Identified in the 19th century, thephotoacoustic effectallows the conversion of light into sound and has been employed in devices such as non-dispersive infrared absorption spectroscopy (NDIR), which was the first commercially available device to detect gases using this effect. Modulating the light intensity produces a periodic pressure variation, which is measured with a sound-detecting device like a microphone. Criteria to compare different implementations of the photoacoustic effect include selectivity, sensitivity and size.
With today’s efforts for increasingly efficient buildings, inherently poor airflow occurs. This lack of air flow can result in depletion of oxygen levels and a build-up of carbon dioxide (CO2) concentrations. However, the detection of harmful levels can prevent health problems. Based on photoacoustic spectroscopy (PAS), Infineon created itsXensiv PAS环境传感器for sensing CO2。微型传感器克服了现有的尺寸，成本和性能挑战。
与市售的真实CO相比2传感器。在PCB上的集成（在14 x 13.8 x 7.5mm²模块中）包括PAS换能器和检测器，红外源和光滤波器，信号和算法处理的微控制器以及MOSFET芯片以驱动红外源。
TheIM69D130传感器中的MEMS麦克风检测到CO产生的压力变化2molecules with a signal-to-noise ratio (SNR) of 69 dB(A).
In addition to smart home and building automation applications such as demand-controlled ventilation systems, air purifiers and thermostats, the small size and low cost of the PAS sensor makes it applicable for in-cabin air quality monitoring in vehicles.
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