Design and microfabrication of new automatic human blood sample collection and preparation devices

For self-sampling or collection of blood by health personal related to point-ofcare diagnostics in health rooms, it may often be necessary to perform automatic collection of blood samples. The most important operation that needs to be done when handling whole blood is to be able to combine automatic sample collection with optimal mixing of anticoagulation liquid and weak xatives. In particular before doing any transport of a sample or point-of-care nucleic acid diagnostics (POCNAD) it is very important to x the gene expression at the time of collection. It is also important to concentrate and separate out the white blood cells of interest from the whole blood before further detection. An automatic sample collection module with a microneedle array in combination with a micromixer is proposed for the blood collection in typical nurse or health rooms. An automatic human blood preparation module is also suggested that could be used for pre-mixing, concentration and lyses. Despite that the concept of microneedle has been intensively studied since several decades ago, the fabrication still remains very challenging. Major challenges concern the high aspect ratio of microneedle structure. In addition, the microneedles have to be su ciently strong to avoid fracture and cracks during practical implementation. The other challenge with small microchannel dimensions on a chip is the lack of turbulences (including fluids that operate with Reynolds number smaller than 2000). Hence a long mixing length is required for good mixing quality. This doctoral thesis focus on the following challenges: (i) design and optimize a continuous concentration and separation unit, (ii) optimize and improve the fabrication process of high aspect ratio metallic microneedle, (iii) develop and investigate the mixing performance of a passive planar micromixer with ellipse-like micropillars, (iv) integrate and demonstrate the pretreatment system. Article I reported the design and optimization of non-clogging counter-flow microconcentrator for enriching epidermoid cervical carcinoma cells. The counter-flow concentration unit with turbine blade-like micropillars were proposed in microconcentrator design. Due to the organization of these micropillar units the functionality cause a unique system of continuous concentration and separation. Due to the unusual geometrical-pro les and extraordinary micro fluidic performance, the cells blocking does not occur even at permeate entrances. The excellent concentration ratio of a fi nal microconcentrator was presented in both numerical and experimental results. Article II proposed a simple and low cost micromixer for laminar blood mixing. The design of micromixer unit was modifi ed from the counter-flow concentration units which mentioned in Article I. The e ciency of the splitting and recombination (SAR) micromixer was examined by theoretical methods, including finite element method and verifi ed by measurement results. Numerical results show that micromixer with ellipse-like micropillars have a well mixing status when its mixing effi ciency is higher than 80% as Re 6 1. Article III presented that the e ciency of the SAR micromixer for cell lysis. Some bacteria, especially gram-positive, may be diffi cult to lyse with conventional lysis bu er. If the cells are not properly lysed, the quality of the analysis results might suff er. With a splitting and recombination concept, homogeneous mixing can be obtained in short distance. Hence, the quality of the sample after lysis for further process (Nucleic Acid Purifi cation, Nucleic Acid Sequence Based Ampli fication) is also improved. The treatment in the SAR micromixer is comparable lysis by long ultrasound exposure. Hence, SAR micromixer proved to be a good alternative method for cell lysis. Moreover, SAR micromixer has the advantage that it can easily be integrated into an automatic system for lysis and sample treatment. Article IV investigated the mixing performance at the outlet of SAR micromixer. The outlet channel of SAR micromixer was split into four sub-channels. Absorbance testing was used to implement to evaluate the outlet concentration of four subchannels. The homogeneous of fluids are varied with the inlet velocities. Article V presented the optimized fabrication process of the template of extremely long microneedles for blood extraction. Backside lithography with a UVlight source was employed to build the high aspect ratio SU-8-based microneedle template. Some major challenges on fabrication process were also shown and discussed in this article. Article VI covers a total process chain from design, fabrication to performance evaluation of the hollow microneedle design. The contribution of this article is a highly applicable theoretical model for the microneedle geometry. The proposed model has been developed to predict the fracture forces. A good agreement was observed between the results obtained from analytical solution and practical measurements of fracture force

GC-MS analysis and cytotoxic activity of the n-hexane fraction from Curcuma sahuynhensis Škornick. & N.S.Lý leaves collected in Vietnam

Curcuma sahuynhensis Škornick. & N.S.Lý is an endemic plant in Vietnam that has been used by the Sa Huynh people as a spice and medicine to cure illnesses linked to digestive disorders. Very little information is available so far about the chemical composition and biological effects of C. sahuynhensis. To find new pharmaceutical ingredients, the in vitro cytotoxic effect and the chemical profile of C. sahuynhensis leaf extract were investigated. In this study, the percolation method and liquid-liquid dispersion technique were used to extract dry sample powder. The chemical composition was detected by gas chromatography-mass spectrometry (GC-MS). The Sulforhodamine B and MTT methods were used to determine the cytotoxic activity. The chemical composition analysis showed that the leaf extract contained 14 components. The major components in the n-hexane extract were 6,10,14-trimethylpentadecan-2-one, phytol, 1-ethylbutyl hydroperoxide, isoborneol, 1-methylpentyl hydroperoxide, and neophytadiene. On human cancer cell lines, namely MFC-7, SK-LU-1, Hela, MKN-7, and HL-60, the leaf extract showed dose-dependent cytotoxic activity, with IC50 values ranging from 221.70±10.24 to 369.42±10.60 ?g/mL. The present study provides significant information on the chemical components and cytotoxic effects of the n-hexane extract from C. sahuynhensis leaves. The findings will continue to be crucial in future research on the evaluation of secondary metabolite compound analysis for cancer therapeutic effects

Computational Fluid Dynamics Approach for Modeling a Non-Newtonian Blood Flow in a Split and Recombine Micromixer

In this work, the blood flow in a passive planar micromixer is analyzed in order to provide a case study for the use of different models of the blood dynamic viscosity in COMSOL Multiphysics. Regarding the Newtonian or non-Newtonian behavior, the blood is best approximated with a non-Newtonian model since its viscosity changes with dependence on the shear rate. The usual Newtonian model of blood viscosity, as well as two non-Newtonian models including Carreau model and the Power law model are used to study the wall shear stress. For the models study, a passive planar micromixer with ellipse-liked micropillars is proposed to operate in the laminar flow regime for high mixing efficiency.acceptedVersio

Design of Optical Collimator System for Vehicle Speed Gun using Non-Imaging Optics

Vehicle speed guns are usually used in normal sunlight conditions (daytime). If we want to use vehicle speed guns in low light conditions (nighttime), the illuminator is needed to provide sufficient light for the vehicle speed gun to take photos. The illuminator must fulfill two requirements: (i) using the infrared wavelength to ensure that the driver is not startled by dazzling eyes by the illuminator of the proposed speed gun system and (ii) high energy efficiency to make the illuminator compact leading to the use a small battery system to improve the portable of the proposed vehicle speed gun. In this study, an illuminator using a collimator system designed by using non-imaging optics is introduced. LEDs with infrared wavelength are chosen from the library of LightToolsTM, the structure of collimated is designed to transfer the illumination from the LEDs array to a square area of 3x3 m2 to cover the vehicle to detect the vehicle number plate. The design process is built based on the conservation of optical path length in the Matlab program. After that, the designed collimator is simulated in LightToolsTM software. The promising results of the simulation in LightToolsTM show that the collimator can efficiently transfer light from the LED array to the target area with a uniformity of about 70 % and optical efficiency of about 80 %

Frequency-Dependent Contrast Enhancement for Conductive and Non-Conductive Materials in Electrical Impedance Tomography

This research investigates the critical role of frequency selection in Electrical Impedance Tomography (EIT), a non-invasive imaging technique that reconstructs internal conductivity distributions through injected electrical currents. Empirical frequency selection is paramount to maximizing the fidelity and specificity of EIT images. The study explores the impact of distinct frequency ranges—low, medium, and high—on image contrast and clarity, particularly focusing on differentiating conductive materials from non-conductive materials. The findings reveal distinct empirical frequency bands for enhancing the respective contrasts: 15–38 kHz for conductive materials (copper) and 45–75 kHz for non-conductive materials (acrylic resin). These insights shed light on the frequency-dependent nature of material contrast in EIT images, guiding the selection of empirical operating ranges for various target materials. This research paves the way for improved sensitivity and broader applicability of EIT in diverse areas

STUDIES ON FUCOIDAN AND ITS PRODUCTION FROM VIETNAMESE BROWN SEAWEEDS

Sulfated fucans are among the most widely studied of all the sulfated polysaccharides of plant origin that exhibit biological activities in mammalian systems. In this report fucoidans from some Vietnamese Sargassumspecies such as S.polycystum, S.oligocystum, S.mcclurei, S. Swartzii and denticaprum were extracted and fractionated on a DEAE-Sephadex A-25 column. On the basis of chemical and spectral analyses, the fucoidan fractions obtained were found to be the sulfated fucogalactans containing sulfate ester groups and uronic acid, and composed essentially of fucose and galactose, as well as a minor amount of other sugars. The polysaccharide fractions were tested for anticancer activity. The primarily obtained results showed that all fucoidan fractions isolated from S. swartziidemonstrate bioactivity effects against cancer cells, while fraction F5 with a highest sulfate content exhibits the strongest anti-invasion activity. This indicates that sulfate content plays an important role in the anticancer activity of the brown algal fucoidans. A laboratory scale pilot for fuco idan production from Vietnamese brown seaweeds has been set with a capacity of 500 g of crude fucoidan per day

STUDIES ON FUCOIDAN AND ITS PRODUCTION FROM VIETNAMESE BROWN SEAWEEDS

Sulfated fucans are among the most widely studied of all the sulfated polysaccharides of plant origin that exhibit biological activities in mammalian systems. In this report fucoidans from some Vietnamese Sargassumspecies such as S.polycystum, S.oligocystum, S.mcclurei, S. Swartzii and denticaprum were extracted and fractionated on a DEAE-Sephadex A-25 column. On the basis of chemical and spectral analyses, the fucoidan fractions obtained were found to be the sulfated fucogalactans containing sulfate ester groups and uronic acid, and composed essentially of fucose and galactose, as well as a minor amount of other sugars. The polysaccharide fractions were tested for anticancer activity. The primarily obtained results showed that all fucoidan fractions isolated from S. swartziidemonstrate bioactivity effects against cancer cells, while fraction F5 with a highest sulfate content exhibits the strongest anti-invasion activity. This indicates that sulfate content plays an important role in the anticancer activity of the brown algal fucoidans. A laboratory scale pilot for fuco idan production from Vietnamese brown seaweeds has been set with a capacity of 500 g of crude fucoidan per day

Large scale in silico prediction of putative rhodopsin and secretin G-coupled protein receptors (GPCRs) across multiple decapod species using a hybrid clustering/phylogenetics approach

The Crustacean Society Mid-Year Meeting (TSC 2019), 26-30 May 2019, Hong Kong.-- 1 pageOrder Decapoda consists of more than 8,000 species of crustaceans (phylum Arthropoda) that include shrimps, lobsters, crayfish, crab.... Despite their importance in terms of economic as well as ecological value, decapod crustacean’s neuropeptidergic components are currently not well characterized. The advancement of next generation sequencing technology has given the research community a tool to predict neuropeptides with an unprecedented pace. On the contrary, for neuropeptide’s receptors, specifically G protein-coupled receptors (GPCRs), the characterization process is hindered due to the complexity of their structure. The traditional approach using molecular phylogenetics has several weaknesses including (1): manual curated GPCRs list that might bias the result, (2) is time and computationally demanding in increment of data size. In the current study, we present a hybrid approach of clustering and phylogenetics analysis to annotate the putative GPCRs in 10 different decapod species including Cancer borealis, Carcinus maenas, Cherax quadricarinatus, Eriochier sinensis, Gecarcinus lateralis, Homarus americanus, Nephrops norvegicus, Palinurus ornatus, Penaeus monodon, and Procambarus clarkii. This approach included clustering of GPCRs based on similarity, then validating the results at a finer resolution using phylogenetic analysis. A web browser that allow data mining (which includes the sequence of GPCRs, expression pattern, as well as gene ontology annotation) is also presented. This study provides a framework to further understand the roles of GPCRs in decapod crustaceans. Given that identification and annotation of GPCRs is hindered by the complexity of this large gene family, our hybrid approach can streamline further discovery at a greater pace and higher accurac

Exploring characteristics of the corner sections of a domain wall trap nanostructure with the two-field direction method

A 2D polycrystalline permalloy domain wall trap nanostructure with a thickness of 20 nm was studied. The structure was alternatively designed and patterned using QCAD/L-Edit software and focused-ion beam technique. With this design, a magnetic domain wall can be created and propagated with a sequence of two-field directions in a Lorentz microscopy. The trap consists of two horizontal nanowires and three 90°-tilted ones. Each nanowire has an in-plane dimension of 200 × 1000 nm(2). The trap corners were curved to allow a created domain wall that easily moves through the structure. A head-to-head domain-wall aims to create using a continuous field, this created wall can be propagated in the trap using a sequence of two-field directions. The designed trap was simulated using the Object Oriented Micro-Magnetic Framework software. Lorentz microscopy and simulation results indicate that the propagation of a domain wall is strongly affected by the precise roughness behavior of the trap elements. Domain wall pinning and transformation of wall chirality are sensitively correlated to the corner sections of the trap structure and field directions at a certain regime. Using the two-field direction method enables us to explore characteristics of the corner sections of the patterned trap nanostructure. This study is vital to fabricate an optimal nano-trap which supports a reproducible domain wall motion. This also suggests a useful method for the domain wall propagation using sequences of two-field directions. This work provides a better understanding of wall creation and propagation in polycrystalline permalloy curved nanowires which are of interest for concepts of nonvolatile data storage devices