Detectivity comparison between thin-film Pd/PVDF photopyroelectric interferometric and optical reflectance hydrogen sensors

Abstract

A novel dual photopyroelectric interference (PPEI)/optical reflectance (OR) solid-state hydrogen sensor system has been developed and demonstrated. Based on the recently developed PPE-interference technique and the variations of optical and electronic properties of Pd metal in the presence of hydrogen, simultaneous signal responses were obtained from a polyvinylidene fluoride (PVDF) thin-film detector and an optical photodiode. The dual measurement of PPEI and OR channels provides not only a more reliable sensor system, but also a powerful tool to identify the operating mechanism(s) in the process of Pd/PVDF/hydrogen interaction. The experimental results show that the detectivity and the signal dynamic range of the PPEI method are much higher than those of the OR method due to the suppression of the large base-line signal and the signal noise. The comparison of PPEI and OR results reveals that both signals are mainly due to the same electronic mechanism.