Optical Sensor Applications Research Articles

Study the Optical Properties of Noble Metal (Au, Ag, and Cu) Thin Film Biosensors Based on Surface Plasmon Resonance Performance by a Simulation Program

In this work, we studied the effect noble metal thicknesses, namely gold (Au), silver (Ag), and copper (Cu) on the surface plasmon resonance (SPR) characteristics for sensitive optical sensor and biosensor applications. SPR spectra for Au, Ag and Cu were widely studied in the Fresnel equation to calculate the total reflection, the wavelength ([Formula: see text] range from 500 nm to 700 nm with the angle of incidence ([Formula: see text] ranging from 0∘ to 90∘ and thickness of the film ([Formula: see text] reaching from 30 nm to 70 nm. Analysis simulation (in MATLAB) has been made for SPR of three metals placed on the N_LASF9 glass prism and the sensing medium is the air. The properties of the angle of resonance [Formula: see text] have been calculated from plotted reflectance via incident angle [Formula: see text]. The results give efficient detection in a change of reflection ([Formula: see text] and full half width maximum FWHM. The minimum reflection was obtained (0.003 a.u.) at wavelength 700 nm and thickness [Formula: see text]= 50 nm for gold Au at [Formula: see text] = 0.0. The best FWHM was recorded at the wavelength (500 nm) at thickness (70 nm) for silver at [Formula: see text] = 0.0, which was equal (0.1 nm).

Coexistence of giant Goos-Hänchen shift and high reflectance in Dirac semimetal based multilayered structure.

Bulk Dirac semimetals (BDSs) possess Fermi energy dependent optical parameters, providing unprecedented opportunities for the study of the controllable Goos-Hänchen (GH) shift. However, the enhancement of GH shifts often comes at the cost of the reflectance in the previous BDS-based structures, which hinders their practical application. In this work, we theoretically present the investigation of the GH shift in a multilayered structure composed of one BDS film and a symmetric one-dimensional photonic crystal (1DPC) with a defect layer. We demonstrate that this well-designed structure supports a large GH shift at the specific working wavelength, whose magnitude can be enhanced up to 3883 times the incident wavelength. In particular, such an enhanced GH shift achieved in this structure is associated with high reflectance (0.94) and these remarkable features can be attributed to the sharp change in the reflective phase and the destructive interference that occurs between the simultaneously excited optical Tamm state (OTS) at the BDS/1DPC interface and the defect state at the 1D defected PC. In addition, we also explore the manipulation of the GH shift by adjusting the Fermi energy of the BDS as well as the geometrical parameter of the multilayered structure. Our results provide a new approach for realizing an enhanced and controllable GH shift in a BDS-based multilayered structure, which endows it with promising prospects for application in optical sensors, optical detectors and beam controllers.

损耗模式共振光学传感器的发展与应用

损耗模式共振光学传感器的发展与应用

001]-Oriented heteroepitaxy for fabricating emissive surface mounted metal–organic frameworks

A hybrid SURMOF with specific crystallographic [001] orientation is fabricated via step-by-step liquid-phase heteroepitaxial method. The preferential [001] orientation of Cu2(BDC)2(DABCO) is retained via Zn2(BDC)2(DABCO) to Zn2(ADC)2(BPy).

Optimization of nanoparticles for application in optical sensors

This study explored the influence of crystallite size on a nanoparticle-coated fiber optic Mach-Zehnder Interferometer (MZI). The primary aim was to enhance the magnetic properties of the nanoparticles for application in fiber optic sensors designed for magnetic field sensitivity. The motion of the nanoparticles within the magnetic field induced alterations in the sensor's transmission, creating an imbalance in the optical signals between the interferometer arms. Nickel ferrites (NiFe2O4) with average crystallite sizes of 3.3 nm, 51.9 nm, and 74.3 nm were used. The nanoparticles were identified by X-ray diffraction, VSM magnetic measurements, and Mössbauer spectroscopy. Structural parameters obtained from X-ray diffraction underwent refinement using the Rietveld method, and the Scherrer equation was applied to determine the average crystallite size. Magnetic sensor performance was assessed for sensitivity, precision, and accuracy for different nanoparticle sizes. The relationship between output power and applied magnetic field exhibited linearity between 87.6% and 99.2%. Sensitivity varied from 1.65 dB/Oe to 3.17 dB/Oe for different particle sizes, indicating an increase in sensitivity with nanoparticle magnetization. This study establishes a correlation between crystallite size and nanoparticle magnetization, enhancing sensor responsiveness. This optimization facilitates the development of tailored electric current and magnetic field sensors, considering nanoparticle size and their distinctive magnetic properties. Although the primary focus was on the optical sensor, a comprehensive nanoparticle characterization was crucial as it directly influenced sensor performance.

Enhancing the Circularly Polarized Luminescence of Europium Coordination Polymers by Doping a Chromophore Ligand into Superhelices.

Lanthanide-based molecular materials showing efficient circularly polarized luminescence (CPL) activity with a high quantum yield are attractive due to their potential applications in data storage, optical sensors, and 3D displays. Herein we present an innovative method to achieve enhanced CPL activity and a high quantum yield by doping a chromophore ligand into a coordination polymer superhelix. A series of homochiral europium(III) phosphonates with a helical morphology were prepared with the molecular formula S-, R-[Eu(cyampH)3-3n(nempH)3n]·3H2O (S/R-Eu-n, n = 0-5%). The doping of chromophore ligand S- or R-nempH2 into superhelices of S/R-Eu-0% not only turned on the CPL activity with the dissymmetry factor |glum| on the order of 10-3 but also increased the quantum yield by about 14-fold. This work may shed light on the development of efficient CPL-active lanthanide-based coordination polymers for applications.

Effect of device coupling mode on output characteristics in piezoelectric grating voltage sensor

Sensor networks provide a physical foundation for distributed data acquisition. Monitoring voltage signals at nodes allows real-time assessment of grid operation. Piezoelectric grating voltage sensors offer advantages of smaller size, lower cost, strong electromagnetic shielding, and easy network integration, appropriating for intelligent voltage sensing. This study investigates the relationship between device coupling mode and output characteristics of these sensors to improve their performance and advance sensor network applications. Using solid mechanics theory, a device coupling mechanical model is established for a temperature-independent piezoelectric grating voltage sensor employing dual-grating spectral overlay demodulation. Then, a flexible structure with variable stiffness is designed to couple the PZT and FBG. Results show linear voltage sensing in the range of 0–6 kV and 0–1500 N using the flexible coupling structure, with a reduction of spectral shift by 50.86–87.82% through structural design. This research provides insights for enhancing sensor performance and improving the application of optical voltage sensors.

Research on the Absorption Performance of Silicon-Based Pyramidal Microstructure with Ultra-Low Reflectivity

Anti-reflective structure can effectively suppress the light reflection on the surface of the object, thereby increasing the absorption of light, it has a wide range of applications in photovoltaics, such as optical sensors and photodetectors. Due to the limitation of low refractive index materials, it is difficult for existing anti-reflective coatings to achieve the expected low reflectance effect. Based on Maxwell’s electromagnetic wave theory, this paper uses Finite-Difference Time-Domain (FDTD)-solutions software to research the reflection spectrum of silicon-based pyramidal microstructure in the wavelength range of 200–1400nm, explores the influence of the height (H) and bottom side length (L) of the pyramidal on its reflection spectrum, and studies the changes of its electromagnetic field. On this basis, the absorption performance of the silicon-based pyramidal microstructure is further studied, and it is found that the absorption efficiency of silicon-based pyramidal microstructure for ultraviolet light reaches almost 100%, which provides important significance for its application in optical sensors and photodetectors.

Transition-free indirect bonding towards 3D multi-layer glass stacking

Optical and photonic devices comprised of fused-silica glass portfolios play an important role in astronomical detections, which requires the bonding interfaces to own robust mechanical properties and less optical loss. Indirect bonding lowers the difficulty of the bonding process than direct bonding by introducing the non-negligible intermediate or transition layers but will inversely diminish the optical properties. In this study, a transition-free indirect bonding (TFB) strategy was developed to realize glass bonding with hard-to-distinguished interfacial boundary. In the process, the oxygen plasma activation was applied to reconstruct the glass surface. Owing to the produced chemical sites with the plasma surface activation, multiple paths could be provided for surface and interface reactions than conventional indirect bonding method hydroxide-catalyzed bonding (HCB). These adequate reactions constructed a whole and uniform Si-O network crossing the bonding interfaces, which was free of transition boundary between the interface and bulk substrates. The uniform and non-transition interface performed higher bonding strength and excellent optical transmittance with less loss than HCB. Based on the TFB strategy, multilayer chips were combined together enabling a 3D multi-layer chip stacking with low transmittance loss and stable mechanical structure for state-of-the-art optical applications in astronomical detection, laser instruments, and optical sensors.

Self-routing dual color nanosource based on the co-excitation via coupling between nano cavities

Optical nano sources play important roles in optical communications, photonic integrated circuits, and quantum information. However, integratable, multi-color and directionally controllable nanoscale optical sources remain a challenge. This work presents a design of a two-channel upconversion nanosource based on phase coupling between metal-dielectric-metal (MDM) cavities. The resonant cavities embedded with upconversion nanoparticles (UCNPs) couple with each other by phase modulation in the bus waveguide, which enables simultaneous excitation and fluorescence enhancement of the UCNPs in cavities. Benefiting from inherent ability of MDM structure, the emitted light can be manipulated directionally for subsequent multi-channel applications. In addition, the relevant optical properties can be accurately described by a theoretical model. The excitation field strength in cavities was found to be sensitive to the coupling phase, and the derived theoretical model can predict the optimal coupling distance for an efficient dual-channel upconversion nano-emitter. This nano-emitter combines the unique fluorescence advantages of UCNPs with the easy preparation of MDM nanocavities for easy integration and nanoscale optical control, promising major applications in photonic chips, optical sensors, and complex energy optoelectronic devices.

The Role of Molecularly Imprinted Polymers In Sensor Technology: Electrochemical, Optical and Piezoelectric Sensor Applications

With the help of molecular imprinting technology, artificial receptors can be made and used for identification. This technique's limitless application increases polymer technology and makes it adaptable to other technologies. In this study, examples of sensor applications are used to explain molecular imprinting technology (MIT) and its brief history. MIT can be used to create polymer-based artificial receptors with remarkable selectivity and affinity to detect any target molecules that can be imprinted on a polymer. A monomer is synthesized around a template molecule to create a selective cavity that serves as an artificial receptor. Molecularly imprinted polymers (MIP) offer a wide range of uses and have recently garnered much attention. These polymers' production methods, production kinds, and molecular imprinting techniques are all thoroughly detailed. The outstanding properties of MIPs make a crucial contribution to sensor applications offering selective, fast, easy, and cost-effective analysis, which became very popular after Clark published his first biosensor study. Apart from the biological recognition receptors, MIPs have the advantage that they are not affected by physical conditions of the environment, such as temperature, pH, and ion strength. To overcome the biological recognition receptors' disadvantages, molecularly imprinted polymers can be used for sensor development. From the point of view of the review, the combination of MIPs and sensors was explained and proposed as an informative paper.

Transparent regenerated cellulose film containing azobenzene group with reversible stimulus discoloration property

The cellulose film, exhibiting color alterations in response to external stimuli, presents itself as a promising functional material. In this study, a universal dissolution-regeneration technique was employed to manufacture a transparent, regenerated cellulose film, characterized by its reversible multi-stimulus discoloration property. This functional cellulose film, endowed with both photochromic and acid-chromic attributes, was synthesized through the introduction of a cellulose-grafted azobenzene derivative into the cellulose solution. The hue of a cellulose film irradiated with ultraviolet light could be inverted upon exposure to visible light or heat. Furthermore, when subject to heating, irradiation, or immersion in an acidic medium, this functional film demonstrated pronounced transparency. The acid-chromic behavior of the film was readily discernible when exposed to highly concentrated acidic aqueous solutions. Both the photochromic and acid-chromic phenomena were discernable to the unaided eye. After ten cycles, no fading of the reversible discoloration properties of the material occurred. This transparent regenerated cellulose film stands as a viable candidate for applications in optical data storage, intelligent switches, and sensors, owing to its capacity for reversible stimulus-triggered discoloration.

A Novel Polymer Inclusion Membrane-Based Green Optical Sensor for Selective Determination of Iron: Design, Characterization, and Analytical Applications.

The design, characterization, and analytical application of a green optical sensor for the selective determination of Fe(II) ions is proposed. The sensor is based on the immobilization of the chromogenic reagent picolinaldehyde salicyloylhydrazone (SHPA) within a polymer inclusion membrane. To reduce solvent usage, the reagent was synthesized using a green mechanochemical procedure. The components for sensor preparation were optimized with a sequential simplex method and the optimal composition was found to be 0.59 g cellulose triacetate (base polymer), 0.04 g SHPA (chemosensor reagent), 4.9 mL dibutyl phthalate (plasticizer), and 38 mL dichloromethane (solvent). The conditions of iron analysis were also optimized resulting in pH 6 for aqueous solution, 90 min exposure time and 10 min short-term stability. The optical sensor showed a linear range from the limit of detection (0.48 µmol L-1) to 54 µmol L-1 Fe(II). The precision of the method was found to be 1.44% and 1.19% for 17.9 and 45 µmol L-1 Fe(II), respectively. The characteristics of the sensor allowed the design of a Fe(II)/Fe(III) speciation scheme. The methodology was successfully applied to the determination of iron in food preservatives, food additives, and dietary supplement. Additionally, the Fe speciation scheme was successfully applied to an agricultural fertilizer.

Novel Applications of Optical Sensors and Machine Learning in Agricultural Monitoring

The rapid development of intelligence and automated technologies has provided new management opportunities for agricultural production [...]

Preparation and Analysis of Structured Color Janus Droplets Based on Microfluidic 3D Droplet Printing.

The microfluidic technique for the three-dimensional (3D) printing of Janus droplets offers precise control over their size, orientation, and positioning. The proposed approach investigates the impact of variables such as the volume ratio of the oil phase, droplet size, and the ratio of nonionic surfactants on the dimensions of the structured color apertures of Janus droplets. The findings reveal that structured color apertures modulate accurately. Furthermore, fabricating color patterns facilitates cat, fish, and various other specific shapes using structured color Janus droplets. The color patterns exhibit temperature-sensitive properties, enabling them to transition between display and concealed states. Herein, the adopted microfluidic technique creates Janus droplets with customizable characteristics and uniform size, solving orientation as well as space arrangement problems. This approach holds promising applications for optical devices, sensors, and biomimetic systems.

Stimuli‐responsive hydrogel microgels on porous silicon one‐dimensional photonic crystals: Tapping the full potential for optical sensor applications

AbstractPorous silicon 1D photonic crystals, namely rugate filters, are covered with a loosely packed hexagonally ordered array of stimuli‐responsive hydrogel microgels, and the optical properties of the resulting hybrid sensor are thoroughly investigated. For this purpose, both rugate filters with and without hydrogel microgel on top are immersed in ethanol/water mixtures possessing different compositions and NaCl solutions. Reflectance spectra of all samples are taken and analyzed concerning the spectral positions and reflectance intensity of the strong peak related to the photonic crystal rugate peak as well as the side bands resulting from Fabry–Pérot interference at the interfaces bordering the porous silicon. For the latter analysis, a Fourier transform is applied to the side bands for calculating the effective optical thickness (EOT). Thereby it can be shown that the spectral position of both the rugate peak and the EOT peak is best suited for monitoring refractive index changes in the immersion medium whereas the swelling and collapse of the stimuli‐responsive hydrogel microgel can be only detected by variations in the amplitude of the rugate peak and the EOT peak. These results are confirmed by simulations using a simple geometrical model and shall serve as guide for developing tailor‐made optical sensors.

Optical Properties of TiO2 Doped ZnO-PVA Nanocomposites

One of the materials with the greatest potential for use in flexible devices is semiconductor nanocomposite material. In this paper, we report the synthesis of ZnO-PVA-TiO2 nanocomposite to be applied as a flexible optical sensor device. The optical property of ZnO-PVA nanocomposite is improved by the addition of TiO2 in this work. The optical characteristics of the ZnO-PVA nanocomposite depend on the concentration of TiO2. Spin coating method was successfully used to synthesize ZnO-PVA-TiO2 with various TiO2 concentrations of 1%, 2%, and 3% w/v, respectively. The absorbance spectrum of ZnO-PVA-TiO2 nanocomposite changes with the addition of TiO2. The absorbance peaks of ZnO-PVA-TiO2 nanocomposites were shifting to a lower wavelength, resulting in increasing the nanocomposite band gap energy. According to this result, future applications of the flexible optical sensor are one of the potential devices based on this study.

Merging of Azulene and Perylene Diimide for Optical pH Sensors.

Polycyclic aromatic hydrocarbons (PAHs) have emerged as promising materials for organic electronics, including organic photovoltaics (OPVs), organic field-effect transistors (OFETs), and organic light-emitting diodes (OLEDs). Particularly, non-hexagonal ring-fused PAHs are highly desirable due to their unique optoelectronic properties. Herein, a new redox-active azulene-perylene diimide triad 1 and its ring-fused counterpart, diazulenocoronene diimide 2, were synthesized and fully characterized by a combination of NMR, cyclic voltammetry, and UV-visible absorption spectroscopy. Direct comparison of their electronic properties leads us to the conclusion that a significant change in the localization of HOMO and LUMO occurs upon the fusion of azulene and perylene diimide in 2, leading to the lack of intramolecular charge-transfer character for transitions in the visible spectral region. Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations were performed to gain further insight into various electronic transitions. Moreover, we found that the adaptive response to acids and bases manifests itself in a reversible two-color change that can be attributed to changes in the chemical structures. Our findings pave the way for manipulating the relative HOMO and LUMO energy levels of organic chromophores by fusing non-alternant azulenes to an otherwise flat PAH, which could possibly lead to applications in organic electronics and optical sensors.

Pure-green upconversion emission and high-sensitivity optical thermometry of Er3+-doped stoichiometric NaYb(MoO4)2

The optical temperature sensor based on fluorescence intensity ratio (FIR) offers significant advantages for rapid and non-contact temperature measurements. However, the application of optical temperature sensors is limited by the challenge of identifying advanced materials with high response sensitivity. In this study, phosphor and single-crystal states stoichiometric NaYb(MoO4)2 with Er3+ doping were prepared by solid-state reaction method and Czochralski method, respectively, for promising optical thermometry applications. The structure of the phosphor and single-crystal state samples were investigated. High-purity upconversion (UC) emissions were achieved from stoichiometric NaYb(MoO4)2:Er3+ samples with a maximum green-to-red ratio up to 70.3, which opens up numerous possibilities for their application as pure-green color converters. Besides, the UC emission spectra were monitored with respect to temperature, and the fluorescence intensity ratios (FIRs) of the 2H11/2→4I15/2 and 4S3/2→4I15/2 transitions of Er3+ ions were investigated to evaluate the optical temperature sensing behaviors of NaYb(MoO4)2:Er3+. Importantly, the distinctions of optical temperature sensing behaviors between phosphor and single-crystal state samples were analyzed. The results suggest that stoichiometric NaYb(MoO4)2:Er3+, especially for single-crystal state NaYb(MoO4)2:Er3+, hold great promise as FIR-based optical temperature sensors. In addition, the results can also open up the research interests for employing stoichiometric materials and single crystal materials as optical thermometry applications.

Current state of the art and future directions for implantable sensors in medical technology: Clinical needs and engineering challenges.

Implantable sensors have revolutionized the way we monitor biophysical and biochemical parameters by enabling real-time closed-loop intervention or therapy. These technologies align with the new era of healthcare known as healthcare 5.0, which encompasses smart disease control and detection, virtual care, intelligent health management, smart monitoring, and decision-making. This review explores the diverse biomedical applications of implantable temperature, mechanical, electrophysiological, optical, and electrochemical sensors. We delve into the engineering principles that serve as the foundation for their development. We also address the challenges faced by researchers and designers in bridging the gap between implantable sensor research and their clinical adoption by emphasizing the importance of careful consideration of clinical requirements and engineering challenges. We highlight the need for future research to explore issues such as long-term performance, biocompatibility, and power sources, as well as the potential for implantable sensors to transform healthcare across multiple disciplines. It is evident that implantable sensors have immense potential in the field of medical technology. However, the gap between research and clinical adoption remains wide, and there are still major obstacles to overcome before they can become a widely adopted part of medical practice.