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This work reports the optimization of an optical system used to detect and quantify volatile organic compounds (VOC). The sensor consisted of a polydimethylsiloxane (PDMS) sensing film deposited on a glass substrate by the spin-coating technique. The PDMS has the property of swelling and/or changing its refractive index when it interacts with molecules of VOC in vapor phase. In order to measure the PDMS swelling, a charge-coupled device (CCD) camera was employed to evaluate the interference fringe shift in a Pohl interferometric arrangement. With this approach, it is possible to use each pixel of the CCD camera as a single photodetector in the arrangement. Similarly, different computer algorithms were developed in order to acquire and process the obtained data. The improvements in the system allowed the acquisition and plot of 1 datum per second. The steady-state responses of the PDMS sensors in the presence of ethanol vapor were analyzed. The obtained results showed that noise level was reduced approximately three times after performing data processing.

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In a previous work the monitoring of the fringes pattern shift produced by the interaction of a polymeric film with volatile organic compounds (VOC), by a Pohl interferometric arrangement has been reported. Such fringes shift was measured by a conventional photodetector. In the present work the optimization of an optoelectronic system for detection and quantification of VOC is presented. In this new arrangement a charge coupled device (camera CCD) was used to monitor such fringes shift. The CCD takes advantage of the fact that each pixel can be used as a single photodetector. A program was realized in matlab for the acquisition and processing of the data, which allows to evaluate faster the obtained results. Up to the moment results of the system performance by the measurement of the steady state response of dimethylpolysiloxane (DMPS) to ethanol vapour are reported.