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 and 2500 cm. The main element is a blazed micro-electro-mechanical reflective grating device with an aperture of 3x3 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.