MEMS-based spectrometric sensor for the measurement of dissolved CO2

In the last few years several types of MEMS-based spectrometer systems emerged, mainly addressing the NIR spectral range. The presented MEMS-based sensor prototype operates in the mid-IR range between 2200 cm^-1 and 2500 cm^-1. The main element is a blazed micro-electro-mechanical reflective grating device with an aperture of 3 times 3 mm². The optical setup of the sensor corresponds to a Czerny-Turner type monochromator with an immense potential for further miniaturization due to its MEMS core. This allows designing and building competitively priced handheld analyzers for a range of applications that up to now has been restricted to large and expensive instruments. This work focuses on the development of an analyzer for dissolved CO₂ showing the methodology and also first implementation steps towards a sensor solution. CO₂(aq) calibration samples were prepared by different NaHCO₃ concentrations in solution. Spectra and calibration data acquired with the prototype are presented.