Plasmonic Refractive Index Sensor Research Articles

Multispectral nano-cavity-based plasmonic refractive index sensor: Higher bulk and surface sensitivity for detection of biological analytes

In this paper, a Nano-cavity based multispectral plasmonic refractive index sensor for prostate-specific antigen (PSA) detection was investigated. The proposed structure includes two cavities in the form of a T and E shape inside a metal layer. The validity of the findings was verified through the use of the 3D finite difference time domain (FDTD) method. The identification of biomolecules is difficult for conventional biosensors in which there is a very limited amount of analyte, other metrics should be used. In most cases, there is enough analyte to completely cover the sensing surface. Here, in addition to bulk sensitivity, the surface sensitivity was analyzed. The proposed structure has three resonance modes. According to our findings, the designed structure has a bulk sensitivity of 958.3 nm/RIU for the third mode (mode III), 550 nm/RIU for the second mode (mod II), and 637.1 for the first mode (mode I). Having three resonance modes makes this structure a suitable option for use in multispectral applications. The surface sensitivity of 429.4, 457.6, and 465.5 nm/RIU was obtained for surface layer thicknesses of 3.5 nm, 5 nm, and 6.5 nm, respectively. Our results show the proposed structure has good potential in different biological applications.

Infrared plasmonic refractive index sensor utilizing 2D grating of nano-bowtie particles for both gas and liquid

We propose a plasmonic structure that can be used for refractive index sensing with different analytes in the same wavelength-domain. A two-dimensional (2D) grating composed of nano-bowtie particles is used as the optical momentum coupling structure. The double-period feature of the 2D grating makes the structure have two excitation approaches with different polarization directions of incident light. The physical mechanisms of the plasmonic structure are revealed in detail by theoretical analysis and finite-difference time-domain method. The simulation results show that the structure can achieve a gas sensing sensitivity of 1235 nm/RIU and a liquid sensing sensitivity of 950 nm/RIU in the same wavelength-domain from 1200 nm to 1400 nm. This structure can be widely used in the field of gas or liquid biochemistry due to its simple geometry and competitive sensing performance.

High sensitivity plasmonic refractive index sensor for early anaemia detection

Plasmonics is gaining prominence in the area of optical sensing due to the unique way that noble metals and light interact to produce subwavelength confinement. A Metal Insulator Metal waveguide based plasmonic nanosensor exhibiting multi Fano resonance is proposed. The characteristics of transmittance of the proposed sensor are investigated using the Finite Difference Time Domain methodology. Three Fano resonances can be seen in the transmission characteristic with different sensitivities of 992.4 nm/RIU, 1294.8 nm/RIU and 2065.5 nm/RIU at 1.0257 μm, 1.3239 μm and 2.0798 μm respectively. Furthermore, the sensor performance is investigated for potential fabrication issues arising out of variation in structural parameters such as the coupling distance and the radius (both inner and outer) of the semi-ring arc resonator. The performance of the sensor is also assessed for performance metrics like the Figure of Merit (FOM), Q factor, and Detection Limit, which are obtained as 39.7 RIU−1, 39.9 and 0.025 respectively. The characteristics of the Fano resonances obtained through simulation is also validated by matching it with the theoretical Fano line shape function. The proposed sensor can find its use in biosensing applications.

Plasmon-induced flexibility and refractive index measurement in a sensor designed by a cavity, two rings, two teeth and two plasmonic waveguides

In this research, we design a plasmonic refractive index sensor and examine it numerically, using transparency, refractive index, sensitivity, FOM fit shape and Q quality factor, to optimize and improve performance quality. We will be. To design the structure of this sensor, we use two plasmonic waveguides, a cavity, two rings and two teeth. The resonant wavelengths and refractive index of the resonators are investigated and simulated by the finite difference time domain (FDTD) method, and we draw the obtained diagrams using MATLAB software. After completing the sensor design, due to the fact that the amplifiers are very sensitive to changes in the refractive index, so by changing the refractive index and changing the dimensions of the structure, we can weaken or strengthen the passage coefficient in the resonant modes. These plasmonic sensors with a simple frame and high optical resolution can be used to measure refractive index in the medical, chemical and food industries.

Enhancing imaging capabilities with a high-sensitivity multichannel optical filter

This research introduces a high-sensitivity multichannel optical filter with combined filtering and imaging capabilities, enabling the separation of wavelengths from visible to near-infrared light into distinct colors. The device design comprises a metal-insulator-metal (MIM) straight waveguide coupled to six pairs of overlapping resonators. The transmittance properties and electromagnetic field distributions are analyzed by varying the geometrical sizes using the finite-element method. The designed structure effectively filters out four to fifteen color channels with a narrow full width at half maximum of approximately 2–6 nm. It provides precise multichannel transmittance wavelength selectivity with high color purity, spanning from visible to near-infrared. Additionally, this structure serves as a plasmonic refractive index sensor, demonstrating impressive sensitivity, figure of merit, quality factor, and dipping strength values of 1450 nm/RIU, 241.67 1/RIU, 259.11, and 81.89 %, respectively. These characteristics highlight the excellent sensing performance of the proposed structure, offering significantly higher resolution and smaller dimensions compared to conventional systems.

Fano-resonance-based plasmonic refractive index sensor with high sensitivity for detection of urea

In the recent context of the post-pandemic world, label-free detection has become a crucial technique in various human physiological testing analyses. In this paper, a plasmonic nanosensor is proposed based on a tapered waveguide cavity resonator, which provides label-free detection with high sensitivity for bio-sensing applications. The transmittance curve is studied using the finite difference time domain method. The transmittance curve exhibits dual Fano resonances with the highest sensitivity of 2544.3 nm/RIU. The resultant simulated transmittance values are further validated by comparing them to the theoretical Fano line shape function. Further, the fabrication complexities have been investigated with respect to changes in geometrical parameters such as the change in width of the tapered waveguide and the height of the cavity resonators. Other performance parameters are also calculated such as FOM, Q factor, and detection limit, which come out at values of 40.54RIU−1, 41.7, and 0.024, respectively. Moreover, a biosensing application has been investigated by testing the detection of urea in a human urine sample.

Enhanced optical sensing with metal-insulator-metal nanohole arrays integrated with silver nanoparticles

The field of plasmonic sensing has witnessed rapid advancements in recent years. This work proposes an innovative methodology that employs metal–insulator-metal (MIM) nanohole arrays integrated with ring-shaped silver nanoparticles (AgNPs) to serve as an effective plasmonic refractive index sensor. The hybrid substrates are prepared using a combination of nanosphere lithography (NSL), reactive ion etching, and an enhanced plasmonic site-selective photocatalytic reaction, ensuring large-area fabrication, high throughput, and cost-effectiveness. The resonance peaks observed in the visible-NIR spectra are attributed to the coupling of surface plasmon resonance modes between MIM structures and AgNPs. The resonance wavelength exhibits sensitively to changes in the surrounding medium within the refractive index range of 1 to 1.5, with a remarkable sensitivity of 835 nm/RIU. Our findings reveal the significant potential of this technology for advancing optical sensing applications.

Design of self-coupled plasmonic hyperbolic metamaterials refractive index sensor based on intensity shift

Achieving efficient, accurate, label-free, and real-time biodetection is urgently required; hence, we propose a miniaturized, easily integrated, high-sensitivity plasmonic metamaterial light intensity refractive index sensor. The main structure of the sensor is layered hyperbolic metamaterial grating comprises eight pairs of Au/Al2O3 thin film, and the highly sensitive bulk plasmon polaritons can be effectively excited inside by the self-coupled effect without external prism or nanograting. The periodic fishnet arrays built in the layered HMM structure can not only be used as nanograting to achieve efficient coupling between incident light and layered HMM, but also increase the volume of the sensing, and the measured substance can get full interaction with the enhancement field to obtain high sensitivity. By detecting the change of reflected optical intensity with the ambient refractive index, the sensor exhibits intensity sensitivity of 36 RIU−1 (refractive index unit) and figure of merit of 403; moreover, the full width at half maximum of resonant peak is low at 5 nm. The sensing performances indicate that the sensor we designed has a significant potential to achieve portable, highly sensitive sensing platforms for precise detection.

Plasmonic refractive index nano sensor based on triplet coupled stub resonators based Fano resonances

AbstractFano resonance arises from the superposition of a narrow discrete resonance with a continuous state. In this paper, a Fano resonance‐based plasmonic refractive index sensor based on nanoscale metal‐insulator‐metal (MIM) waveguides is proposed and evaluated by applying the two‐dimensional finite‐difference time‐domain (2D FDTD) method. An MIM‐based single stub vertically attached to an MIM waveguide is considered as the unit cell of the waveguide system of the proposed structure. A transfer matrix of transmission and coupling complex coefficients is defined for the unit cell of the waveguide system of the proposed sensor, and the conditions for the authenticity of its modeling based on the transmission line theory are evaluated. A system of triplet coupled stub resonators (TCSRs) attached to an MIM waveguide is coupled with a disk resonator to induce Fano resonances in the transmission spectrum of the sensor. Fano resonance and its characteristics are utilized to improve the essential operating parameters of the sensor, such as full width at half maximum (FWHM) and figure of merit (FOM). In optimized conditions, for the system of TCSRs coupled to a disk resonator, a resonance with a sensitivity of 684 nm/RIU and an FOM of 621.8 1/RIU exhibited. Also, for the system of TCSRs coupled to a ring resonator, a resonance with a sensitivity of 3524 nm/RIU and an FOM of 35.24 1/RIU was achieved. Eventually, the numerically achieved results for the operating parameters of the sensor are validated using governing analytical methods.

A wide measurement range plasmonic refractive index sensor based on side-polished photonic crystal fiber

A wide measurement range plasmonic refractive index (RI) sensor based on side-polished photonic crystal fiber (PCF) was proposed and studied in this paper. A composite film containing an Au layer and a TiO2 layer was coated on the polished surface of PCF to excite and modulate the surface plasmon resonance (SPR) effect. The sensing characteristics were analyzed using the finite element method (FEM). Numerical results showed that the sensing performances were significantly improved through introducing the unique optoelectronic material of TiO2 film. The designed RI sensor showed an ultra-wide measurement range of 1.20–1.38 with a highest sensitivity of 14600 nm RIU−1. The best resolution (R) and figure of merit (FOM) reached 6.85 × 10−6 RIU and 224.62 RIU−1, respectively. The designed side-polished PCF which is coated with an optimized TiO2/Au composite membranes has a promising performance in the field of RI sensing requiring high sensitivity and wide range monitoring.

Oxidation-resistant nanosensor: A label free, on-chip sensing approach of protein concentration, salinity, tissue classification

Numerous studies have used the Drude model to optimize silver-based Metal-Insulator-Metal plasmonic sensors for some limited sensing applications; however, Lab-on-a-chip sensing for cell protein concentration measurement still needs to be accomplished. Furthermore, little study has been conducted on sensing for the salinity measurement of seawater, Bovine serum albumin concentration measurement, human tissue categorization, mitigating the oxidation issue of these sensors, and nanofabrication challenges. In this article, a Metal-Insulator-Metal based oxidation free material (gold modeled with Drude-Lorentz model) built round-edged hexagonal plasmonic refractive index sensor with nanorods embedded both in the straight waveguide and resonator has been investigated using the Finite element method (FEM) for all of the above sensing applications. This sensor achieves 19.05 nm/g/100mL and 1476.6 nm/ppm sensitivity for cell protein concentration and salinity measurement. The sensor’s max sensitivity and Sensing Resolution are 9231.7 nm/RIU and 1.083∗10−7. This sensor has also been employed as an electromagnetic interference-free temperature sensor using toluene, achieving 5.16 nm/°C sensitivity. Thus, this label-free and low-footprint sensor can be employed to study the salinity of seawater, which is linked with global warming and the earth’s hydrologic cycle, study protein concentration for nanomedicine applications, and Lab-on-chip sensing as an oxidation-free alternative to silver-based sensors.

Plasmonic Refractive Index Sensor Including Two Waveguides, Rings and Two Cavities with Teeth Connected on Fano Resonances

A plasmonic refractive index sensor based on a metal-insulator-metal (MIM) waveguide coupled with rings and two cavities and interconnected teeth is proposed and investigated numerically. Transfer (T), sensitivity (S) and Figure of Merit (FOM) were calculated and analysed via Finite Difference Time Domain method (FDTD). The simulation results show the generation of double Fano resonances in the system that the resonance line-shapes and the resonance wavelength can be adjusted by changing the geometry of the device. By optimizing the structure in the initial configuration, the maximum sensitivity of 2832 nm / RIU and FOM of 15.1 is achieved. Then we change the structure parameters and the number of resonators. In this case, the maximum sensitivity and FOM are 2083nm / RIU and 18.9 respectively. Therefore two detection points can be used for the refractive index sensor. Such a plasmonic sensor with simple and optimal framework could be suitable and practical for sensing systems and integrated optical circuits.

Construction and Evaluation of Plasmonic Refractive Index Sensors Based on Dimensional Change and Number of Resonators

In this paper, a plasmonic refractive index sensor based on metal insulated metal waveguide (MIM) with two plasmonic waveguides and five rings and two teeth and four rectangular cavities is proposed and designed. The resonant wavelengths and refractive index of the resonators will be investigated by the time domain finite difference method. To achieve an optical sensor with excellent quality and performance, we change the number and type of amplifiers and their dimensions. In each step of the simulation, we change the refractive index of the middle ring located in the middle of the two waveguides and the refractive index of the other resonators remains constant. This challenge will help to form a more appropriate structure for optical sensors. The sensor built in this simulation has a balanced and suitable function for integrated circuits and helps researchers to better understand the design of plasmonic structures. It also has wide applications in biomedical research, healthcare, pharmaceuticals, environmental monitoring, internal security and battlefield

Construction and Evaluation of Plasmonic Refractive Index Sensors Based on Dimensional Change and Number of Resonators

In this paper, a plasmonic refractive index sensor based on metal insulated metal waveguide (MIM) with two plasmonic waveguides and five rings and two teeth and four rectangular cavities is proposed and designed. The resonant wavelengths and refractive index of the resonators will be investigated by the time domain finite difference method. To achieve an optical sensor with excellent quality and performance, we change the number and type of amplifiers and their dimensions. In each step of the simulation, we change the refractive index of the middle ring located in the middle of the two waveguides and the refractive index of the other resonators remains constant. This challenge will help to form a more appropriate structure for optical sensors. The sensor built in this simulation has a balanced and suitable function for integrated circuits and helps researchers to better understand the design of plasmonic structures. It also has wide applications in biomedical research, healthcare, pharmaceuticals, environmental monitoring, internal security and battlefield.

"Design and Measurement of Plasmonic Refractive Index Sensor Based on Resonance System with Two Rings, Two Cavities and Two Plasmonic Waveguides"

"Design and Measurement of Plasmonic Refractive Index Sensor Based on Resonance System with Two Rings, Two Cavities and Two Plasmonic Waveguides"

Dual core photonic crystal fiber based plasmonic refractive index sensor with ultra-wide detection range.

In this study, an ultra-wide range plasmonic refractive index sensor based on dual core photonic crystal fiber is suggested and analyzed numerically. The proposed design achieves fabrication feasibility by employing external sensing mechanism in which silver is deposited onto the flat outer surface of the fiber as plasmonic material. A thin layer of titanium oxide (TiO2) is considered on top of the silver layer for preventing its oxidation problem. The sensor attains identification of a vast array of analytes consisting a wide range of refractive indices of 1.10 - 1.45. It achieves a maximum spectral sensitivity of 24300 nm/RIU along with its corresponding resolution of 4.12 × 10-6 RIU. The maximum figure of merit of the sensor is 120 RIU-1. The sensor also supports amplitude interrogation approach and exhibits a maximum amplitude sensitivity of 172 RIU-1. The impact of the design parameters such as radius of air holes, polishing distance, thickness of silver and titanium oxide layers are investigated thoroughly. An ultra-wide detection range with high sensitivity, fabrication feasibility, and easy application make the sensor a potential candidate for detection of a wide array of bio-originated materials, chemicals, and other analytes.

ZrN-based plasmonic sensor: a promising alternative to traditional noble metal-based sensors for CMOS-compatible and tunable optical properties.

In this article, we introduce a novel comb shaped plasmonic refractive index sensor that employs a ZrN-Insulator-ZrN configuration. The sensor is constructed using Zirconium Nitride (ZrN), an alternative refractory material that offers advantages over traditional metals such as silver and gold, as ZrN is standard Complementary Metal Oxide Semiconductor (CMOS)-compatible and has tunable optical properties. The sensor has recorded a maximum sensitivity, figure of merit (FOM), and sensing resolution of 1445.46 nm/RIU, 140.96, and 6.91 × 10-7RIU-1, respectively. Beyond that, the integration of ZrN offers the sensor with various advantages, including higher hardness, thermal stability at high temperatures, better corrosion and abrasion resistance, and lower electrical resistivity, whereas traditional plasmonic metals lack these properties, curtailing the real-world use of plasmonic devices. As a result, our suggested model surpasses the typical noble material based Metal-Insulator-Metal (MIM) arrangement and offers potential for the development of highly efficient, robust, and durable nanometric sensing devices which will create a bridge between nanoelectronics and plasmonics.

Quintuple grids plasmonic refractive index sensor for organic gas sensing application

In this article, an optical refractive index (RI) nanosensor has been presented. The layout is arranged in a metal–insulator-metal (MIM) waveguide configuration with gold being the plasmonic metal. The waveguides are coupled with quintuple grids resonant cavity where the grids are uneven in length. The transmission spectral profile of the schematic is numerically analyzed employing the two-dimensional Finite Element Method (FEM) within the mid-infrared region (MIR). Moreover, the key structural parameters are optimized individually to realize the maximum performance of the schematic. The most optimal structure displays a high sensitivity of 4737.87 nm/RIU and a FOM of 9.37. Furthermore, the structure can be suitably used in applications such as sensing organic gas vapors and temperature. Due to the practicality of the applications and the simplicity of the schematic along with the higher longevity provided by gold, this device can replace complex structures effectively.

Plasmonic sensor for rapid detection of water adulteration in honey and quantitative measurement of lactose concentration in solution

In this article, a novel surface plasmon polariton-based plasmonic refractive index sensor is proposed and numerically investigated. It consists of a structure of an octagonal cavity resonator inside a square disk along with silver nanodots and two slits which are coupled to a straight metal–insulator–metal (MIM) waveguide arrangement. The finite element method (FEM) has been employed to perform a numerical analysis of the proposed structure in the near-IR (Infrared) and mid-IR spectrum. The sensor detects changes in refractive index in terms of changes in resonant wavelength which can be measured using an optical spectrum analyzer. The recorded maximum sensitivity is 2527.6 nm per refractive index unit (RIU) with a sensing resolution of 3.956×10−7 RIU. The proposed sensor has been further numerically analyzed, and its ability to measure the quality of honey samples and detect lactose concentration in a solution has been verified.

Plasmon-Induced Flexibility and Refractive Index Measurement in a Sensor Designed By A Cavity, Two Rings, Two Teeth and Two Plasmonic Waveguides

In this research, we design a plasmonic refractive index sensor and examine it numerically, using transparency, refractive index, sensitivity, FOM fit shape and Q quality factor, to optimize and improve performance quality. We will be. To design the structure of this sensor, we use two plasmonic waveguides, a cavity, two rings and two teeth. The resonant wavelengths and refractive index of the resonators are investigated and simulated by the finite difference time domain (FDTD) method, and we draw the obtained diagrams using MATLAB software. After completing the sensor design, due to the fact that the amplifiers are very sensitive to changes in the refractive index, so by changing the refractive index and changing the dimensions of the structure, we can weaken or strengthen the passage coefficient in the resonant modes. These plasmonic sensors with a simple frame and high optical resolution can be used to measure refractive index in the medical, chemical and food industries.