Portable Optical System Research Articles

Development and evaluation of a lateral flow-based portable optical system for determination of the pregnancy status of dairy cows

Our objectives were to develop and evaluate an integrated system consisting of a lateral-flow immunoassay (LFIA) and an electronic portable imaging device for determination of pregnancy status of cows based on plasma concentrations of pregnancy-specific protein B (PSPB). Experiment 1 was conducted to test the performance of the LFIA for PSPB (PSPB-LFIA) whereas experiment 2 was conducted to evaluate the performance of the integrated system including both the LFIA and imaging device. The PSPB-LFIA strips were made of nitrocellulose membrane with polystreptavidin, anti-mouse antibody, Europium-anti-PSPB conjugates, and biotin-PSPB. After adding buffer and plasma in a 96-well plate, strips were dipped to initiate flow and were read in a fluorescence microscope to estimate PSPB concentrations based on the test-to-control line signal (T/C ratio). The T/C ratio of standards was linearly associated with PSPB (R2 = 0.99 in both experiments) concentrations. To test the ability to identify pregnant cows of the PSPB-LFIA only or the integrated system, plasma samples were collected and transrectal ultrasonography (TUS) was conducted 29 to 35 d post AI in lactating Holstein cows (Experiment 1: n = 83; Experiment 2: n = 205). A cow was considered pregnant (Preg) if concentrations of PSPB in plasma obtained by ELISA were ≥2 ng/mL or if an embryo was visible by TUS. In Experiment 1, the accuracy of the PSPB-LFIA compared with ELISA was 92.7% (91.2% Se; 96.1% Sp; 98.1% PPV; 83.3% NPV) and compared with TUS was 90.4% (100% Se; 78.9% Sp; 84.9% PPV; 100% NPV). The agreement between LFIA and ELISA (kappa = 0.84; 95%CI 0.71-0.96) or LFIA and TUS (kappa = 0.80; 95%CI 0.67-0.93) as methods to classify cows as Preg or Non-Preg was high. In Experiment 2, the accuracy of the PSPB-LFIA compared with ELISA was 96.1% (93.8% Se; 100% Sp; 100% PPV; 90.5% NPV) and compared with TUS was 92.2% (99.0% Se; 84.7% Sp; 87.6% PPV; 98.8% NPV). The agreement between LFIA and ELISA (kappa = 0.92; 95%CI 0.86-0.97) or LFIA and TUS (kappa = 0.84; 95%CI 0.77-0.92) as methods to classify cows as Preg or Non-Preg was high. We conclude that a system integrating a fluorescence-based LFIA and an optical reader was effective for classifying cows as pregnant or not pregnant based on estimations of plasma concentrations of PSPB. This novel system serves as a platform for further development of on-farm pregnancy testing tools based on measurement of biomarkers of pregnancy in bodily fluids of cattle.

Design and development of a novel colorimetric assay and a portable optical system for the detection of aminoglycoside antibiotics

In recent years, environmental contamination with antibiotics has become a severe threat to humankind requiring urgent attention. Presence of incompletely metabolized antibiotics in water bodies, leads to their entry into food chain via live stock and serve as a severe threat to human health. Hence it is imperative that the antibiotics are detected at the source itself. Aminoglycosides are broad spectrum antibiotics known to be more toxic and resistant to multidrug resistant (MDR) organisms compared to other classes of antibiotics. Accordingly in the present work a selective, sensitive and low-cost detection technique for aminoglycoside based antibiotics has been developed. An iron-dependent lipid peroxidation has been explored for the first time to develop a rapid and sensitive colorimetric assay for detecting aminoglycoside antibiotics. A lab-on-chip model (LoC) was designed and developed to miniaturize the colorimetric assay based model for its applications in the real-time analysis of antibiotics. The LoC was integrated with optical fibers, electronic components and associated signal processing circuitry to construct a portable device for antibiotic quantification. Interestingly a selective response towards gentamicin amongst the tested antibiotic was observed. The formation of a colored product within five minutes of reaction time enables a swift and less cumbersome analysis and compared to existing sophisticated analytical techniques. The detection method was validated for gentamicin spiked environmental samples and showed a recovery of more than 90%. This method can serve as a suitable alternative in limited laboratory setups and provides a generic platform for developing a rapid, user-friendly and economical detection methods for environmental monitoring of antibiotics.

Flexibility and versatility enhancements due to a portable optical system for the Background-Oriented Schlieren techniques

Flexibility and versatility enhancements due to a portable optical system for the Background-Oriented Schlieren techniques

Portable, Automated and Deep-Learning-Enabled Microscopy for Smartphone-Tethered Optical Platform Towards Remote Homecare Diagnostics: A Review.

Globally new pandemic diseases induce urgent demands for portable diagnostic systems to prevent and control infectious diseases. Smartphone-based portable diagnostic devices are significantly efficient tools to user-friendly connect personalized health conditions and collect valuable optical information for rapid diagnosis and biomedical research through at-home screening. Deep learning algorithms for portable microscopes also help to enhance diagnostic accuracy by reducing the imaging resolution gap between benchtop and portable microscopes. This review highlighted recent progress and continued efforts in a smartphone-tethered optical platform through portable, automated, and deep-learning-enabled microscopy for personalized diagnostics and remote monitoring. In detail, the optical platforms through smartphone-based microscopes and lens-free holographic microscopy are introduced, and deep learning-based portable microscopic imaging is explained to improve the image resolution and accuracy of diagnostics. The challenges and prospects of portable optical systems with microfluidic channels and a compact microscope to screen COVID-19 in the current pandemic are also discussed. It has been believed that this review offers a novel guide for rapid diagnosis, biomedical imaging, and digital healthcare with low cost and portability.

Impact of the rolling shutter effect in optical phase measurements using spatial carrier

The impact of the rolling shutter effect in interferometry using the spatial carrier method is presented. A spatial carrier method is of interest as it avoids moveable devices inside the interferometer, thus allowing the design of low-cost and portable optical systems. An out-of-plane digital holographic interferometer is used to analyze the retrieved optical phase acquired by a camera sensor which can be hardware switched between rolling and global shutter mode. Under well-controlled and repeatable deformations, a series of image holograms were recorded. Optical phase comparison is performed for both shutter modes to analyze the presence or absence of the rolling shutter effect (RSE) in the spatial carrier. The optical phase study involves the Fourier spectrum, where this spatial carrier could be explored in a bi-dimensional form. Results show a significant distortion of the spatial carrier at the Fourier space, close to the edges of the optical aperture image, indicating a phase error that can be reduced using a reduced section of the aperture.

Adaptive adversarial neural networks for the analysis of lossy and domain-shifted datasets of medical images.

In machine learning for image-based medical diagnostics, supervised convolutional neural networks are typically trained with large and expertly annotated datasets obtained using high-resolution imaging systems. Moreover, the network's performance can degrade substantially when applied to a dataset with a different distribution. Here, we show that adversarial learning can be used to develop high-performing networks trained on unannotated medical images of varying image quality. Specifically, we used low-quality images acquired using inexpensive portable optical systems to train networks for the evaluation of human embryos, the quantification of human sperm morphology and the diagnosis of malarial infections in the blood, and show that the networks performed well across different data distributions. We also show that adversarial learning can be used with unlabelled data from unseen domain-shifted datasets to adapt pretrained supervised networks to new distributions, even when data from the original distribution are not available. Adaptive adversarial networks may expand the use of validated neural-network models for the evaluation of data collected from multiple imaging systems of varying quality without compromising the knowledge stored in the network.

Lensless on-chip LED array microscope using amplitude and phase masks

A cost-effective, compact, and portable optical system using multi-angle illumination for retrieval of the amplitude and phase of a sample is implemented in this paper. The system consists of a matrix of LED followed by a mask, a USAF resolution chart, and a detector in a column. The sample information is collected by the detector directly without any objective lens. The sample information is encoded by the mask at a sensor plane during the reconstruction process. To retrieve the sample information from captured raw images corresponding to each LED illumination, the backward propagation model is applied. Three types of masks are used: a phase mask having pixel values from 0 to 2 π , an amplitude mask, and a combination of a phase and an amplitude mask with random distribution. The applications of such type of technique are most common in biomedical engineering for infection diagnostic purposes. In the future, the commercial demand of such lensless microscope would be high due to its simplicity and fast image processing capacity.

Microwave polarization characteristics of snow at 6.9 and 18.7 GHz: Estimating the water content of the snow layers

ABSTRACT Theoretical and empirical tools for the exploration of the radio-thermal radiation of the snow cover in C and K-bands are developed taking into account the method of polarization measurements of the integral reflection coefficient of a snow layer. In addition, experimental in-situ measurements were performed at 6.9 and 18.7 GHz using a new portable optical system. The analyses of the measurements showed that the difference in polarization increases by increasing the thickness of the snow layer according to its physical characteristics. The study of reflection coefficient of the snow layer includes volumetric diffusion and coherent components determined by effective dielectric conductivity and volumetric scattering. The results showed that the value of the effective dielectric conductivity depends on the correlations between the roughness parameter and the wavelength, and increases with the growth of crystal size, as shown by the increase in the polarization difference when the size of the snow grains is increased. Moreover, the reflection coefficient was found to depend weakly on the polarization irradiance. The calculated snow depths and snow water equivalents are in a very good agreement with the observations made.

Development and evaluation of inexpensive automated deep learning-based imaging systems for embryology.

Embryo assessment and selection is a critical step in an in vitro fertilization (IVF) procedure. Current embryo assessment approaches such as manual microscopy analysis done by embryologists or semi-automated time-lapse imaging systems are highly subjective, time-consuming, or expensive. Availability of cost-effective and easy-to-use hardware and software for embryo image data acquisition and analysis can significantly empower embryologists towards more efficient clinical decisions both in resource-limited and resource-rich settings. Here, we report the development of two inexpensive (<$100 and <$5) and automated imaging platforms that utilize advances in artificial intelligence (AI) for rapid, reliable, and accurate evaluations of embryo morphological qualities. Using a layered learning approach, we have shown that network models pre-trained with high quality embryo image data can be re-trained using data recorded on such low-cost, portable optical systems for embryo assessment and classification when relatively low-resolution image data are used. Using two test sets of 272 and 319 embryo images recorded on the reported stand-alone and smartphone optical systems, we were able to classify embryos based on their cell morphology with >90% accuracy.

Power spectral density-based nearinfrared sub-band detection for noninvasive blood glucose prediction in both in-vitro and in-vivo studies

Diabetes is a widespread and serious disease and noninvasive measurement has been in high demand. To address this problem, a power spectral density-based method was offered for determining glucose sensitive sub-bands in the nearinfrared (NIR) spectrum. The experiments were conducted using phantoms of different optical properties in-vitro conditions. The optical bands 1200–1300[Formula: see text]nm and 2100–2200[Formula: see text]nm were found feasible for measuring blood glucose. After that, a photoplethysmography (PPG)-based low cost and portable optical system was designed. It has six different NIR wavelength LEDs for illumination and an InGaAs photodiode for detection. Optical density values were calculated through the system and used as independent variables for multiple linear regression analysis. The results of blood glucose levels for 24 known healthy subjects showed that the optical system prediction was nearly 80% in the A zone and 20% in the B zone according to the Clarke Error Grid analysis. It was shown that a promising easy-use, continuous, and compact optical system had been designed.

An ultrasensitive fluorescent biosensor using high gradient magnetic separation and quantum dots for fast detection of foodborne pathogenic bacteria

Rapid screening of contaminated foods is the key to prevent and control the outbreaks of foodborne diseases. In this study, a novel fluorescent biosensor was developed for ultrasensitive and rapid detection of E. coli O157:H7. The proposed fluorescent biosensor used the double-layer channel with the immune magnetic nanoparticles (MNPs) for specific separation and efficient concentration of the target bacteria, and the immune quantum dots (QDs) with the portable optical system for quantitative detection of the bacteria. First, the bacteria were captured by the immune MNPs in the channel at the presence of the high gradient magnetic fields (HGMFs) to form the MNP-bacteria complexes. Then, the immune QDs were used to react with the target bacteria to form the MNP-bacteria-QDs complexes in the channel. Finally, the enriched complexes were collected and detected using the portable optical system to obtain the fluorescence intensity for final determination of the E. coli O157:H7 cells in the sample. This proposed biosensor was demonstrated to be able to detect E. coli O157:H7 as low as 14 CFU/mL within 2 h. The recovery of E. coli in the spiked milk samples ranged from 95.92% to 108.15%, indicating that it was capable of detecting E. coli in real samples. Besides, this proposed biosensor was able to detect the bacteria in the volume of 10 mL, and has the potential to detect the bacteria in a larger volume to increase the sensitivity.

Hybrid imprinting process to fabricate a multi-layer compound eye for multispectral imaging.

We present a high-precision hybrid imprinting method to fabricate multi-layer micro-optical structures on nonplanar substrates using a custom-built vacuum imprinting system; with the application of kinematic couplings that align the flexible stamps in all six degrees of freedom, a cross-layer pattern registration precision of 400 nm has been achieved on nonplanar substrates. To demonstrate the precision and feasibility of the new process and instrument, we have designed and fabricated a multi-layer artificial compound eye (ACE) for multispectral imaging. The shapes and sizes of all 12 micro-lenses on the ACE are optimized and integrated with different color filers (red, green and blue) so that the light from different channels and of different spectral contents will focus to the same plane, where the photodetector is located. Next, the multi-layer ACE is installed in a portable optical system for simultaneous multispectral imaging, i.e., to perform pattern detection by looking at specific frequency windows. Imaging experiments are devised and performed on (1) color blindness test cards, (2) space image, and (3) breast and gastric tumor samples. The results confirm the system's capabilities of frequency separation, extraction of hidden information, and tumor identification.

SiPM as miniaturised optical biosensor for DNA-microarray applications

A miniaturized optical biosensor for low-level fluorescence emitted by DNA strands labelled with CY5 is showed. Aim of this work is to demonstrate that a Si-based photodetector, having a low noise and a high sensitivity, can replace traditional detection systems in DNA-microarray applications. The photodetector used is a photomultiplier (SiPM), with 25pixels. It exhibits a higher sensitivity than commercial optical readers and we experimentally found a detection limit for spotted dried samples of ∼1nM. We measured the fluorescence signal in different operating conditions (angle of analysis, fluorophores concentrations, solution volumes and support). Once fixed the angle of analysis, for samples spotted on Al-TEOS slide dried, the system is proportional to the concentration of the analyte in the sample and is linear in the range 1nM–1μM. For solutions, the range of linearity ranges from 100fM to 10nM. The system potentialities and the device low costs suggest it as basic component for the design and fabrication of a cheap, easy and portable optical system.

Container weld identification using portable laser scanners

Identification and integrity verification of sealed containers for security applications can be obtained by employing noninvasive portable optical systems. We present a portable laser range imaging system capable of identifying welds, a byproduct of a container’s physical sealing, with micrometer accuracy. It is based on the assumption that each weld has a unique three-dimensional (3-D) structure which cannot be copied or forged. We process the 3-D surface to generate a normalized depth map which is invariant to mechanical alignment errors and that is used to build compact signatures representing the weld. A weld is identified by performing cross correlations of its signature against a set of known signatures. The system has been tested on realistic datasets, containing hundreds of welds, yielding no false positives or false negatives and thus showing the robustness of the system and the validity of the chosen signature.

Advanced Structural Engineering of Nanoporous Photonic Structures: Tailoring Nanopore Architecture to Enhance Sensing Properties

In this study, we demonstrate that an optimal design of the pore geometry and shape of sensing platforms based on nanoporous anodic alumina (NAA) photonic structures is critical to develop optical sensors with improved capabilities. To this end, two types of NAA photonic structures featuring different pore geometries (i.e., pore lengths and diameters) and shapes (i.e., straight and modulated pores) were produced, and their optical characteristics were assessed systematically by reflectometric interference spectroscopy. The geometric features (i.e., pore lengths, diameters, and shapes) were systematically modified in order to establish the optimization paths for the sensitivity, low limit of detection, and linearity of these optical sensing platforms. The obtained results reveal that an optimal design of these nanoporous photonic structures can enhance their sensitivity, achieve a lower limit of detection, and improve their linearity for both nonspecific and specific detection of analytes. Therefore, as this study demonstrates, the rational design of optical nanoporous sensing platforms is critical in the development of reliable, sensitive, robust, inexpensive, and portable optical systems for a broad range of sensing applications.

The development of a portable line-shaping optical system for silicon surface treatment

This study proposes a beam shaper for converting a circle beam profile generated with a Gaussian intensity distribution by an 808 nm diode laser into a line beam profile for silicon surface treatment applications. To produce a hand-held and low-cost device with a large spot-size laser, this study uses a portable optical system consisting of a diode laser source, a collimator, a cylindrical lens, and a plano-convex lens to generate an approximately 40 × 3:5mm2 line beam profile at a working distance of 200 mm. The silicon surface treated by the line-shaped laser beam has significantly reduced reflectance spectra. The proposed system is also suitable for the surface cleaning of materials.

Real‐time fluorescence detection of multiple microscale cell culture analog devices in situ

We investigated multiple microscale cell culture analog (microCCA) assays in situ with a high-throughput imaging system that provides quantitative, nondestructive, and real-time data on cell viability. Since samples do not move between measurements, captured images allow accurate time-course measurements of cell population response and tracking the fate of each cell type on a quantitative basis. The optical system was evaluated by measuring the short-term response to ethanol exposure and long-term growth of drug-resistant tumor cell lines with simultaneous samples. The optical system based on epi-fluorescent excitation consists of an LED and a CCD as well as discrete optical components for imaging a large number of cells simultaneously. HepG2/C3A and MESSA cell lines were cultured in two microCCA systems for continuous cell status monitoring in cell death experiments with ethanol and long-term cell growth. The experiment that tested ethanol uptake showed that ethanol immediately caused cell death. The system was applied to extracting dynamic constants in the uptake process. In the long-term cell growth experiment, growth of MESSA cells was followed by a stationary phase and eventual cell death attributed to nutrient and oxygen depletion and a change in the pH because of the accumulation of wastes by cell metabolism. HepG2/C3A cells were subject to contact inhibition and cell number did not change significantly over time. Issues related to long-term assays are also discussed. The quantitative results have been consistent with qualitative images and confirm the applicability of the portable optical system, and potential application to high-throughput analysis of cell-based assays to measure long-term dynamics.

Optical systems for in vivo molecular imaging of cancer.

Progress toward a molecular characterization of cancer would have important clinical benefits; thus, there is an important need to image the molecular features of cancer in vivo. In this paper, we describe a comprehensive strategy to develop inexpensive, rugged and portable optical imaging systems for molecular imaging of cancer, which couples the development of optically active contrast agents with advances in functional genomics of cancer. We describe initial results obtained using optically active contrast agents to image the expression of three well known molecular signatures of neoplasia: including over expression of the epidermal growth factor receptor (EGFR), matrix metallo-proteases (MMPs), and oncoproteins associated with human papillomavirus (HPV) infection. At the same time, we are developing inexpensive, portable optical systems to image the morphologic and molecular signatures of neoplasia noninvasively in real time. These real-time, portable, inexpensive systems can provide tools to characterize the molecular features of cancer in vivo.