Designing a new optical biosensing platform based on an insulator-metal-insulator nanostructure

Abstract

The insulator-metal-insulator (IMI) structure is potential for the fabrication of biosensor platform devices because of its unique optical properties, especially surface plasmon resonance (SPR). In this study, the optical properties of the IMI structure in the visible wavelength range were calculated using the transfer matrix method. The results indicated that the IMI structure exhibited high absorbance at the proper wavelength due to the SPR. This phenomenon was resulted from the resonance of incident light and the free electrons in the metal surface. The SPR signal relied on the thickness of layers in the IMI structure and the refractive index of the surrounding medium. Based on calculation results, the IMI structure applied for the biosensor was designed and optimised with respects to optical properties. In addition, sensitivity calculation demonstrated that IMI structure was more sensitive than biosensor based on attenuated total reflection (ATR), SPR method while similar results were attained with the metal-insulator-metal (MIM) structure method.