Abstract
We propose a novel langasite crystal microbalance (LCM) sensor with a graphene-based sensing medium to detect and discriminate volatile organic compounds (VOCs) at room temperature. A thin film of graphene oxide embedded with Pt nanostructures (GO-Pt nanocomposite) was deposited on the electrode surface of the LCM, a thickness-shear acoustic wave resonator. Ethyl acetate, acetic acid, and ethanol were chosen as typical VOCs for this study. Sensitivity and selectivity of coated LCM were investigated for different concentrations of the VOCs by analysing the resonant properties of the sensor. When exposed to VOCs, a negative shift in series resonance frequency was observed due to the mass loading of VOC molecules. Simultaneously, changes in equivalent resistance and parallel resonance frequency of the sensor were also observed due to the interaction of VOCs with charge carriers on the GO-Pt nanocomposite film surface. This dual measurement of both series and parallel resonance frequencies allowed for detection and discrimination of VOCs. Moreover, the high thermal stability of langasite makes the proposed sensor suitable even for harsh environmental conditions.
Highlights
Volatile organic compounds (VOCs) are encountered in every aspect of our daily life
In this paper we report the first implementation of a VOC sensor that combines langasite crystal microbalance (LCM)
When the VOC molecules are removed during the desorption process, the electrons move back to the the hole concentration of This graphene andincreases reduces the resistance of sensor. and reduces the
Summary
Volatile organic compounds (VOCs) are encountered in every aspect of our daily life. Some VOC molecules are non-toxic, while others are detrimental to our wellbeing in terms of health and safety. Commercial VOC sensors available currently are predominantly based on metal oxide sensing layer which necessitates a heating element to operate [1] This limits the uses of the metal oxide-based sensors to static scenarios and are, inappropriate for modern applications such as wearables where portability, low power consumption, and ambient temperature sensing are essential [7]. These commercial sensors merely sense the total VOCs present and lack the ability to discriminate the type of VOC molecules. In this paper we report the first implementation of a VOC sensor that combines LCM with Pt nanoparticle-decorated GO as the sensing layer for selective VOC molecular detection at RT. The sensor characteristics were explained based on multiple output parameters and equivalent circuit of the LCM
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