Hexanal was identified as one of the major volatile gases which are produced in degraded dairy products and wood industries. Therefore, preliminary study on hexanal gas detection with the laboratory scale was carried out in this paper. Electrical testing with chitosan as a sensing material to sense hexanal gas in low concentration was carried out at room temperature. Chitosan sensor was fabricated by using electrochemical deposition technique to form active sensing layer. The response of the chitosan film sensor (CFS) towards hexanal was tested via electrical testing by exposing different hexanal concentrations ranging between 20 ppm, 100 ppm, 200 ppm, and 300 ppm using air as a carrier gas. Sensing properties of the CFS toward hexanal exposure including responsibility, recovery, repeatability, stability, and selectively were studied. Overall, our result suggested that hexanal sensor based on chitosan was able to perform well at room temperature demonstrated by good response, good recovery, good repeatability, good stability, and good selectively. This simple and low cost sensor has high potential to be utilized in early quality degradation detection in dairy products and can be used to monitor the level of hexanal exposure in wood industries.
Abstract. This work is to study the sensing properties of chitosanpolyvinyl alcohol film sensors upon hexanal gas exposure using vapour sensing technique. The sensor fabrication process was done using electrochemical deposition method by deposit the sensing materials on the gold patterned electrode with chitosan/PVA. The response value of chitosan-PVA film sensors towards hexanal was taken as an output voltage using electrical testing method. In this study, 1.75% of chitosan with 5% of PVA were mixed with the ratio of (95:5) was tested upon exposure to hexanal gas. The concentration of the hexanal was varied as 10 ppm, 20 ppm, 30 ppm. It was found that the chitosan-PVA film sensors showed fast response, stable, good stability, good recovery, repeatable and good sensitivity towards hexanal exposure. The morphology of the pure chitosan and chitosan-PVA was analyzed by scanning electron microscope (SEM) and the interaction between chitosan and PVA was examined by Fourier Transform Infrared Spectroscopy (FTIR). The FTIR results indicate the changes in characteristics of the spectral peaks due to the formation of the intermolecular bonds between chitosan and PVA. The SEM morphology of the composites showed flat smooth surface that be a sign of uniform distribution of chitosan and PVA mixture throughout the films.
The use of organic thin film transistors (OTFTs) is growing rapidly as an alternative to their inorganic counterparts due to their advantageous properties, such as easy processing and flexibility. The performance of OTFTs is still undergoing improvement and taking this as a recognition, this paper reviews various factors that influence the performance of the OTFTs, primarily in terms of field-effect mobility. The influencing factors reviewed in this article are divided into intrinsic and extrinsic factors for different organic semiconducting materials (OSMs). The intrinsic factors include the OSMs’ molecular orientation, OSM/dielectric interaction, and OSM/electrode interaction. The extrinsic factors are basically related to the OSM processing and OTFTs fabrication. For example, the article discusses how mixing, blending, and annealing affect the properties of the OSMs. The effect of the ambient atmosphere on OTFTs’ performance is also discussed. The aim of this article is to discuss the current trends related to one of the critical figures of merit of OTFTs, which is the mobility of charge carriers.
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