Infrared wavelength-specific gas sensing with pyroelectricity at room temperature

Abstract

Pyroelectricity is a phenomenon when electricity is generated upon the detection of temperature change. The pyroelectric effect occurs when spontaneous polarization changes result in charge accumulation on the material's surface. Therefore, sandwiching pyroelectric material between two metal layers enables charges to be collected at the pyroelectric-metal interfaces to generate electrical signals. Our work highlights a new combination of high transmittance (84.5%) and a lower number of layers alternating stack of Germanium/Aluminum oxide bandpass filter centered at 3250 nm with a customized thin lithium tantalate (LiTaO3, 60 mu m) pyroelectric detector to demonstrate gas sensing with pyroelectricity at room temperature. In the presence of ethanol in the gas cell, the detection system shows a voltage signal drop attributed to the pyroelectric effect. This effect happens when light is absorbed by the ethanol molecules, thus, altering the detected temperature. As the ethanol volume concentration increases from 6% to 100%, the detected voltage difference increases from 0.1 V to 0.8 V. Thus, enabling the system to distinguish the various ethanol concentrations. The measurement system's sensitivity can detect and quantify the concentration of alcoholic beverages like beer(5%) and wine(13%). Notably, a complete detection is possible in less than 2 min, and the corresponding minimum detection level of 1700 ppm.