Low-Cost Multispecies Air Quality Sensor

Field measurements of volatile organic compounds (VOCs) are important in a range of disciplines including air pollution science, medical diagnostics and security screening. There is an enduring need for a portable device that provides reliable compound-specific measurements, at mixing ratios in the part per billion and part per trillion range. Outdoor VOCs sources are primarily from traffic, and the information provided from such measurements could inform the public of the sources of emission and potentially affect their decisions and behaviour. Similarly, measurements of VOCs in indoor environments could increase awareness of emissions from building materials or the use of various consumer products and provide information on indoor ventilation. This work describes the development of a lab-on-a-chip (LOC) device for VOC measurements, a collaboration of multiple disciplines, involving research and development from a number of different fields in sciences and engineering. The objective is to develop a multispecies sensor for measuring VOCs in gas phase samples, through the deployment of thermal desorption methods in combination with a micro-fabricated gas chromatography – photoionization detection (GC-PID) device. Most of the work has been done in the evaluation of the PID detection means, which has shown to offer substantial potential for the development of a field portable air quality sensor. Initial tests on a Peltier device to control the temperature of a GC column have also been carried out. The use of such device removes the dependence on the bulky GC oven which has high power consumption, and allows the initial temperature of the column to be as low as 10^oC, potentially enabling the analysis of VOCs without the need for cryogenic cooling. The final developed system will be validated using controlled experiments and against reference standards and measurement techniques, and applied in number of real-world monitoring investigations, including indoor atmospheres and air pollution studies.