Abstract

Based on silicon-on-insulator (SOI) rib waveguide with large cross-section, a micro integrated surface plasmon resonance (SPR) biochemical sensor platform is proposed. SPR is excited at the deeply etched facet of the bend waveguide by the guiding mode and a bimetallic configuration is employed. With the advantages of SOI rib waveguide and the silicon microfabrication technology, an array of the SPR sensors can be composed to implement wavelength interrogation of the sensors’ output signal, so the spectrometer or other bulky and expensive equipment are not necessary, which enables the SPR sensor to realize the miniaturization and integration of the entire sensing system. The performances of the SPR sensor element are verified by using the two-dimensional finite-different time-domain method. The parameters of the sensor element and the array are optimized for the achievement of high performance for biochemical sensing application. As a typical example, a single bimetallic SPR sensor with 3 nm Au over 32 nm Al possesses a high sensitivity of 3.968 × 104 nm/RIU, a detection-accuracy of 14.7 μm−1. For a uniparted SPR sensor, it can achieve a detection limit of 5.04 × 10−7 RIU. With the relative power measurement accuracy of 0.01 dB, the refractive index variation of 1.14 × 10−5 RIU can be detected by the SPR sensor array.

Highlights

  • Surface plasmon resonance (SPR) phenomenon has been widely applied in biochemical sensing in recent decades, and this technology possesses a profound developing potential due to their unique advantages for real-time in-situ and label-free sensing [1,2]

  • It is found that the changes of the metal-layer thickness lead to the variation of the resonance positions, and the reason is that the propagation constant of multilayer surface plasmon resonance (SPR) with a thin metal layer is different to that of ideal semi-infinite configuration as the KSPR expressed in Equation (1)

  • Sensors with thinner metal layer exhibit higher Contrast and larger FWHM, so a tradeoff of the Al-layer thickness is necessary for high performance of Al SPR sensors

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Summary

Introduction

Surface plasmon resonance (SPR) phenomenon has been widely applied in biochemical sensing in recent decades, and this technology possesses a profound developing potential due to their unique advantages for real-time in-situ and label-free sensing [1,2]. The most common SPR sensors are based on Kretschmann prism configuration, which is bulky and not compatible with the current MEMS technology, and not good for realizing miniaturized integrated sensing system [6]. As another popular configuration, the fiber optic SPR biosensor require complex micromachining process and some high-performance equipment, it is difficult to achieve low cost and small size of the overall sensing system [7,8]. A new SPR excitation is proposed and analyzed

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