A novel single camera combined with Risley prisms is proposed to achieve a super-resolution (SR) imaging and field-of-view extension (FOV) imaging method. We develop a mathematical model to consider ...the imaging aberrations caused by large-angle beam deflection and propose an SR reconstruction scheme that uses a beam backtracking method for image correction combined with a sub-pixel shift alignment technique. For the FOV extension, we provide a new scheme for the scanning position path of the Risley prisms and the number of image acquisitions, which improves the acquisition efficiency and reduces the complexity of image stitching. Simulation results show that the method can increase the image resolution to the diffraction limit of the optical system for imaging systems where the resolution is limited by the pixel size. Experimental results and analytical verification yield that the resolution of the image can be improved by a factor of 2.5, and the FOV extended by a factor of 3 at a reconstruction factor of 5. The FOV extension is in general agreement with the simulation results. Risley prisms can provide a more general, low-cost, and efficient method for SR reconstruction, FOV expansion, central concave imaging, and various scanning imaging.
Multivariate kernel sparse learning models have attracted wide attention due to their efficient decomposition of nonlinear feature structures in the time–frequency space. Nevertheless, problems ...involving multi-modal signal sources have become more common such that the kernel weights selected by these methods are not strictly the sparsest possible solution. This paper presents a novel multivariate sparse learning model that focuses on the decomposition of multicomponent multivariate signals that partially and arbitrarily overlap. The multivariate signal components can be discriminatively reconstructed based on their representation in the kernel space. The model is based on the multivariate extension of the chirplet transform: the time–frequency distribution that can achieve good accuracy when estimating the instantaneous frequency of the overlapping signal components. To improve the decomposition accuracy, discriminative multilayer sparse learning is introduced to this scheme in both the training and testing frameworks in algorithm design. The discriminative structures of the dictionary maximize the weighted difference between the feature variance and the noise variance. The effectiveness of the proposed algorithm is confirmed by the results from decomposing several multicomponent signals that overlap in the time–frequency domain.
Tetracycline is widely used as medicine for disease treatments and additives in animal feeding. Unfortunately, the abuse of tetracycline inevitably causes tetracycline residue in animal-origin foods. ...Though classical methods can detect tetracycline in high sensitivity and precision, they often rely on huge and expensive setups as well as complicated and time-consuming operations, limiting their applications in rapid and on-site detection. Here, we propose a handheld inkjet printing paper chip based smart tetracycline detector: tetracycline can be determined by inkjet printing prepared paper chip based enzyme-linked immunosorbent assay (ELISA) with the advantages of high sensitivity, excellent specificity and low cost; moreover, a smartphone based paper chip reader and application is designed for automatically determining tetracycline with simple operations, high precision and fast speed. The smart tetracycline detector with a compact size of 154 mm × 80 mm × 50 mm and self-supplied internal power can reach a rather low detection limit of ~0.05 ng/mL, as proved by practical measurements. It is believed the proposed handheld inkjet printing paper chip based smart tetracycline detector is a potential tool in antibiotic sensing for routine uses at home and on-site detection in the field.
In order to realize rapid THz detecting and imaging, a line beam scanning-based ultra-fast THz imaging platform is designed combining simple optical components and lightweight mechanical system. The ...designed THz imaging platform has the resolution of 12 mm, the scanning angle range of ±10.5°, the scanning speed of 0.17 s/frame, and the scanning range of 2 m × 0.8 m; moreover, it can realize rapid human body THz imaging and distinguish metallic objects. Considering its high-quality performance in THz imaging and detecting, it is believed the proposed line beam scanning-based ultra-fast THz imaging platform can be used in the future in various safe screening applications.
•A quantitative ciprofloxacin (CIP) immunochromatographic test strip is designed.•It is very sensitive with an extremely low detection limit of 0.05 ng/mL.•It has wide linear detection range ...supporting quantitative CIP detection.•It supports automatic, rapid and cost-effective CIP detection.•It is proved with good selectivity, reproducibility and stability.
The ciprofloxacin (CIP) abuse has caused many problems threatening to human health. Here, we design the quantum dot microsphere (QDM) based immunochromatographic quantitative CIP test strip: when the sample under detection contains CIP, the QDM-monoclonal antibody (mAb) probes bound with the CIP and cannot be captured by CIP-bovine serum albumin (BSA) conjugation dispersed on the T lines, reducing the fluorescence intensities. These test strips can provide a low detection limit of 0.05 ng/mL and a wide linear detection range from 0.1 ng/mL to 100 ng/mL in high sensitivity and accuracy as well as good selectivity, reproducibility and stability. Moreover, a smartphone based test strip reader with the size of 85 mm × 48 mm × 44 mm is also fabricated using 3-D printing to automatically and quantitatively detect CIP. The whole process of CIP detection can be finished within 15 min, but only cost ~1 RMB (10 cents).
•An immunochromatographic test strip is designed for multiple mycotoxin detection.•It sensitively detects AFB1/OTA/ZEN with detection limits of 0.01/0.2/0.032 ng/mL.•It is proved with good ...selectivity tested by mixed mycotoxin solutions.•It is stable since it can be preserved nearly for one year at 4 °C.•It supports rapid multiple mycotoxin on-site detection within 45 min.
In this work, we design a sensitive and quantitative on-site detecting solution for Aflatoxin B1 (AFB1), Ochratoxin A (OTA) and Zearalenone (ZEN) as often found in moldy grains and harmful to human health. Using quantum dot microsphere-based immunochromatography test strip, the proposed method can sensitively detect AFB1, OTA and ZEN in low detection limits of 0.01 ng/mL, 0.2 ng/mL and 0.032 ng/mL, and quantitatively measure their concentrations from 0.01 ng/mL to 1 ng/mL, from 0.2 ng/mL to 200 ng/mL and from 0.032 ng/mL to 32 ng/mL in high accuracy and good selectivity. More importantly, these multiple mycotoxin detections only relying on simple manual operations and portable handheld test strip reader can be finished on site within 45 min. Therefore, the proposed method is a promising solution supporting sensitive and quantitative on-site detections for multiple mycotoxins.
Mercury is a bio-accumulative and toxic pollutant causing severe damages to human health and environment. Since Hg2+ is the most stable form of mercury, selective and sensitive Hg2+ detection is ...required. Though classical approaches can realize accurate Hg2+ detection, the complicated instruments and the time-consuming operations inevitably limit their on-site applications. Here, we design a smart Hg2+ detection approach using the fluorescence biosensor, the smartphone fluorescence microscope and the smartphone application for Hg2+ on-site detection. Based on the thymine-Hg2+-thymine coordination chemistry, a selective and sensitive fluorescence biosensor is designed for capturing Hg2+ in aqueous solution; besides, a miniaturized smartphone fluorescence microscope for fluorescence signal collection and an image processing application for quantitative Hg2+ measurements are constructed. A highly specific detection of Hg2+ with a linear relation between 1 nM and 1 μM with a limit of detection of 1 nM is obtained using the smart Hg2+ detection approach. Considering it can realize selective and sensitive quantitative Hg2+ measurements in high precision with simple operations and cost-effective system, it is believed the proposed smart Hg2+ detection approach owns great potentials in Hg2+ detection for routine uses at home and in the field.
We develop a smart Hg2+ detection approach combining the fluorescence biosensor relying on T-Hg2+-T coordination chemistry to selectively and sensitively capture Hg2+ in the aqueous solution, the smartphone fluorescence microscope for signal collection, and the smartphone application for quantitative Hg2+ concentration measurements. Display omitted
•The detector is based on smartphone microscope and fluorescence biosensor.•The smart Hg2+ detector is compact and cost-effective for on-site detection.•The smart Hg2+ detector has a linear relation between 1 nM and 1 uM.•The smart Hg2+ has a limit of detection of 1 nM.
We present a sunlight based handheld smartphone spectrometer. The device first gathers the sunlight to pass through the sample, and then the transmitted light illuminates on a grating to generate ...spectrum finally recorded by the smartphone monochrome camera. All the optical elements are assembled with the smartphone to integrate a handheld device with the size of 140.2 mm × 67.4 mm × 80.5 mm. Besides, a smartphone application is also developed for automatic spectral calibration, detection, analysis and display. Compared to the white light emitting diode and the halogen lamp, the sunlight has more uniform distribution covering the entire visible spectral range; and the proposed device also avoids the bulky sizes of those broadband light sources. Additionally, the monochrome camera is used instead of the color camera not only to pursue a high spectral resolution as 0.276 nm/pixel but also to avoid the color overlapping. We demonstrate the device capability on detecting avian influenza virus H7N9 and porcine circovirus type 2 antibodies, proving the device has rather high sensitivity similar to the commercial microplate reader. Considering its advantages as compact size, high spectral resolution and detecting sensitivity, it is believed the proposed sunlight based handheld smartphone spectrometer is potential to be broadly applied in on-site detections.
For the first time to our best knowledge, we have proposed a sunlight based handheld smartphone spectrometer which has compact size and high spectral resolution; and it has been successfully used for virus detection with favorable sensitivity and detection precision. Display omitted
•The first example of sunlight based handheld smartphone spectrometer.•The device has compact size and high spectral resolution.•An Android application simplifies the detection procedures.•The device has favorable sensitivity and detection precision.•The device has been successfully used for virus detection.
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as a causal agent of Coronavirus Disease 2019 (COVID-19) has led to the global pandemic. Though the real-time reverse transcription ...polymerase chain reaction (RT-PCR) acting as a gold-standard method has been widely used for COVID-19 diagnostics, it can hardly support rapid on-site applications or monitor the stage of disease development as well as to identify the infection and immune status of rehabilitation patients. To suit rapid on-site COVID-19 diagnostics under various application scenarios with an all-in-one device and simple detection reagents, we propose a high-throughput multimodal immunoassay platform with fluorescent, colorimetric, and chemiluminescent immunoassays on the same portable device and a multimodal reporter probe using quantum dot (QD) microspheres modified with horseradish peroxidase (HRP) coupled with goat anti-human IgG. The recombinant nucleocapsid protein fixed on a 96-well plate works as the capture probe. In the condition with the target under detection, both reporter and capture probes can be bound by such target. When illuminated by excitation light, fluorescence signals from QD microspheres can be collected for target quantification often at a fast speed. Additionally, when pursuing simple detection without using any sensing devices, HRP-catalyzed TMB colorimetric immunoassay is employed; and when pursuing highly sensitive detection, HRP-catalyzed luminol chemiluminescent immunoassay is established. Verified by the anti-SARS-CoV-2 N humanized antibody, the sensitivities of colorimetric, fluorescent, and chemiluminescent immunoassays are respectively 20, 80, and 640 times more sensitive than that of the lateral flow colloidal gold immunoassay strip. Additionally, such a platform can simultaneously detect multiple samples at the same time thus supporting high-throughput sensing; and all these detecting operations can be implemented on-site within 50 min relying on field-operable processing and field-portable devices. Such a high-throughput multimodal immunoassay platform can provide a new all-in-one solution for rapid on-site diagnostics of COVID-19 for different detecting purposes.
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•We propose a multimodal immunoassay platform for multi-purpose COVID-19 diagnostics.•Fluorescent high-throughput immunoassay can be used for common screening.•Chemiluminescent one has improved sensitivity, and colorimetric one is rather simple.•A multimodal immunoassay sensing system (MISS) is designed for automatic sensing.•On-site diagnostics can be done in 50 min with high accuracy and good selectivity.
We design a honey antibiotic detection system (HADS), which provides honey antibiotic residue rapid on-site detecting solution relying on simple sample preparation tactics, lateral-flow ...immunochromatographic assay (LFIA)-based strip and handheld sensor reader. Relying on the quantum dot microsphere probes conjugated to the antibiotic monoclonal antibodies, the LFIA strip can simultaneously detect sulfonamides (SAs) and tetracyclines (TCs) in high sensitivity with extremely low detecting limits of 0.4 μg/kg and good specificity. Moreover, the fabricated LFIA strips can be well conserved in vacuum-sealed bags at 4 °C for at least 6 months. Combining with the handheld sensor reader, both SAs and TCs can be quantitatively and automatically measured in high accuracy. All the operations including sample preparation and detection can be finished within 20 min at room temperature on site without any extra devices or complicated operations.
•We design honey antibiotic detection system (HADS) for antibiotic residue detection.•HADS can detect sulfonamides (SAs) and tetracyclines (TCs) in high sensitivity.•HADS supports rapid (20 min) and cost-effective (75 cents) antibiotic detection.•HADS is proved with high accuracy, good stability, selectivity and specificity.•HADS supports rapid on-site detection for honey antibiotic residues.
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