Olfactory Sensing Using Quartz Crystal Microbalances with Radio-Frequency Sputtered Organic Films Based on Phenomenological Gas-Sorption Dynamics

Abstract

Olfactory information is made up of a wide range of volatile chemical compounds that can be detected by gas sensors with sensing layers, which play a crucial role in gas detection. The sorption-desorption dynamics in the vicinity of the top surface of the sensing layer are largely responsible for the sensor response. Carbonaceous films produced by the radio frequency sputtering of organic materials have granular structures with unsaturated chemical bonds that make them promising olfactory sensing layers. The pre-adsorbates of carbonaceous films, such as water in realistic circumstances, are regarded as dynamic active sites that affect the gas sorption characteristics. The authors have focused on surface water as the most common pre-adsorbate and ionic liquid as an artificial ionic pre-adsorbate. These pre-adsorbates modulate the structures of the sensing layers and act as an absorbent that generates dynamic changes in the sensory responses.