Towards a Miniaturized Ambient Ammonia Detection System

Abstmct The development of a miniaturized ammonia sensor is described. First, gas is sampled into an acid sample solution using a miniaturized gas sampler. Subsequently, the solution is pumped into a selector, comprising two channels separated by a gas permeable, water repellent polypropylene membrane, while adding an alkaline solution to dissociate all acid gasses and neutralize the alkaline gasses. The resulting gaseous ammonia can diffuse through the membrane into a purified water stream where an electrolyte conductivity sensor quantifies the resulting ammonium concentration. The realized system has a detection limit for ammonia below 1 ppm and is shown to be selective with respect to normal ambient carbon dioxide concentrations.