Detecting amine vapours with thermally carbonized porous silicon gas sensor

Abstract

A capacitive type porous silicon based gas sensor for detecting amine vapours has been developed. The sensor is highly sensitive, e.g., to methylamine and trimethylamine vapours, and its electrical parameters recover totally after exposure to studied gases. Thermal carbonization of porous silicon under acetylene atmosphere was carried out to produce stable and attractive surface to amine vapours. The sensor response to studied amine vapours can be separated from its response to humidity changes since their electrical responses act reversely. In addition to the vapours of methylamine/water and trimethylamine/water solutions, the sensor was also used to detect different amines, which are generated during spoilage of raw shrimps and Baltic herring fillets at room temperature. Fourier Transform Infrared spectroscopy was used to detect the amine vapours and other volatile compounds simultaneously with sensor measurements. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Thermally Carbonized Porous Silicon and Its Recent Applications

“…The conductivity of TCPSi was also found to be well described by a thermistor equation and the temperature sensitivity was found to be very good (5% K −1 at 25 °C). This is a very beneficial property when accurate and easy electrical measurements are considered and has been exploited in several different sensor applications of TCPSi, including sub‐ppm humidity detection and amine detection …”

“…This is a very beneficial property when accurate and easy electrical measurements are considered and has been exploited in several different sensor applications of TCPSi, including sub-ppm humidity detection [70] and amine detection. [70,71] Although carbonization at higher temperatures (>700 °C) may have considerable impact on the optical properties of PSi, thermal hydrocarbonization at lower temperature has only small impacts on the optical properties of Psi as it has only mild effects on the refractive index and absorbance, and practically not much effect at all on, e.g., optical transmission. [72] These changes can be predicted which allow considerations of the optical multilayer structures already before fabrication, which minimizes the potential drawbacks arising from the change in optical properties.…”

“…Both TCPSi and THCPSi have been used for different gas [71] and humidity sensing [53,54,70] applications for years. The improved chemical stability and electrical properties are necessary for obtaining stable gas sensing systems that are calibrated infrequently.…”

Pentacene Nano-Particles Film Modified Microstructure Silicon for NH3 Gas Sensor Application

“…In order to improve the properties of PS sensors, a number of methods have been developed to modify the PS, such as thermal carbonization, depositing sensitive films on the PS surface and adopting micro-nano composite structure. M. Björkqvist et al used acetylene gas as a carbon source to substitute Si-H surface bonds for Si-C bonds to improve the stability of the PS [6]. Ming Hu et al deposited WO 3 on the macro-PS surface to fabricate high sensitive gas sensor, but the response/recovery times were 15mins and 27mins, respectively [7].…”

Room temperature detection of amine vapours using copper phthalocyanine based thin films

“…Phthalocyanine films have been widely used as gas sensors for detection of various harmful gases like Cl 2 , NO, NO 2 , NH 3 , amines and alcohols etc. 18–20 They are chemically sensitive to reactive gases and their selectivity towards different gases can be modulated by incorporating functional groups or by changing central metal atom 21, 22. Both peripheral and non‐peripheral substituted phthalocyanines have been exploited for gas sensing applications 23, 24.…”