Blend of chitosan and spinach extract has been successfully prepared using acetic acid as a solvent medium to produce chitosan-spinach films. The conductivity measurements showed that chitosan-spinach films for all ratios of 95 : 5, 90 : 10, 85 : 15, and 80 : 20 had better conductivity than the chitosan film. The optical band gap reduced with the addition of the spinach extract into chitosan. Chitosan-spinach film with the ratio of 85 : 15 gave the best electrical properties in this work with the conductivity of 3.41 × 10−6 S/m and optical band gap of 2.839 eV. SEM-EDX spectra showed the existence of potassium, phosphorus, sulphur, iron, and oxygen in chitosan-spinach films. AFM image showed that the surface morphology of the films became rougher as the spinach incorporated into chitosan. The minerals which exist in spinach extract play a role in enhancing electrical properties of chitosan film.

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.