Plasmonics最新文献

A multispectral photoresponse feature of a self-powered photodetector device is quickly becoming a key technology to address the scaling challenges in emerging multifunctional optoelectronic systems. The heterostructure of different materials has opened new pathways to design broadband self-driven photoresponse using a single device. In this work, a new multispectral photodetector based on SnS/GeSn heterostructure with optimized gold nanoparticles is proposed. Moreover, broadband photodetector performances are improved by using a new design framework based on coupling particle swarm optimization approach and plasmonic effects. Numerical models based on the finite difference time domain method are carried out. A broadband photodetection is achieved in a single SnS/GeSn heterostructured photodetector with optimized surface gold nanoparticles, with a high on/off ratio of 160 dB, improved responsivity of 8.5 A/W and specific detectivity of over 5 × 10¹² Jones in the self-powered mode. Therefore, the proposed design framework based on the strategic combination between SnS/GeSn heterostructure and optimized gold nanoparticles array provides new paths and efficient strategy to enhance the optoelectronic performance of broadband photodetectors by exploiting the light trapping engineering combined with band-gap tuning aspects.

Our research involved the synthesis of a double core-shell structure using gold and silver NPs. The core material used was gold. The initial shell had a silver coating, while the subsequent shell was encased in gold. The wavelength of the laser was 1046 nm and was employed, along with 250 pulses at a frequency of 1 Hz, delivering an energy of 500 mJ into 5 ml of deionized water; the focal length of the lens was 12 cm. A comparison was made between the double core-shell construction consisting of individual silver (Ag) and gold (Au) nanoparticles and the single core-shell structure. Various tests were conducted on the samples, including XRD, TEM, UV-visible, FTIR, and zeta potential, to analyze their characteristics. Additionally, the energy gap was determined for each sample. Next, the study examined the impact of particles with a double core-shell and single particles on S. aureus and E. coli bacteria. The findings revealed that a double coating exhibited exceptional effectiveness in eliminating bacterial cells when compared to single particles and a single core-shell. This was demonstrated through the implementation of a zone of inhibition and antibiofilm activity. They were able to verify the existence of the two metal substances (Au and Ag) in each and every sample by using X-ray diffraction (XRD). TEM images clearly depict the formation of the core-shell system. Also presented were TEM images of colloidal particles made of gold and silver, which were smaller than 10 nm in size. The formation of certain nanoparticles resulted in a shift in the peak wavelength, confirming the occurrence of a superficial overlap. The energy transition was calculated using the Tauc relation, with specific values for the different nanoparticles involved. Based on the zeta potential, it is observed that the stability of Ag NPs is greater than that of Au NPs. Additionally, the core double-shell structure formed is found to be less stable compared to the individual Au NPs and Ag NPs. During the ICP-MS analysis, it was observed that the amount of the double shells reduced in comparison to both the individual shell and the individual gold and silver particles. The particles were linked to each other to produce the shells. The current study suggested the potential role of Au@Ag@Au NPs for antibacterial applications in the future.

Resonant excitation of terahertz surface plasmons by optical rectification over rippled graphene surface, deposited on (text {SiO}_{2}) using a mode conversion of amplitude modulated p-polarized laser beam. A pump surface plasmons exert a ponderomotive force on the free electrons of the graphene surface and impart a linear oscillatory velocity at the modulation frequency. The current density develops by coupling the linear oscillatory velocity with modulated electron density and resonantly excites the terahertz surface plasmons at the modulation frequency. The amplitude of terahertz surface plasmons can be tunable by Fermi energy of graphene surface (text {E}_text {F}). There is a possibility that the current study will be used to utilize THz detectors and sensors.

A surface plasmonic refractive index (RI) sensor is proposed based on a square hole array and gold film coupling structure. This sensor enables high-sensitivity sensing with self-reference characteristics in gas and liquid environments. The reflectance spectrum and electric fields are calculated using a finite-difference time-domain (FDTD) method. Meanwhile, the cases of rotating square-hole arrays and changing the incident light of the polarization direction are discussed, respectively. The results show that the varying polarization direction of the incident light does not affect the reflectance spectrum of the composite structure. Rotating the array of square holes further enhances the signal strength of the resonance modes excited by the proposed sensor. The sensor has two resonance modes with different functions: one for self-reference and the other for sensing. In the sensing mode, the sensor sensitivity is 1037 and 1063 nm/RIU in gas and liquid environments, respectively; whereas in self-reference mode, the sensitivity decreases to 0 and 21 nm/RIU in gas and liquid environments, respectively. The sensor has a maximum figure of merit (FOM) of 103 RIU^-1. These characteristics realize a highly sensitive sensors with a high FOM and self-reference capabilities, which are advantageous for bioassay detection applications.

In this research, the production of zinc oxide nanoparticles (ZnO NPs) was made using various pulsed laser ablation energy (PLA) embedded in substrates made up of porous silicon (PS). The PS substrates were created using the photoelectrochemical etching (PECE) technique of Si n-type (111). The research examined the impact of pulse laser ablation energy for some features on the prepared samples that involved the structural, electrical, optical, and morphological properties in photodetector application. XRD analysis reveals a broad diffraction peak at an angle of 28.4° for the porous silicon with other diffraction peaks at different angles, indicating the presence of the ZnO NPs phase corresponding to the structure of hexagonal wurtzite. The SEM image demonstrates that PS is sponge-like, while ZnO NPs display randomly dispersed spherical grains. The optical characteristics of the fabricated specimens were analyzed using photoluminescence and UV-vis absorption spectroscopy. It was observed that an increase in laser pulse energy results in a shift of the absorption wavelengths and a change in the energy gap. The J-V characteristics of the created specimens were analyzed under two conditions: in dark and light while varying the laser pulse energy. The photodetectors consisting of ZnO NPs/PS/n-Si exhibited rectifying characteristics and remarkable responsivity to a wide range of wavelengths, from UV to near-infrared. Furthermore, the constructed photodetectors exhibited enhanced quantum efficiency (Q.E), specifically in the ultraviolet (UV) range. The results of this research are significant in the progress of optoelectronic and photodetector devices that rely on ZnO NPs and PS.

Graphene-based materials have been the subject of extensive research due to its exceptional ability to kill a diverse array of microorganisms. The benefits of graphene-based materials include ease of fabrication, renewable resources, special catalytic properties, and remarkable physical properties including tensile strength and a large specific surface area. Our study utilizes an environmental method (laser production) to produce GONPs. GONPs are tested as potential; this study assesses the molecular docking simulation, anti-microbial, against clinically pathogenic strains of Klebsiella pneumoniae and Bacillus cereus. Antioxidant by DPPH assay and anti-cancer properties of graphene nanoparticles (GONPs) with Doxorubicin on lung cancer (A549 cell line). TEM images demonstrated types of produced GO-NP spherical nanoparticles with a size ranging at approximately 15–40 nm. Atomic force microscopy (AFM) was used to examine the morphological and topological characteristics of the NPs. The structural and crystal characteristics were examined by X-ray diffraction (XRD). Among the anti-bacterial-evaluated GONPs, concentrations of 100, 50, and 25 µg/ml exhibited the most substantial growth inhibition zone against Klebsiella pneumoniae and Bacillus cereus. The molecular docking simulation of GONP-OH modified gave more effective results against Bacillus cereus bacterial organism (ID: 5V8D) and (ID: 5GT6). Conversely, the highest anti-biofilm activity was observed against Bacillus cereus than Klebsiella pneumoniae, notably with 100 µg/ml GONPs. On the toxicity examination of cancer cells, the impact of nanoparticles was investigated. The produced nanoparticles had a higher cytotoxicity rate. The cytotoxicity of GONP alone, Doxorubicin alone, and/or combination therapy (GONP + Doxorubicin) found to be in 25 µg/ml concentration and time dependent manner also increased as combination therapy. The analysis for cell cytotoxicity revealed a noteworthy decrease in the number of cancer cells after GONP + Doxorubicin were treated for 72 h. The average cell cytotoxicity of GONP +Doxorubicin were 54, 61.31, and 76.41% for 24, 48, and 72 h, respectively. Both GONPs exhibited higher cell toxicity and cell death contract control. Additional GONPs showed strong antioxidant properties by DPPH assay. The present research demonstrates the advantageous effectiveness of a simpler production procedure, like laser production, for producing high-purity nanoparticles with low hazard that may be utilized as future possible cancer therapies.

Developing sensitive and specific methods for detecting malaria is a substantial challenge in biomedical research. Here, we introduce a novel approach utilizing a metasurface sensor based on graphene for the detection of malaria. Modelled on a silicon dioxide (SiO₂) substrate, this sensor allows seamless integration with current electronic and optical technologies. The sensor design incorporates square and quadrant-based resonators, optimized through comprehensive parametric analysis to assess their geometric effects on sensor performance. The results demonstrate an enhanced sensitivity of 600 GHzRIU⁻¹. Analysis of the electric field illustrates frequency-dependent transmittance properties, alongside promising 2-bit encoding capabilities. Furthermore, the research establishes a direct correlation between resonance frequency, refractive index, and analyte concentration. This sensor offers a promising avenue for swift, precise, and non-invasive malaria detection, potentially enhancing point-of-care diagnostic capabilities in healthcare settings.

Cervical cancer is a significant risk to women’s lives, and early detection is crucial to secure patient quality of life. Currently, doctors’ diagnosis relies on their subjective assessments, as there is no standardized measuring method. The problem can be solved with the optical biosensor as it provides precise and quick consequences in the determination of cancerous cells. This manuscript presents a novel double c-shaped copper-based refractivity biosensor (DCSCRIB) for the recognition of cervical nucleus as well as cervical cytoplasm cells. The double c-shaped copper-based resonator provides high spatial resolution, upper sensitivity, and upper-quality factor making them for novel choice to detect the nucleus and cytoplasm of cervical cancer. The upper sensitivity (S) has been spotted at 1600 nm/RIU for the cervical nucleus with the upper-quality factor (QF) being 1618.37 for the cervical cytoplasm. The upper rate of the figure of merit (FOM) is 1107.18, the detection area (DR) rate is 1925.17, the signal noise ratio (SNR) rate is 33.2155, and the sensor resolution (SR) rate is 0.93 which has been spotted of cervical cytoplasm. The upper detection limit of 0.0004 has been achieved for the natural cytoplasm. This propounded sensor can highly intellect the cervical cancer biomarkers.

A highly sensitive hybrid structure for biosensing application based on surface plasmon resonance for the detection of blood cancer has been proposed in this article. The biosensor comprises of a CaF₂ Prism, Ag metal, an oxide layer Al₂O₃ and a 2D nanomaterial graphene, which is grounded on Kretschmann configuration. The transfer matrix method is used to interrogate the performance parameters of proposed biosensor. To analyze the change in refractive index, the analyte has been considered over the graphene layer. To achieve maximum sensitivity and minimum reflectance the thickness of Ag, Al₂O₃ layers and number of graphene layers have been optimized. The suggested structure’s sensitivity can be enhanced up to 427.43 deg/RIU with the optimized value for the detection accuracy and FOM of 0.7027 deg⁻¹ and 217 RIU⁻¹ respectively. The work focuses on the development of plasmonic sensors with high performance and stability. Role of different material layers is also analyzed in terms of enhancement in sensitivity and evanescent field. The paper offers better optimization technique and selection of material than previously reported works, which eventually leads to enhancement in both sensitivity and FOM. This research could lead to the development of a useful biological sample sensing tool for the quick and precise detection of the blood cancer in its early stages.