MTS2SENS Dual-Channel Thermopile IR CO2 Sensor – TO-39, NDIR Gas Detection

The MTS2SENS CO2 sensor is a dual-channel thermopile infrared (IR) detector designed for non-dispersive infrared (NDIR) carbon dioxide measurement. Manufactured by Micro-Hybrid Electronic GmbH, the MTS2SENS series is characterized by particularly high detectivity and durability, making it suitable for demanding gas-analysis applications in medical technology, environmental engineering, industrial process control, and safety systems.

Each detector contains two independent thermopile chips housed in a compact TO-39 metal package. The CO₂ measurement channel is equipped with a narrow-band filter optimized for the 4.26µm absorption band of carbon dioxide, while the second channel serves as a reference channel with a filter at a wavelength where no CO₂ absorption occurs. This dual-channel configuration compensates for drift and interference from source aging, temperature changes, and window contamination, significantly improving long-term measurement stability. The detector is backfilled with krypton gas to enhance sensitivity and detectivity, and it includes an integrated PTC Ni1000 thermistor for accurate reference temperature determination.

Two variants are available in the MTS2SENS family: the MTS2SENS200, which uses 200 BiSb/Sb thermocouples per chip for maximum sensitivity (up to 171 V/W) and detectivity (up to 6.27 × 10⁸ cm√Hz/W), and the MTS2SENS44, which uses 44 thermocouples per chip for a more cost-effective solution with sensitivity up to 39 V/W and detectivity up to 1.61 × 10⁸ cm√Hz/W. Both variants operate over a -20°C to +85°C temperature range and are optimized for CO₂ detection with a filter center wavelength (CWL) of 4265 ± 25 nm and a half-bandwidth (HBW) of 120 ± 10 nm; the reference channel uses a CWL of 3910 ± 28 nm with an HBW of 70 ± 10 nm. The sensor is a passive thermopile detector—it generates a voltage signal proportional to the absorbed IR radiation and does not include a built-in signal-processing IC, UART interface, or digital output. It is intended for integration into an external NDIR gas-analysis circuit that provides the IR source, optical path, and signal amplification.