Crystal Sensor Research Articles

One-Dimensional Defect Layer Photonic Crystal Sensor for Purity Assessment of Organic Solvents.

This paper presents the design and analysis of a one-dimensional defect layer photonic crystal (1D-DLPC) sensor for the assessment of the purity of chemical solvents with enhanced accuracy. Chemical solvents are frequently used in chemical processes as reaction mediums. It is essential to ascertain its purity since impurities can significantly affect the outcome of the reaction. The structure of the proposed one-dimensional defect layer photonic crystal sensor consists of a defect layer sandwiched between alternate layers of ZnO and SiO2 organized with a certain periodicity. It has been shown that the localized defect modes inside the structure can detect minute refractive index changes based on the degree of impurity of chemical solvents. Simulation studies have been performed through the transfer matrix method (TMM) and the performance of the design is evaluated using several metrics such as sensitivity, full width at half-maximum, figure of merit, quality factor, and dynamic range. Results indicate that the designed one-dimensional defect layer photonic crystal sensor has a significantly high efficiency and is suitable for detecting impure solvents.

New Trend of Amperometric Gas Sensors Using Atomic Gold-Decorated Platinum/Polyaniline Composites

The Amperometric Gas Sensor (AGS) uses an electrode as the transducer element which converts its signal into a current from the electrochemical reaction of analytes taking place at the electrode surface. Many attempts to improve AGS performance, such as modifying the working electrode, applying a particular gas-permeable membrane, and selecting the proper electrolyte, etc., have been reported in the scientific literature. On the other hand, in the materials community, atomic gold has gained much attention because its physicochemical properties dramatically differ from those of gold nanoparticles. This paper provides an overview of the use of atomic gold in AGSs, both in a bulky AGS and a miniaturized AGS. In the miniaturized AGS, the system must be redesigned; for example, the aqueous electrolyte commonly used in a bulky AGS cannot be used due to volatility and fluidity issues. A Room Temperature Ionic Liquid (RTIL) can be used to replace the aqueous electrolyte since it has negligible vapor pressure; thus, a thin film of RTIL can be realized in a miniaturized AGS. In this paper, we also explain the possibility of using RTIL for a miniaturized AGS by incorporating a quartz crystal microbalance sensor. Several RTILs coated onto modified electrodes used for isomeric gas measurement are presented. Based on the results, the bulky and miniaturized AGS with atomic gold exhibited a higher sensor response than the AGS without atomic gold.

Au-MgF2-Coated Photonic Crystal Fiber Surface Plasmon Resonance Sensor with High FOM

Au-MgF2-Coated Photonic Crystal Fiber Surface Plasmon Resonance Sensor with High FOM

Design, simulation, and optimization of a polymer-based photonic crystal pressure sensor

Design, simulation, and optimization of a polymer-based photonic crystal pressure sensor

Spatially tuned photonic crystal fiber sensor mimics visible and near-infrared regimes for wide-range multi-analyte detection

In this study, we report a novel dual-core photonic crystal fiber (PCF) sensor designed to mimic visible (VIS) and near-infrared (n-IR) regimes through the utilization of surface plasmon resonance (SPR). The sensor design aims to achieve wide refractive index (IR) sensing capabilities and simultaneous detection of multiple analytes. The PCF design features two concentric rings forming the cladding in a circular lattice configuration, strategically omitting air holes on both sides adjacent to the metal layer to enhance coupling effects. To induce plasmon resonance, a chemically inert thin layer of gold (Au) is applied to the half-ellipse-shaped sensing channel. Utilizing the finite element method in COMSOL Multiphysics, we systematically explore the optical characteristics of the proposed SPR-based PCF. Operating within the VIS band, the sensor demonstrates the ability to simultaneously detect multiple analytes within the range of 1.35–1.44. Furthermore, it exhibits a wider RI sensing range from 1.15 to 1.44 in the n-IR band. The sensor showcases a wavelength sensitivity of ∼ 1840 nm/RIU and an amplitude sensitivity of ∼ 168.13 RIU−1 with a resolution of 6.71 × 10−5 RIU in the n-IR band. Conversely, in the VIS band, the sensor demonstrates higher sensitivity, reaching up to 4520 nm/RIU, and an amplitude sensitivity of ∼ 1093.29 RIU−1 with a resolution of 5.43 × 10–5 RIU. These findings underscore the potential of the dual-core SPR-based PCF sensor for versatile and high-performance applications in RI sensing and multi-analyte detection for VIS and n-IR spectroscopy.

Dual D-Shaped Photonic Crystal Fiber Sensor for Three-Parameter Sensing Based on Surface Plasmon Resonance

Dual D-Shaped Photonic Crystal Fiber Sensor for Three-Parameter Sensing Based on Surface Plasmon Resonance

Bidirectional Design for SPR-Photonic Crystal Fiber Magnetic Field Sensor Based on Deep Learning

Bidirectional Design for SPR-Photonic Crystal Fiber Magnetic Field Sensor Based on Deep Learning

High FOM PCF-SPR refractive index sensor based on MgF2-Au double-layer films.

A simple twin-core D-shape photonic crystal fiber sensor based on surface plasmon resonance (SPR) is designed for the measurement of refractive indices (RI). The twin-core D-shape structure enhances the SPR effect, and the M g F 2-Au dual-layer film narrows the linewidth in the loss spectrum, consequently improving both the sensitivity and figure of merit (FOM). The properties of the sensor are analyzed by the finite element method. In the RI range of 1.32-1.42, the maximum wavelength sensitivity, FOM, and resolution are 62,000nm/RIU, 1281R I U -1, and 1.61×10-6, respectively.

D-type photonic crystal fiber refractive index sensor with ultra-high fabrication stability and ultra-wide detection range

D-type photonic crystal fiber refractive index sensor with ultra-high fabrication stability and ultra-wide detection range

Sensitivity and quality factor improvement of photonic crystal sensors by geometrical optimization of waveguides and micro-ring resonators combination

In this work, the process of designing and simulating optical sensors based on photonic crystal (PC) micro-ring resonators (MRRs) has been investigated. According to the PC type, different waveguides and resonators can be designed, and various topologies can be proposed from their combination, for optical sensor applications. Here, the investigated MRR is of the symmetrical micro-hexagonal ring resonator (MHRR) type. Different arrays of MHRR arrangement have been designed to investigate their effects on the output spectrum. The results of the design and simulation of different topologies have been analyzed and compared with other numerical researches. Considering all the necessary aspects of PC optical sensors, a detailed and comprehensive algorithm has been presented for designing these devices and choosing the optimal structure. In a more complementary process, the effects of reflector rods have been investigated, which indicates the existence of similarity and compatibility in the design between the distance of reflector rods and the length of MHRRs to obtain the optimal structure. Finally, the effect of different values of lattice constant and radius of dielectric rods on FWHM, transmission (TR) and resonant wavelength is studied, and the most optimal mode is presented. In order to measure the performance of the proposed optimal sensor, its application for gas detection has been analyzed. TR, FWHM, quality factor (QF), sensitivity (S) and figure of merit (FOM) of the proposed sensor were equal to 96%, 0.31 nm, 2636, 6451 nm/RIU and 2960 RIU−1 respectively. An examination of results from similar research indicates a rational and effective approach for generating diverse topologies, aiming to attain the most optimal configuration for optical sensors employing MRRs. Furthermore, employing a systematic design process based on established principles and the proposed algorithm helps prevent arbitrary parameter variations, facilitating the attainment of desired outcomes in a more streamlined and efficient manner. Given the comprehensive nature of this research, it presents a viable solution for designing optical devices based on MRRs for use in optical integrated circuits (OICs) applications.

Gamma radiation detector using Cantor quasi-periodic photonic crystal based on porous silicon doped with polymer

The measurement of patients’ dosages of radiation caused by medical diagnostics continues to be challenging. A Cantor sequence photonic crystal structure using porous silicon doped with a polymer of polyvinyl alcohol, carbol fuchsin and crystal violet (DPV) is proposed. The influence rules of geometrical and optical parameters such as the radiation doses, number of periods, porosity of porous layers, incident angle and thickness of layers are investigated using MATLAB based on the transfer matrix method. The transmittance of the Cantor sequence of a defective photonic crystal sensor under different conditions is investigated to select the optimum conditions. The proposed system recorded the accepted sensitivity of 0.265[Formula: see text]nm/Gy, FoM of 6.5[Formula: see text]Gy[Formula: see text], Q of 12,701, RS of [Formula: see text] and LoD of [Formula: see text] for gamma radiation. The suggested detector has simple design, accurate monitoring efficiency and immense potential for gamma radiation sensing.

Dual Polarized High Sensitivity Photonic Crystal Fiber Surface Plasmon Resonance Sensor Coated with Indium Tin Oxide

Dual Polarized High Sensitivity Photonic Crystal Fiber Surface Plasmon Resonance Sensor Coated with Indium Tin Oxide

D-type photonic crystal fiber low refractive index sensor based on surface plasmon

This study presents the design and analysis of a novel surface plasmon resonance sensor based on D-type photonic crystal fiber. The analyte channel in the sensor comprises an open ring with a thin gold film deposited on the channel, inducing the surface plasmon resonance effect to enhance the resonance effect and improve the spectral sensitivity of the sensor. The proposed design eliminates the need to introduce liquid into the analyte channel. Upon inserting the sensor into the vessel, the analyte automatically flows into the liquid channel. Simulations illustrate the capability of the proposed sensor to detect low refractive indices spanning from [Formula: see text] to [Formula: see text], exhibiting a remarkable spectral sensitivity of up to 9000[Formula: see text]nm/RIU. The surface plasmon resonance sensor presented in this study emerges as a competitive candidate for applications requiring low refractive index detection. It is all because of its promising sensing results, wide refractive index sensing range, and simple, compact fiber design.

Direct laser writing photonic crystal hydrogel sensors for in-situ sensing in microfluidic device

Photonic crystal hydrogels (PCHs) are promising materials for in-situ sensing demands in cell incubation systems such as microfluidic devices. However, the lack of ability to precisely construct and settle PCH sensors limits their future development. In this paper, we developed a versatile and highly controllable strategy to fabricate PCH sensing systems via direct laser writing (DLW) technology. We show that, PCH microsensors with precise geometries and diverse compositions could be exactly generated at desired positions using two-photon lithography (TPL). With such smart sensors, in-situ and spatiotemporal monitor of environmental parameters in liquid microdomains could easily be achieved using a microscope. This is demonstrated by generating PCH sensors for in-situ pH and metal ion strength analysis in microfluidic devices.

Ultrasensitive Point-of-Care Detection of Protein Markers Using an Aptamer-CRISPR/Cas12a-Regulated Liquid Crystal Sensor (ALICS).

Despite extensive efforts, point-of-care testing (POCT) of protein markers with high sensitivity and specificity and at a low cost remains challenging. In this work, we developed an aptamer-CRISPR/Cas12a-regulated liquid crystal sensor (ALICS), which achieved ultrasensitive protein detection using a smartphone-coupled portable device. Specifically, a DNA probe that contained an aptamer sequence for the protein target and an activation sequence for the Cas12a-crRNA complex was prefixed on a substrate and was released in the presence of target. The activation sequence of the DNA probe then bound to the Cas12a-crRNA complex to activate the collateral cleavage reaction, producing a bright-to-dark optical change in a DNA-functionalized liquid crystal interface. The optical image was captured by a smartphone for quantification of the target concentration. For the two model proteins, SARS-CoV-2 nucleocapsid protein (N protein) and carcino-embryonic antigen (CEA), ALICS achieved detection limits of 0.4 and 20 pg/mL, respectively, which are higher than the typical sensitivity of the SARS-CoV-2 test and the clinical CEA test. In the clinical sample tests, ALICS also exhibited superior performances compared to those of the commercial ELISA and lateral flow test kits. Overall, ALICS represents an ultrasensitive and cost-effective platform for POCT, showing a great potential for pathogen detection and disease monitoring under resource-limited conditions.

Molecularly imprinted 2D photonic crystal hydrogel sensor for sodium dichloroisocyanurate.

Sodium dichloroisocyanurate (SDIC) is an efficient, safe and convenient halogen disinfectant that is widely used for hospital, tableware and swimming pool disinfection. In order to ensure its effective use and safety, especially in clinical settings, effective identification methods are necessary. The effective chlorine content is one of the quality standards for chlorine-containing disinfectants, but its complex experimental operation as well as poor specificity and portability limit its application. In contrast, testing based on molecularly imprinted photonic crystal sensors provides excellent performance. Therefore, it is of great significance to establish a new and simple SDIC recognition method. We prepared a novel molecularly imprinted two-dimensional (2D) photonic crystal hydrogel (MIPH) for sensitive and label-free recognition of SDIC. The response performance of the resultant MIPH sensor was determined by monitoring particle spacing changes in the polystyrene (PS) 2D photonic crystals embedded in the hydrogel. Particle spacing changes were recorded by measuring changes in the diameter of the Debye diffraction ring of the MIPH sensor. As the concentration of SDIC in solution increased from 1 × 10-2 to 1.0 mmol L-1, the diameter of the Debye diffraction ring increased by 6 mm, and the corresponding photonic crystal particle spacing decreased by 56 nm. The particle spacing changes in the MIPH sensor showed a linear relationship with the SDIC concentration in the range of 1 × 10-2-1.0 mmol L-1, and the limit of detection (S/N = 3) was found to be 3 × 10-3 mmol L-1. The constructed hydrogel sensor was successfully used to detect SDIC in sodium dichloroisocyanurate disinfectant powder, demonstrating recoveries of 96-100% and RSD of 7.2-7.6%. Our molecularly imprinted SDIC photonic crystal hydrogel provides a universal strategy for designing sensors for other clinical disinfectants.

Photonic crystal gas sensors based on metal-organic frameworks and polymers.

A photonic crystal (PC) is an optical microstructure with an adjustable dielectric constant. The PC sensor was deemed a powerful tool for gas molecule detection due to its excellent sensitivity, stability, online use and tailorable optical performance. The detection signals are generated by monitoring the changes of the photonic band gap when the sensing behavior occurs. Recently, many efforts have been devoted to improving the PC sensor's detection performance and reducing technical costs by selecting and refining functional materials. In this case, metal-organic frameworks (MOFs) with a large specific surface, tunable structural properties and polymers with unique swelling properties have attracted increasingly attention. In this review, a systematic review of PC gas sensors based on MOFs and polymers was carried out for the first time. Firstly, the optical properties and gas sensing mechanism of PCs were briefly summarized. Secondly, a detailed discussion of the structural properties and rapid preparation methods of distributed Bragg reflectors (DBRs), opals and inverse opals (IOPCs) was presented. Thirdly, the recent advances in MOF, polymer and MOF/polymer-based PC sensors over the past few years were summarized. It should be noted that the sensitivity and selectivity enhancement strategy by appropriate material species selection, organic ligand functionalization, metal-ion doping, diverse functional material arrays, and multi-component compounding were analyzed in detail. Finally, prospects on PC gas sensors are given in terms of preparation methods, material functionalization and future applications.

A phenylboronic acid-based smart photonic crystal hydrogel sensor for colorimetric detection of glucose

A phenylboronic acid-based smart photonic crystal hydrogel (PNAPB) sensor with good recyclability was reported for the sensitive and colorimetric detection of glucose.

Bioinspired colloidal crystal hydrogel pressure sensors with Janus wettability for uterus cervical canal tension perception.

The pursuit of flexible, sensitive, and cost-effective pressure sensors plays a pivotal role in medical diagnostics, particularly in the domain of cervical health monitoring. However, significant challenges remain in the economical production of flexible piezoresistive materials and the integration of microstructures aimed at enhancing sensor sensitivity. This urge highlights the use of innovative, stable hydrogel films that demonstrate robust adherence to soft biological tissues, thereby enabling prolonged bio-signal monitoring. In this study, we introduce an innovative integration of a flexible pressure electrical signal sensor with structural color hydrogel scaffolds. This integration leverages the tunability of the inverse opal structure to fine-tune the scaffold's adherence to the endocervical wall under varying environmental conditions and to amplify the sensitivity of pressure measurements. Our findings indicate that this novel approach holds promise for substantial enhancements in the manufacturing and functional capabilities of cervical pressure sensors, potentially revolutionizing personalized medical treatments and improving patient monitoring.

Detection of sulfur mustard simulant by trisaryl phosphoric triamide-based resin using a quartz crystal microbalance sensor.

Chemical warfare agents (CWAs) pose a persistent threat to human safety, and bis(2-chloroethyl) sulfide, or sulfur mustard (SM) is one of the most dangerous substances and is able to cause serious harm. Detecting SM gas is vital, but current methods have high-temperature requirements and limited selectivity, mainly because of the lack of CWA receptor development, and this makes them challenging to use. To address this issue, we present a trisaryl phosphoric triamide-based resin receptor that preferentially interacts with a SM simulant 2-chloroethyl ethyl sulfide (2-CEES) through dipole interactions. The receptor was synthesized through a facile process using an amine and a triethyl phosphate and the properties of its coating were enhanced using epoxy chemistry. The receptor's superior triamide structure was evaluated using a quartz crystal microbalance and reactivity was confirmed by observing the variations in reactivity according to the number of phosphoramides. The receptor showed better reactivity to 2-CEES vapor than to the known poly(epichlorohydrin) and showed selectivity to other volatile organic compounds. Moreover, its durability was evident even 30 days post-coating. The applicability of this receptor extends to array sensors, sound acoustic wave sensors, and chemo-resistive and chemo-capacitive sensors, and it promises advances in chemical warfare agent detection.