Breaking the Size Barrier in CO2 Sensing

11 janv. 2022

Consumers in today’s economy are increasingly preferring smaller and smaller devices. In this article, learn how the latest ultra-compact CO2 sensor from Sensirion achieves an unparalleled price/performance ratio while taking up less board space.

Sensirion once again proves to be a pioneer in innovation for environmental sensing solutions. The SCD4X represents the first CO₂ sensor in miniature format, having a space requirement of only one cubic centimeter. This innovation is based on the principle of photoacoustic sensor technology, combining minimum size with maximum performance and opening up numerous new possibilities for integration and application. Due to its unparalleled price-performance ratio, the SCD4x is particularly suitable for series production and cost-sensitive applications.

PASens^® Technology is the photoacoustic CO₂ measurement innovation that makes the SCD4X possible. In short, the CO₂ concentration is determined as follows:

● The SCD4X’s light source is switched on and emits narrowband IR light into the measurement volume. This leads to vibrational excitations of the gas molecules to be measured, here CO₂.

● After a short time (typically a few milliseconds) the oscillations subside, which leads to an increase in temperature, which in turn leads to an increase in pressure.

● Compared to the excitation and de-excitation times of the gas molecules, the pressure inside the measuring chamber balances out quickly, so that the pressure increase can be recorded by a microphone connected to the measuring chamber.

● After several 10ms the light source is switched off, whereby the temperature and thus the pressure decreases due to thermalization of the measuring cell with the environment and the system returns to its initial state.

● The measurement process is repeated several times to increase the signal-noise ratio of the generated signal.