Performance Analysis of a Novel Pyroelectric Device for Non-Dispersive Infra-Red CO2 Detection

We present the performance characteristics of a digital output thin-film pyroelectric sensor for use in non-dispersive infra-red detection. The single channel pyroelectric sensor device was fitted with band-pass optical filter with a central wavelength of 4:26$\mu$m for the detection of carbon dioxide. The classification reported here is concerned with the stability of the device for long-term measurements, with systematic drift not dominating measurement error even after 10 hours operation. Comparative NDIR measurements were made for this novel pyroelectric device using two different optical sources, a standard filament lamp and a black body radiation source, operated at 5 Hz repetition rates. The overall limit of detection for the NDIR sensor was calculated to be 6 ppm and 3 ppm for CO2 for the filament and blackbody source respectively, when the sensor was temperature stabilised at 35 oC and data was averaged over 110 minutes. The single shot measurement error was calculated to be 48 ppm and 22 ppm for the lamp and blackbody respectively, when the sensor temperature was stabilised at 35 oC. The response of the detector to increasing temperature was found to exhibit a trend in the signal output directly proportional to the pyroelectric coefficient, this was also evident during flow tests when the flowing gas cooled the device. The result of changing both the concentration of analyte and flow rate is also covered. This is the first time the performance of a fully digital output pyroelectric detector has been reported.