Work

A MEMS Microbolometer-Based ATR Mid-Infrared Sensor for Direct Dissolved CO2 Detection and UV-Induced Sediment Carbon Assay in Aquatic Environments

Year: 2026

Type: article

Abstract: Monitoring dissolved carbon dioxide (CO2) in aquatic and sediment systems is critical for understanding carbon cycling and climate feedback. This study develops and characterizes a compact, low-cost microbolometer-based attenuated total reflectance (ATR) mid-infrared sensor for direct dissolved CO2 measurement in liquid and soil-water environments. The system integrates a ZnSe ATR crystal with custom suspended SiN membrane microbolometers and uses evanescent-wave absorption at 4.26 μm with a broadband LED source and computational spectral reconstruction, eliminating the need for an interferometer. Calibration shows excellent linearity (R2 ≈ 0.99) over 50–1000 ppm CO2, with a practical limit of detection (LOD) of ~26–35 ppm at 5–25 °C. UV-induced CO2 generation from soil-water mixtures was investigated across UV wavelengths, revealing UV-C (254 nm) as optimal, producing net ΔCO2 ≈ 339 ppm above ambient levels in 30 min. Environmental factors (temperature 5–35 °C, pH 5–11, pressure 1–1.5 ATM, dissolved organic carbon) were systematically evaluated, confirming robust sensor performance (accuracy >90%, correlation r > 0.98 with reference instrument). This sensor represents the first integration of MEMS microbolometer detectors with ATR evanescent-wave spectroscopy for liquid-phase dissolved CO2, enabling real-time monitoring and rapid sediment organic carbon assessment in a field-deployable platform.

Source: Sensors

DOI: 10.3390/s26092689