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Research Article


Environmentally damaging gases, such as carbon dioxide (CO2), must be sensed for ecological observing or in the vehicle industry. CO2 gas sensing can be done theoretically through designing a biosensor based on a surface plasmon resonance (SPR) principle. The effect of gas respond can be demonstrated by means of SPR spectra shifting and a change in the utilized light reflectance. In general, The CO2 gas sensor monitors the changes of the air refractive index through measuring the position of the resonance dip value with respect to its position for normal air structure . In addition, a tiny variation in the concentration of the CO2 gas molecules alongside the surface of the metal film in sensor leads to a shift in resonance dip angle. In this study, a theoretical design has been proposed, for an optical sensor based on SPR concept, which can be operated in both visible and infrared region. The proposed model, mainly, relies upon new parameter values such as the proposed values of metal thickness and incident wavelength, which allows the change in the incident light angle. Moreover, the proposed sensor has ability to increase the functionality of the setup, which leads to a high precision of the measurements. The MATLAB® program has been utilized throughout this study in order to analysis the available results in this area as well as to propose additional conditions. This study showed that, the optimum value of the average detection sensitivity can be obtained is about 68.8 degree/RIU (refractive index units), and the figure of merit (FOM) is about 1527 RIU-1 for incident light in infrared region. Correspondingly, the intensity of reflectivity for the surface plasmon resonance dip within this study is only 0.195%, and the full widths at half maximum (FWHMs) of the bandwidth of the angle is 0.1883◦. Finally, it was found that the SPR sensitivity became highly dependent on the metal film thickness, between 10-80nm, and different incident wavelength, i.e. 400-5500nm.


Surface plasmon, CO2 molecule gas detection, optical sensors, air pollution monitoring.

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