Optimised film thickness for maximum evanescent field enhancement of a bimetallic film surface plasmon resonance biosensor

Ong, Biow Hiem; Yuan, Xiaocong; Tjin, Swee Chuan; Zhang, Jingwen; Ng, Hui Min

doi:10.1016/j.snb.2005.07.064

Cited by 201 publications

(120 citation statements)

References 9 publications

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“…Gold film keeps the biosensor to be chemically stable and capable for biological molecule accretion, and silver film at the inner layer provides the high sensitivity. For the four-layer structure like prism (layer 1)/silver film (layer 2)/gold film (layer 3)/biologic molecule layer (layer 4), based on the Fresnel reflection formula [15], the reflectivity is shown below,…”

Section: Design Of the Gold-silver Bimetallic Nanofilm Configuration mentioning

confidence: 99%

“…A reasonable idea can be generated by employing gold-silver bimetallic nanofilm configuration owning the virtues of both gold film and silver film. B. H.Ong et al analyzed bimetallic silver-gold film configuration for high sensitivity surface plasmon resonance sensing and achieved a narrow resonance fullwidth-half-maximum and evanescent field enhancement [15]. However, the sensing mechanism is based on the relationship between the reflectivity and the incident angle, which works in the second work mode and is not suitable for the multi-channel and imaging sensing.…”

Section: Introductionmentioning

confidence: 99%

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Sensitivity Enhancement for Surface Plasmon Resonance Imaging Biosensor by Utilizing Gold–Silver Bimetallic Film Configuration

et al. 2011

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Gold-silver bimetallic film configuration is brought forward to realize surface plasmon resonance imaging (SPRI) biosensor with the virtues of both high sensitivity and chemical stability. The theoretical calculation is adopted to optimize the thicknesses of the metal films, and bimetallic film configuration with high refractive index sensitivity and a good linearity between reflectivity and refractive index is presented. Then, the property of the detection system is discussed. The results show that in comparison to most commercial SPRI biosensors which use single gold films, the sensitivity and molecule detection ability of the gold-silver bimetallic film configuration can be improved to a great extent. For the substrate of BAK3 glass used in this paper, the sensitivity enhancement reaches as high as 80%, which makes it a much better choice for SPRI biosensing applications.

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Section: Design Of the Gold-silver Bimetallic Nanofilm Configuration mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Sensitivity Enhancement for Surface Plasmon Resonance Imaging Biosensor by Utilizing Gold–Silver Bimetallic Film Configuration

et al. 2011

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“…The resolution of a SPR sensor is improved as the linewidth of the SPR reflectivity dip curve decreases and a shift in the resonance angle or wavelength in response to the environmental index change increases [17,18]. With limited available metals for plasmonic application, most current efforts have been concentrated on decreasing the linewidth of the resonance curve [19][20][21]. In the last two decades, few methods were proposed to improve the sensitivity of the SPR sensor using the long range SPR method [22,23], the addition of gratings and nanostructures [24,25], combinations of metals and interferometric methods based on phase measurement [26,27], although a recent study [28] showed that the enhanced sensitivity reported by phase measurement techniques is questionable.…”

Section: Introductionmentioning

confidence: 99%

Surface plasmon optical sensor with enhanced sensitivity using top ZnO thin film

Bao

Jiang

et al. 2012

Appl. Phys. A

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Surface plasmon resonance (SPR) is one of the most sensitive label-free detection methods and has been used in a wide range of chemical and biochemical sensing. Upon using a 200 nm top layer of dielectric film with a high value of the real part ε of the dielectric function, on top of an SPR sensor in the Kretschmann configuration, the sensitivity is improved. The refractive index effect of dielectric film on sensitivity is usually ignored. Dielectric films with different refractive indices were prepared by radio frequency magnetron (RF) sputtering and measured with spectroscopic ellipsometry (SE). The imaginary part ε of the top nanolayer permittivity needs to be small enough in order to reduce the losses and get sharper dips. The stability of the sensor is also improved because the nanolayer is protecting the Ag film from interacting with the environment. The response curves of the Ag/ZnO chips were obtained by using SPR sensor. Theoretical analysis of the sensitivity of the SPR sensors with different ZnO film refractive indices is presented and studied. Both experimental and simulation results show that the Ag/ZnO films exhibit an enhanced SPR over the pure Ag film with a narrower full width at half maximum (FWHM). It shows that the top ZnO layer is effective in enhancing the surface plasmon resonance and thus its sensitivity.

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“…Bimetallic structures, such as films and nanoparticles, have attracted considerable attention for plasmon resonance excitation [9][10][11][12][13][14][15][16]. The preferred metals are silver and gold: the advantage of gold is that it possesses a higher shift of resonance dip at the change of the ambient refractive index; hence, gold provides high sensitivity.…”

Section: Introductionmentioning

confidence: 99%

Plasmon Modes Management

2011

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A new plasmonic structure based on bimetallic layer is proposed. We analyze the structure and show that bimetallic film plays a crucial role in the management of surface plasmons. The roll of the buffer is discussed, as well. Up to three surface plasmons can be excited simultaneously in the structure. Two of plasmons can be used for two-plasmon spectroscopy. The third plasmon can be used for controlling the temperature of the structure.

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Optimised film thickness for maximum evanescent field enhancement of a bimetallic film surface plasmon resonance biosensor

Cited by 201 publications

References 9 publications

Sensitivity Enhancement for Surface Plasmon Resonance Imaging Biosensor by Utilizing Gold–Silver Bimetallic Film Configuration

Sensitivity Enhancement for Surface Plasmon Resonance Imaging Biosensor by Utilizing Gold–Silver Bimetallic Film Configuration

Surface plasmon optical sensor with enhanced sensitivity using top ZnO thin film

Plasmon Modes Management

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