Multi-Function Sensory System for Detection of Ammonia

Abstract

Ammonia is a highly toxic gas with implications for human and animal health. This effort aims to develop a low-cost multi-array orthogonal sensor for detecting a low concentration of ammonia in a poultry house. To approach this problem, a novel multi-array electro-thermal and Metal oxide solid state gas sensor are developed. Its design consists of a microfabricated suspended MEMS bridge, a resistance temperature detector (RTD), a low-pass loop filter H(s), and a heater amplifier for the micro-oven. The resistive element is used as the micro-oven heater. The sensing platform comprises of a low-cost thermal conductivity sensor (TCD), and Metal oxide (ZnO, NiO-ZnO, Au-ZnO) solid-state sensors. From this study. we concluded that the thermal conductivity sensor provides a linear level of detection(LOD) of 1 ppm at 30-80 % relative humidity with 100 ns response time and 5 years of lifetime while the Au-ZnO solid state sensor has sub ppm limit of detection and response time of ~ 2 minutes. Figure 1