TDK uses MEMS to detect CO2 in smart buildings

  • January 11, 2021
  • Steve Rogerson

TDK subsidiary InvenSense has used MEMS technology to create a device that detects CO2 gases in smart buildings.

The TCE-11101 is for direct and accurate detection of CO2 in home, automotive, IoT, healthcare and other applications. Part of the SmartEnviro family, it is housed in a 5 by 5 by 1mm 28-pin LGA package.

The California-based company hopes this will get round problems with other gas sensors that use bulky, power-intensive and expensive optical techniques, or an intrinsically inaccurate eCO2 (equivalent CO2) approach. It consumes less than 1mW of power and provides accurate measurement of CO2 gas concentration.

Sreeni Rao, senior director of InvenSense

“Optical sensors are bulky and expensive,” said Sreeni Rao, senior director of InvenSense. “And eCO2 can be inaccurate because they don’t detect CO2 directly. So what we have done is use a MEMS approach for direct CO2 sensing.”

The InvenSense device suits applications such as fixed or robotic indoor air quality monitoring. Further, in applications such as demand controlled ventilation, it allows granular control of a HVAC system by accurately measuring CO2 levels that precisely indicate occupancy in a room or given space, information that can be used to optimise energy consumption for HVAC in smart buildings or homes.

“One of the main drivers is that air quality has become a public health issue,” said Rao. “Children are in the front line because the quality of air in schools is bad. This is also important in offices and the car, especially if you drive long distances. People also think that kitchens are safe places, but the process of cooking can cause changes that can lead to cancer.”

Specifically, heterocyclic amines created by stir frying fish are known to cause lung and other cancers.

“Of all the gases, CO2 is the biggest culprit for causing harm,” said Rao, “all the way from global warming to allergies. It is also a very difficult gas to measure. In a building, it can be affected by the level of occupancy. Sensors play a big part in controlling this.”

Features of the device include an I2C digital interface, 400 to 50,000ppm sensing range, on-board programmability via a 16bit microcontroller, background calibration for long-term stability, and RoHS and Green compliance.

Power consumption assuming a 300s measurement cycle is 0.215mA or 0.7mW. Estimated life time is more than eight years.

The device has a metal cap and integrated particle ingress filter to ensure long life operation. It includes an ASIC that provides automatic calibration and reporting, and a serial interface for data output and configuration, making it easy to integrate into an application. 

An evaluation kit and supporting software help developers evaluate the device and integrate it into their designs.

Samples of the device are available now with production due to start mid-2021.