Design analysis of doped-silicon surface plasmon resonance immunosensors in mid-infrared range

Abstract

This paper reports the design analysis of a microfabricatable mid-infrared (mid-IR) surface plasmon resonance (SPR) sensor platform. The proposed platform has periodic heavily doped profiles implanted into intrinsic silicon and a thin gold layer deposited on top, making a physically flat grating SPR coupler. A rigorous coupled-wave analysis was conducted to prove the design feasibility, characterize the sensor's performance, and determine geometric parameters of the heavily doped profiles. Finite element analysis (FEA) was also employed to compute the electromagnetic field distributions at the plasmon resonance. Obtained results reveal that the proposed structure can excite the SPR on the normal incidence of mid-IR light, resulting in a large probing depth that will facilitate the study of larger analytes. Furthermore, the whole structure can be microfabricated with well-established batch protocols, providing tunability in the SPR excitation wavelength for specific biosensing needs with a low manufacturing cost. When the SPR sensor is to be used in a Fourier-transform infrared (FTIR) spectroscopy platform, its detection sensitivity and limit of detection are estimated to be 3022 nm/RIU and ~70 pg/mm(2), respectively, at a sample layer thickness of 100 nm. The design analysis performed in the present study will allow the fabrication of a tunable, disposable mid-IR SPR sensor that combines advantages of conventional prism and metallic grating SPR sensors.

Polymer-based surface plasmon resonance biochip: construction and experimental aspects

“…Some future possibilities are the use of silicon-based biochips, where the multilayer receipt for biosensing is deposited over a silicon (or similar material) wafer. It provides, besides a good alternative to solve problems with polymer and glass-based devices, a great possibility to miniaturize the SPR biosensor (DiPippo et al, 2010;Vivien and Pavesi, 2013). Another possibility is the use of microstructured optical fibers as biochips, but they have the complex construction way as a limiting factor (Hassani and Skorobogatiy, 2006;Lee et al, 2011;Yu et al, 2010).…”

Recent Advances in Integrated Photonic Sensors

“…Photonic sensors based on SPR have been realized for detection of DNA, RNA, allergens and human-blood group, exhibiting a refractive index resolution as low as 1.4 × 10 −7 [63]. In case of infrared spectroscopy, an immunosensor characterized by a sensitivity as high as 3,022 nm/RIU and a LOD of 70 pg/mm 2 has been demonstrated by Di Pippo et al [64]. Recently, a high-resolution biosensor based on localized surface plasmon resonance (LSPR) excited on an array of gold nanorods have been proposed for detection of DNA hybridization [65].…”

Chemical Sensors Based on Photonic Structures

“…In particular, plasmonic related sensing procedure has been used for label-free detection of biological analytes at pico/femto-molar level, pesticides, immunoassays, DNA with a refractive index resolution of 1.4×10 -7 (Le et al 2011), RNA, allergens and human blood-group identification (Jha & Sharma, 2010). For example, a SPR mid-infrared immunosensor used in a Fourier-transform infrared (FTIR) spectroscopy platform, exhibits a sensitivity of 3022 nm/RIU and a limit of detection of ~70 pg/mm 2 (DiPippo et al, 2010). Generally, the detection of the SPR change due to the adsorption of target molecules on the sensing surface, can be quantified by monitoring the resonant intensity, wavelength or angle change.…”