scholarly journals Reusable TiN Substrate for Surface Plasmon Resonance Heterodyne Phase Interrogation Sensor

Nanomaterials ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1325 ◽  
Author(s):  
Ru-Jing Sun ◽  
Hung Ji Huang ◽  
Chien-Nan Hsiao ◽  
Yu-Wei Lin ◽  
Bo-Huei Liao ◽  
...  

A TiN-based substrate with high reusability presented high-sensitivity refractive index measurements in a home-built surface plasmon resonance (SPR) heterodyne phase interrogation system. TiN layers with and without additional inclined-deposited TiN (i-TiN) layers on glass substrates reached high bulk charge carrier densities of 1.28 × 1022 and 1.91 × 1022 cm−3, respectively. The additional 1.4 nm i-TiN layer of the nanorod array presented a detection limit of 6.1 × 10−7 RIU and was higher than that of the 46 nm TiN layer at 1.2 × 10−6 RIU when measuring the refractive index of a glucose solution. Furthermore, the long-term durability of the TiN-based substrate demonstrated by multiple processing experiments presented a high potential for various practical sensing applications.

2018 ◽  
Vol 8 (7) ◽  
pp. 1172 ◽  
Author(s):  
Nunzio Cennamo ◽  
Luigi Zeni ◽  
Ester Catalano ◽  
Francesco Arcadio ◽  
Aldo Minardo

In this paper, we show that light-diffusing fibers (LDF) can be efficiently used as host material for surface plasmon resonance (SPR)-based refractive index sensing. This novel platform does not require a chemical procedure to remove the cladding or enhance the evanescent field, which is expected to give better reproducibility of the sensing interface. The SPR sensor has been realized by first removing the cladding with a simple mechanical stripper, and then covering the unclad fiber surface with a thin gold film. The tests have been carried out using water–glycerin mixtures with refractive indices ranging from 1.332 to 1.394. The experimental results reveal a high sensitivity of the SPR wavelength to the outer medium’s refractive index, with values ranging from ~1500 to ~4000 nm/RIU in the analyzed range. The results suggest that the proposed optical fiber sensor platform could be used in biochemical applications.


Micromachines ◽  
2018 ◽  
Vol 9 (12) ◽  
pp. 640 ◽  
Author(s):  
Xudong Li ◽  
Shuguang Li ◽  
Xin Yan ◽  
Dongming Sun ◽  
Zheng Liu ◽  
...  

In this paper we propose a gold-plated photonic crystal fiber (PCF) refractive index sensor based on surface plasmon resonance (SPR), in which gold is coated on the external surface of PCF for easy fabrication and practical detection. The finite element method (FEM) is used for the performance analysis, and the numerical results show that the thickness of the gold film, the refractive index of the analyte, the radius of the air hole in the first layer, the second layer, and the central air hole can affect the sensing properties of the sensor. By optimizing the sensor structure, the maximum wavelength sensitivity can reach 11000 nm/RIU and the maximum amplitude sensitivity can reach 641 RIU−1. Due to its high sensitivity, the proposed sensor can be used for practical biological and chemical sensing.


Biosensors ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 455
Author(s):  
Wei Du ◽  
Lucas Miller ◽  
Feng Zhao

A new waveguide-based surface plasmon resonance (SPR) sensor was proposed and investigated by numerical simulation. The sensor consists of a graphene cover layer, a gold (Au) thin film, and a silicon carbide (SiC) waveguide layer on a silicon dioxide/silicon (SiO2/Si) substrate. The large bandgap energy of SiC allows the sensor to operate in the visible and near-infrared wavelength ranges, which effectively reduces the light absorption in water to improve the sensitivity. The sensor was characterized by comparing the shift of the resonance wavelength peak with change of the refractive index (RI), which mimics the change of analyte concentration in the sensing medium. The study showed that in the RI range of 1.33~1.36, the sensitivity was improved when the graphene layers were increased. With 10 graphene layers, a sensitivity of 2810 nm/RIU (refractive index unit) was achieved, corresponding to a 39.1% improvement in sensitivity compared to the Au/SiC sensor without graphene. These results demonstrate that the graphene/Au/SiC waveguide SPR sensor has a promising use in portable biosensors for chemical and biological sensing applications, such as detection of water contaminations (RI = 1.33~1.34), hepatitis B virus (HBV), and glucose (RI = 1.34~1.35), and plasma and white blood cells (RI = 1.35~1.36) for human health and disease diagnosis.


Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3399
Author(s):  
Haoyuan Cai ◽  
Shihan Shan ◽  
Xiaoping Wang

Surface plasmon resonance (SPR) biosensors consisting of alternate layers of silver (Ag) and TiO2 thin film have been proposed as a high sensitivity biosensor. The structure not only prevents the Ag film from oxidation, but also enhances the field inside the structure, thereby improving the performance of the sensor. Genetic algorithm (GA) was used to optimize the proposed structure and its maximum angular sensitivity was 384°/RIU (refractive index unit) at the refractive index environment of 1.3425, which is about 3.12 times that of the conventional Ag-based biosensor. A detailed discussion, based on the finite difference time domain (FDTD) method, revealed that an enhanced evanescent field at the top layer–analyte region results in the ultra-sensitivity characteristic. We expect that the proposed structure can be a suitable biosensor for chemical detection, clinical diagnostics, and biological examination.


Nanoscale ◽  
2021 ◽  
Author(s):  
Qi Wang ◽  
Zihan Ren ◽  
Wan-Ming Zhao ◽  
Lei Wang ◽  
Xin Yan ◽  
...  

The surface plasmon reso-nance (SPR) phenomenon is of wide interest for its sen-sitivity to changes in sur-face refractive index for label-free, high sensitivity and rapid detection of bi-omarkers. This paper...


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