Deconstructing Innovations In IoT Sensors: New Combinations

Making CO2 sensors suitable for the cost-sensitive IoT market.


In 1883, Professor Warren Seymour Johnson (1847-1911) received his first patent for an electric tele-thermoscope, a device that could automatically control and regulate room temperature. Globally, this energy-efficient and comfortable thermostat system has been widely used in large buildings. To market his system, Johnson established the Johnson Electric Service Company, which eventually became Johnson Controls.

The story of Johnson Controls shows us that the innovation of end products often goes hand in hand with the differentiated innovation of sensors. For more than 100 years, sensors have continued to improve people’s work and life. As technologies for semiconductors and IoT evolve, the sensor market also faces new opportunities and missions. Sensors with smaller size, higher accuracy, better energy efficiency and lower costs are continually emerging.

New combinations

The first type of innovation comes from new combinations. “New Combinations” is an idea proposed by Schumpeter, and its connotation is to realize innovation by recombining the basic elements. Infineon’s XENSIV PAS CO2 sensor is an innovation in this mold. The XENSIV PAS CO2 sensor module integrates the highly sensitive MEMS microphones, a microcontroller and other technologies for the most cost-effective CO2 sensing solution.

At present, CO2 levels can be measured by a lot of technologies. NDIR (non-dispersive infrared) COsensors are one of the main technologies, which use the principle that CO2 to be measured absorbs infrared rays with a wavelength of 4.26μm.

Photoacoustic spectroscopy (PAS) CO2 sensors take advantage of the solid photoacoustic effect, discovered by Alexander Graham Bell in 1880. The heat produced by air absorbing light energy is presented as acoustic pressure, which is measured by pickups. The content of CO2 can then be detected based on its acoustic pressure characteristics.

PAS has many advantages such as high sensitivity, good selectivity, long life and small measurement range, but it is difficult to apply it widely in the cost-sensitive IoT market. Infineon optimizes the MEMS microphone for low-frequency signal acquisition to achieve lower-cost pickups, greatly reducing the cost.

Moreover, to increase user convenience, Infineon XENSIV PAS COintegrates on the PCB the PAS transducer, including a detector, infrared source, and optical filter; a microcontroller for signal processing and algorithms; and a MOSFET chip to drive the infrared source, so that the surface-mount device (SMD) modular packaging mode makes it easier for customers to develop and manufacture. The integrated microcontroller runs ppm calculations as well as advanced compensation and configuration algorithms to ensure long-term stability and reliability and support rich peripheral interfaces (UART, PWM, I2C, etc.).

In addition to the CO2 sensor application in indoor air quality monitoring, Infineon has announced a collaboration with Rainforest Connection (RFCx) and planned to use CO2 sensors in more intelligent IoT applications, such as forest fire prevention.

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