The sensor assembly (50) includes a reaction assembly (72) having a housing (52) and a detector assembly (54) within which a layered member assembly (60) is provided. The layered member assembly (60) is a -luminophore containing reaction layer body (62) of a second wavelength different from the first wavelength upon irradiation of the first electromagnetic radiation of the first wavelength. A reaction layer body (62) that is excitable for the emission of a second electromagnetic radiation, and a temperature detection layer body (64) that emits infrared radiation, the housing (52) comprising an opening ( 78a, 78b) through which the fluid can be guided through the openings (78a, 78b), the housing (52) spatially from the reaction window (66a) and from the reaction window (66a). A temperature detection window (66b) arranged apart from each other, and the reaction window (66a) transmits the first electromagnetic radiation (E1) and the second electromagnetic radiation (E2), and the detection window (66a). 66b) is transmissive by infrared radiation (I), the detector assembly (54) comprises:-a radiation source (82) adapted to emit a first electromagnetic radiation (E1)； A radiation detector (86) configured to detect electromagnetic radiation (E2), and-to detect infrared radiation (I) emitted by the temperature sensing layer body (64), which passes through the temperature sensing window (66b). And an infrared detector (90) configured as described above. According to the invention, the reaction layer body (62) and the temperature detection layer body (64) are constructed separately from each other.センサアセンブリ（５０）は、ハウジング（５２）と検出器アセンブリ（５４）とを有する反応アセンブリ（７２）を含んでおり、ハウジング（５２）内には層状部材アセンブリ（６０）が設けられており、層状部材アセンブリ（６０）は、－発光団を含有する反応層体（６２）であって、第１の波長の第１の電磁放射線の照射によって、第１の波長とは異なる第２の波長の第２の電磁放射線の放射のために励起可能である反応層体（６２）と、－赤外線を放射する温度検出層体（６４）と、を含んでおり、ハウジング（５２）は、開口部（７８ａ、７８ｂ）を有しており、開口部（７８ａ、７８ｂ）を通って、流体が誘導可能であり、ハウジング（５２）は、反応ウィンドウ（６６ａ）と、反応ウィンドウ（６６ａ）から空間的に離れて配置された温度検出ウィンドウ（６６ｂ）とを有しており、反応ウィンドウ（６６ａ）は、第１の電磁放射線（Ｅ１）
