Plasmonics最新文献

Surface plasmon resonance (SPR) sensors have attracted great attention in recent years for various applications such as medical diagnosis and biochemical materials. Among SPR sensors, D-shaped structures based on photonic crystal fibers (PCFs) have shown very high performance and are easy to use. In this paper, a simple design of SPR sensors based on the D-shaped PCFs with the optimized geometrical parameters is proposed. Gold and silver are considered as plasmonic layers on the surface of the D-shaped PCF sensor. By performing multiple simulations using the finite-difference eigenmode (FDE) method, various values of gold and silver thicknesses are investigated to achieve the highest sensitivity and resolution. The results indicate that the highest sensitivity and resolution of 25,600 nm/RIU and (3.9times {10}^{-6}) are achieved respectively for a gold thickness of 44 nm at the analyte refractive index (RI) of 1.41. Meanwhile, for an analyte RI range of 1.29 to 1.40, silver demonstrates greater sensitivity than gold in the same range. The proposed sensor with superior characteristics compared with other SPR sensors can be considered as a very good candidate for RI measurement with high sensitivity, linearity, and resolution.

This study introduces a biosensor utilizing photonic crystal fiber (PCF) technology to detect breast cancer biomarkers. The biosensor features a unique flower core composed of square and circular air holes. The sensing mechanism relies on variations in the resonant wavelength induced by changes in the sample’s concentration or refractive index. As the sample’s concentration increases, the transmission spectrum shifts at higher wavelengths, enabling differentiation between malignant and normal cancer cells. The study demonstrates that the biosensor has achieved its highest recorded sensitivity of 22,069 nm/RIU. Furthermore, comprehensive values to judge the performance are obtained for loss, coupling length, V parameter, propagation constant, amplitude sensitivity, and transmission, in addition to birefringence on the order of 10⁻⁵. Thus, the reported biosensor is of high quality and has good potential for sensitive detection of breast cancer. Also, the biosensor presented in this study provides a viable and cost-efficient alternative to molecular biotechnology examination and imaging techniques for the diagnosis of cancer.

This study proposes a photonic crystal fiber (PCF) biosensor using the surface plasmon resonance (SPR) phenomenon. Active plasmonic nanomaterials, consisting of gold (Au) and silver (Ag) nanoparticles, were prepared via the pulsed laser ablation in liquids (PLAL) method, characterized using different techniques. These nanoparticles were subsequently mixed with a polyvinyl alcohol (PVA) solution to enhance sensitivity and compatibility for sensor applications. The PVA-Au/Ag nanoparticles were coated on the outer surface of the PCF for a simplified sensor configuration. The results showed that the sensitivities for PCF coated with PVA-gold and PVA-silver NPs are 1927 and 1397 nm/RIU with a maximum resolution of 2.51 × 10⁻⁵ RIU for samples with glucose concentration in water ranging from 80 to 600 mg/dl and maximum FOM are 853 and 855 for PCF coated with gold and silver NPs, respectively. Notably, this innovative sensor design, coupled with comprehensive nanoparticle characterization and PVA integration, holds great promise for precise and real-time glucose monitoring in many practical applications.

Iron and copper are essential for all living organisms, and their balance is crucial as both deficiency and excess can cause health problems. Therefore, this study presents a colorimetric method for detecting Fe³⁺ and Cu²⁺ ions in aqueous samples using silver nanoparticles (AgNPs) synthesised from Ocimum sanctum (Tulasi) leaf extract (TLE). It is observed that AgNPs show optimum plasmonic properties at a precursor-leaf extract ratio of 1:5, reaction temperature of 60 °C and reaction time of 2 h. The AgNPs exhibit the face-centred cubic (fcc) structure and show a surface plasmon resonance peak at 413 nm, hydrodynamic size of 18 ± 5 nm, zeta potential of − 25.5 mV and particle size of 57 nm. FTIR spectra confirm the stabilisation of AgNPs. It is worthy to note that, AgNPs exhibit selective detection of Fe³⁺ and Cu²⁺ over other metal ions and the detection mechanism is proposed based on the reduction potential values. The quantitative detection range for Fe³⁺ and Cu²⁺ are found to be 0–800 μM and 0–600 μM, with the detection limits of 9.1 µM and 19.5 µM, respectively. Additionally, AgNP-based paper sensors for Cu²⁺ detection show qualitative and quantitative colorimetric performance with a detection limit of 23.1 µM. These findings suggest that both AgNPs solution and AgNP-based paper sensors are the potential candidates for metal ion detection.

This paper presents a surface plasmon resonance (SPR) sensor utilizing a prism-coupled Ag/ZnSe/BP hybrid structure with improved sensitivity for glucose detection in urine samples. In this Kretschmann configuration, multilayers are vertically stacked together to improve the optical and electronic properties of the proposed SPR sensor. The transfer matrix method (TMM) is used for the theoretical model and to analyze the performance of the sensors. The proposed SPR sensor comprises 2D materials such as black phosphorus (BP), which improve the sensitivity of the SPR-based sensor through efficient interactions with biomolecules. The resonance angle of surface plasmons shifts due to a difference in the refractive index from 1.330 to 1.337 in urine samples with various glucose levels. Initially, the study aims to compare the sensor performance parameters among different prisms (CaF2, BK7, FK51A, and SF10) coupled with a hybrid structure. The proposed sensor achieved a noticeably higher value sensitivity of 511 (deg./RIU), a quality factor of 108.377 (1/RIU), and a figure of merit of 108.374 when a CaF2 prism with an optimized thickness was used. The performance parameters, including the sensitivity, full width at half maximum (FWHM), figure of merit (FoM), and detection accuracy (DA), were measured, and the results were compared to evaluate the findings. The proposed structure can be more effective in detecting different liquid analytes in biosensing applications, including glucose detection.

In this paper, a gold/graphene/Ti₃C₂T_x-MXene hybrid layered D-type photonic crystal fiber (PCF) design based on surface plasmon resonance (SPR) sensors is proposed for cancer cell detection. This design uniquely combines gold, graphene, and Ti₃C₂T_x-MXene materials to achieve a synergistic effect, significantly enhancing the sensitivity and specificity of the sensor. The full vector finite element method (FVFEM) is used for the entire numerical analysis of the proposed biosensor. The cladding of the D-type PCF has a hexagonal arrangement of air holes. In the first cladding, the two air holes closest to the metal layer are narrowed down to enhance the plasma wave and provide an efficient leakage channel. The last two air holes closest to the metal layer in the same layer are enlarged to limit light scattering and couple more energy to the surface plasmon polariton (SPP) mode. The sensitivity of the sensor improves by using these different diameter air holes and coating the D-type PCF surface with a hybrid gold/graphene/Ti₃C₂T_x-MXene layer. The geometrical parameters are optimized to obtain higher sensor sensitivity. The corresponding wavelength sensitivities are 3000 nm/RIU for Basal cells, 5000 nm/RIU for HeLa cells (Henrietta Lacks cells), 5714 nm/RIU for Jurkat cells (Human T lymphocyte cells), 7143 nm/RIU for PC12 cells (Pheochromocytoma cells), 8571 nm/RIU for MDA-MB-231 cells (Breast cancer cells), and 9286 nm/RIU for MCF-7 cells (Michigan Cancer Foundation-7, a breast cancer cell line), respectively, confirming the excellent performance of the proposed sensor. The sensor proposed paves the way for efficient, simple, low-cost, and highly sensitive cancer detection techniques that could replace surgical and chemical techniques.

Pulsed laser ablation in liquid (PLAL) is a convenient, single step and green method for nanomaterial synthesis. Controlling nanoparticle size is crucial for various scientific and technological applications. In this paper, the effect of mixing ratio of composite liquid media and laser pulse energy on size distribution of silver nanocollides was exhibited. Mixing ratio of blend of high and low viscosity fluids—ethylene glycol and deionized water—was varied in the range from 0% to 100%. Additionally, the impact of laser pulse energy on AgNP size was explored while keeping the mixing ratio constant. Properties of the particles, including morphology, size, and plasmonic behavior, were examined using SEM, EDX, and optical absorption spectroscopy, and the underlying mechanisms are discussed. The colloids were of spherical shape and showed surface plasmon resonance around 400 nm. The size of the nanoparticle appeared to vary from 15 nm to 86 nm by increasing the concentration of ethylene glycol in the mixture. A similar effect was observed with the laser energy: the particle size increased from 24 nm to 75 nm as the laser energy was varied from 70 mJ to 150 mJ. The nanocolloids were also effective as antibacterial agents against Gram-positive and Gram-negative bacteria: the small-sized particles showed higher toxicity compared to the large particles. In addition to the laser energy, variation in nanoparticle size distribution by the interplay of mixing ratio of the liquid media is an interesting aspect of the findings.

In this work, a refractive index sensor based on Tamm plasmons mode is proposed, capable of concurrent functionality across multiple photonic bandgaps. The proposed sensor structure consists of an analyte cavity sandwiched between a one-dimensional photonic crystal of SiO₂/TiO₂ and a thin metal film. Multiple photonic bandgaps are observed in multilayer structures composed of SiO₂/TiO₂ layers, each with a thickness of 150 nm. Tamm plasmon resonances have been demonstrated in various photonic bandgaps, enabling the detection of subtle changes in refractive index within the cavity region. Simulation studies utilizing the transfer matrix method (TMM) have been conducted to evaluate the performance of the proposed design. Several sensor metrics including sensitivity, full width at half-maximum, quality factor, and detection accuracy were assessed for evaluating sensor performance. The functioning principle of this optical sensor relies on altering the refractive index of the analyte, resulting in a shift in either the transmission or reflection spectrum. The study reveals that the resonance wavelength demonstrates a linear variation with the change in the analyte’s refractive index. The results demonstrate that the one-dimensional photonic crystal sensor based on multiple Tamm plasmons exhibits high quality factor and enhanced detection accuracy and is well-suited for detecting minute changes in analyte refractive index. Tamm resonance-based sensors, notable for their main advantage of prism-free coupling, offer a compelling alternative to other optical sensors like surface plasmon resonance-based sensors.

Traditionally, biosensors are indeed designed to detect one specific analyte. However, recent advancements in biosensor technology have enabled the development of multiplexed biosensors capable of detecting multiple analytes simultaneously. This work proposes the detection of cervical cancer (HeLa cells), skin cancer (basal cells), and breast cancer (MDA-MB-231 cells) by analyzing the refractive index of these cells. This analysis is based on comparing the absorption spectra of healthy and cancerous cells. The proposed structure comprises three layers: a copper layer with a conductivity of 5.18 × /m, a silicon dioxide layer with a refractive index of 3.9 containing a cross-shaped hole with a depth of 3.5 µm, and a graphene layer. For the basal cell biosensor, the graphene layer is assigned a chemical potential of 0.7 eV; for the HeLa cell biosensor, it is 0.8 eV, and for the MDA-MB-231 cell biosensor, it is 0.9 eV. The absorption output extracted from CST software yields the highest sensitivity values. For basal cell detection, the highest sensitivity (7100) and a figure of merit (FOM) of 22 are achieved in mode B. For HeLa cell detection, a sensitivity of 5250 and FOM of 28 are attained in mode B. Finally, for MDA-MB-231 detection, a sensitivity of 5357 and FOM of 23 are achieved in mode B. This innovation is particularly beneficial in complex biological samples where the presence of multiple analytes may provide more comprehensive diagnostic information. The proposed multi-band high-sensitivity polarization-independent absorber serves as a notable example of this trend, demonstrating the potential for biosensors to evolve toward simultaneous detection of multianalyte targets, such as different types of cancer cells.

A sodium-based hybrid plasmonic waveguide consists of the Na film and wedge-shape Si ridge waveguide is designed. The overall performance of the waveguide and its application as a nano-laser are studied by using the finite element method (FEM) with emphasis on effective index, propagation length, normalized mode area, figure of merit, confinement factor, gain threshold, and Purcell factor. The results point out that the designed waveguide exhibits the strong field confinement ability as well as high figure of merit. Particularly, a large Purcell factor of 536 and an ultra-low gain threshold of 0.066 μm⁻¹ could be concurrently obtained, which is far smaller than that of conventional Ag-based plasmonic waveguides. The proposed waveguide could potentially advance the utilization of sodium-based plasmonic waveguides in the field of nano-laser, resonator, modulator, and other nanophotonic devices.