Poor air quality is known to cause different health issues both for short-and long-term exposure. Regulating organizations such as WHO, DEFRA, and EPA have specified acceptable limits of exposure to the main pollutants present in air. Portable multi-sensor devices are needed, with high accuracy and selectivity to multiple polluting and toxic agents present in air, to allow high spatial and temporal resolution in personal exposure monitoring. When compared to large centralized air quality monitoring centres, portable multi-sensor devices for air quality monitoring allow individuals to monitor their personal exposure levels in real time and costeffectively. Environmental sensors are adopted in smart buildings, cars and gradually being integrated in portable form factor, for ambient air quality monitoring. We propose a non-intrusive air quality monitoring platform capable of sensing multiple gases and particulate matter, suitable for personal exposure monitoring and studies. The same platform integrates capabilities and bespoke frontend electronics for both capacitive and resistive sensors, with high accuracy and versatility. To demonstrate the significance of the proposed platform we report here the results of both simulations and measurements in monitoring PM2.5, PM10 and NO2 as an example of capabilities toward the overarching goal of covering the entire spectrum of air pollutants, and to integrate it into smart portable devices.

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A novel metamaterial structure has been proposed for its operation at 2.4 GHz. A circular disc patch antenna resonating at dual band frequency with 2.4 GHz and 3.36 GHz has been designed using full field solver CST MWS tool and the loading effect of the metamaterial has been shown. The loading of metamaterial shows a radial size reduction of 56.71% in the circular disc patch (dimensional space reduction by 81.26%) while the effect of loading the metamaterial array and loading the metamaterial with defected ground plane show that without reducing the disc patch radius, the patch antenna can resonate at 1.00 and 1.942 GHz respectively, these yield a lower frequency shift of 58.33% and 19.79%. The designed metamaterial consists of two copper conductive concentric circular rings over a polyimide substrate. Various antenna parameters such as S11, VSWR, Bandwidth, Gain, Directivity and Radiation efficiency have been obtained for the circular disc patch antenna, circular disc patch antenna loaded with the metamaterial, circular disc patch antenna loaded with an array of metamaterial and are compared. A spice circuit has been derived for the reflection coefficient of the circular disc patch without loading the metamaterial, circular disc patch loaded with metamaterial using Keysight based ADS tool for its inclusion in a traditional electrical circuit solver tool.

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