Resonance Sensor Research Articles

Four-state Fano resonance electro-optical modulator and sensor based on double borophene-dielectric grating structure

In this paper, we propose a borophene-based double-dielectric-grating structure (BDDGS) to realize the Fano resonance electro-optical modulator and sensor. The Fano resonance originated from the coupling of two resonance modes excited by the upper borophene grating (UBG) and the lower borophene grating (LBG). The coupling mode theory (CMT) is utilized to fit the Fano transmission spectrum. The calculated result fits well with the simulated spectrum. We found the Fano resonance wavelengths exhibit a blue shift with increasing the carrier density of the borophene layer. Further, we utilize this property to achieve a Four-state Fano resonance electro-optical modulator. The working wavelengths of the ON-ON (11), ON–OFF (10), OFF–ON (01), and OFF-OFF (00) states are 1.321 μm and 1.676 μm, respectively. The asymmetric Fano spectra exhibit high sensing sensitivity S=21THz/RIU and figure of merit FOM=3.9RIU−1. Moreover, our proposed structure possesses a slow-fast light effect with the maximum group index are 57.84 and −332.3, respectively. Although several Fano resonance and electro-optical modulators based on two- dimensional (2D) material, like graphene, black phosphorus, and transition metal dichalcogenides (TMDs) are previously reported, this paper designed a borophene-based metamaterial to achieve Fano resonance electro-optical modulator and sensor, because borophene possesses a series of excellent physical and chemical properties, for example, mechanical compliance, high carrier mobility, and optical transparency. Therefore, the proposed borophene-based metamaterial will be beneficial in the fields of high-performance plasmonic sensors, slow light, and electro-optical modulators in the near future.

Design of Encoded and Tunable Graphene-Gold Metasurface-Based Surface Plasmon Resonance Sensors for Glucose Detection in the Terahertz Regime

Design of Encoded and Tunable Graphene-Gold Metasurface-Based Surface Plasmon Resonance Sensors for Glucose Detection in the Terahertz Regime

Highly sensitive near-field leakage-enhanced optical fiber SPR sensor based on gold nanoarrays modulation

A novel near-field leakage-enhanced optical fiber surface plasmon resonance (NLF-SPR) sensor based on the synergistic sensitization of cuboid gold nanoarrays and WSe2 film is proposed for the first time to our knowledge. The sensor is composed of a side-polished multimode fiber, a continuous gold film, a continuous tungsten selenide (WSe2) film, and well-arranged cuboid gold nanoarrays. The sensor leverages the high carrier mobility characteristic of the WSe2 film, the near-field leakage enhancement arising from the nanoarrays structure, and the localized electric field enhancement property introduced by nanotips to enhance the refractive index sensitivity. In order to optimize the spectral characteristic, the modulation of electric field distribution and spectral characteristic by the structural parameters of gold nanoarrays is investigated through three-dimensional (3D) finite element simulation. Results show that in the refractive index range of 1.3332–1.3432 refractive index unit (RIU), the average sensitivity of the NLF-SPR sensor can reach up to 10108 nm/RIU, and the highest sensitivity can reach up to 14692.46 nm/RIU. The average sensitivity and the highest sensitivity are 1.87 times and 2.56 times higher, respectively, than those of the side-polished fiber SPR sensor with a monolayer gold film. Furthermore, the experimental results demonstrate that the near-field leakage enhancement introduced by gold nanoarrays improves the performance of the fiber SPR sensor, resulting in a 49.3 % increment in sensitivity. The experimental results are in agreement with the trend of the simulation results. Even better performance improvements have been achieved compared to existing methods and a more flexible approach to performance tuning is provided. With the maturity and development of various nanoarray processing techniques such as focused ion beam, electron beam lithography, and nanoimprint lithography, the proposed NLF-SPR sensor has the potential to be fabricated on a large scale and is expected to be widely employed in biomedical, clinical applications, and other fields.

Design and Optimization of a MXene-Based Terahertz Surface Plasmon Resonance Sensor for Malaria Detection

Design and Optimization of a MXene-Based Terahertz Surface Plasmon Resonance Sensor for Malaria Detection

Surface plasmon resonance (EC-SPR) sensor based on molecularly imprinted strategy for the determination of stimulant modafinil in saliva samples

A highly sensitive and selective molecularly imprinted polymer-based electrochemical-surface plasmon resonance (MIP-based EC-SPR) sensor was developed for the determination of modafinil in saliva samples. The optimal MIPpy film was synthesized using a modafinil concentration of 1 mM and a constant potential electropolymerization method. The fabricated sensor exhibited a wide linear range (0.1 μM to 10 μM), low detection limits (LOD: 50 nM, LOQ: 170 nM), and high selectivity towards modafinil, with selectivity coefficients of 8.5, 6.2, and 12.7 for adrafinil, armodafinil, and caffeine, respectively. The sensor also demonstrated excellent reproducibility (RSD: 4.2 %) and long-term stability (92 % response after one month). Furthermore, the applicability of the sensor in real samples was validated using spiked saliva samples, with recovery values ranging from 94.7 % to 103.5 %. These results highlight the potential of the MIP-based EC-SPR sensor as a powerful tool for the rapid, sensitive, and selective detection of modafinil in complex biological matrices.

Surface plasmon resonance sensors: Temperature effects

In this paper, we present a detailed study of the temperature effect (0−100°C), on the plasmonic resonance and sensitivity of a surface plasmon resonance (SPR) to the medium detection refraction index change. We examine this SPR based on the Kretschmann multilayer configuration constituted by a BK7 prism, an Ag/Au bimetallic layer deposited on TiO2/SiO2 and a BlueP/MoS2 heterostructure monolayer. First, a simple numerical calculation is provided to analyze the temperature effect on the plasmonic resonance. The model take into account the dependence on temperature of the refractive index of different materials composing the investigated structures. The main idea is to show how the sensitivity of the SPR based sensor is influenced according to operating temperature which is critical parameter when considering bio-sensing applications.

High-sensitive surface plasmon resonance sensor for melamine detection in dairy products based on graphene oxide /chitosan nanocomposite

Accurate diagnosis and determination of the appropriate dose of melamine is crucial, especially in children's food, due to the potential for severe side effects such as kidney stones. This research has demonstrated the effectiveness of the graphene oxide-chitosan (GOCS) composite in modifying the gold chip surface as a sensor platform, resulting in a significant 1.17° angular change relative to the bare gold chip for the detection of melamine. The GOCS composite was analyzed using SEM, XRD, and FTIR. The GOCS sensor exhibited high sensitivity with a value of 239.1◦μM−1, a linear range (L.R) of 0.01–200 μM, affinity constant of 1.73 × 104 and an impressive limit of detection (LOD) of 10 nM. These findings highlight the potential of the GOCS sensor for accurately and precisely detecting melamine. Additionally, we compared the obtained results from the sensor with those from the standard method of HPLC, which is referred to as the gold standard in analytical chemistry, by conducting tests using GOCS/Au to identify melamine in commercial samples. The comparison showed that the GOCS sensor offers desirable features for analyzing real samples, making it a promising tool for accurately and efficiently detecting melamine in various samples.

Optical Sensitive Detection of Cervical Cancer Based on Surface Plasmon Resonance Nanostructure

Cervical cancer is a disease that affects a lot of people all over the world. The success of treatment is significantly increased by early detection. The new surface plasmon resonance sensor (SPRS) described in this article is constructed from layers of silver, BaTiO3, and graphene, as well as a coupling prism. The transfer matrix (TM) approach is used to evaluate the SPRS structure. To obtain the highest sensitivity of the suggested SPRS, the thicknesses of the Ag and BaTiO3 and the number of Gr sheets are evaluated. Investigations are done on all factors of performance of the proposed device. Exemplary efficiency is achieved using 4 nm (BaTiO3) and 60 nm (Ag) materials. Three layers are chosen as the optimal amount of graphene after investigation. When the optimal thicknesses are employed, the suggested SPRS's greatest sensitivity of 300° RIU−1 has been attained. The suggested SPRS displays better sensitivity when compared to SPRS structures that have already been published in the literature. This SPRS is promising to be used in different biosensing applications due to its high performance.

Dual parameter sensor for RI and temperature detection by cascading Ag/WO3 film PCF and Ag/MoS2/PDMS film PCF.

Multi-parameter surface plasmon resonance (SPR) sensors generally have low detection sensitivity due to detection wavelength limitations. We developed a two-parameter SPR sensor for refractive index (RI) and temperature detection by cascading Ag/WO3 film photonic crystal fiber (PCF) and Ag/MoS2 film PCF together. By using WO3 film with a low effective refractive index to prevent oxidation of silver-based PCF and maintain a wider RI sensing channel detection band; at the same time, MoS2 film with a high effective refractive index is used to modulate the detection range of temperature sensing channel. The detection performance and stability of the two-parameter SPR sensor were verified by software simulation and experiments. The data results indicate that the sensor can perform stable and independent tests during RI and temperature detection. The maximum sensitivity of the sensor within the RI detection range of 1.333 to 1.395 is as high as 6443 nm/RIU; the maximum temperature sensitivity within the temperature detection range of 40 °C∼90 °C is 8.72 nm/°C. This sensor can achieve high-sensitivity RI measurement in a high-temperature environment. This will have broad application prospects in the field of biochemistry.

Plasmonic Optical Fiber Sensors and Molecularly Imprinted Polymers for Glyphosate Detection at an Ultra-Wide Range

In this study, a surface plasmon resonance (SPR) sensor based on modified plastic optical fibers (POFs) was combined with a specific molecularly imprinted polymer (MIP), used as a synthetic receptor, for glyphosate (GLY) determination in aqueous solutions. Since GLY is a non-selective herbicide associated with severe environmental and health problems, detecting glyphosate in environmental and biological samples remains challenging. The selective interaction between the MIP layer and GLY is monitored by exploiting the SPR phenomenon at the POF’s gold surface. Experimental results show that in about ten minutes and by dropping microliter volume samples, the presented optical–chemical sensor can quantify up to three orders of magnitude of GLY concentrations, from nanomolar to micromolar, due to a thin MIP layer over the SPR surface. The developed optical–chemical sensor presents a detection limit of about 1 nM and can be used for onsite GLY measurements. Moreover, the experimental analysis demonstrated the high selectivity of the proposed POF-based chemical sensor.

Accurate thickness evaluation of thermal barrier coatings using microwave resonator sensor

Thermal barrier coatings (TBC) are frequently employed in aircraft engines and turbine blades for protection against high temperatures. Constant exposure to in-service stresses, however, leads to a variety of anomalies in TBC that could prove to be potentially catastrophic for the assemblies they protect. This raises the need for inspection using non-destructive techniques (NDT) to ensure the reliability and structural integrity of the coated assemblies. Thickness evaluation of the topcoat of the TBC is paramount to determining structural integrity of the TBC. Microwaves are particularly suited for such applications since they readily penetrate low loss TBC. However, the performance of previous microwave-based TBC thickness evaluation techniques was limited in accuracy to 15 μm. In this paper, accurate thickness evaluation of thermal barrier coating (TBC) is performed using a microwave resonator sensor operating at a relatively low frequency (<1 GHz). TBC thicknesses as low as 100 μm are evaluated based on shift in resonant frequency of the probe. Overall, practically relevant thicknesses ranging from 100 μm to 600 μm are evaluated herein and multiple trials are performed to ascertain repeatability and assess uncertainty in measurements. For a 250 μm thick TBC sheet, a mean error of 0.9 μm was accomplished which translates to 0.36 % error with a standard deviation of 1.5 μm. Compared to other microwave sensors reported in the literature, a better estimation accuracy is demonstrated in this work, in particular for thicknesses less than <250 μm.

Triple-Channel Optical Fiber Surface Plasmon Resonance Sensor for Simultaneous Detection of Relative Humidity, Magnetic Field, and Temperature

Triple-Channel Optical Fiber Surface Plasmon Resonance Sensor for Simultaneous Detection of Relative Humidity, Magnetic Field, and Temperature

Surface plasmon resonance sensor of hollow microstructure fiber based on ZIF-8 thin film

An annular hollow microstructured fiber surface plasmon resonance (SPR) sensor based on ZIF-8 film is proposed for the measurement of CO2 concentration in air. Internal detection is adopted to enhance the spectral response to CO2 gas, and nano-gold pillars are embedded on both sides of the channel. The geometric parameters of the sensor are optimized to achieve an average sensitivity of 1.01 nm/% over the range of CO2 concentration from 0% to 100%. The results indicate that the sensor is a promising SPR gas sensor with great potential in CO2 detection applications.

Phage based biosensors: Enhancing early detection of emerging pathogens in diagnostics

Global health is seriously threatened by an increase in antibiotic resistance among ESKAPE pathogens- E- E. faecium, S- S.aureus, K- K.pneumoniae, A-A.baumannii, P- P.aeruginosa, and E-Enterobacter. The resistance of many bacteria to traditional antibiotics is increasing, making the search for novel approaches critical. In order to minimize the effect of these diseases, early detection, diagnosis, and treatment are important. However, there are drawbacks to traditional detection techniques such molecular-based, biochemical, and microbiological assays. These include the inability to detect on-site, as well as their time-consuming, expensive, and labour-intensive nature. Viral agents that target bacteria exclusively, known as bacteriophages, have shown promise in combating over infections resistant to antibiotics. Bacteriophage-based biosensors are adaptable to many environmental conditions and offer special features such as host specificity and ability to identify active infections. They're very accurate, very specific, and have quick assay times, which makes them beneficial tools for detection. Also, phages are more easily produced than antibodies and can withstand high pH, temperature, and chemical solvents. The potential of bacteriophage-based biosensors in the fight against ESKAPE pathogens is highlighted by this review. Bacteriophage-based biosensors provide simplified detection processes in contrast to conventional approaches, which makes them invaluable in environmental and clinical situations. Numerous platforms, including electrochemical, magnetoelastic, quartz crystal microbalance, and surface plasmon resonance sensors, being investigated for their potential use to detect pathogenic bacteria in a range of sample types.

Grating Structures for Silver-Based Surface Plasmon Resonance Sensors with Adjustable Excitation Angle.

Silver-based grating structures offer means for implementing low-cost, efficient grating couplers for use in surface plasmon resonance (SPR) sensors. One-dimensional grating structures with a fixed periodicity are confined to operate effectively within a single planar orientation. However, two-dimensional grating structures as well as grating structures with variable periodicity allow for the plasmon excitation angle to be seamlessly adjusted. This study demonstrates silver-based grating designs that allow for the plasmon excitation angle to be adjusted via rotation or beam position. The flexible angle adjustment opens up the possibility of developing SPR sensor designs with an expanded dynamic range and increased flexibility in sensing applications. The results demonstrate that efficient coupling into two diffraction orders is possible, which ultimately leads to an excitation angle range from 16° to 40° by rotating a single structure. The findings suggest a promising direction for the development of versatile and adaptable SPR sensing platforms with enhanced performance characteristics.

Dual-spectral narrow bandwidth surface lattice resonance sensors

Dual-spectral narrow bandwidth surface lattice resonance (SLR) sensors consisting of semiconductor/SiO2 nanoparticle dimer arrays are proposed to achieve two high figures of merit (FOM). We demonstrate that FOM can be optimized by the change of semiconductor nanoparticles’ shape. The best shape of Si nanoparticles with high FOM is pillar because of the narrowest FWHM of SLR. The FOM of Si/SiO2 nanopillar dimer array can reach a value of 180 due to the high sensitivity and narrow bandwidth. Besides, the influences of different structural parameters (such as the gap of the Si nanopillars in each dimer, Si nanopillars’ diameter and height) on FOM of Si/SiO2 nanopillar dimer arrays are investigated. In the trade-off between the strong SLR and the high FOM, the gap of 50[Formula: see text]nm, the Si nanopillars’ diameter of 80[Formula: see text]nm, and the Si nanopillars’ height of 100[Formula: see text]nm, are chosen as suitable values. Furthermore, a comparison of FOM between Si, Ge, GaAs nanopillars with fixed sizes is implemented to select the appropriate materials. The best semiconductor material to obtain a high FOM is Si because of a narrower FWHM and higher sensitivity. This work is of great significance for the design of multi-spectral SLR sensors.

Enhanced Pressure Response of Edge-Deposited Graphene Nanomechanical Resonators.

Nanomechanical resonators made of suspended graphene exhibit high sensitivity to pressure changes. Nevertheless, the graphene resonator pressure performance is affected owing to the gas permeation problem between the graphene film and the substrate. Therefore, we prepared edge-deposited graphene resonators by focused ion beam (FIB) deposition of SiO2, and their gas leakage velocities and pressure-sensing ability were demonstrated. In this paper, we characterize the pressure-sensing response and gas leakage velocities of graphene membranes using an all-optical actuation system. The gas leakage velocities of graphene resonators with diameters of 10, 20, and 40 μm are reduced by 5.0 × 106, 2.0 × 107, and 8.1 × 107 atoms/s, respectively, which demonstrates that the edge deposition structure can reduce the gas leakage of the resonator. Furthermore, the pressure-sensing performance of three graphene resonators with different diameters was evaluated, and their average pressure sensitivities were calculated to be 3.4, 2.4, and 1.9 kHz/kPa, with the largest full-range hysteresis errors of 0.6, 0.7, and 1.0%, respectively. The temperature stabilities of the three sizes of resonators in the temperature range of 300-400 K are 0.016, 0.015, and 0.016%/K, and the maximum resonance frequency drift over 1 h is 0.0058, 0.0048, and 0.0112%, respectively. This work has great significance for the improvement of gas leakage velocity characterization of graphene membrane and graphene resonant pressure sensor performance optimization.

Concept, simulation, and fabrication of inverted grating structures for surface plasmon resonance sensors

Abstract. Surface plasmon resonance (SPR) sensors offer the possibility of label-free analysis of biosamples. The long-term stability of standard approaches is limited due to degradation of the grating upon contact with the analyte, and strategies to improve the performance in this regard include the use of so-called inverted configurations. By exciting surface plasmons from the back side of the grating, this design overcomes limitations of traditional grating-based SPR sensors caused by direct contact with the analyte medium and offers new design possibilities for implementing microfluidic analytical systems. Here a simulation for optimizing design parameters and a corresponding microfabrication technology to create the inverted grating are presented. An experimental evaluation of surface plasmon excitation and sensitivity enhancement demonstrates the feasibility of the approach. While the observed coupling effect of inverted grating structures is not as strong as the conventional configuration, it offers benefits like preventing surface oxidation, enabling repeated usage and new concepts for biosample processing.

Highly sensitive surface plasmon resonance sensor based on the anti-resonant fiber with six nested tubes

On the heels of the continuous development of optical fiber sensing technology, optical fiber sensors based on surface plasmon resonance (SPR) have attracted widespread attention. Herein, an SPR sensor based on the six nested anti-resonant fiber (ARF) is designed and analyzed by the finite element method (FEM). All the structural parameters are optimized to achieve high-sensitivity liquid refractive index detection. Filling the anti-resonant tube with plasmonic materials to excite SPR can further reduce the manufacturing complexity. The optimal ARF-SPR sensor has excellent characteristics, including an average wavelength sensitivity of 42,000 nm/RIU, maximum sensor length of 0.08 cm, and resolution of 1.61×10−6RIU. The ARF-SPR sensor has great potential in chemical analysis, biomedicine, and other fields.

Side-Opened Hollow Fiber-Based SPR Sensor for High Refractive Index Detection.

To facilitate the sensor fabrication and sensing operation in microstructured optical fiber-based surface plasmon resonance (SPR) sensors for high refractive index (RI) detection, we propose a special hollow fiber-based SPR sensor that comprises an opening on its body side and a thin gold layer coated on its outer surface. The analyte is able to flow into the hollow core through the side-opening to form new fiber core, with the Gaussian-like mode propagating in it. We investigate the sensing performance of the proposed sensor in a higher RI range of 1.48 to 1.54 at two feasible schemes: one is to only fill the fiber core with analyte (Scheme A), and the other is to directly immerse the sensor in the analyte (Scheme B). The results demonstrate that our sensor exhibits higher wavelength sensitivity at Scheme A with a maximum wavelength sensitivity of 12,320 nm/RIU, while a greater amplitude sensitivity was found at Scheme B with a maximum amplitude sensitivity of 1146 RIU-1. Our proposed sensor features the advantages of simple fabrication, flexible operation, easy analyte filling and replacing, enhanced real-time detection capabilities, high RI detection, and very high wavelength sensitivity and amplitude sensitivity, which makes it more competitive in SPR sensing applications.