The POD instrument have been designed and built at The University of Leicester as an alternative to the commercial air quality instrumentation currently available. PODs are compact (115 x 115 x 155mm), relatively inexpensive air quality instruments incorporating metal oxide semiconducting sensors to measure a variety of air pollutants. The aim of these instruments is to provide a flexible air quality monitor capable of a wide range of experimental usage, from monitoring long term trends to being deployed as personnel exposure monitors.
Each POD has a main ‘control board’, called the Small Open General Sensor (SOGS), which provides instructions the all of the instrument boards attached to it. This SOGS board allows the user to specify what the instrument boards do, from parameters measured, to the rate at which measurements are taken. The main instrument board attached to the control board houses sensors capable of measuring NO2, O3, NH3, total VOCs, CO and pressure. The gas sensors use a metal oxide semiconducting material which, once heated to the correct temperature, will react with the target gas to cause a change in the voltage, which is representative of a change in the ambient concentrations.
The SOGS board also separately measures the temperature, humidity and the time when the measurement was taken, providing a specific time stamp to order all data measured. Beyond this, the control board has been designed to be very flexible, able to incorporate a wide range of other instrument technologies, such as electrochemical gas sensors or infrared particulate matter counters. The control of all of the parameters, and the vast capacity to incorporate different sensing technology, set the POD apart from other available air quality sensors.