The Construction And Applications Of Carbon Black Doped Polymer Composites Gas Sensor And Sensor Array

Chemiresistor sensors and sensor array were fabricated with carbon black(CB)-doped insulator composites as sensing interface, and applied for the analysis of volatile organic compounds(VOCs) and VOC mixtures. The main work is as below:(1) The sensor parameters including the film thickness, interdigital electrode gap, membrane compositions, and signal frequency were optimized with toluene and water vapor as target. The optimum parameters are: electrode gap: 1.50mm, weight percent of CB: 52.3 wt%, signal frequency: 150 kHz, coating thickness represented as resistance: 200-1000 Ω. The contribution of CB to the absorption was also tested using QCM.(2) A serial of VOCs were analyzed with the as-prepared sensor, and both the resistance and the capacitance responses were measured. A good linearity was obtained. The humidity effect on sensor responses was investigated. The results show that at high humidity, the resistance and capacitance response mode is different. The response mechanism was illustrated using Neugebauer and Webb theory. Based on our results not the permeability change resulting from the sorption but the film swelling governs the capacitance change at low humidity. Only at humidity over 65%, the permeability change contributes to the capacitance response.(3) The mixtures of CB with 5 kinds of polymers (PIB (polyisobutylene) , OV-25(polyphenylmethylsilicone),PECH(polyepichlorohyron),PU(polyurethane), POTT(poly(3-octylthiothene))) were tested as the sensing interface, and three (PECH, PU, POTT) among them were finally chosen to construct a sensor array. The sensor array was employed to detect 4 kinds VOCs, including heptane, toluene, dicloromethane and ethanol. Chemometrics methods such as Principle Compounds Analysis (PCA), Principle Compounds Regression (PCR), Partial Least Squares (PLS) were used to classify and recognize these VOCs as well as their mixtures.