Sensing Performance Analysis Research Articles

Screening and application of aptamers as fluorescent biosensors for selective and sensitive detection of hepatocellular carcinoma and in vivo targeted delivery studies.

The incidence of primary hepatocellular carcinoma (HCC) has recently ranked fifth in the world, and the incidence rate is increasing year by year worldwide. Therefore, early diagnosis is the highest priority in the treatment of HCC. In this paper, four anti-HCC aptamers were obtained using magnetic bead SELEX technology. Among them, Apt-1 had the smallest Kd value(5.9nM) and the highest affinity. Flow cytometry results showed that the FITC-aptamers only specifically recognized HCC serum. Circular dichronism (CD) spectral characterization showed a positive peak near 275nm and a negative peak near 250nm for all aptamers, elucidating that the secondary structure formed by the candidate aptamers was a stem-loop B-DNA structure. In addition, molecular docking simulations showed that the binding of the HCC target to the candidate aptamer sequences was mainly dominated by hydrogen bonding. The results of the aptamer sensing performance analysis showed that under the optimized assay conditions, a linear relationship (ranging from 1nM to 1µM) was achieved, with a limit of detection (LOD) down to 0.75nM and a LOQ of 2.32nM. This was further validated in clinical samples, with a positive detection rate of more than 90%. Furthermore, aptamer-mediated in vivo delivery of luciferase mRNA showed that Apt-1-luciferase mRNA could be targeted to the liver and hepatic luciferase expression was significantly increased. These results demonstrate that the aptamer paves the way for clinical application, evidencing significant potential to offer reference information for early diagnosis.

First Principles Calculation of Gas Sensitive Properties of Pd3‐Modified Monolayer PtSe2 to SF6 Decomposition Products

Based on density functional theory (DFT), the effect of Pd3 cluster modification on the surface properties of PtSe2 monolayer and the gas sensitive detection performance of PtSe2/Pd3–PtSe2 on sulfur hexafluoride (SF6) decomposition is studied, in terms of the adsorption energy, density of states (DOS), and sensing characteristic. It is found that that the Pd3 cluster exhibit stable modified structure on monolayer PtSe2, the adsorption capacity of Pd3–PtSe2 monolayer is the highest, significantly improves the surface activity and sensing performance of PtSe2 monolayer. Further, the large charge transfer, bandgap, and conductivity changes indicate that the monolayer Pd3–PtSe2 has strong chemical interaction and high sensitivity to SO2, H2S, and SO2F2 gas molecules. Pd3–PtSe2 can be used as a potential candidate for gas sensors. Finally, the sensing performance analysis of the system shows that the recovery time of Pd3–PtSe2 for SO2F2 is only 10.7 s, which can be repeated for a long time. These analyses illustrate the potential application of Pd3–PtSe2 in the detection and removal of harmful gases in gas insulated switch‐gear (GIS). The calculations may provide new insights for researchers to explore gas‐sensitive materials based on PtSe2.

Antibacterial Defective‐ZIF‐8/PPY/BC‐Based Flexible Electronics as Stress‐Strain and NO2 Gas Sensors

AbstractIntelligent wearable sensors play a crucial role in the detection of toxic gases and monitoring physiological signals, thereby effectively ensuring environmental and personal health safety. Nonetheless, achieving the requirements for antibacterial properties, comfortable wear, and multifunctional detection remains a major challenge. In this study, a novel Def‐ZIF‐8/PPY/BC‐based flexible sensor is developed by in situ growth of zeolitic imidazolate frameworks‐8 (ZIF‐8) and polypyrrole (PPY) on bacterial cellulose (BC), followed by water immersion. The Def‐ZIF‐8/PPY/BC‐based flexible sensor demonstrates effective dual‐sensitivity responses to nitrogen dioxide (NO2) toxic gas and stress‐strain behaviors at room temperature. The structural characterization and theoretical calculations affirm that the innovative water treatment method successfully introduces defects into ZIF‐8, resulting in a significant 2.57‐fold improvement in response intensity to 80 ppm NO2. Stress‐strain sensing performance analysis reveals that the Def‐ZIF‐8/PPY/BC‐based flexible sensor exhibited high sensitivity (6.44 kPa−1), rapid response and recovery times (0.7/0.4 s), and exceptional cyclic stability (8000 cycles). Further, the inhibitory effect of ZIF‐8 on common bacterial strains contributes to the exceptional antibacterial properties (antibacterial rate exceeding 99%) of the Def‐ZIF‐8/PPY/BC based on the flexible sensor. This study offers a significant advancement in metal‐organic framework defect engineering and provides an effective strategy for developing multifunctional wearable sensors.

Accurate Analysis of Multi-Mode Interferometric Optical Fiber Sensor

In view of the problem that the sensing characteristics of the multi-mode interferometric fiber sensors cannot be accurately analyzed, an analysis method based on the fast Fourier transform (FFT) and inverse fast Fourier transform (IFFT) is proposed and demonstrated theoretically and experimentally. The suitabilities of the rectangular window function with the narrow main lobe (high spectrum resolution) and low side lobe (high main mode energy leakage) and the Hanning window function with the wide main lobe (low spectrum resolution) and high side lobe (high energy concentration) in this kind of sensor analysis are discussed, respectively. This method can not only realize the sensing performance analysis of the various modes, but also overcome the inconsistency of the different interference wavelength (dip) sensing characteristics in the conventional analysis methods. At the same time, this method is also beneficial to solve the repetitive problem of such sensors.

Thermal sensing performance analysis, preparation and application of bimetallic layer MFBG

The FBG(fiber Bragg grating) can be embedded in metal to form smart structure, and to protect the FBG, the surface can be coated with high melting point metal such as Ni. MFBG(metalized FBG) will affect the temperature sensing performance of the FBG. In this paper, the thermal sensing performance of MFBG with single and double metal layers is investigated and the main factors affecting its temperature sensitivity and temperature response are analyzed. The thermal sensitivity of the MFBG gradually stabilizes as the thickness of the metal layer increases. The Ni-Ti MFBG (double-layer MFBG with Ni as the outer metal and Ti as the inner metal) was fabricated by magnetron sputtering and electroplating thickening, and a comparative thermal sensing performance experiment was conducted together with the bare FBG. Metallization of the FBG can improve the temperature sensitivity of the FBG. Samples with different metal layer thicknesses were subjected to thermal tests from 0 to 70 °C, the obtained data verified the soundness of the presented model. To verify the temperature sensing performance of the prepared Ni-Ti MFBG, it was embedded in a three-phase induction motor and the internal temperature of the motor was monitored. The experiments show that the prepared Ni-Ti MFBG has good temperature sensing performance and can accurately sense the motor temperature.

Slow-Light and Sensing Performance Analysis Based on Plasmon-Induced Transparency in Terahertz Graphene Metasurface

In this article, a polarization-independent graphene metasurface structure is designed to realize the excellent functions of slow-light and sensing generated based on plasmon-induced transparency (PIT) in terahertz (THz) region. The structure includes a cross-shaped and four square graphene resonators that are identical. The unique PIT transparent window generated by bright–bright mode coupling is studied by using finite difference time domain (FDTD) and coupled mode theory (CMT), which are highly consistent. By changing the Fermi level and carrier mobility of graphene, the transmission spectrum of PIT can be tuned effectively. Interestingly, due to the field enhancement and strong dispersion properties of surface plasma, the graphene metasurface proposed in this article has excellent effects in slow-light, and the maximum group index can reach 658. At the same time, because the transmission spectrum of PIT is sensitive to the external refractive index, the sensitivity and figure of merit (FOM) used to evaluate the sensing performance of the structure are 1.7134 THz/RIU and 144.45, respectively. Finally, because the graphene metasurface is a center symmetric structure, it has polarization-insensitive performance. The proposed structure can be used as a slow-light device or applied to biomolecular recognition, environmental monitoring, and other THz sensing fields.

Modeling of surface plasmon resonance biosensor based on Ag/BiFeO3/Ni using 2D nanomaterial perovskite MAPbBr3

In the present work, the sensing performance analysis of a surface plasmon resonance (SPR) sensor for biological and chemical applications is reported. The structure studied consists of a silver nanofilm, the hybrid nanostructure of bismuth ferrite material (BiFeO 3 ), and a nickel nanofilm covered by a layer of perovskite CH 3 NH 3 PbBr 3 (MAPbBr 3 ) nanomaterial. Our analyses are based on the finite element method (FEM) and a monochromatic excitation of wavelength 633 nm. We numerically analyzed performance parameters such as angular sensitivity, sensitivity enhancement, factor of merit (FoM) and electric field distribution. We have shown that the proposed SPR biosensor exhibits very good detection performance in terms of sensitivity and FoM. Compared with the conventional SPR structure, the 2D nanomaterials have excellent properties, such as stronger absorption capacity, which improves the biological and chemical sensing ability of the sensor. The sensitivity and FoM of the optimized biosensor reaches 408 deg/RIU with 240% enhancement, and 93.12 RIU −1 with 138.78% improvement respectively, when the perovskite material layer covered the BK7/Ag/BiFeO 3 /Ni hybrid nanostructure; for a 0.005 RIU variation in the refractive index of the sensing medium. Therefore, our proposed design and study would be practically suitable for bio/chemical sensing and in biomedical application has excellent performance, with the available fabrication technologies. • We proposed a SPR nanostructured as a high multi-functional detection biosensor by the MAPbBr 3 perovskite nanomaterial layer: BK7/Ag/BiFeO 3 /Ni/MAPbBr 3 . • The optimized nanostructure shows the highest angular sensitivity of 408 deg/RIU. • Highest sensitivity enhancement 240% for bimetallic/nanomaterials based SPR biosensor. • This study demonstrated high FoM of 105.78 RIU {-1} with an enhancement of 171.23%.

High gas sensing performance of inorganic and organic molecule sensing devices based on the BC3N2 monolayer.

Recently, a novel two-dimensional (2D) BC3N2 monolayer has gained a lot of attention due to its graphene-like structure, and it was first reported by using the particle swarm optimization algorithm and ab initio calculations. Combining density functional theory with the non-equilibrium Green's function method, a 2D BC3N2-based nanodevice has been theoretically constructed and the gas sensing performance of the BC3N2 monolayer for inorganic and organic molecules has been extensively investigated. The results revealed that the BC3N2 monolayer remains metallic with thermodynamic stability. Meanwhile, the results of sensing performance analysis show that the inorganic molecules CO, NO, and NO2 and organic molecules C2H2 and HCHO have strong chemical interactions with BC3N2 and were chemically adsorbed onto BC3N2. In contrast, the interactions between NH3, SO2, CH4, C2H4 and CH3OH and BC3N2 are very weak and these molecules adopt physical adsorption. In the case of chemisorption, the electronic transport behaviors of the 2D BC3N2 devices are sensitive to molecules, and the gas sensitivity of BC3N2 is strongly anisotropic, especially for organic C2H2 with the gas sensing ratios from 7.30 to 10.43 (from 2.51 to 2.79) under different bias voltages along the zigzag (armchair) direction. For inorganic molecules, the gas sensing device is not particularly sensitive, and the maximum gas sensing ratio is only 1.36 for CO. Meanwhile, the large anisotropic gas sensitivity can reach up to 2.66/6.22 for electron transport along the armchair and zigzag directions for CO/C2H2 in the BC3N2-based sensing devices. Accordingly, the high gas sensitivity can be disclosed by displaying the scattering state around the Fermi level at different bias voltages during the transport process. As a result, BC3N2 could be used in 2D gas sensing devices, especially for sensing organic molecule C2H2.

Enhanced CO sensing performance of WO3 nanorods with PtAg nanoparticles modification: A combined experimental and first-principle study

WO3 nanorods and PtAg-loaded WO3 nanorods with a length of 50–100 nm were synthesized for CO detection. The samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis absorption spectra and Fourier transform infrared spectroscope (FTIR). The analysis results indicated that PtAg nanoparticles with the diameter of 20–30 nm were loaded on the surface of WO3 nanorods. CO sensing performance analysis results indicated that modification by PtAg nanoparticles could improve the sensing performance of WO3. The sensitivity value is significantly improved and the optimal temperature decreased 20 °C, the response value is 2.79 toward 100 ppm CO and response/recovery time is 75/24 s. Additionally, the first-principles calculation results based on density functional theory (DFT) showed that the best adsorption sites of CO on the surface of Pt (111) and Ag (111) are top site and the adsorption energy of Pt (111) is better than Ag (111) on each site. The enhanced gas sensitivity may be attributed to the special sensitization mechanism of Pt and Ag and their strong interaction. The combination of experiment and theoretical calculation research provides a feasible strategy for the design of CO gas sensor.

Using NASA Earth observations and Google Earth Engine to map winter cover crop conservation performance in the Chesapeake Bay watershed

Winter cover crops such as barley, rye, and wheat help to improve soil structure by increasing porosity, aggregate stability, and organic matter, while reducing the loss of agricultural nutrients and sediments into waterways. The environmental performance of cover crops is affected by choice of species, planting date, planting method, nutrient inputs, temperature, and precipitation. The Maryland Department of Agriculture (MDA) oversees an agricultural cost-share program that provides farmers with funding to cover costs associated with planting winter cover crops, and the U.S. Geological Survey (USGS) and the U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS) have partnered with the MDA to develop satellite remote sensing techniques for measuring cover crop performance. The MDA has developed the capacity to digitize field boundaries for all fields enrolled in their cover crop programs (>26,000 fields per year) to support a remote sensing performance analysis at a statewide scal,e and has requested assistance with the associated imagery processing from the National Aeronautics and Space Administration (NASA). Using the Google Earth Engine (GEE) cloud computing platform, scripts were developed to process Landsat 5/7/8 and Harmonized Sentinel-2 imagery to measure winter cover crop performance. We calibrated cover crop performance models using linear regression between satellite vegetation indices and USGS / USDA-ARS field sampling data collected on Maryland farms between 2006 and 2012 (1298 samples). Satellite-derived Normalized Difference Vegetation Index (NDVI) values showed significant correlation with the natural logarithm of cover crop biomass (p ≤0.01, R2 = 0.56) and with observed percent vegetative ground cover (p ≤0.01, R2 = 0.68). The GEE scripts were used to composite seasonal maximum NDVI values for each enrolled cover crop field and calculate performance metrics for the winter and spring seasons of three enrollment years (2014–15, 2015–16, and 2017–18) for four Maryland counties. Results from winter 2017–18 demonstrate that rye and barley fields had higher biomass than wheat fields, and that early planting, along with planting methods that increase seed-soil contact, increased performance. The processing capabilities of GEE will support the MDA in scaling up remote sensing performance analysis statewide, providing information to evaluate the environmental outcomes associated with various agronomic management strategies. The tool can be modified for different seasonal cutoffs, utilize new sensors to capture phenology in winter and spring, and scale to larger regions for use in adaptive management of winter cover crops planted for environmental benefit. Project supportThis project was supported by the USGS Land Change Science Program within the Land Resources Mission Area, the USDA Choptank River Conservation Effects Assessment Project (CEAP), the USDA Lower Chesapeake Bay Long Term Agricultural Research (LTAR) Project; the Maryland Department of Agriculture; and the NASA DEVELOP National Program.

Simulation and analysis of 2D material/metal carbide based fiber optic SPR probe for ultrasensitive cortisol detection

Cortisol, a steroid hormone, plays a vital part in regulating various activities such as metabolism and immune response. It is a well-known stress biomarker and should be measured with as high precision as possible. In this work, a non-invasive fiber optic surface plasmon resonance (FOSPR) based sensor probe is proposed for detection of salivary cortisol at the w avelength (λ) of 830 nm. Proposed sensor design consists of chalcogenide glass core, polymer clad, silver (Ag) layer with two-dimensional (2D) materials such as conventional (graphene, WS2 and MoS2) and transition metal carbides (MXenes) based layered materials considered one at a time. Angular and intensity interrogation methods have been envisaged for simulation and analysis purpose. The sensing performance analysis is carried out in terms of figure of merit (FOM) and combined performance factor (CPF). A comprehensive analysis of all the probe variants reveals that among all the sensor design variants, the Ti3C2O2-based probe is able to provide superior overall sensing performance including a detection limit as fine as 15.7 fg/mL, which is finer compared to existing cortisol sensors based on diverse techniques.

A High-Q AFM Sensor Using a Balanced Trolling Quartz Tuning Fork in the Liquid.

A quartz tuning fork (QTF) has been widely used as a force sensor of the frequency modulation atomic force microscope due to its ultrahigh stiffness, high quality factor and self-sensing nature. However, due to the bulky structure and exposed surface electrode arrangement, its application is limited, especially in liquid imaging of in situ biological samples, ionic liquids, electrochemical reaction, etc. Although the complication can be resolved by coating insulating materials on the QTF surface and then immersing the whole QTF into the liquid, it would result in a sharp drop of the quality factor, which will reduce the sensitivity of the QTF. To solve the problem, a novel method, called the balanced trolling quartz tuning fork (BT-QTF), is introduced here. In this method, two same probes are glued on both prongs of the QTF separately while only one probe immersed in the liquid. With the method, the hydrodynamic interaction can be reduced, thus the BT-QTF can retain a high quality factor and constant resonance frequency. The stable small vibration of the BT-QTF can be achieved in the liquid. Initially, a theoretical model is presented to analyze the sensing performance of the BT-QTF in the liquid. Then, the sensing performance analysis experiments of the BT-QTF have been performed. At last, the proposed method is applied to atomic force microscope imaging different samples in the liquid, which proves its feasibility.

Synthesis, Fabrication and Characterization of ZnO-Based Thin Films Prepared by Sol–Gel Process and H2 Gas Sensing Performance

In this paper, an attempt is made to deposit ZnO thin films using sol–gel process followed by dip-coating method on p-silicon (100) substrates for intended application as a hydrogen gas sensor owing to the low toxic nature and thermal stability of ZnO. The thin films are annealed under annealing temperatures of 350, 450 and 550 °C for 25 min. The crystalline quality of the fabricated thin films is then analyzed by field-emission scanning electron microscopy and transmission electron microscope. The gas sensing performance analysis of ZnO thin films is demonstrated at different annealing temperatures and hydrogen gas concentrations ranging from 100 to 3000 ppm. Results obtained show that the sensitivity is significantly improved as annealing temperature increases with maximum sensitivity being achieved at 550 °C annealing temperature and operating temperature of 150 °C. Hence, the modified ZnO thin films can be applicable as H2 gas sensing device showing to the improved performance in comparison with unmodified thin-film sensor.

Sensing Performance Analysis on Quartz Tuning Fork-Probe at the High Order Vibration Mode for Multi-Frequency Scanning Probe Microscopy.

Multi-frequency scanning near-field optical microscopy, based on a quartz tuning fork-probe (QTF-p) sensor using the first two orders of in-plane bending symmetrical vibration modes, has recently been developed. This method can simultaneously achieve positional feedback (based on the 1st in-plane mode called the low mode) and detect near-field optically induced forces (based on the 2nd in-plane mode called the high mode). Particularly, the high mode sensing performance of the QTF-p is an important issue for characterizing the tip-sample interactions and achieving higher resolution microscopic imaging but the related researches are insufficient. Here, we investigate the vibration performance of QTF-p at high mode based on the experiment and finite element method. The frequency spectrum characteristics are obtained by our homemade laser Doppler vibrometer system. The effects of the properties of the connecting glue layer and the probe features on the dynamic response of the QTF-p sensor at the high mode are investigated for optimization design. Finally, compared with the low mode, an obvious improvement of quality factor, of almost 50%, is obtained at the high mode. Meanwhile, the QTF-p sensor has a high force sensing sensitivity and a large sensing range at the high mode, indicating a broad application prospect for force sensing.

Monitoring Traffic Information with a Developed Acceleration Sensing Node.

In this paper, an acceleration sensing node for pavement vibration was developed to monitor traffic information, including vehicle speed, vehicle types, and traffic flow, where a hardware design with low energy consumption and node encapsulation could be accomplished. The service performance of the sensing node was evaluated, by methods including waterproof test, compression test, sensing performance analysis, and comparison test. The results demonstrate that the sensing node is low in energy consumption, high in strength, IPX8 waterproof, and high in sensitivity and resolution. These characteristics can be applied to practical road environments. Two sensing nodes were spaced apart in the direction of travelling. In the experiment, three types of vehicles passed by the monitoring points at several different speeds and values of d (the distance between the sensor and the nearest tire center line). Based on cross-correlation with kernel pre-smoothing, a calculation method was applied to process the raw data. New algorithms for traffic flow, speed, and axle length were proposed. Finally, the effects of vehicle speed, vehicle weight, and d value on acceleration amplitude were statistically evaluated. It was found that the acceleration sensing node can be used for traffic flow, vehicle speed, and other types of monitoring.

Sensing performance analysis on Fano resonance of metallic double-baffle contained MDM waveguide coupled ring resonator

Based on the transmission property and the photon localization characteristic of the surface plasmonic sub-wavelength structure, a metallic double-baffle contained metal-dielectric-metal (MDM) waveguide coupled ring resonator is proposed. Like the electromagnetically induced transparency (EIT), the Fano resonance can be achieved by the interference between the metallic double-baffle resonator and the ring resonator. Based on the coupled mode theory, the transmission property is analyzed. Through the numerical simulation by the finite element method (FEM), the quantitative analysis on the influences of the radius R of the ring and the coupling distance g between the metallic double-baffle resonator and the ring resonator for the figure of merit (FOM) is performed. And after the structure parameter optimization, the sensing performance of the waveguide structure is discussed. The simulation results show that the FOM value of the optimized structure can attain to 5.74×104 and the sensitivity of resonance wavelength with refractive index drift is about 825 nm/RIU. The range of the detected refractive index is suitable for all gases. The waveguide structure can provide effective theoretical references for the design of integrated plasmonic devices.

Study on gas sensing of reduced graphene oxide/ZnO thin film at room temperature

We report the synthesis, characterization and gas sensing performance of reduced graphene oxide (RGO) and RGO/ZnO bilayer thin films prepared by facile sol-airbrush technology at room temperature. We found that RGO/ZnO bilayer films exhibit enhanced surface roughness and more spacing compared to RGO. Sensing performance measurements showed that RGO/ZnO film has 30% enhancement of ΔR/R0 to chloroform vapor compared to pure RGO film due to the improvement of film structure. A slight enhancement of ΔR/R0 was also observed on exposure to other vapors (water, ethanol, acetone and formaldehyde), with response and recovery time less than 10s. To explore the stability of RGO film, we studied the effect of various flow rates of background gas on the electric resistance variation. It was found that electric resistance fell at a larger flow rate, rose at a smaller rate, and ΔR/R0 became smaller after annealing. These results can be understood by the air pressure-induced deformation of RGO film. We further proposed a new method to calculate the sensing response, which was verified to be more reliable for sensing performance analysis with negligible hysteresis. We expect these findings to shed new light on future development of high-performance gas sensors based on bilayer films.

Refractive index sensing performance analysis of photonic crystal containing graphene based on optical Tamm state

A photonic crystal’s refractive index sensor is proposed based on the photonic crystal (PC) optical properties and the surface wave resonance principle. The optical Tamm state existing at the interface between one-dimensional (1D) PCs and the metal layer can overcome the disadvantage of the surface plasmon resonance (SPR) sensor in which the incident light can only be TM polarized light. The resonant wavelength can be changed by adjusting the optical parameters of the PC. Through coating the metal surface with graphene, the resolution and sensitivity of the sensor can be improved obviously. The relationship model between the graphene parameters and the reflectivity is established by analyzing the reflective properties of the graphene. In the numerical simulation, the graphene layer is optimized to improve the refractive index sensing properties. The numerical simulation results show that the quality factor ([Formula: see text] value) can attain to 1418.2 and the sensitivity is about 1178.6 nm RIU[Formula: see text], which can demonstrate the effectiveness of the senor structure and provide some theoretical references for the design of the refractive index sensors with high [Formula: see text] value and sensitivity.

Refractive index sensing performance analysis of photonic crystal Mach–Zehnder interferometer based on BP neural network optimization

According to the band gap and photon localization characteristics, the single-arm notching and the double-arm notching Mach–Zehnder interferometer (MZI) structures based on 2D triangular lattice air hole-typed photonic crystal waveguide are proposed. The back-propagation (BP) neural network is introduced to optimize the structural parameters of the photonic crystal MZI structure, which results in the normalized transmission peak increasing from 85.3% to 97.1%. The sensitivity performances of the two structures are compared and analyzed using the Salmonella solution samples with different concentrations in the numerical simulation. The results show that the sensitivity of the double-arm notching structure is 4583 nm/RIU, which is about 6.4 times of the single-arm notching structure, which can provide some references for the optimization of the photonic devices and the design of high-sensitivity biosensors.

Asymmetric hybrid double dielectric loaded plasmonic waveguides for sensing applications

In this paper we report on the design of Long-Range Surface Plasmon Polariton hybrid double dielectric loaded plasmonic waveguides suitable for sensing applications. We investigate the optical properties of these plasmonic waveguides, in terms of propagation lengths and effective refractive index, when they are immersed in different analytes. We show that high refractive index spacers can be optimized to compensate the asymmetry that is always present in biosensors due to the refractive index mismatch between the analyte and the substrate. This compensation permits the propagation of Long-Range Surface Plasmon Polariton modes that can be successfully exploited for sensing applications due to their weaker confinement and long propagation lengths. The sensing performance analysis of the plasmonic waveguides shows resolution of the order of 10−6–10−7, values comparable or better than those proposed by other plasmonic sensor configurations.