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In this paper, we will present the development of a compact LED-based optical gas sensing system in the ultraviolet-C spectral region. This includes the design of the LED heterostructure emitting near 226 nm, the development of an LED chip, and the implementation into a gas sensing system capable of detecting nitrogen oxide concentrations in the ppm range.

A real time, high resolution LED based, spectroscopic gas concentration measurement system is presented. This kind of measuring techniques was enabled by the advances in the fabrication of ultraviolet LEDs (UV-LEDs). The system presented here has a relatively compact design and small application efforts. Different hardware setups have been evaluated to design a system for real time high resolution LED absorption spectroscopy. Applied are two concave mirrors, two photo detector diodes and a 405nm LED mounted in a small device. A standard low power microcontroller was applied as signal processor. The few, robust, reasonable priced components enables high volume applications for this sensor. Different optical simulations provide optimized system parameters for gas concentration measurements in the low ppm range. NO2 concentrations of 200 ppm have been measured with a resolution of ∼1.5% counts (16-Bit-ADC). Therefore the ppb range becomes an available measurement range with higher ADC-Resolutions.