productivity, and overall well-being. 

The PAS principle works as follows. Pulses of light from an infrared source pass through an optical filter tuned specifically to the CO₂ absorption wavelength (λ= 4.2 µm). The CO₂ molecules inside the measurement chamber absorb the filtered light, causing the molecules to shake and generate a pressure wave with each pulse. This is called the photoacoustic effect. The highly sensitive MEMS acoustic detector detects the pressure change generated by CO₂ molecules within the sensor cavity, and the microcontroller converts the output into a CO₂ concentration reading. In order to achieve a ppm reading as accurate as possible, the acoustic detector is optimized for low frequency operation, and the absorption chamber is acoustically isolated from external noise.

Infineon’s Toolbox supports this platform with a software to enable the evaluation of XENSIV^TM PAS CO2 performance.

Where to download the libraries* for XENSIV^TM PAS CO2:

Arduino library: Arduino library for Infineon's XENSIV™ PAS CO2 sensor covering interfacing and code examples.

PSoC library: This library provides APIs to interface with the XENSIV™ PAS CO2 sensor that allows user to read the CO2 concentration.

_{* We don’t have any library at the moment for apple support}

With its small footprint, XENSIV™ PAS CO2 is ideal for smart home appliances and IoT CO₂ sensor devices such as demand-controlled ventilation systems, air purifiers, thermostats, smart lighting systems, air quality monitors, weather stations, and smart speakers. By integrating CO₂ gas sensor modules into these systems, significant amounts of energy can be saved, and indoor air quality can be greatly improved. This leads to a lower energy bill and a healthier indoor environment. Infineon is making a valuable contribution enabling everyone to track their environment in a smart, easy-to-use, and affordable way – for a better and healthier life!

Using CO2 sensors in HVAC (heating, ventilation, and air conditioning) systems ensures that optimal levels of indoor air quality are achieved. Furthermore, by facilitating DCV (demand-controlled ventilation), carbon dioxide sensors lead to an increase in the energy efficiency of HVAC systems as well as significant savings on energy bills.

• Smart building
• Condition monitoring and predictive maintenance in HVAC systems
• Smart home
• Wearables