Traditional Optical Detection Research Articles

Drip-Dry Strategy Assisted Blu-Ray Disc Biosensor for Fast Point of Care Testing.

Discs and numerous other consumer products have been developed for point of care testing (POCT) to replace traditional large and expensive biochemical devices in certain scenarios. Herein, we propose a drip-dry strategy (2D strategy) assisted Blu-ray disc (BD) biosensor, termed BDB, for rapid and portable POCT within 30 min with the cost of a single test < $1. The platform utilizes the covered area formed by the deposition of the substance to be measured on the activated BD surface after the evaporation of water and realizes the quantitative detection of the target through the error readout of free disc quality diagnosis software. As a proof of concept, we first demonstrated the feasibility of direct quantitative detection of substances in solution in a single system through the detection of pure proteins avoiding colorimetric reagent used in traditional optical detection. For the complex mixed systems, we then innovatively utilize the principle that soluble targets promote/inhibit the dissolution of insoluble precipitates to achieve specific detection of targets and successfully apply BDB to the indirect quantitative detection of glutathione (GSH) with LOD of 0.447 mM in the range of 2-16 mM and organophosphorus pesticides (OPs) with LOD of 2.122 × 10-7 M in the range of 1.289 × 10-7-1.289 × 10-4 M. The BDB is widely applicable, easy to operate, and less time-consuming, which is anticipated to provide an alternative method for early, on-site detection or screening.

Development of silver nanoparticles based on the method using quince seed mucilage for ascorbic acid determination.

Nanoparticles are used in various fields such as chemistry, pharmacy, biotechnology, and food science since they provide higher sensitivity than traditional optical detection methods. Recently, synthesis of nanomaterials using green chemistry has become popular. Many phytochemical components are used in the synthesis of nanoparticles, including vitamins, proteins, polysaccharides, glycosides, essential oils and phenolic compounds. A novel green nanotechnology-based method using quince seed mucilage (QSM) was designed for the determination of ascorbic acid in pharmaceutical preparations. QSM, a natural polysaccharide, was used as a bioreducing and stabilizing reagent in the proposed silver nanoparticle (SNP)-based method. In the first stage of the developed method, silver(I) is reduced to silver(0) via QSM and spherical, homogeneous SNPs were prepared (QSM-SNPs). In the second stage of the developed method, SNPs nuclei were enlarged with the addition of ascorbic acid. The developed method was validated by performance parameters (linearity, recovery, and precision). Ascorbic acid determination was performed by measuring increase in absorbance at 420 nm. The limit of detection and limit of quantification for ascorbic acid were, respectively, found to be at 0.27 and 0.90 μM. The QSM-SNP-based method was successfully applied to effervescent tablets containing ascorbic acid. The standards of the excipients frequently used in pharmaceutical preparations did not interfere with the developed method. The developed QSM-SNP-based method satisfies the requirements of green nanotechnology. The developed QSM-SNP-based method is simple, fast, eco-friendly and low-cost.

Fusion Detection via Distance-Decay Intersection over Union and Weighted Dempster–Shafer Evidence Theory

In recent years, increasing attention has been paid to object detection in remote sensing imagery. However, traditional optical detection is highly susceptible to illumination and weather anomalies. It is a challenge to effectively utilize the cross-modality information from multisource remote sensing images, especially from optical and synthetic aperture radar images, to achieve all-day and all-weather detection with high accuracy and speed. Toward this end, a fast multisource fusion detection framework FusionDet is proposed in the current paper. A novel distance-decay intersection over union is employed to encode the shape properties of the targets with scale invariance. Therefore, the same target in multisource images can be paired accurately. Furthermore, the weighted Dempster–Shafer evidence theory is utilized to combine the optical and synthetic aperture radar detection, which overcomes the drawback in a feature-level fusion that requires a large amount of paired data. In addition, the paired optical and synthetic aperture radar images are taken to demonstrate our fusion algorithm. Considerable experiments and ablation studies on multiple datasets show that our method is generally effective and achieves state-of-the-art detection performance.

Laser ultrasonic loading and optical interference detection of closed cracks in K9 glass.

The traditional optical detection method has a limitation in detecting closed cracks in optical elements. In this Letter, a novel, to the best of our knowledge, method has been developed for the detection of closed cracks in transparent samples. Firstly, behaviors of closed cracks under ultrasonic waves loading are demonstrated through the finite-element method (FEM). Simulation results show that the crack can be opened by the laser ultrasonic shear wave (S-wave). Then, a Mach-Zehnder interferometer system is experimentally established to detect closed cracks under ultrasonic waves loading in the sample. It is demonstrated that closed cracks which cannot be detected by interferometry become visible in interferogram images under ultrasonic waves loading. The width of the opened crack can also be quantitatively estimated. Thus the method would be a promising approach to detect initially closed cracks in optical elements.

A Magnetic Field Imaging System Based on TMR Sensors for Banknote Recognition

The high sensitivity and MEMS-compatible process of tunneling magnetoresistance (TMR) sensors provide great opportunities to develop high-resolution magnetic field detection and imaging systems. In this work, we designed a magnetic field imaging (MFI) system based on TMR sensors to detect the uniaxial magnetic field components of banknotes including US dollars (USD) and Chinese Yuan (CNY), which clearly reveals the distribution of magnetic anti-counterfeiting markers inside the banknotes. Measurement results of the USD show that the magnetic ink signal is around μT level, and the person portraits on banknotes can be revealed by the sensor signals. The testing results of the CNY banknotes indicate magnetic color-shifting ink images, as well as a clear magnetic anti-counterfeiting thread. Different from the traditional optical detection, magnetic detection provides unique signals and identification methods. With a satisfactory recognition rate, the proposed MFI system based on TMR sensors demonstrates its promising potential forgery detection and denomination identification of banknotes.

Development of a Novel Detection Method to Measure the Cage Slip of Rolling Bearing

A novel, non-contacted method is proposed to determine the cage slip of rolling bearing. Findings show that the roller and inner raceway can generate weak magnetic field (WMF). The WMF detection technology is introduced into the measurement domain of cage slip. The feature frequency of a roller and inner raceway, which reflect the cage slip, can be extracted simultaneously by the WMF sensor output signal. Here, the roller shares the same feature frequency with the cage. Compared with the traditional optical detection method, the proposed method does not require any pre-processing for rolling bearing. The cage slip is detected under different work conditions. The cage slip, which is determined by the proposed method, is consistent with that of the traditional optical method. It shows that the proposed method can be used to detect cage slip of rolling bearing.

Detectorless measurements of the operational linewidth of NIR VCSELs by self-mixing interferometry.

Self-mixing based on vertical-cavity surface-emitting lasers (VCSELs) offers a compact and low-cost coherent detection scheme for interferometric accessible measurements. The direct detection of the change in the junction voltage, in contrast to the traditional optical detection method by means of an external photodiode, further simplifies the setup by adding detector-less capability. The linewidth of an NIR VCSEL was estimated by using the method based on the statistical analysis of the laser self-mixing fringe period in the moderate feedback regime. We investigate the junction voltage noise and optical power noise, simultaneously acquired, in order to establish the best operational condition for both detection schemes. When comparing the laser linewidth measured by the traditional optical power modulation with that of the detector-less voltage self-mixing signal, the agreement is within the experimental errors.

Strategies for the development of an electrochemical bioassay for TNF-alpha detection by using a non-immunoglobulin bioreceptor

TNF-α is an inflammatory cytokine produced by the immune system. Serum TNF-α level is elevated in some pathological states such as septic shock, graft rejection, HIV infection, neurodegenerative diseases, rheumatoid arthritis and cancer. Detecting trace amount of TNF-α is, also, very important for the understanding of tumor biological processes. Detection of this key biomarker is commonly achieved by use of ELISA or cytofluorimetric based methods. In this study the traditional optical detection was replaced by differential pulse voltammetry (DPV) and an affinity molecule, produced by evolutionary approaches, has been tested as capture bioreceptor. This molecule, namely a combinatorial non-immunoglobulin protein (Affibody®) interacts with TNF-α selectively and was here tested in a sandwich assay format. Moreover magnetic beads were used as support for bioreceptor immobilization and screen printed carbon electrodes were used as transducers.TNF-α calibration curve was performed, obtaining the detection limit of 38pg/mL, the quantification range of 76–5000pg/mL and RSD%=7. Preliminary results of serum samples analysis were also reported.

Nanoprobes for enhanced electrochemical DNA sensors.

Biosensors, small devices enabling selective bioanalysis because of properly assembled biological recognition molecules, represent the fortuitous results of years of interdisciplinary and complementary investigations in different fields of science. The ultimate role of a biosensor is to provide coupling between the recognition element and the analyte of interest, bringing a quantitative value of its concentrations into a complex sample matrix. They offer many advantages. Among them, portability, low cost with fast response times, and the possibility to operate in situ without the need for sample preparation are certainly the most important. Among biosensors, a large space is occupied by DNA biosensors. Screening genomic DNA is of fundamental importance for the development of new tools available to physicians during the clinical process. Sequencing of individual human genomes, accomplished principally by microarrays with optical detection, is complex and expensive for current clinical protocols. Efforts in research are focused on simplifying and reducing the cost of DNA biosensors. For this purpose, other transduction techniques are under study to make more portable and affordable DNA biosensors. Compared with traditional optical detection tools, electrochemical methods allow the same sensitivity and specificity but are less expensive and less labor intensive. Scalability of electrochemical devices makes it possible to use the advantages introduced by nanosized components. The involvement of nanomaterials and nanostructures with custom-tailored shapes and properties is expected to rapidly boost the field of electrochemical DNA biosensors and, in general, that of next-generation sequencing technologies.

Multidimensional optomechanical cantilevers for high-frequency force sensing

High-frequency atomic force microscopy has enabled extraordinary new science through large bandwidth, high-speed measurements of atomic and molecular structures. However, traditional optical detection schemes restrict the dimensions, and therefore the frequency, of the cantilever—ultimately setting a limit to the time resolution of experiments. Here we demonstrate optomechanical detection of low-mass, high-frequency nanomechanical cantilevers (up to 20 MHz) and anticipate their use for single-molecule force measurements. These cantilevers achieve 2 fm displacement noise floors, and force sensitivity down to 132 aN . Furthermore, the ability to resolve both in-plane and out-of-plane motion of our cantilevers makes them excellent candidates for ultrasensitive multidimensional force spectroscopy, and optomechanical interactions, such as tuning of the cantilever frequency in situ, provide opportunities in high-speed, high-resolution experiments.

Biosensor Based on Giant Magnetoresistance Material

In recent years, giant magnetoresistance (GMR) sensors have shown a great potential as sensing elements for biomolecule detection. The resistance of a GMR sensor changes with the magnetic field applied to the sensor, so that a magnetically labeled biomolecule can induce a signal. Compared with the traditional optical detection that is widely used in biomedicine, GMR sensors are more sensitive, portable, and give a fully electronic readout. In addition, GMR sensors are inexpensive and the fabrication is compatible with the current VLSI (Very Large Scale Integration) technology. In this regard, GMR sensors can be easily integrated with electronics and microfluidics to detect many different analytes on a single chip. In this article, the authors demonstrate a comprehensive review on a novel approach in biosensors based on GMR material.