Optical Detection Technology Research Articles

Eos: conceptual design for a demonstrator of hybrid optical detector technology

Eos is a technology demonstrator, designed to explore the capabilities of hybrid event detection technology, leveraging both Cherenkov and scintillation light simultaneously. With a fiducial mass of four tons, Eos is designed to operate in a high-precision regime, with sufficient size to utilize time-of-flight information for full event reconstruction, flexibility to demonstrate a range of cutting edge technologies, and simplicity of design to facilitate potential future deployment at alternative sites. Results from Eos can inform the design of future neutrino detectors for both fundamental physics and nonproliferation applications. This paper describes the conceptual design and potential applications of the Eos detector.

Nanoplasmonic assay platforms for reproducible SERS detection of Alzheimer's disease biomarker

AbstractWith the recent developments in high‐sensitivity optical detection technologies, many studies have been conducted to accurately detect biomarkers with low concentrations of 1.0 pM or less as well as apply them to in vitro diagnostics. The tubulin‐associated unit (tau‐381) protein, a biomarker of Alzheimer's disease, is one such representative example, and its cut‐off value reported in clinical practice is 5.5 fM. Therefore, a robust sensing technology that can stably detect such low concentrations of biomarkers is needed. In this study, tau‐381 was detected with high sensitivity and reproducibility by a plasmonic Au nanopopcorn substrate fabricated via thermal evaporation. Here, aptamer DNAs labeled with Raman reporters on the terminal were used as the receptors. The plasmonic nanopopcorn substrate used in this study is composed of uniform gold nanoparticles (AuNPs) of average size 64 nm. The reproducibility was significantly improved through more uniform nanogaps than those formed by aggregation of AuNPs in solution. An assay was conducted by first reacting tau‐381 with the corresponding aptamers, and the remaining aptamer DNAs were then reacted with capture DNAs immobilized on the surface of the Au substrate. The assay results for tau‐381 showed a limit of detection value of 2.2 fM, which is below the cut‐off value (5.5 fM).

Packaged butter adulteration evaluation based on spatially offset Raman spectroscopy coupled with FastICA

Optical detection technology has been widely used in unpackaged food adulteration detection. However, due to the interference of packaging materials on the internal food optical signal, including signal occlusion, mixing and overlap precluded the accurate detection of internal food quality. In this study, a method of packaged butter adulteration evaluation based on spatially offset Raman spectroscopy (SORS) combined with fast independent component analysis (FastICA) was proposed. The adulterated butter from 0% to 100% w/w margarine at 10% intervals was covered with packaging sheets as test samples. A line-scan Raman hyperspectral imaging system was used to obtain a scattering spectral image of the packaged butter samples. The region of interest of the scattering image is extracted as the input of FastICA model to separate the internal butter signals. The extracted butter Raman features were input into four quantitative analysis models to assess the content of butter adulteration. The results showed that the ensemble model Extra-tree has the best performance with RMSEp, Rp2, and RPD values of 0.6, 0.93, and 4.73, respectively. Additionally, the applicability of the method was validated with four types of packaging materials. This rapid non-destructive testing method is beneficial to the effective testing method of packaged butter and other products industry.

Emerging nanophotonic biosensor technologies for virus detection

Abstract Highly infectious viral diseases are a serious threat to mankind as they can spread rapidly among the community, possibly even leading to the loss of many lives. Early diagnosis of a viral disease not only increases the chance of quick recovery, but also helps prevent the spread of infections. There is thus an urgent need for accurate, ultrasensitive, rapid, and affordable diagnostic techniques to test large volumes of the population to track and thereby control the spread of viral diseases, as evidenced during the COVID-19 and other viral pandemics. This review paper critically and comprehensively reviews various emerging nanophotonic biosensor mechanisms and biosensor technologies for virus detection, with a particular focus on detection of the SARS-CoV-2 (COVID-19) virus. The photonic biosensing mechanisms and technologies that we have focused on include: (a) plasmonic field enhancement via localized surface plasmon resonances, (b) surface enhanced Raman scattering, (c) nano-Fourier transform infrared (nano-FTIR) near-field spectroscopy, (d) fiber Bragg gratings, and (e) microresonators (whispering gallery modes), with a particular emphasis on the emerging impact of nanomaterials and two-dimensional materials in these photonic sensing technologies. This review also discusses several quantitative issues related to optical sensing with these biosensing and transduction techniques, notably quantitative factors that affect the limit of detection (LoD), sensitivity, specificity, and response times of the above optical biosensing diagnostic technologies for virus detection. We also review and analyze future prospects of cost-effective, lab-on-a-chip virus sensing solutions that promise ultrahigh sensitivities, rapid detection speeds, and mass manufacturability.

The State-of-art Analytical Models and Detectors for Black Holes

Since the 19th century, human beings have a much better understanding on the black holes with the fast progress on the optical detection technology. In this paper, the recent progress and the state-of-art detection scenarios for black holes are discussed, especially for the primordial black holes. With the result of evidence and theory, the current status of detecting black holes is detailly demonstrated. Specifically, five parts will be presented, the formation of the black holes, the growth of the black holes, the types of the black holes, the detection of the black holes and the relationship between primordial black holes and black matter. Overall, these results shed light on the astrophysics, the interaction between the black holes and the surrounding heavenly bodies and the universe with deeper insight.

Simulation and experimental study on adsorption of SF6 decomposition components and optical gas cell materials

Fourier transform infrared spectroscopy (FTIR) is widely used in gas detection of SF6 decomposition components. A gas cell is an important element in the detection system, which can directly affect the accuracy and sensitivity of detection. During the long-term use of the gas cell, SF6 decomposition components may be adsorbed on the inner wall of the gas cell, which affects the detection results and the life of the gas cell. Therefore, the study on the adsorption between the gas cell material and the SF6 decomposition component is of great significance for improving the accuracy of detection. In this paper, based on the density functional theory, the adsorption process and adsorption degree of SF6 decomposition components (SOF2, SO2F2, CO, SO2, and H2S) with three typical main gas cell materials (Al, Cu, and Fe) and two gas cell coating materials (Teflon and Au) were simulated. It was found that the adsorption of Teflon and Au with gas was weak in the five materials and that of Teflon was the weakest. The adsorption energy of the three main gas cell materials was 2.65–6.31 times that of Teflon. The simulation results were also verified by FTIR and the GC-Materials Studio (MS) method. FTIR results showed that Teflon and Au had the weakest influence on the infrared spectral absorption peak and the effect of the two materials on SOF2 and SO2F2 gas absorption peaks is only less than 0.1. The results of gas chromatograph-mass spectrometer (GC-MS) showed that the effects of Teflon materials and Au on gas concentration were 2%–9.41% and the effects of Cu, Fe, and Al on gas concentration were 4.48%–65.43%. Therefore, Au and Teflon are suitable as coating materials for gas cells, which can reduce the adsorption of gas and improve the accuracy of infrared spectroscopy measurement. The results of this paper provide a reference for the development of application of optical gas detection technology in SF6 decomposition component detection.

Research on Distributed Optical Fiber Pipeline Micro Leakage Detection Technology Based on Recursive Least Square

A very weak vibration signal is generated when the pipeline leaks slightly. However, the commonly used pipeline leakage detection technology cannot obtain this kind of signal normally, thus causing large positioning error. Aiming at the above problems, a pipeline micro leakage detection technology based on Recursive Least Squares distributed optical fiber is proposed. The technology utilizes a dual Mach-Zehnder interference system with high sensitivity and simple optical path structure to monitor the interference signal caused by pipeline micro leakage at all times. Then, the adaptive filter based on Recursive Least Square method is used to denoise the interference signal. On this basis, the cross-correlation algorithm is used to obtain the delay estimation of the two test signals. This article clarifies the positioning principle of the detection technology and conducts the positioning experiment of pipeline micro leakage. The experimental results show that this technology can effectively detect the weak vibration signal generated by pipeline micro leakage and greatly improve the positioning accuracy of micro leakage points. The relative error can be controlled within 1%.

External Perspective of Lung Airflow Model Through Diaphragm Breathing Sensor Using Fiber Optic Elastic Belt

Optical fiber-based detector technology is highly appreciated and developed in the field of medical physics. Through its fiber-optic wave pattern performance, this detector has great potential for monitoring difficult-to-calculate parameters such as airflow in the lungs. To realize this reality, a theoretical and experimental approach is needed in this research. The lung tissue model was formed using the Navier-Stokes equation using the finite element method by taking into account the continuity and momentum equations. While experimentally, single-mode fiber and fiber Bragg grating (FBG) was installed with a sinusoidal macro bending pattern as a strain sensor which was applied to the elastic belt and mounted on the diaphragm. The simulation model carried out depicts the velocity of air moving from the pulmonary duct to increase as it flows into smaller branches. While the experimental results show that the detected power parameter is a maximum of -0.16 dBm during inhalation and a minimum of -0.19 dBm during expiration. Due to the bending approach, the FBG sensor belt obtained the highest sensitivity at a sinusoidal bending diameter of 0.8 cm. Therefore, this is good news as a more accurate detector approach for medical purposes.

Optical fiber intrusion signal unmixing by nonorthogonal principal skewness analysis

The optical fiber intrusion signal detection technology adopts the distributed optical fiber as sensor to monitor and identify perimeter intrusion signals. Due to the diversity of perimeter intrusion, the optical fiber intrusion signals are composed of various types of pure signals. Therefore, direct identification on mixed signals will cause the system performance degradation. A more effective method is to first unmix the mixed signal to obtain each pure signal component, and then perform signal identification. In this paper, nonorthogonal principal skewness analysis (NPSA) based unmixing algorithm is proposed. By introducing supersymmetric tensors, the mixed fiber signal unmixing problem is transformed into the skewness analysis problem, and then the non-orthogonal solution is further solved which significantly improves the accuracy of solving pure signal components. The effectiveness of the proposed algorithm is verified by actual data experiments.

Optical techniques in non-destructive detection of wheat quality: A review

Wheat quality detection is essential to ensure the safety of wheat circulation and storage. The traditional wheat quality detection methods mainly include artificial sensory evaluation and physicochemical index analysis, which are difficult to meet the requirements for high accuracy and efficiency in modern wheat quality detection due to the disadvantages of subjectivity, destruction of sample integrity and low efficiency. With the rapid development of optical technology, various optical-based methods, using near-infrared spectroscopy technology, hyperspectral imaging technology and terahertz, etc., have been proposed for wheat quality detection. These methods have the characteristics of non-destructiveness and high efficiency which make them popular in wheat quality detection in recent years. In this paper, various state-of-the-art optical-based techniques of wheat quality detection are analyzed and summarized in detail. Firstly, the principle and process of common optical non-destructive detection methods for wheat quality are introduced. Then, the optical techniques used in these detection methods are divided into seven categories, and the comparison of these technologies and their advantages and disadvantages are further discussed. It shows that terahertz technology is regarded as the most promising wheat quality detection method compared with other optical detection technologies, because it can not only detect most types of wheat deterioration, but also has higher accuracy and efficiency. Finally, the research of optical technology in wheat quality detection is prospected. The future research of optical technology-based wheat quality detection mainly includes the construction of wheat quality optical detection standardization database, the fusion of multiple optical detection technologies and multiple quality index information, the improvement of the anti-interference of optical technology and the industrialization of optical inspection technology for wheat quality. These studies are of great significance to improve the detection technology of wheat and ensure the storage safety of wheat in the future.

Effects of transcranial magneto-acoustic electrical stimulation on calcium signals in prefrontal nerve clusters

Transcranial magneto-acoustic electrical stimulation (TMAES) is a novel method of brain nerve regulation and research, which uses induction current generated by the coupling of ultrasound and magnetic field to regulate neural electrical activity in different brain regions. As the second special envoy of nerve signal, calcium plays a key role in nerve signal transmission. In order to investigate the effect of TMAES on prefrontal cortex electrical activity, 15 mice were divided into control group, ultrasound stimulation (TUS) group and TMAES group. The TMAES group received 2.6 W/cm 2 and 0.3 T of magnetic induction intensity, the TUS group received only ultrasound stimulation, and the control group received no ultrasound and magnetic field for one week. The calcium ion concentration in the prefrontal cortex of mice was recorded in real time by optical fiber photometric detection technology. The new object recognition experiment was conducted to compare the behavioral differences and the time-frequency distribution of calcium signal in each group. The results showed that the mean value of calcium transient signal in the TMAES group was (4.84 ± 0.11)% within 10 s after the stimulation, which was higher than that in the TUS group (4.40 ± 0.10)% and the control group (4.22 ± 0.08)%, and the waveform of calcium transient signal was slower, suggesting that calcium metabolism was faster. The main energy band of the TMAES group was 0-20 Hz, that of the TUS group was 0-12 Hz and that of the control group was 0-8 Hz. The cognitive index was 0.71 in the TMAES group, 0.63 in the TUS group, and 0.58 in the control group, indicating that both ultrasonic and magneto-acoustic stimulation could improve the cognitive ability of mice, but the effect of the TMAES group was better than that of the TUS group. These results suggest that TMAES can change the calcium homeostasis of prefrontal cortex nerve clusters, regulate the discharge activity of prefrontal nerve clusters, and promote cognitive function. The results of this study provide data support and reference for further exploration of the deep neural mechanism of TMAES.

Current situation and development trend of aspheric optical surface defect detection technology (invited)

Current situation and development trend of aspheric optical surface defect detection technology (invited)

Chromaticity Evolutionary Detection of Food Contaminant Semicarbazide through an Upconversion Luminescence-Based Nanosensor.

Semicarbazide (SEM) is a widespread carcinogenic and neurotoxic food contaminant, originating from the metabolite of antibiotic nitrofurazone, which is used in aquaculture, or thermal decomposition byproduct of a flour blowing agent azodicarbonamide. Although optical detection technologies are powerful tools considering the advantages of fast response and visualization detection, there are few optical nanosensors for highly sensitive and visual assays of SEM due to no luminescence response and UV absorbance of SEM. Herein, an upconversion luminescence (UCL)-based nanosensor was designed for visual detection of SEM with high sensitivity and good selectivity. The nanosensor was constructed by combining upconversion nanoparticles (UCNPs) and phosphomolybdic acid (PMA), which was used as the specific recognition element of SEM. The developed nanosensor exhibited selective absorbance enhancement and UCL quenching behavior with the addition of SEM based on the inner filter effect (IFE). Since the change in absorbance translated into an exponential change in the luminescence, the sensitivity of the nanosensor was greatly improved. The nanosensor realized a highly sensitive and visual response to SEM in the linear range of 0.5-16 μM with a low limit of detection of 58 nM. Moreover, satisfactory recovery values ranging from 90 to 112% in spiked real samples indicated the practical applicability of the nanosensor. The nanosensor designed here provides a sensitive and convenient sensing strategy for visual detection of hazardous substances and is expected to develop the upconversion sensing application in food safety.

Smartphone-Based Device for Colorimetric Detection of MicroRNA Biomarkers Using Nanoparticle-Based Assay

The detection of microRNAs (miRNAs) is emerging as a clinically important tool for the non-invasive detection of a wide variety of diseases ranging from cancers and cardiovascular illnesses to infectious diseases. Over the years, miRNA detection schemes have become accessible to clinicians, but they still require sophisticated and bulky laboratory equipment and trained personnel to operate. The exceptional computing ability and ease of use of modern smartphones coupled with fieldable optical detection technologies can provide a useful and portable alternative to these laboratory systems. Herein, we present the development of a smartphone-based device called Krometriks, which is capable of simple and rapid colorimetric detection of microRNA (miRNAs) using a nanoparticle-based assay. The device consists of a smartphone, a 3D printed accessory, and a custom-built dedicated mobile app. We illustrate the utility of Krometriks for the detection of an important miRNA disease biomarker, miR-21, using a nanoplasmonics-based assay developed by our group. We show that Krometriks can detect miRNA down to nanomolar concentrations with detection results comparable to a laboratory-based benchtop spectrophotometer. With slight changes to the accessory design, Krometriks can be made compatible with different types of smartphone models and specifications. Thus, the Krometriks device offers a practical colorimetric platform that has the potential to provide accessible and affordable miRNA diagnostics for point-of-care and field applications in low-resource settings.

Analysis of Embedded Optical Interferometry in Transparent Elastic Grating for Optical Detection of Ultrasonic Waves.

In this paper, we propose a theoretical framework to explain how the transparent elastic grating structure can be employed to enhance the mechanical and optical properties for ultrasonic detection. Incident ultrasonic waves can compress the flexible material, where the change in thickness of the elastic film can be measured through an optical interferometer. Herein, the polydimethylsiloxane (PDMS) was employed in the design of a thin film grating pattern. The PDMS grating with the grating period shorter than the ultrasound wavelength allowed the ultrasound to be coupled into surface acoustic wave (SAW) mode. The grating gaps provided spaces for the PDMS grating to be compressed when the ultrasound illuminated on it. This grating pattern can provide an embedded thin film based optical interferometer through Fabry–Perot resonant modes. Several optical thin film-based technologies for ultrasonic detection were compared. The proposed elastic grating gave rise to higher sensitivity to ultrasonic detection than a surface plasmon resonance-based sensor, a uniform PDMS thin film, a PDMS sensor with shearing interference, and a conventional Fabry–Perot-based sensor. The PDMS grating achieved the enhancement of sensitivity up to 1.3 × 10−5 Pa−1 and figure of merit of 1.4 × 10−5 Pa−1 which were higher than those of conventional Fabry–Perot structure by 7 times and 4 times, respectively.

Method of GIL partial discharge localization based on natural neighbour interpolation and ECOC‐MLP‐SVM using optical simulation technology

Partial discharge (PD) is one of the main causes rendering the deterioration of the insulation state in gas-insulated transmission line (GIL). Accurate and timely localization of the PD source is essential to ensure the safe and stable operation of the GIL. At present, optical PD detection technology shows advantages in terms of high sensitivity and strong anti-interference performance. Therefore, an optical PD localization method based on optical simulation fingerprint database is proposed. The introduction of simulation conquers the difficulty of obtaining a PD fingerprint database in field experiments. This method constructs a simulation fingerprint database by performing PD simulation in a GIL simulation model of the same size as the actual GIL. The natural neighbour interpolation algorithm is applied to expand the simulation fingerprint database to cover all locations in the GIL. The two-level localization method proposed is to match the PD fingerprint to be tested with the expanded fingerprint database, which can reduce the amount of calculation while maintaining the localization accuracy. The experimental results show that the average localization error of this method is only 9.7 mm, and the localization time is reduced by about 11 times compared with the normal one-level localization method.

Bulk-Effect-Free Method for Binding Kinetic Measurements Enabling Small-Molecule Affinity Characterization.

Optical technologies for label-free detection are an attractive solution for monitoring molecular binding kinetics; however, these techniques measure the changes in the refractive index, making it difficult to distinguish surface binding from a change in the refractive index of the analyte solution in the proximity of the sensor surface. The solution refractive index changes, due to solvents, temperature changes, or pH variations, can create an unwanted background signal known as the bulk effect. Technologies such as biolayer interferometry and surface plasmon resonance offer no bulk-effect compensation, or they alternatively offer a reference channel to correct in postprocessing. Here, we present a virtually bulk-effect-free method, without a reference channel or any computational correction, for measuring kinetic binding using the interferometric reflectance imaging sensor (IRIS), an optical label-free biomolecular interaction analysis tool. Dynamic spectral illumination engineering, through tailored LED contributions, is combined with the IRIS technology to minimize the bulk effect, with the potential to enable kinetic measurements of a broader range of analytes. We demonstrate that the deviation in the reflectivity signal is reduced to ∼8 × 10–6 for a solution change from phosphate-buffered saline (PBS) (n = 1.335) to 1% dimethyl sulfoxide (DMSO) in PBS (n = 1.336). As a proof of concept, we applied the method to a biotin–streptavidin interaction, where biotin (MW = 244.3 Da) was dissolved at a final concentration of 1 μM in a 1% solution of DMSO in PBS and flowed over immobilized streptavidin. Clear binding results were obtained without a reference channel or any computational correction.

Hybrid energy surface plasmon modes supported by graphene-coated circular chirowaveguide

In-depth analysis of hybrid SPP wave propagation at the Chiral–Graphene–Dielectric (CGD) interface is carried out. The single-layer graphene is modeled using Kubo formulism and the impedance matching boundary conditions are utilized to derive the dispersion relation. TM-TE decoupled modes at the CGD interface are shown. The effective mode index and propagation length of hybrid plasmon modes are found to be sensitive to chiral strength (ξ), chemical potential (μc), radius of waveguide, and refractive index of chiral (nc). It is observed that the cutoff values of chiral strength and radius promote Goos–Henchen effect at CGD interface. The present work may have potential applications for on-chip optical, chiral sensing and enantiomeric detection and renewable energy technologies in the terahertz frequency regime.

An Optical Chiral Sensor Based on Weak Measurement for the Real-Time Monitoring of Sucrose Hydrolysis.

A chiral sensor with optical rotation detection based on weak measurement for the kinetic study of sucrose hydrolysis is presented. Based on the polarization modulation to the pre-selection state, the optical rotation of chiral sample was accurately determined through the central wavelength shift of the output spectrum. With this approach, the concentration response curves of sucrose and its hydrolysis products, i.e., fructose and glucose, were experimentally obtained for the hydrolysis analysis. By collecting the output spectrum with a frequency of 100 Hz and fitting the central wavelength shift synchronously during the measurement, the sucrose hydrolysis process was monitored in real time. Different hydrolysis conditions with varied concentration of invertase enzyme and citrate were implemented in this work. As a consequence, the real-time hydrolysis curves of the hydrolysis process with distinct velocities was achieved and analyzed. Such a kinetic monitoring about sucrose hydrolysis with optical rotation detection technology played a critical role in the researches involving sucrose, and also revealed the great potential of weak measurement in intersections, such as food safety inspection and chemical analysis.

Nonlinear Mid‐Infrared Metasurface based on a Phase‐Change Material

AbstractThe mid‐wave infrared (MWIR) spectral region (3–5 µm) is important to a vast variety of applications in imaging, sensing, spectroscopy, surgery, and optical communications. Efficient third‐harmonic generation (THG), converting light from the MWIR range into the near‐infrared, a region with mature optical detection and manipulation technologies, offers the opportunity to mitigate a commonly recognized limitation of current MWIR systems. In this work, the possibility of boosting THG in the MWIR through a metasurface design is presented. Specifically, a 30‐fold enhancement in a highly nonlinear phase‐change material Ge2Sb2Se4Te1 (GSST) is demonstrated by patterning arrays of subwavelength cylinders supporting a magnetic dipolar resonance. The unprecedented broadband transparency, large refractive index, and remarkably high nonlinear response, together with unique phase‐change properties, make GSST‐based metasurfaces an appealing solution for reconfigurable and ultra‐compact nonlinear devices operating in the MWIR.