Sensitivity Optimization of Au/Ti Based-SPR Sensor by Controlling Light Incident Wavelength for Gas Sensing Application

Abstract

Exposure to harmful gases may cause health problems like bone marrow deficiency, which eventually drops the number of red blood cells, causing anemia and many other dangerous diseases. This work was carried out to study the potential development of a highly sensitive Kretschmann-based surface plasmon resonance (SPR) sensor for gas sensing applications using hybrid thin films of gold/titanium (Au/Ti). To optimize the excitation of surface plasmon polaritons (SPP), the light incident wavelength was varied from visible to infrared spectra. The thickness of Au thin film with a refractive index of n= 0.1758 + 3.4101k was fixed at 50 nm. Meanwhile, the thicknesses of Ti were controlled between 1 nm to 5 nm to optimize the SPR signal. Four different types of gas samples, such as benzene, methane, carbon monoxide, and carbon dioxide, were exposed to the sensor's surface. The proposed Au/Ti-based SPR sensor with thicknesses of Ti within 1 nm to 5 nm using visible and IR wavelengths able to detect various types of gaseous. Apparently, the deployment of infrared wavelength (λ=1550 nm) at Ti thickness of 3 nm resulted in the highest sensitivity up to 2412.06°/RIU and showed excellent selectivity to differentiate different types of gases. In conclusion, Au/Ti thin films are promising hybrid materials for gas sensing applications. Obviously, the sensor's sensitivity with total hybrid thin films of 53 nm was successfully enhanced as additional material, Ti, coated on the Au thin film's surface.