Development of MOS sensor-based NH3 monitor for use in poultry houses

To ensure poultry performance and welfare, ammonia (NH3) concentrations inside poultry houses have to be within acceptable limits; this requires regular NH3 monitoring. While there are low-cost, portable NH3 measuring devices have drawbacks. Due to its low cost, long lifetime, and short response time, a metal oxide semiconductor (MOS) sensor was used to develop a handheld NH3 monitor for use in poultry houses. Since the MOS sensor is affected by humidity and temperature, collocating relative humidity (RH) and temperature sensors with the MOS NH3 sensor and applying temperature and RH compensations greatly improved its performance. Compared to the boric acid scrubber, using broiler litter exhaust gas as the NH3 source, the relative error (RE) and coefficient of variation (CV) of the monitor averaged 7%, comparable to research-grade instruments. The monitor was more accurate than the electrochemical sensor and required less frequent purging. The response time of the unit was ∼1.5 min, the total mass was <1.4 kg while material cost was <$430. Hence, in addition to being convenient, the monitor provided accurate and precise measurements. With further refinements, the monitor has the potential to be used in poultry houses to control ventilation rates as a component of precision livestock farming to improve poultry performance and welfare.