Design and analysis of biosensor based on surface plasmon resonance

A unique wheel-shaped exposed core LSPR-PCF sensor for dual-peak sensing: Applications in the optical communication bands, M-IR region and biosensing

Photonic Crystal Fibers (PCF) effectiveness in practice decreases if the fabrication of the sensor becomes too complex. Keeping this in mind, we propose a one-of-a-kind wheel shaped PCF sensor with an exposed core containing only three air holes with exceptional sensing features. The sensor is equipped with dual plasmonic layers, Indium Tin Oxide (ITO, 10 % wt) and silver (Ag) with a coating of TiO2 to enhance the sensing capabilities and provide protection against oxidation. The sensor's distinctive configuration enables it to exhibit two distinct peaks within a range of refractive index from 1.32 to 1.38 for y-polarization and from 1.35 to 1.38 for x-polarization. The sensor specifications have been optimized to achieve the maximum levels of wavelength sensitivity (WS) and double peak shift sensitivity (DPSS). The sensor portrays a WS of 50,652 nm/RIU and the highest DPSS ever recorded, measuring 50,000 nm/RIU. Additionally, the sensor exhibits a significantly high scale of amplitude sensitivity (AS) of 1668.34 RIU-1 which is a very remarkable value considering silver as plasmonic material along with an outstanding figure of merit (FOM) of 1017.11 RIU-1. In addition, our sensor is able to manifest resolutions in the order of 10-6, demonstrating a resolution of 5.94 × 10-6 RIU with the deployment of amplitude interrogation method and 1.97 × 10-6 RIU with the wavelength interrogation method. The design spans an extensive spectrum, covering ultraviolet to mid-infrared wavelengths, enabling detection of biomolecules and biochemicals, along with operation in the optical communication band.

PCF Based Four-Channel SPR Biosensor With Wide Sensing Range

In this article, we have demonstrated a highly sensitive four-channel photonic crystal fiber (PCF) based surface plasmon resonance (SPR) biosensor which can detect four different analytes simultaneously. To ease practical implementation, four analyte sensing layers and plasmonic materials such as gold (Au) and gold (Au) with Tantalum Pentoxide (Ta2O5) are placed on the exterior of the four arms of the square shaped structure. The sensor's structure consists of only nine circular air holes, making it simple and easy to fabricate using currently available technologies. Finite element method (FEM) based numerical analysis is used to evaluate the sensing performance of the proposed sensor. With optimum structure parameters, the sensor achieves maximum wavelength sensitivity of 11000, 25000, 11000 and 25000 nm/RIU for Channel-1, Channel-2, Channel-3, and Channel-4 respectively. It shows maximum amplitude sensitivity of 803.732, 709.171, 803.827, 709.146 RIU -1 for Channel 1, 2, 3, and 4 respectively. It also shows maximum FOM of 232.55, 352.36, 231.57, 352.36 RIU -1 in Ch-1, Ch-2, Ch-3 and Ch-4 respectively. Moreover, the proposed sensor shows a wide range of refractive index sensing capability from 1.30 to 1.41. Due to multi-analyte detection capability, large sensing range, and excellent sensitivity the proposed sensor unfolds unrivalled capacity of detecting chemicals, carcinogenic agents, biomolecules, and other analytes.

Overview of Optical Biosensors for Early Cancer Detection: Fundamentals, Applications and Future Perspectives

Conventional cancer detection and treatment methodologies are based on surgical, chemical and radiational processes, which are expensive, time consuming and painful. Therefore, great interest has been directed toward developing sensitive, inexpensive and rapid techniques for early cancer detection. Optical biosensors have advantages in terms of high sensitivity and being label free with a compact size. In this review paper, the state of the art of optical biosensors for early cancer detection is presented in detail. The basic idea, sensitivity analysis, advantages and limitations of the optical biosensors are discussed. This includes optical biosensors based on plasmonic waveguides, photonic crystal fibers, slot waveguides and metamaterials. Further, the traditional optical methods, such as the colorimetric technique, optical coherence tomography, surface-enhanced Raman spectroscopy and reflectometric interference spectroscopy, are addressed.

A High Refractive Index Plasmonic Micro-Channel Sensor Based on Photonic Crystal Fiber

A new concave shaped high refractive index plasmonic sensor with a micro-channel is proposed in this work, which comprises an analyte channel in the core hole. The sensor is elaborately designed to reduce the interference effect from the metal coating. Furthermore, the impact of the proposed structure on the sensitivity is also investigated by engineering the geometric parameters using the finite element method. We select gold as the plasmonic material in this theoretical study because it is widely used to fabricate plasmonic and metamaterial devices due to its chemical stability and compatibility. According to wavelength interrogation technique, simulations results show that this sensor can obtain maximal wavelength sensitivity of 10,050 nm/refractive index unit. In view of the excellent indicators of this device, it has important development potential in chemical and biological research fields.

Detection of kerosene adulteration in automobile fuel by a low-loss surface plasmon resonance (SPR) chemical sensor

A surface plasmon resonance (SPR) chemical sensor with gold as the sensitive material has been designed to detect the adulteration of petrol by kerosene. Samples of petrol adulterated with kerosene were prepared in different ratios by volume (v/v). Kerosene concentrations ranging from 0% to 80% can be detected by monitoring the optical spectra, and the properties of the sensor were analyzed using the COMSOL Multiphysics software. The sensor shows a high spectral sensitivity of 7117 nm per RIU and a sensing resolution of 1.4 × 10^-4 RIU. The excellent sensing properties and a low confinement loss of 5.4 dB cm^-1 render the sensor competitive in SPR sensing applications.

Surface Plasmon Resonance-Based Temperature Sensor with Outer Surface Metal Coating on Multi-Core Photonic Crystal Fibre

We report an innovative design of a multi-core photonic crystal fibre-based surface plasmon resonance temperature sensor using ethanol and benzene as temperature-sensitive materials with a segmented outer-surface metal coating scheme. A stable sensing performance for a detection range of 10–80 ∘ C was found while using ethanol as the temperature-sensitive material; while using benzene both blue and red frequency shifts were observed. The maximum temperature sensitivities obtained from this proposed temperature sensor were 360 pm/ ∘ C and 23.3 nm/ ∘ C with resolutions of 2.78 × 10 − 1 ∘ C and 4.29 × 10 − 3 ∘ C, respectively, when using ethanol or benzene as the sensing medium.

Dual-polarized highly sensitive surface-plasmon-resonance-based chemical and biomolecular sensor

As the research work in surface plasmon resonance (SPR)-based photonic crystal fiber (PCF) is getting tighter, a perfectly circular-shaped PCF with elliptical air holes is proposed where the performance parameters are improved significantly. The performances among our designed elliptical, circular, and rectangular air holes are compared, and the best result is achieved with the elliptical air holes. The technique used for the investigation is the finite element method, and for the simulation of data COMSOL Multiphysics 5.3a software is used. The method covers a wider range of the optical spectrum from 0.59 to 1.05 µm. The highest confinement loss achieved through our design is 340 dB/cm. The wavelength sensitivity and amplitude sensitivity are 13,000 nm/RIU and ${1189.46}\;{{\rm RIU}^{ - 1}}$1189.46RIU^-1, respectively. The sensor resolution is ${7.69} \times {{10}^{ - 6}}$7.69×10^-6 for our proposed design. The proposed sensor also achieved a maximum birefringence of ${2.8} \times {{10}^{ - 3}}$2.8×10^-3, which is, to our knowledge, the highest birefringence reported so far for a PCF-SPR sensor. This enables the fiber to be operated in a dual-polarized mode. The RI for the analyte ranges from 1.33 to 1.40. Based on all the characteristics, the proposed PCF structure can be used effectively for chemical and biomolecular sensing.

Enzyme-Based Electrochemical Biosensors for Microfluidic Platforms to Detect Pharmaceutical Residues in Wastewater

Emerging water pollutants such as pharmaceutical contaminants are suspected to induce adverse effects to human health. These molecules became worrisome due to their increasingly high concentrations in surface waters. Despite this alarming situation, available data about actual concentrations in the environment is rather scarce, as it is not commonly monitored or regulated. This is aggravated even further by the absence of portable and reliable methods for their determination in the field. A promising way to tackle these issues is the use of enzyme-based and miniaturized biosensors for their electrochemical detection. Here, we present an overview of the latest developments in amperometric microfluidic biosensors that include, modeling and multiphysics simulation, design, manufacture, testing, and operation methods. Different types of biosensors are described, highlighting those based on oxidases/peroxidases and the integration with microfluidic platforms. Finally, issues regarding the stability of the biosensors and the enzyme molecules are discussed, as well as the most relevant approaches to address these obstacles.