Sensor assembly for spectroscopically detecting substances

A spectroscopic sensor assembly for detecting at least one predetermined analyte constituent of a measurement fluid, where the sensor assembly comprises:

• a sensor housing with an instrument section and a specimen section,
• a radiation source which is arranged in the instrument section and is configured to emit in the direction towards the specimen section electromagnetic measurement radiation which interacts with the at least one predetermined analyte constituent,
• a detector device which is arranged in the instrument section and is configured to detect electromagnetic radiation radiating in the direction from the specimen section,
• a barrier arrangement which is transparent to the measurement radiation and impermeable to the at least one predetermined analyte constituent, where the barrier arrangement is arranged between the instrument section and the specimen section,
• a polymer matrix which is arranged in the specimen section and is configured to take up and to release again the at least one analyte constituent,
• a reflector assembly which is arranged in the specimen section with a signal side facing towards the polymer matrix and towards the barrier arrangement and with a fluid side opposite to the signal side,
• where the reflector assembly exhibits at least one passage penetrating through it through which during normal measurement operation of the sensor assembly there takes place an exchange of the at least one analyte constituent between an external measurement environment on the fluid side of the reflector assembly which during normal measurement operation contains the measurement fluid and the polymer matrix situated on the signal side of the reflector assembly, where the reflector assembly is configured and is arranged to reflect measurement radiation radiating onto its signal side from the instrument section through the polymer matrix back in the direction towards the instrument section,
• wherein the sensor assembly exhibits a spacing-securing means different from the polymer matrix which is configured to prevent an approach of the reflector assembly to the barrier arrangement.