NDIR Thermopile-Based Gas Sensing Circuit

Complete thermopile-based gas sensor using the nondispersive infrared (NDIR) principle. This circuit is optimized for CO2 sensing, but can also accurately measure the concentration of a large number of gases by using thermopiles with different optical filters. The printed circuit board (PCB) is designed in an Arduino shield form factor and interfaces to the EVAL-ADICUP360 Arduino-compatible platform board. The signal conditioning is implemented with the AD8629 and the ADA4528-1 low noise amplifiers and the ADuCM360 precision analog microcontroller, which contains programmable gain amplifiers, dual 24-bit analog-to-digital converters (ADCs) and an ARM Cortex-M3 processor