An optical waveguide sensor based on mesoporous silica films with a comparison to surface plasmon resonance sensors

Abstract

Mesoporous silica films (MSF) with large surface areas and high stability were fabricated by a simple Stöber solution growth method. The sensitivity and limit of detection (LOD) for an optical waveguide transverse electric mode (TE-OWG) sensor are 62.869 deg/RIU and 5.8250 × 10−6 RIU, respectively. The sensitivity and LOD for a surface plasma resonance (SPR) sensor are 131.58 deg/RIU and 1.0551 × 10−5 RIU, respectively. The MSF sensor can detect both small and large molecules. In the detection of non-adsorbing glucose, a LOD of 40.416 mg/L was recorded, which resulted from the change of the refractive index of the solution. For the detection of CTAB, which may adsorb onto the film, the LOD significantly decreases to 1.6315 nM. Although, large molecules, such as BSA, cannot diffuse into the mesoporous structure of MSF to adsorb onto the inner pore walls, physical adsorption on the outer surface of MSF still leads to a LOD of 84.209 pM. Fresnel calculations suggested higher potential sensitivity of the current system compared to that of the conventional SPR sensors. Thus, the MSF may be used as a versatile platform for high-sensitive label-free optical biosensing due to the high performance and the large potential of the surface functionality.