XENSIV™ PAS CO2 Shield2Go Board

Measuring CO2 allows users to optimize comfort, energy efficiency, and health as it is a key indicator of indoor air quality. SHIELD_PASCO2_SENSOR is a development board equipped with a XENSIV™ PAS CO2 sensor. The photoacoustic spectroscopy (PAS) concept is the building block of this design.  The development kit comes with a ready-to-use Arduino library, giving users a way to develop their own system solutions by combining Shield2Go boards with Infineon My IoT adapters. My IoT adapters are gateways to external but popular IoT hardware platforms, including Arduino and Raspberry PI. This enables fast development, evaluation, and deployment of any IoT system. SHIELD_PASCO2_SENSOR is used for low- and high-volume applications alike. The intended audience for this module is application engineers, system engineers, and developers. 

Photoacoustic Spectroscopy (PAS) Principle

The photoacoustic principle was first discovered by Alexander Graham Bell in 1880. It involves the formation of sound waves due to pressure changes following light absorption in a material sample. Microphones quantify the resultant sound signal. Light intensity must be different in order to obtain this effect. The foundation of a PAS gas sensor is the idea that gasses absorb light at a particular infrared wavelength. CO2 molecules strongly absorb light at a wavelength (λ = 4.2 μm).

In PAS, pulses of light from an infrared source pass through an optical filter specifically tuned to the CO2 absorption wavelength. As a result of absorbing the filtered light at each pulse, the CO2 molecules inside the measurement chamber shake and generate a pressure wave. 

The acoustic detector, optimized for low-frequency operation, detects the sound, and the microcontroller changes the output into a CO2 concentration reading. The absorption chamber is acoustically insulated from outside noise in order to deliver accurate CO2 sensing readings.

XENSIV™ PAS CO2 Shield2Go Board Features 

The XENSIV™ PAS CO2 sensor is a carbon dioxide (CO2) sensor in a small form factor (14 x 13.8 x 7.5 mm3). The sensor saves more than 75 percent space than other available modules due to its unique PAS concept. Its simple design, SMD capability, and direct ppm readings allow quick integration into users' systems in normal or complex applications alike. 

The PAS CO2 sensor module integrates  a MOSFET, a PAS transducer, a microcontroller for signal processing, and algorithms on the same PCB. The PAS transducer has a narrowband optical filter, an infrared emitter that gives off blackbody radiation, and Infineon's XENSIV™ IM69D130 high-SNR MEMS microphone. The microphone detects the pressure changes generated by the CO2 molecules.

The XENSIV™ PAS CO2 sensor delivers high performance and accuracy at the ppm level. It comes with different self-calibration algorithms and advanced compensation features. There are a variety of configuration options, including baseline calibration and sampling rate. The SMD package is delivered in tape and reel, offering a high degree of protection against damage, dust, and electrostatic discharge (ESD). 

The XENSIV™ PAS CO2 sensor is ideal for weather stations, thermostats, air purifiers, personal assistants, and building automation. The sensor gives users the ability to monitor, analyze, and improve the air quality around them while consuming less energy. 

Shield2Go Platform

Infineon's Shield2Go boards are equipped with a single-featured Infineon IC, a standardized form factor, and a pin layout for fast orientation. Designers can stack the boards rather than soldering them because all boards have solderless connectors, which make them flexible and reusable. Shield2Go includes a specifically designed free software library for Arduino. With Infineon's My IoT adaptor, these boards are compatible with Arduino Uno. 

My IoT adapter board gives users the option to combine Shield2Go boards into systems. As a part of the evaluation environment, it also acts as a gateway to external hardware like Arduino, Raspberry Pi, or Espressif Wi-Fi Chips. The adapter offers multiple sockets, which allow a flexible combination of different Shield2Go boards. As a result, pin distribution, level shifting, or system integration turns out to be done swiftly.

Applications

XENSIV™ PAS CO2 Shield2Go Board is for applications including air quality monitoring and demand-controlled ventilation. It is also used as a major component in HVAC (heating, Ventilation, Air Conditioning) in residential and commercial areas. It is also used in lighting, air quality devices, smart thermostats, smart agriculture, and greenhouses.