Abstract
This paper presents the development of a metal oxide semiconductor (MOS) sensor for the detection of volatile organic compounds (VOCs) which are of great importance in many applications involving either control of hazardous chemicals or noninvasive diagnosis. In this study, the sensor is fabricated based on tin dioxide (SnO2) and poly(ethylene oxide) (PEO) using electrospinning. The sensitivity of the proposed sensor is further improved by calcination and gold doping. The gold doping of composite nanofibers is achieved using sputtering, and the calcination is performed using a high-temperature oven. The performance of the sensor with different doping thicknesses and different calcination temperatures is investigated to identify the optimum fabrication parameters resulting in high sensitivity. The optimum calcination temperature and duration are found to be 350 °C and 4 h, respectively and the optimum thickness of the gold dopant is found to be 10 nm. The sensor with the optimum fabrication process is then embedded in a microchannel coated with several metallic and polymeric layers. The performance of the sensor is compared with that of a commercial sensor. The comparison is performed for methanol and a mixture of methanol and tetrahydrocannabinol (THC) which is the primary psychoactive constituent of cannabis. It is shown that the proposed sensor outperforms the commercial sensor when it is embedded inside the channel.
Highlights
The global gas sensor market size is evaluated at $1 billion and is predicted to reach $5 billion by 2020 [1]
There is a wide range of industries applying gas sensors for monitoring and diagnosis, for example, in healthcare; agriculture; defence; and environment (for detection of volatile organic compounds (VOCs) pollutants accounting for 37% (693 kilotons/year) of total emission according to Environment and Climate Change Canada report [9])
Several studies have shown differences in concentration of volatile organic compounds (VOCs) in exhaled breath between healthy people and people with a particular disease [11]; these changes are often on the scale of parts per billion. For these reasons highly sensitive gas sensors would be an invaluable tool for lethal gas detection and early, noninvasive disease diagnosis
Summary
The global gas sensor market size is evaluated at $1 billion and is predicted to reach $5 billion by 2020 [1]. Sensitive gas detectors are essential, especially for applications involving detection of toxic gases and disease diagnosis. Sensitive gas sensors are required to detect toxic vapors (such as arsine gas) and prevent unnecessary injuries or death. For these reasons highly sensitive gas sensors would be an invaluable tool for lethal gas detection and early, noninvasive disease diagnosis.
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