Robust table recognition for printed document images.

The recognition and analysis of tables on printed document images is a popular research field of the pattern recognition and image processing. Existing table recognition methods usually require high degree of regularity, and the robustness still needs significant improvement. This paper focuses on a robust table recognition system that mainly consists of three parts: Image preprocessing, cell location based on contour mutual exclusion, and recognition of printed Chinese characters based on deep learning network. A table recognition app has been developed based on these proposed algorithms, which can transform the captured images to editable text in real time. The effectiveness of the table recognition app has been verified by testing a dataset of 105 images. The corresponding test results show that it could well identify high-quality tables, and the recognition rate of low-quality tables with distortion and blur reaches 81%, which is considerably higher than those of the existing methods. The work in this paper could give insights into the application of the table recognition and analysis algorithms.

Passive Dielectrophoretic Focusing of Particles and Cells in Ratchet Microchannels.

Focusing particles into a tight stream is critical for many microfluidic particle-handling devices such as flow cytometers and particle sorters. This work presents a fundamental study of the passive focusing of polystyrene particles in ratchet microchannels via direct current dielectrophoresis (DC DEP). We demonstrate using both experiments and simulation that particles achieve better focusing in a symmetric ratchet microchannel than in an asymmetric one, regardless of the particle movement direction in the latter. The particle focusing ratio, which is defined as the microchannel width over the particle stream width, is found to increase with an increase in particle size or electric field in the symmetric ratchet microchannel. Moreover, it exhibits an almost linear correlation with the number of ratchets, which can be explained by a theoretical formula that is obtained from a scaling analysis. In addition, we have demonstrated a DC dielectrophoretic focusing of yeast cells in the symmetric ratchet microchannel with minimal impact on the cell viability.

A PET/paper chip platform for high resolution sulphur dioxide detection in foods.

A convenient assay platform comprising a PET/paper chip (PP-chip) and a smart analytical device is developed for detection of sulphur dioxide (SO2) concentration. In the presented approach, the distilled SO2 solution is dropped onto the detection region of the PP-chip and undergoes a reaction with an acid-based reagent. The resulting color variation is analyzed through a high-resolution camera (CMOS) and the reacted image is processed by a RGB (red, green and blue) analytical app installed on a smartphone. Results show that the known SO2 concentrations ranging from 10 to 300 ppm indicate that the high linear relationship (R2 = 0.9981) between the (R (red) + G (green) - B (blue)) value and SO2 concentration. Moreover, a high measurement resolution is equal to 1.45 ppm/a.u. The presented assay platform was proved to detect the SO2 concentrations of twenty-five practical food samples. Compared with the developed assay platform and certified inspection technique, the deviation of SO2 measurement does not exceed 3.82%. It was satisfactory to apply this developed assay platform to analyze the SO2 concentration in the practical samples.

Electroosmotic flow of non-Newtonian fluids in a constriction microchannel.

Insulator-based dielectrophoresis has to date been almost entirely restricted to Newtonian fluids despite the fact that many of the chemical and biological fluids exhibit non-Newtonian characteristics. We present herein an experimental study of the fluid rheological effects on the electroosmotic flow of four types of polymer solutions, i.e., 2000 ppm xanthan gum (XG), 5% polyvinylpyrrolidone (PVP), 3000 ppm polyethylene oxide (PEO), and 200 ppm polyacrylamide (PAA) solutions, through a constriction microchannel under DC electric fields of up to 400 V/cm. We find using particle streakline imaging that the fluid elasticity does not change significantly the electroosmotic flow pattern of weakly shear-thinning PVP and PEO solutions from that of a Newtonian solution. In contrast, the fluid shear-thinning causes multiple pairs of flow circulations in the weakly elastic XG solution, leading to a central jet with a significantly enhanced speed from before to after the channel constriction. These flow vortices are, however, suppressed in the strongly viscoelastic and shear-thinning PAA solution.

Microfluidic paper-based chip platform for benzoic acid detection in food.

An integrated microfluidic platform comprising a microfluidic paper-based analytical device (µPAD) and a portable detection system is proposed for the concentration detection of benzoic acid via Janovsky reaction theory. In the proposed approach, the reaction zone of the µPAD is implanted with 5 N sodium hydroxide and dried at 30 °C for 20 min. The benzoic acid sample is derived to 3,5-Dinitrobenzoic acid using KNO3 and H2SO4 at 40 °C for 40 min and is then dripped on the reaction zone of the µPAD. Finally, the µPAD is transferred to the portable detection system and heated at a temperature of 45 °C for 20 min on a hot plate to prompt a Janovsky reaction. The resulting color change of the detection zone is observed using a CMOS camera. The reaction color image is delivered to a smartphone via a connector and the benzoic acid concentration is determined using self-written RGB analysis software. The experimental results obtained using control samples with known benzoic acid concentrations in the range of 500-4000 ppm show that the R(ed) + B(lue) intensity (Y) and benzoic acid concentration (X) are related as Y =  -0.0264 X + 408.79. Moreover, the correlation coefficient is equal to R2 = 0.9953. The proposed detection platform is used to measure the benzoic acid concentrations of twenty-one commercial food samples. It is shown that the concentration measurements deviate by no more than 6.6% from those obtained using a standard HPLC macroscale method. Overall, the results presented in this study show that the proposed integrated microfluidic paper-based chip platform provides a compact and reliable tool for benzoic acid concentration measurement purposes.

Multi-parameter analysis using photovoltaic cell-based optofluidic cytometer.

A multi-parameter optofluidic cytometer based on two low-cost commercial photovoltaic cells and an avalanche photodetector is proposed. The optofluidic cytometer is fabricated on a polydimethylsiloxane (PDMS) substrate and is capable of detecting side scattered (SSC), extinction (EXT) and fluorescence (FL) signals simultaneously using a free-space light transmission technique without the need for on-chip optical waveguides. The feasibility of the proposed device is demonstrated by detecting fluorescent-labeled polystyrene beads with sizes of 3 µm, 5 µm and 10 µm, respectively, and label-free beads with a size of 7.26 µm. The detection experiments are performed using both single-bead population samples and mixed-bead population samples. The detection results obtained using the SSC/EXT, EXT/FL and SSC/FL signals are compared with those obtained using a commercial flow cytometer. It is shown that the optofluidic cytometer achieves a high detection accuracy for both single-bead population samples and mixed-bead population samples. Consequently, the proposed device provides a versatile, straightforward and low-cost solution for a wide variety of point-of-care (PoC) cytometry applications.

Pharmacokinetic-Pharmacodynamic Analysis on Inflammation Rat Model after Oral Administration of Huang Lian Jie Du Decoction.

Huang-Lian-Jie-Du Decoction (HLJDD) is a classical Traditional Chinese Medicine (TCM) formula with heat-dissipating and detoxifying effects. It is used to treat inflammation-associated diseases. However, no systematic pharmacokinetic (PK) and pharmacodynamic (PD) data concerning the activity of HLJDD under inflammatory conditions is available to date. In the present study, the concentration-time profiles and the hepatic clearance rates (HCR) of 41 major components in rat plasma in response to the oral administration of a clinical dose of HLJDD were investigated by LC-QqQ-MS using a dynamic multiple reaction monitoring (DMRM) method. Additionally, the levels of 7 cytokines (CKs) in the plasma and the body temperature of rats were analyzed. Furthermore, a PK-PD model was established to describe the time course of the hemodynamic and anti-inflammatory effects of HLJDD. As one of the three major active constituents in HLJDD, iridoids were absorbed and eliminated more easily and quickly than alkaloids and flavonoids. Compared with the normal controls, the flavonoids, alkaloids and iridoids in inflamed rats exhibited consistently changing trends of PK behaviors, such as higher bioavailability, slower elimination, delays in reaching the maximum concentration (Tmax) and longer substantivity. The HCR of iridoids was different from that of alkaloids and flavonoids in inflamed rats. Furthermore, excellent pharmacodynamic effects of HLJDD were observed in inflamed rats. The levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), IL-1ß, IL-10, and macrophage inflammatory protein-2 (MIP-2) and body temperature significantly decreased after the administration of HLJDD. Based on PK-PD modeling with the three-phase synchronous characterization of time-concentration-effect, flavonoids exhibited one mechanism of action in the anti-inflammatory process, while iridoids and alkaloids showed another mechanism of action. Taken together, the results demonstrated that HLJDD may restrain inflammation synergistically via its major constituents (alkaloids, flavonoids and iridoids). A correlation between the exposure concentration of different types of compounds and their anti-inflammatory effects in the body was shown. This study provides a comprehensive understanding of the anti-inflammatory activity of HLJDD.

Modular design and development methodology for robotic multi-axis F/M sensors.

Accurate Force/Moment (F/M) measurements are required in many applications, and multi-axis F/M sensors have been utilized a wide variety of robotic systems since 1970s. A multi-axis F/M sensor is capable of measuring multiple components of force terms along x-, y-, z-axis (Fx, Fy, Fz), and the moments terms about x-, y- and z-axis (Mx, My and Mz) simultaneously. In this manuscript, we describe experimental and theoretical approaches for using modular Elastic Elements (EE) to efficiently achieve multi-axis, high-performance F/M sensors. Specifically, the proposed approach employs combinations of simple modular elements (e.g. lamella and diaphragm) in monolithic constructions to develop various multi-axis F/M sensors. Models of multi-axis F/M sensors are established, and the experimental results indicate that the new approach could be widely used for development of multi-axis F/M sensors for many other different applications.

Microfluidic distillation chip for methanol concentration detection.

An integrated microfluidic distillation system is proposed for separating a mixed ethanol-methanol-water solution into its constituent components. The microfluidic chip is fabricated using a CO2 laser system and comprises a serpentine channel, a boiling zone, a heating zone, and a cooled collection chamber filled with de-ionized (DI) water. In the proposed device, the ethanol-methanol-water solution is injected into the microfluidic chip and driven through the serpentine channel and into the collection chamber by means of a nitrogen carrier gas. Following the distillation process, the ethanol-methanol vapor flows into the collection chamber and condenses into the DI water. The resulting solution is removed from the collection tank and reacted with a mixed indicator. Finally, the methanol concentration is inversely derived from the absorbance measurements obtained using a spectrophotometer. The experimental results show the proposed microfluidic system achieves an average methanol distillation efficiency of 97%. The practicality of the proposed device is demonstrated by detecting the methanol concentrations of two commercial fruit wines. It is shown that the measured concentration values deviate by no more than 3% from those obtained using a conventional bench top system.

Metabolic fate analysis of Huang-Lian-Jie-Du Decoction in rat urine and feces by LC-IT-MS combining with LC-FT-ICR-MS: a feasible strategy for the metabolism study of Chinese medical formula.

1. Huang-Lian-Jie-Du Decoction (HLJDD) is widely used for the treatment of hypertension, diabetes, inflammation and neural system diseases in clinic. In the present study, the comprehensive metabolic profile of HLJDD was demonstrated reliably and rapidly followed by the metabolic pathway analysis of six typical pure compounds (four alkaloids, one flavonoid and one iridoid) in HLJDD using LC-IT-MS combined with high resolution LC-FT-ICR-MS. 2. Totally, 85 compounds, including 32 prototype components and 53 biotransformed metabolites were detected and characterized in the urine and feces after oral administration of HLJDD and six pure compounds to rats, respectively. Among them, 17 prototypes were identified definitely with standard references. 3. Hydroxylation, demethylation and glucuronidation reactions of alkaloids, as well as glucuronidation and sulfonation reactions of iridoids and flavonoids, were observed as the major metabolic pathways of HLJDD. Flavonoids, iridoids and their metabolites were mainly excreted from urine. However, amount of alkaloids were detected in feces. 4. In general, the distinctive metabolic process of three kinds of representative components in HLJDD was clarified. The in vivo metabolic network of HLJDD was demonstrated. Meanwhile, the investigation of representative pure compounds in metabolic study provided a valuable strategy to elucidate the full-scale metabolic fate of HLJDD. This might be helpful to understand the in vivo mechanism of Traditional Chinese medicine (TCM).

Multichannel lens-free CMOS sensors for real-time monitoring of cell growth.

A low-cost platform is proposed for the growth and real-time monitoring of biological cells. The main components of the platform include a PMMA cell culture microchip and a multichannel lens-free CMOS (complementary metal-oxide-semiconductor) / LED imaging system. The PMMA microchip comprises a three-layer structure and is fabricated using a low-cost CO2 laser ablation technique. The CMOS / LED monitoring system is controlled using a self-written LabVIEW program. The platform has overall dimensions of just 130 × 104 × 115 mm(3) and can therefore be placed within a commercial incubator. The feasibility of the proposed system is demonstrated using HepG2 cancer cell samples with concentrations of 5000, 10 000, 20 000, and 40 000 cells/mL. In addition, cell cytotoxicity tests are performed using 8, 16, and 32 mM cyclophosphamide. For all of the experiments, the cell growth is observed over a period of 48 h. The cell growth rate is found to vary in the range of 44∼52% under normal conditions and from 17.4∼34.5% under cyclophosphamide-treated conditions. In general, the results confirm the long-term cell growth and real-time monitoring ability of the proposed system. Moreover, the magnification provided by the lens-free CMOS / LED observation system is around 40× that provided by a traditional microscope. Consequently, the proposed system has significant potential for long-term cell proliferation and cytotoxicity evaluation investigations.

Full assignments of the 1H, 13C and 15N magnetic resonance spectra of two porphyrin compounds.

Two chlorin derivatives, rhodochlorin dimethyl ester (7) and chlorin-e6 trimethyl ester (8), were prepared from methyl pheophobide a (6) through base-degradation of the E ring and methylation of the carboxylic acids. Full assignments of the 1H, 13C and 15N magnetic resonance spectra of compounds 7 and 8 were made by 2D NMR techniques (1H-1H COSY, 1H-13C HMQC, 1H-13C HMBC, 1H-15N HMBC).

Particles small angle forward-scattered light measurement based on photovoltaic cell microflow cytometer.

A method is proposed for detecting microparticles in a microflow cytometer by means of small angle forward-scattered light measurements. The proposed cytometer comprises a commercial photovoltaic cell, an adjustable power laser module, and a PDMS microfluidic chip. The detection performance of the proposed device is evaluated using particles with dimensions of 5, 8, 10, and 15 µm, respectively, given forward-light scattering angles of 5 and 8° and laser powers ranging from 15-25 mW. It is shown that for a constant laser power and particle size, the S/N of the detected light signal increases with a reducing forward-scattering angle. Moreover, for a constant forward-scattering angle and particle size, the S/N increases with an increasing laser power. The intensity of the forward-scattered light signal is found to vary linearly with the particle size and has a correlation coefficient of R(2) = 0.967, 0.967, and 0.963 given laser powers of 15, 20, and 25 mW, respectively, and a forward-scattering angle of 5°. Moreover, the CV of the forward-scattered light intensity is found to lie within the range of 20-30% for both forward-scattering angles. Overall, the present results suggest that the proposed device has significant potential for detection applications in the medical, environmental monitoring, and biological science fields.

Microfluidic rectifier based on poly(dimethylsiloxane) membrane and its application to a micropump.

A microfluidic rectifier incorporating an obstructed microchannel and a PDMS membrane is proposed. During forward flow, the membrane deflects in the upward direction; thereby allowing the fluid to pass over the obstacle. Conversely, during reverse flow, the membrane seals against the obstacle, thereby closing the channel and preventing flow. It is shown that the proposed device can operate over a wide pressure range by increasing or decreasing the membrane thickness as required. A microfluidic pump is realized by integrating the rectifier with a simple stepper motor mechanism. The experimental results show that the pump can achieve a vertical left height of more than 2 m. Moreover, it is shown that a maximum flow rate of 6.3 ml/min can be obtained given a membrane thickness of 200 µm and a motor velocity of 80 rpm. In other words, the proposed microfluidic rectifier not only provides an effective means of preventing reverse flow but also permits the realization of a highly efficient microfluidic pump.

Optical microflow cytometer based on external total reflection.

A novel optical microflow cytometer based on external total reflection comprising a laser-induced fluorescence system, a PDMS chip, a plane mirror and a dichroic beamsplitter is proposed for the simultaneous detection, enumeration and sizing of labeled and nonlabeled microparticles. In the proposed approach, the total number and size of the particles passing through the detection region is determined via the nonscattered light signal reflected from a plane mirror positioned over the microchip, while the number of fluorescence-labeled particles is determined via the back scattered fluorescence signal. The experimental results confirm the ability of the proposed system to count and size fluorescent and nonfluorescent particles with nominal diameters ranging from 6 to 10.2 µm. In addition, it is shown that for a mixed sample containing both labeled and nonlabeled particles, the number of nonlabeled particles can be determined by subtracting the number of peaks in the fluorescence signal from that in the reflected light signal.

An improved AhR reporter gene assay for analyzing dioxins in soil, sediment and fish.

Our goal was to develop a fast-screening bioassay to determine dioxin levels in the environmental and biological samples from dioxin-contaminated areas. Our original dioxin-responsive-element (DRE)-driven luciferase bioassay (using Huh7-DRE-Luc cells) was modified by reducing the incubation temperature of the cell culture from 37 to 35°C and by adding phorbol-12-myristate-13-acetate, and the modified bioassay was used to examine samples from soil, sediment, and fish. The results of this bioassay were shown to be significantly related to those of the high-resolution gas chromatography/high-resolution mass spectrometry assay of dioxins. The correlative equation was: log (PCDD/Fs I-TEQs) = 1.19 × log (BEQs) - 1.15 with R(2) = 0.95 (p < 0.001).

Integrated microfluidic chip for rapid DNA digestion and time-resolved capillary electrophoresis analysis.

An integrated microfluidic chip is proposed for rapid DNA digestion and time-resolved capillary electrophoresis (CE) analysis. The chip comprises two gel-filled chambers for DNA enrichment and purification, respectively, a T-form micromixer for DNA/restriction enzyme mixing, a serpentine channel for DNA digestion reaction, and a CE channel for on-line capillary electrophoresis analysis. The DNA and restriction enzyme are mixed electroomostically using a pinched-switching DC field. The experimental and numerical results show that a mixing performance of 97% is achieved within a distance of 1 mm from the T-junction when a driving voltage of 90 V/cm and a switching frequency of 4 Hz are applied. Successive mixing digestion and capillary electrophoresis operation clearly present the changes on digesting φx-174 DNA in different CE runs. The time-resolved electropherograms show that the proposed device enables a φx-174 DNA sample comprising 11 fragments to be concentrated and analyzed within 24 min. Overall, the results presented in this study show that the proposed microfluidic chip provides a rapid and effective tool for DNA digestion and CE analysis applications.

A hydrodynamic focusing microchannel based on micro-weir shear lift force.

A novel microflow cytometer is proposed in which the particles are focused in the horizontal and vertical directions by means of the Saffman shear lift force generated within a micro-weir microchannel. The proposed device is fabricated on stress-relieved glass substrates and is characterized both numerically and experimentally using fluorescent particles with diameters of 5 µm and 10 µm, respectively. The numerical results show that the micro-weir structures confine the particle stream to the center of the microchannel without the need for a shear flow. Moreover, the experimental results show that the particles emerging from the micro-weir microchannel pass through the detection region in a one-by-one fashion. The focusing effect of the micro-weir microchannel is quantified by computing the normalized variance of the optical detection signal intensity. It is shown that the focusing performance of the micro-weir structure is equal to 99.76% and 99.57% for the 5-µm and 10-µm beads, respectively. Overall, the results presented in this study confirm that the proposed microcytometer enables the reliable sorting and counting of particles with different diameters.

Convenient quantification of methanol concentration detection utilizing an integrated microfluidic chip.

A rapid and simple technique is proposed for methanol concentration detection using a PMMA (Polymethyl-Methacrylate) microfluidic chip patterned using a commercially available CO2 laser scriber. In the proposed device, methanol and methanol oxidase (MOX) are injected into a three-dimensional circular chamber and are mixed via a vortex stirring effect. The mixture is heated to prompt the formation of formaldehyde and is flowed into a rectangular chamber, to which fuchsin-sulphurous acid is then added. Finally, the microchip is transferred to a UV spectrophotometer for methanol detection purposes. The experimental results show that a correlation coefficient of R(2) = 0.9940 is obtained when plotting the optical density against the methanol concentration for samples and an accuracy as high as 93.1% are compared with the determined by the high quality gas chromatography with concentrations in the range of 2 ∼ 100 ppm. The methanol concentrations of four commercial red wines are successfully detected using the developed device. Overall, the results show that the proposed device provides a rapid and accurate means of detecting the methanol concentration for a variety of applications in the alcoholic beverage inspection and control field.

Experimental and numerical analysis of high-resolution injection technique for capillary electrophoresis microchip.

This study presents an experimental and numerical investigation on the use of high-resolution injection techniques to deliver sample plugs within a capillary electrophoresis (CE) microchip. The CE microfluidic device was integrated into a U-shaped injection system and an expansion chamber located at the inlet of the separation channel, which can miniize the sample leakage effect and deliver a high-quality sample plug into the separation channel so that the detection performance of the device is enhanced. The proposed 45° U-shaped injection system was investigated using a sample of Rhodamine B dye. Meanwhile, the analysis of the current CE microfluidic chip was studied by considering the separation of Hae III digested ϕx-174 DNA samples. The experimental and numerical results indicate that the included 45° U-shaped injector completely eliminates the sample leakage and an expansion separation channel with an expansion ratio of 2.5 delivers a sample plug with a perfect detection shape and highest concentration intensity, hence enabling an optimal injection and separation performance.