Optical integrated chips with micro and nanostructures for refractive index and SERS-based optical label-free sensing

Abstract:Label-free optical biosensing technologies have superior abilities of quantitative analysis, unmodified targets, and ultrasmall sample volume, compared to conventional fluorescence-label-based sensing techniques, in detecting various biomolecules. In this review article, we introduce our recent results in the field of evanescent-wavebased refractive index sensing and surface enhanced Raman scattering (SERS)-based sensing, both of which are promising platforms for label-free optical biosensors. First, silicon-on-insulator (SOI) nanowire waveguide and metallic surface plasmon resonance (SPR)-based refractive index sensing are discussed. In order to improve the detection limit, phase interrogation techniques are introduced to these types of sensors based on prism-coupled SPR and SOI microring resonators. A detection limit in the order of 10−6 refractive index unit is achieved. Detection of 16.7 pM anti-IgG is also demonstrated based on the SPR devices. Second, SERS substrates based on various nanometallic structures are discussed. Metallic nanowire arrays and inverted nanopyramids and grooves with a thin metal surface are fabricated based on anisotropic wetetching of silicon substrates. Both structures have demonstrated a Raman signal enhancement on the order of 107. In order to improve the extraction efficiency of the Raman signal at a high wave number, a nano-bowtie array substrate is fabricated, which exhibits double resonances at both the excitation wavelength and the desired Raman scattering wavelength. Experimental results have shown that this double-resonance structure can further enhance the received Raman signal, as compared to conventional SERS substrates with only one resonance at the excitation wavelength.

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Perfect Absorption and Refractive-Index Sensing by Metasurfaces Composed of Cross-Shaped Hole Arrays in Metal Substrate

Nanomaterials ◽

10.3390/nano11010063 ◽

2020 ◽

Vol 11 (1) ◽

pp. 63

Author(s):

Zhendong Yan ◽

Chaojun Tang ◽

Guohua Wu ◽

Yumei Tang ◽

Ping Gu ◽

...

Keyword(s):

Refractive Index ◽

High Performance ◽

Narrow Band ◽

Label Free ◽

Hybrid Mode ◽

Perfect Absorption ◽

Refractive Index Sensing ◽

Sensing Applications ◽

Silver Substrate ◽

Hole Arrays

Achieving perfect electromagnetic wave absorption with a sub-nanometer bandwidth is challenging, which, however, is desired for high-performance refractive-index sensing. In this work, we theoretically study metasurfaces for sensing applications based on an ultra-narrow band perfect absorption in the infrared region, whose full width at half maximum (FWHM) is only 1.74 nm. The studied metasurfaces are composed of a periodic array of cross-shaped holes in a silver substrate. The ultra-narrow band perfect absorption is related to a hybrid mode, whose physical mechanism is revealed by using a coupling model of two oscillators. The hybrid mode results from the strong coupling between the magnetic resonances in individual cross-shaped holes and the surface plasmon polaritons on the top surface of the silver substrate. Two conventional parameters, sensitivity (S) and figure of merit (FOM), are used to estimate the sensing performance, which are 1317 nm/RIU and 756, respectively. Such high-performance parameters suggest great potential for the application of label-free biosensing.

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Indirect Quantification of Glyphosate by SERS Using an Incubation Process With Hemin as the Reporter Molecule: A Contribution to Signal Amplification Mechanism

Frontiers in Chemistry ◽

10.3389/fchem.2020.612076 ◽

2020 ◽

Vol 8 ◽

Author(s):

Karen A. López-Castaños ◽

Luis A. Ortiz-Frade ◽

Erika Méndez ◽

Enrique Quiroga-González ◽

Miguel A. González-Fuentes ◽

...

Keyword(s):

Limit Of Detection ◽

Excitation Wavelength ◽

Raman Signal ◽

Sers Substrate ◽

Silver Surface ◽

Indirect Determination ◽

Sers Substrates ◽

Resonance Properties ◽

Equilibrium Process ◽

Vinyl Group

The indirect determination of the most used herbicide worldwide, glyphosate, was achieved by the SERS technique using hemin chloride as the reporter molecule. An incubation process between hemin and glyphosate solutions was required to obtain a reproducible Raman signal on SERS substrates consisting of silicon decorated with Ag nanoparticles (Si-AgNPs). At 780 nm of excitation wavelength, SERS spectra from hemin solutions do not show extra bands in the presence of glyphosate. However, the hemin bands increase in intensity as a function of glyphosate concentration. This allows the quantification of the herbicide using as marker band the signal associated with the ring breathing mode of pyridine at 745 cm−1. The linear range was from 1 × 10−10 to 1 × 10−5 M and the limit of detection (LOD) was 9.59 × 10−12 M. This methodology was successfully applied to the quantification of the herbicide in honey. From Raman experiments with and without silver nanoparticles, it was possible to state that the hemin is the species responsible for the absorption in the absence or the presence of the herbicide via vinyl groups. Likewise, when the glyphosate concentration increases, a subtle increase occurs in the planar orientation of the vinyl group at position 2 in the porphyrin ring of hemin over the silver surface, favoring the reduction of the molecule. The total Raman signal of the hemin-glyphosate incubated solutions includes a maximized electromagnetic contribution by the use of the appropriate laser excitation, and chemical contributions related to charge transfer between silver and hemin, and from resonance properties of Raman scattering of hemin. Incubation of the reporter molecule with the analyte before the conjugation with the SERS substrate has not been explored before and could be extrapolated to other reporter-analyte systems that depend on a binding equilibrium process.

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Synthesis and surface-enhanced Raman scattering of indium nanotriangles and nanowires

RSC Advances ◽

10.1039/c7ra03317f ◽

2017 ◽

Vol 7 (51) ◽

pp. 32255-32263 ◽

Cited By ~ 10

Author(s):

Rupali Das ◽

R. K. Soni

Keyword(s):

Raman Scattering ◽

Reduction Method ◽

Surface Enhanced Raman Scattering ◽

Resonant Excitation ◽

Raman Signal ◽

Sers Substrates ◽

Surface Enhanced ◽

Surface Enhanced Raman ◽

Enhanced Raman Scattering ◽

Nano Wires

Indium nano-wires and -triangles are synthesizedviaa modified polyol reduction method and self-assembled on silane treated glass coverslips as SERS substrates, giving large Raman signal enhancement from adsorbed tryptophan molecules under non-resonant excitation at 632.8 nm.

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Refractive-Index-Insensitive Nanolaminated SERS Substrates for Label-Free Raman Profiling and Classification of Living Cancer Cells

Nano Letters ◽

10.1021/acs.nanolett.9b02864 ◽

2019 ◽

Vol 19 (10) ◽

pp. 7273-7281 ◽

Cited By ~ 9

Author(s):

Wonil Nam ◽

Xiang Ren ◽

Seied Ali Safiabadi Tali ◽

Parham Ghassemi ◽

Inyoung Kim ◽

...

Keyword(s):

Refractive Index ◽

Cancer Cells ◽

Label Free ◽

Sers Substrates

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Modeling of a Single-Notch Microfiber Coupler for High-Sensitivity and Low Detection-Limit Refractive Index Sensing

Sensors ◽

10.3390/s16050672 ◽

2016 ◽

Vol 16 (5) ◽

pp. 672 ◽

Cited By ~ 3

Author(s):

Jiali Zhang ◽

Lei Shi ◽

Song Zhu ◽

Xinbiao Xu ◽

Xinliang Zhang

Keyword(s):

Refractive Index ◽

Detection Limit ◽

High Sensitivity ◽

Refractive Index Sensing ◽

Low Detection Limit

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Development and Application of Aptamer-Based Surface-Enhanced Raman Spectroscopy Sensors in Quantitative Analysis and Biotherapy

Sensors ◽

10.3390/s19173806 ◽

2019 ◽

Vol 19 (17) ◽

pp. 3806 ◽

Cited By ~ 2

Author(s):

Hai-Xia Wang ◽

Yu-Wen Zhao ◽

Zheng Li ◽

Bo-Shi Liu ◽

Di Zhang

Keyword(s):

Surface Enhanced Raman Spectroscopy ◽

Raman Signal ◽

Label Free ◽

Sers Substrates ◽

Highly Active ◽

Detection Technology ◽

Surface Enhanced ◽

Surface Enhanced Raman ◽

Sers Detection ◽

Target Molecules

Surface-enhanced Raman scattering (SERS) is one of the most special and important Raman techniques. An apparent Raman signal can be observed when the target molecules are absorbed onto the surface of the SERS substrates, especially on the “hot spots” of the substrates. Early research focused on exploring the highly active SERS substrates and their detection applications in label-free SERS technology. However, it is a great challenge to use these label-free SERS sensors for detecting hydrophobic or non-polar molecules, especially in complex systems or at low concentrations. Therefore, antibodies, aptamers, and antimicrobial peptides have been used to effectively improve the target selectivity and meet the analysis requirements. Among these selective elements, aptamers are easy to use for synthesis and modifications, and their stability, affinity and specificity are extremely good; they have been successfully used in a variety of testing areas. The combination of SERS detection technology and aptamer recognition ability not only improved the selection accuracy of target molecules, but also improved the sensitivity of the analysis. Variations of aptamer-based SERS sensors have been developed and have achieved satisfactory results in the analysis of small molecules, pathogenic microorganism, mycotoxins, tumor marker and other functional molecules, as well as in successful photothermal therapy of tumors. Herein, we present the latest advances of the aptamer-based SERS sensors, as well as the assembling sensing platforms and the strategies for signal amplification. Furthermore, the existing problems and potential trends of the aptamer-based SERS sensors are discussed.

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Distributed feedback lasers based on perylenediimide dyes for label-free refractive index sensing

Sensors and Actuators B Chemical ◽

10.1016/j.snb.2015.07.055 ◽

2015 ◽

Vol 220 ◽

pp. 1368-1375 ◽

Cited By ~ 23

Author(s):

Marta Morales-Vidal ◽

Pedro G. Boj ◽

José A. Quintana ◽

José M. Villalvilla ◽

Aritz Retolaza ◽

...

Keyword(s):

Refractive Index ◽

Distributed Feedback ◽

Distributed Feedback Lasers ◽

Label Free ◽

Refractive Index Sensing

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IP-Dip-Based SPR Structure for Refractive Index Sensing of Liquid Analytes

Nanomaterials ◽

10.3390/nano11051163 ◽

2021 ◽

Vol 11 (5) ◽

pp. 1163

Author(s):

Petra Urbancova ◽

Dusan Pudis ◽

Matej Goraus ◽

Jaroslav Kovac

Keyword(s):

Refractive Index ◽

Photon Absorption ◽

Resonance Structure ◽

Angle Of Incidence ◽

Two Photon Absorption ◽

Two Photon ◽

Refractive Index Sensing ◽

External Angle ◽

Direct Laser ◽

Index Unit

In this paper, we present a two-dimensional surface plasmon resonance structure for refractive index sensing of liquid analytes. The polymer structure was designed with a period of 500 nm and prepared in a novel IP-Dip polymer by direct laser writing lithography based on a mechanism of two-photon absorption. The sample with a set of prepared IP-Dip structures was coated by 40 nm thin gold layer. The sample was encapsulated into a prototyped chip with inlet and outlet. The sensing properties were investigated by angular measurement using the prepared solutions of isopropyl alcohol in deionized water of different concentrations. Sensitivity of 478–617 nm per refractive index unit was achieved in angular arrangement at external angle of incidence of 20°.

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Preparation of ZnO nanoflowers for surface enhance Raman scattering applications

VNU Journal of Science Mathematics - Physics ◽

10.25073/2588-1124/vnumap.4369 ◽

2020 ◽

Vol 36 (1) ◽

Author(s):

Tuyen Nguyen Viet

Keyword(s):

Raman Scattering ◽

Self Assembly ◽

Noble Metals ◽

Zno Nanorods ◽

Raman Signal ◽

Sers Substrate ◽

Chemical Substances ◽

Sers Substrates ◽

Electromagnetic Enhancement ◽

Surface Enhanced Raman

Thanks to unique Raman spectra of chemical substances, a growing number of applications in environmental and biomedical fields based on Raman scattering has been developed. However, the low probability of Raman scattering hindered its potential development and thus, many different techniques were developed to enhance Raman signal. A key step of surface-enhanced Raman scattering technique is to prepare active SERS substrate from noble metals. The main enhancement mechanism is electromagnetic enhancement resulted from surface plasmon resonance. The disadvantages of nanoparticles based SERS substrates include high randomness due to self - assembly process of nanoparticles. Recently, a new kind of SERS substrates with order nanostructures of semiconductors combining with noble metals can serve as active SERS substrates, which are expected to possess high enhancement of Raman signals. In this study, ordered ZnO nanorods were first prepared by galvanic hydrothermal method and gold was sputtered on the as prepared ZnO nanomaterials to enhance Raman. Our SERS substrates exhibit promising high enhancement factors, and can detect chemical substances at concentration in nano molar range.

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