Rozprawy doktorskie na temat „Centrifugal Microfluidics”

Microfluidic platforms allow the implementation of classical analytical operations at a mere fraction of the time, cost and resources required conventionally while granting the potential for measurements to be taken directly in the field by untrained personnel. Centrifugal microfluidic (CM) platforms, a subset of microfluidic platforms, use centrifugal force to direct liquid flow and perform a variety of analytical operations.Although the use of centrifugal force grants CM platforms many advantages such as a high degree of parallelism, the potential for portability, and the capability to pump liquids irrespective of their physicochemical properties, it creates a design paradigm that requires all platform operations to occur while the platform is in motion. Stopping a CM platform may result in unintended capillary induced flow in channels that can disrupt the intended operation and even cause a loss of sample. In accordance with this paradigm, it is important to develop measurement techniques that can be utilized while CM platforms are in motion. One measurement of importance is the volume of liquid aliquots inside a CM platform. The capability to measure volume directly on CM platforms in motion could allow experiments to quantify liquid flow in real time and avoid the use of volume metering chambers, which occupy valuable platform space. In this thesis, a new technique based on image segmentation was created to perform volume measurements on CM platforms in motion. Evaluation platforms containing a black contrast layer were fabricated and injected with liquid aliquots. High-resolution images of the evaluation platforms in motion were obtained with a high speed camera synchronized to a strobe light and the images were processed digitally. Platform images were then converted to an intensity space before image segmentation was applied to trace the inner contour of each liquid aliquot. The contour of each measured aliquot was filled and an area was computed. This area was ratioed against that obtained for a calibration volume located on the same image to obtain the volume of the aliquot.The volume measurement technique was characterized through experiments designed to test its precision and accuracy over a range of volumes. The results were found to be 1 and 2% respectively. Further characterization of the technique revealed its flexibility in regards to optical magnification, chamber shape, size and aspect ratio and platform rotational frequency. An investigation into the effects of surface tension on the method precision was also conducted. The applicability of the technique to liquids of various colours was successfully demonstrated. The versatility of the method should allow it to be used for a variety of applications including real time metering of volumes in platforms, quantitative monitoring of a design's performance in real time and the elimination of metering chambers in designs.
Les systèmes microfluidiques permettent la miniaturisation de techniques classiques d'analyse chimique en n'utilisant qu'une fraction du temps et des ressources requises conventionnellement. Ces systèmes offrent la possibilité d'effectuer des mesures directement sur le terrain sans avoir recours à un personnel qualifié. Des systèmes microfluidiques ont été développés qui utilisent la force centrifuge pour diriger le débit de liquides injectés et accomplir une variété de processus analytiques. Bien que l'utilisation de la force centrifuge accorde à ces systèmes plusieurs avantages tels qu'un haut niveau de parallélisme, un potentiel de portabilité et la capacité de pomper des liquides indépendamment de leurs propriétés physicochimiques, elle crée aussi un modèle de conception qui requière l'accomplissement de toutes les opérations analytiques pendant que le système est en rotation.En accord avec ce modèle, il est important de développer des techniques de mesure qui peuvent être appliquées pendant qu'un système microfluidique centrifuge est en mouvement. Une mesure importante est celle du volume de liquides injectés dans un système microfluidique centrifuge. La capacité d'effectuer la mesure des volumes directement sur des systèmes microfluidiques en mouvement pourrait permettre la quantification du débit de liquide en temps réel et éliminer le besoin d'utiliser des chambres de comptage qui occupent un espace déjà restreint sur le système.Dans cette thèse, une technique basée sur la segmentation d'images a été développée pour mesurer le volume d'aliquotes de liquide dans des systèmes microfluidiques en rotation. Des systèmes d'évaluation contenant une couche de peinture contrastante ont été conçus, fabriqués et injectés avec des aliquotes de liquides. Des images de haute résolution de ces systèmes en mouvement ont été acquises avec une caméra numérique à haute vitesse synchronisée avec une lumière stroboscopique et traitées numériquement. Ces images ont été converties à un espace colorimétrique de niveau de gris et segmentées pour tracer un contour autour de chaque aliquote de liquide. Ces contours ont ensuite été utilisés pour calculer l'aire de chaque aliquote qui a ensuite été divisée par l'aire d'une aliquote de calibration située sur la même image pour obtenir le volume de chaque aliquote. La technique de mesure de volume a été caractérisée par des études conçus pour tester sa précision et son exactitude pour différents volumes. La précision et l'exactitude obtenues ont été de 1 et 2 % respectivement. Une caractérisation supplémentaire de la technique a révélé sa flexibilité quant au grandissement du système optique, la taille, la forme et le rapport hauteur/largeur des chambres du système et la fréquence de rotation du système. Une enquête sur les effets de la tension de surface du liquide mesuré sur la précision de la méthode a aussi été effectuée. L'applicabilité de la technique à des liquides de diverses couleurs a aussi été démontrée avec succès. La versatilité de cette méthode devrait permettre son utilisation dans une variété d'applications incluant la mesure de volumes en temps réel, le contrôle quantitatif de la performance de designs de systèmes microfluidiques centrifuges en temps réel et l'élimination de chambres de comptage dans leur conception.

In an industrial society it is critical that techniques be developed for the measurement of chemical species in the environment, in humans and as both intended and unintended products of manufacturing. Initially, these techniques were developed around sophisticated instruments and often involved complex procedures. It is obviously advantageous if the cost of analyses can be reduced and the experimental procedures simplified, while still maintaining the quality of the data collected. Furthermore, it is often desirable to have measurements performed rapidly, with on-site measurement sometimes deemed useful or even essential. All of these desirable outcomes may, in some cases, be obtained by miniaturisation. The interest in miniaturisation has led to rapid growth of the field of microfluidics, an area of study which involves using small volumes of liquids, often with detection systems specifically tailored to these reduced volumes. Microfluidic systems must have some way of moving liquids through various stages of chemical or physical processes. One particularly interesting pumping method involves the use of centrifugal force, which eliminates the need for pumps and minimises connections to the platform on which the analysis is done. Up to this point, centrifugal systems have generally been constrained to a limited number of sequential analytical steps as liquid could only flow in the direction demanded by the applied centrifugal force.In this thesis, a variety of liquid manipulation techniques on centrifugal microfluidic platforms were developed and characterised. These techniques were used to miniaturise standard classical analytical methods and implement them on centrifugal microfluidic platforms with the goal of monitoring environmentally important compounds such as aqueous sulfide. A two-phase liquid displacement pumping technique and a pneumatic-centrifugal pumping technique are demonstrated and presented. The developed pneumatic-centrifugal system was used to significantly increase the toolbox of capabilities for centrifugal microfluidic platforms, simultaneously enabling critical microfluidic operations such as valveless liquid transfer, metering, liquid flow switching, agitative micromixing, and liquid recirculation. This technique is based on contactless implementation of pneumatic pressure using compressed air on a continually rotating centrifugal microfluidic platform, thereby enabling complete liquid flow control by combining the effects of pneumatic pressure and centrifugal force.This new type of pneumatically enhanced centrifugal microfluidic platform greatly simplifies the fabrication process by minimising valving requirements, as well as improving efficiency by performing analyses in a highly automated manner. The pneumatic approach was applied to an on-disk calibration and spectrophotometric measurement using the method of standard additions. Similarly, another pneumatically enhanced platform was developed for performing liquid-liquid extractions between an aqueous phase and an organic phase, demonstrating that these centrifugal platforms are not only capable of performing complex multi-step reactions, but also multi-cycle reactions and processes. Finally, an application-specific pneumatically enhanced centrifugal platform was developed for the spectrophotometric determination of aqueous hydrogen sulfide.All of the developed analytical methods only required small sample and reagent volumes, are highly automated and convenient, and have the potential to be performed in a field environment without the need for highly trained personnel.
Dans notre société industrielle, la conception de techniques pour la quantification d'espèces chimiques dans l'environnement, les humains et les dérivés de la production manufacturière est primordiale. Au départ, ces techniques avaient été élaborées à partir d'instruments sophistiqués et se basaient sur des procédures complexes. Il serait donc avantageux de pouvoir réduire les coûts d'analyse et simplifier les procédures expérimentales, tout en maintenant un niveau élevé de la qualité des données recueillies. De plus, il est souvent souhaitable de pouvoir effectuer ces mesures rapidement, et si possible sur le site où l'échantillon à analyser est recueilli. Toutes ces caractéristiques bénéfiques des méthodes analytiques peuvent être obtenues, dans certains cas, à travers la miniaturisation. L'intérêt pour la miniaturisation a mené à une croissance rapide des systèmes microfluidiques, un domaine d'études qui se concentre sur l'utilisation de petits volumes de liquide et des systèmes de détection spécialement adaptés à ces volumes réduits. Tout système microfluidique doit intégrer une méthode de transfert des liquides à travers différentes étapes de traitements chimiques ou physiques. Une méthode de pompage particulièrement intéressante utilise la force centrifuge, ce qui permet d'éliminer l'utilisation de pompes ou connections externes au système où s'effectue l'analyse chimique. Jusqu'à présent, les systèmes employant la force centrifuge ont été limités par le nombre d'étapes analytiques consécutives, le liquide ne pouvant se déplacer que dans une seule direction définie par la force centrifuge appliquée.Pour cette thèse, plusieurs techniques de manipulation des liquides sur un système microfluidique à base de force centrifuge ont été dévelopées et caractérisées. Ces techniques ont été utilisées pour miniaturiser les méthodes analytiques classiques pour ensuite les intégrer à des plateformes microfluidiques à base de force centrifuge, l'objectif final étant la surveillance d'espèces chimiques dans l'environnement. Une technique de pompage par déplacement de deux phases liquides et une technique de pompage pneumatique à base de force centrifuge sont démontrées. La technique pneumatique à base de force centrifuge qui a été développée augmente de façon significative les capacités de la boîte à outils des systèmes microfluidiques à base de force centrifuge. Ce nouveau système permet d'effectuer simultanément des opérations essentielles dans les systèmes microfluidiques telles que le transfert de liquides sans valves, les dosages, la commutation du débit des liquides, les micromélanges par agitation ainsi que la recirculation des liquides. Cette technique se base sur l'application sans contact d'une pression pneumatique en utilisant de l'air comprimé sur un système microfluidique à base de force centrifuge en rotation constante. Ceci permet un contrôle complet du débit des liquides en combinant les effets de la pression pneumatique et de la force centrifuge. Le processus de fabrication de ce nouveau système est grandement simplifié par l'ajout du système pneumatique car cela diminue le nombre de valves à intégrer dans le système. De plus, son efficacité est accrue grâce à la possibilité d'effectuer des analyses de façon automatisée. Cette approche pneumatique a été appliquée à des mesures spectrophotométriques par la méthode des additions connues effectuées directement sur le disque. Dans le même ordre d'idées, un autre système employant la fonction pneumatique a été développé pour effectuer des extractions liquide-liquide entre une phase liquide et une phase organique. Ceci a démontré que la plateforme centrifuge est capable non seulement d'effectuer des réactions chimiques complexes en plusieurs étapes, mais aussi de répéter les cycles de réactions et autres processus.

A growing number of pollutants are being shown to have a large environmental and health impact resulting in stricter legislative limits. Increased environmental monitoring is forcing analytical chemists to consider automating and miniaturizing current standard methods. Instrumentation and sample handling techniques for centrifugal microfluidic devices in motion have been developed with the objective of integrating multi-step reactions into a single device for the analysis of environmental solid samples.In order to study and optimize centrifugal microfluidic devices in motion, motorized stages integrating a camera, strobe and a variety of other peripheral components were developed. These allowed precise control of the devices throughout the methods' spin sequences and simultaneous acquisition of a series of stop action photographs of the devices.Non-contact methodologies for sample introduction, preparation and extraction on centrifugal microfluidic devices in motion are presented. To achieve this, hybrid fabrication techniques including the use of 3D printers were investigated and a World-to-Disk interface permitting the introduction of a solution gradient to a spinning device was developed. The interaction of integrated mobile magnets with a series of fixed magnets placed below the spinning devices was also investigated resulting in the development of both a magnetically actuated solid sample preparation and a magnetically actuated liquid-solid extraction technique. New automated and miniaturized methods for the analysis of environmentally important species such as polycyclic aromatic hydrocarbons and pesticides in solid samples are presented.
Les polluants ont des impacts importants sur la santé et l'environnement résultant à des restrictions accrues des limites législatives. Cette surveillance environnementale accrue pousse les chimistes analytiques vers l'automatisation et la miniaturisation des méthodes de référence actuelles. L'analyse d'échantillons environnementaux solides bénéficiera de cette envolée par le développement de nouveaux instruments et techniques de manipulation d'échantillon via des dispositifs microfluidiques centrifuges qui intègrent des réactions à étapes multiples sur un dispositif unique.Afin d'étudier et d'optimiser les dispositifs microfluidiques centrifuges en mouvement, des plateformes motorisées qui incluent une caméra, une lumière stroboscopique et une variété d'autres composantes périphériques ont été développées. Celles-ci ont permis le contrôle efficace des dispositifs tout au long des séquences giratoires et l'acquisition simultanée de séries de photographies en arrêt sur image.Des méthodologies sont présentées pour l'introduction, la préparation et l'extraction d'échantillons sur des dispositifs microfluidiques centrifuges en mouvement. Ceci fut réalisé grâce à la recherche de techniques de fabrication hybrides incluant l'utilisation d'imprimantes 3D menant au développement d'une interface permettant l'introduction de solutés à concentrations variables aux dispositifs en mouvement. De plus, l'interaction d'aimants mobiles intégrés avec une série d'aimants fixes placée sous les dispositifs en mouvement a mené au développement des techniques de préparation d'échantillons solides par force magnétique et d'extraction liquide-solide d'échantillons par force magnétique. De nouvelles méthodes automatisées et miniaturisées ont été développées pour l'analyse d'espèces environnementales importantes telles que les hydrocarbures polycycliques aromatisés et les pesticides dans des échantillons solides.

碩士
逢甲大學
化學工程學所
96
Surface forces and the design of the microchannels play important role on the performance of the microfluidic functions. It is especially important when naoliter-sized liquid is processed on a centrifugal microfluidic platform. The driving force provided by the centrifugal force is not sufficient to overcome the surface force under a large surface to volume ratio and resulting in the failure in microfluidic functions. In this work, we performed an intensive study on the effect of the surface forces that hinder the microfluidic functions. It is found that by increasing the depth of the reservoir along with the surface modification can effectively improve the stability of the microfluidic functions.

碩士
元培醫事科技大學
生物醫學工程系福祉科技與醫學工程碩士班
106
This study developed a microfiber manufacturing technology and explored the effects of process parameters on fiber size and characteristics. This method can produce high quality and axial gelatin fiber from gelatin solution by using a centrifugal force machine. The self-made centrifugal microfluidics device was used as the spinning equipment, and 20% ~ 40% gelatin solutions were prepared as the test material, and the test volume was 10ml ~ 40ml. The outlet of microchannel has a diameter of 700±0.1 μm and a length of 1.3 cm and a centrifugal speed of 7500 rpm to 15000 rpm. Silicone rubber temple were set from the centrifugal device 15 cm, spinning with a speed of 15000rpm. Next, the collected temples were observed with an optical microscope on the size and pattern of the filaments and analyzed for the producing efficiency and transparency of the sample filament with varying light transmittance and weight, respectively. Finally, the friction coefficient meter was used to analyze the relationship between the adhesive degree of testing temples and fiber amount. The fiber strength and fiber surface roughness of the prepared gelatin fibers were measured using a friction coefficient meter and a material testing machine. The research results provide biomedical microfiber manufacturing technology with commercial value and mass production potential.

碩士
逢甲大學
自動控制工程所
97
A real-time automatic centrifugal detection system with a novel pneumatically enhanced microfluidic inspection platform and a controllable background light is developed based on the opto-microelectromechamical technology. The developed system can be used to detect various physical, chemical and biomedical samples effectively with reducing sample’s amount, lowering manufacture cost, speedy reaction time and inspection time, and promoting stability and sensitivity. Adjustable pressure ranges of airflow are of 0 to 3 bar, and adjustable angle of the airflow nozzles are ± 60°. The distance of airflow nozzles can be adjusted up to 3cm for controlling different detection that makes the system more flexible to achieve multi-functional microfluidic tests.

碩士
逢甲大學
自動控制工程所
96
A novel centrifugal inspection system with operation modules for real-time dynamic imaging, temperature control and wireless transmission has been studied and fabricated based on the technologies of motor rotation and tracking control, temperature feedback control, and quasi-static images inspection. The developed platform performs well in motor speed control, sample location tracking, constant temperature setting, background light adjustment, and real-time images acquisition with wireless transmission function. The microfluidic images can be analyzed and stored on man-machine interface to examine microfluidic reactions. The system performance has improved in comparison to former developed platform that includes reduction of eccentric vibration, enhancement of signal transmission, and integration of interface programs. The goal of research aimed at the characteristics improvement of the centrifugal microfluidic platform. A rubber cushion was settled to reduce vibration effectively for steady operation in various measurement speeds. The wireless transmission module has designed to simplify signal transmission and processing. Furthermore, a constant temperature control unit has built to supply different temperature environments for dynamic microfluidic inspection. Moreover, the centrifugal disk-platform with complicated fluidic microstructures has been designed to demonstrate the applications of real-time biochemical or biomedical analysis.

碩士
逢甲大學
化學工程學所
97
In this work, a simple, robust microfluidic design for liquid aliquoting on a centrifugal platform is proposed. This microfluidic function can be used in high throughput assays to solve the labor-intensive problems for the sample and reagent loading. On the centrifugal platform, while the liquid is driven by the centrifugal force, the Coriolis force is also acting on the liquid and results in deflection of the flow direction. Therefore, a regular inverse-Y design failed to achieve the aliquoting function on a centrifugal platform. In order to reduce the Coriois effect, a parallel flow design is proposed. Experimental results showed that the total liquid volume, rotational speed play important roles on governing liquid aliquoting. Higher liquid volume and lower rotational speed result in better liquid aliquoting. Under similar condition, parallel flow design showed much better results in liquid aliquoting than the inverse-Y design.

碩士
國立臺灣大學
醫學工程學研究所
103
Viscosity is an important marker in biological industry and medical predictions. It corresponds to the “thickness” of sample fluid and plays an important role in cardiovascular disease. The device used to measure the viscosity is viscometer. The traditional viscometers utilize mechanical forces for pumping and control sample fluid. In this study, we design a disc-shape centrifugal microfluidic device in order to measure the fluidic viscosity. There are many benefits of disc-shape microfluidic devices as the same with other ordinary microfluidic devices. Furthermore, it is possible and easier to manipulate the flow conditions by controlling the rotational speed. In this study, we use computer simulations to develop the relationship between sample viscosities with their flow conditions and manufacture the microfluidic device. Viscosity is inversely proportion to the flow distance regardless of rotational speed within 0.8 ~ 16m Pa-s.

Chen, Qiulan.
"November 2010."
Thesis (Ph.D.)--Chinese University of Hong Kong, 2011.
Includes bibliographical references (leaves 140-152).
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstract also in Chinese.

碩士
逢甲大學
自動控制工程所
99
Based on centrifugal microfluidic detection and micro-optoelectromechanical system (MOEMS) technology, a platform of the real-time photoelectric fluorescence centrifugal microfluidic detection is developed and applied to detect food and drug constituents rapidly. Fluorescence detection and analysis are experimented based on the fluorescene-dim response by reacting a photosensitive chemical luminescence material with a tannic acid. To detect of tannic acid concentrations of tea and Chinese Gall, the varied light intensity response by reacting samples and catalysts are experimented. The higher the sample’s is, the lower the light intensity produces. The catalyst concentration of CuCl2 in 1×10-4 mol/l can provide optimal tannic acid detection in the concentration range of 7~80×10-3 mol/l. The developed real-time fluorescence detection system can be applied to analyze tannic acid concentration quantitatively in food, tea and Chinese Gall. The more extract time is, the higher tannic acid concentration is. The light intensity response shows that the maximum voltage can be achieved with shorter rise time and longer recover time. The system has the advantage of a rapid and correct analysis in medicines and foods that contain tannic acid.

碩士
國立臺灣大學
應用力學研究所
105
Cancer management can be better served by suitable biomarkers ranging from diagnosis and monitoring of therapeutic progress. Over the past few years, clinical relevance of exosomes as a marker during tumor progression and early disease detection has been validated. However, the enrichment of exosomes remains technically challenging, where purity, reproducibility and automation are highly desirable. In this thesis, a centrifugal microfluidic platform was presented to enrich exosomes directly from blood. The platform contains a microfluidic disk and a mechanism to collect plasma into an Eppendorf tube. A range of parameters of immunomagnetic beads to plasma ratio and system performance could be obtained from 100 to 600 μl of human whole blood. Western blotting was used for protein quantification. Besides, the performance of exosome enrichment was compared with that from ultracentrifugation and a commercial exosome isolation kit. Results showed that the microfluidic device successfully enriches exosomes from three breast cancer patients directly from whole blood. Averaged 98.3% red blood cells from whole blood was depleted in the plasma separation process. Taken together, our microfluidic platform provides a simple-to-use and robust approach to enrich specific exosomes by recognizing the exosomal surface markers. Moreover, the automated system reduces variation in operator biases and may serve as a standard device for clinical uses.

碩士
國立臺灣大學
應用力學研究所
106
Liquid biopsy has been applied to clinical research and disease management in recent years. It provides a non-invasive, low risk and time saving approach to access bio-samples such as RNA, DNA, proteins, exosomes, and cells from body fluids. Given that nucleic acid is the origin of abnormal mutants, detecting RNA might be able to collect information before other biomarkers show disease signal which might be suitable for early disease detection. Enrichment of RNA is an important process to characterize the nucleic acid. Although there are many RNA isolation kits on the market, most of them are manually operated, which is time-consuming and operator dependent. Only a few methods are automated, and they are operated by high-throughput, large-volume devices. This thesis aims to developing an automated RNA enrichment method and a microfluidic assay. Considering the automation of a centrifuge and input of reagents, a disk-based RNA isolation was designed. The protocol modified from CatchGeneTM Cell/Exosome miRNA Kit was applied to an acrylic disk with chambers and microfluidic channels motivated by the ease of fluid manipulation via centrifugation. First, the mixing ability of the disk was tested and compared with that from standard kit protocol. Then, the stability and the quality of the RNA enriched by the disk protocol were validated using MCF7 cells as samples. Results of electrophoresis showed that the RNA samples enriched by three identical disks had the same quality as tube protocol, which suggest the performance of the system was stable. Results detected by NanodropTM and QubitTM showed that the performance of the disk was stable since the coefficient of variation of the RNA concentration was only 0.18 and the quantity of total RNA was as high as 75.5% of that enriched by standard kit protocol with only 13% standard deviation. The quality of the RNA sample was evaluated by the similarity between positive control and disk outcome, which is the similarity of the genetic expression proportion of four biomarkers: RPP30, ER, HER2 and Ki67. Overall, the proportion of genetic expression level of RNA sample enriched by the disk was very similar to that enriched by the standard protocol. Besides MCF7 cells, other cells such as BT474 and WBC were also used to validate the application of the microfluidic platform to different samples. Results of electrophoresis and qPCR both showed high quality. The genetic expression proportion of RNA sample enriched from BT474 and WBC in two methods showed high similarity. After validation using cells, exosomes from plasma of healthy donor were introduced to the system. Results detected by qPCR with three biomarkers, miR21, let-7 and GAPDH, showed that the microfluidic platform was able to enrich exosomal RNA with high sensitivity. In conclusion, the microfluidic platform was able to enrich extracellular and exosomal RNA with high quality and stability. System automation was the motivation may enable further utilization of the microfluidic disk-based technology.

碩士
國立虎尾科技大學
自動化工程研究所
103
This study focuses on changing geometrical shapes and different inlet angles to design a variety of square-wave micromixers for mixing blood plasma on a centrifugal microfluidic platform and achieve optimal results through numerical analysis, thus reducing the cost of the experiment. Micromixers can generally be divided into 21, 31 and 31 3D square-wave mixers. Micromixers on rotating platforms propel blood plasma and reagent in the buffer reservoir to perform the first stir mixing under centrifugal force and Coriolis force, and increasing the vortex effect at the corner of square-wave channel, as well as improving mixing efficiency. During the design process, finite element software (COMSOL) is first applied to simulate the flow field and determine the optimal square-wave micromixer. The microfluidic mixers were fabricated using both conventional soft lithography techniques and CNC machining process. The experimental results show that a mixing efficiency of up to 91.4% can be achieved within 5 s when using a 3D mixer on a centrifugal platform under 1,000 rpm. The feasibility of the proposed device for clinical applications has been demonstrated by performing prothrombin time (PT) tests using plasma samples obtained from 20 healthy male donors, the mean time required for coagulation was determined to be approximately 11.4 s. It is shown that the mean time required to complete the entire PT test (including loading, mixing and coagulation) is less than 45 s.

碩士
國立虎尾科技大學
自動化工程研究所
102
In performing blood tests for clinical diagnosis purposes, it is first necessary to separate the plasma from the whole human blood. However, traditional methods for separating and preparing plasma are labor intensive and time consuming. Accordingly, the present study proposes a simple lab-on-CD device in which the plasma is first separated from the whole human blood, then divided into two samples of equal volume, and finally decanted into a detection chamber for analysis purposes. The optimal geometry parameters of the Y-shaped microchannel used to divide the plasma sample are determined by means of computational fluid dynamics (CFD) simulations. The performance of the proposed device is then evaluated using blood samples with hematrocrit concentrations ranging from 6~48%. The results show that given a CD rotation speed of 1800 rpm for a blood sample with a hematocrit concentration of 6%, a separation efficiency of 96% can be achieved within 5~6 s. Moreover, the two plasma samples collected from the left and right branches of the optimized Y-shaped splitter network differ in volume by no more than 0.5 nL. Finally, it is shown that the volume of plasma decanted into the detection chamber can be precisely controlled through an appropriate manipulation of the disk rotation speed. The second objective of this work is to design a microfluidic platform for the separation of plasma from whole human blood and the subsequent mixing of the plasma with a prothrombin time reagent. The results show that mixing efficiency of more than 97% can be obtained within 5 s given a CD rotation speed of 3400 rpm.

碩士
國立虎尾科技大學
機械與機電工程研究所
99
A CD-based Enzyme linked immunosorbent assay (CD-ELISA) is used in a wide range of applications including cancer and HIV testing, drug screening and micro-organism identification. Bifurcation design is the most important structure for microfluidic channels in CD-ELISA. In this study, a bifurcation design feasible for mass production and suitable for applications over a wide range of rotational speeds is proposed. Simulations based on two phase flow theories along with incompressible flow theories were used in this study to confirm the feasibility of the novel design. The factors that influenced the bifurcation ratio for microfluidic channels in CD-ELISA were also investigated. The geometric length for bifurcation, opening angles, and the bifurcation shape in the middle section were varied to investigate the effects of each factor on the bifurcation ratio. From the experimental results, the factors with the greatest influence on the bifurcation ratio were the geometry of the end face of the partitioning plate and the distance from the opening end. These factors can be used as controlling factors for the design of microfluidic channels.

碩士
國立交通大學
生醫工程研究所
108
In the past few decades, microfluidic devices are vigorously implementing the idea of point of care testing (POCT)；However, due to size effects, serious problems such as bubble blocking or low mixing efficiency appeared during operations, which led to inaccurate results. In addition, expensive and relatively bulky pumps are required in the microsystem to initiate liquid transport and control fluids. Recently, centrifugal microfluidics have become more and more popular for its simple-operating and easy-to-setup driving method；Although the above problems were solved in the system, these driving machines ranging from CD-players to bulky centrifuges still demand on the electricity to trigger, which means that it was impossible to manipulate in the electricity-lacking country, not even to mention practicing POCT concept. In this paper, we focused on the drug-resistant bacteria infection detection (The drug-resistant Streptococcus pneumoniae, DRSP, was taken as an example). We designed a centrifugal microfluidic (CMF) disc on a hand-powered rotor with magnetic chitosan beads (MCBs) to detect circulating antibody against the DRSP. The antibody-spiked human whole blood was used to simulate the real healthcare situation and the comparison between that and antibody-spiked PBS was shown to prove the high compatible and low interference with bio-fluid. The limit-of-detection (LOD) in PBS and human whole blood were 14.45 ng/ml and 38.9 ng/nl, respectively. The recovery rate was 95%. In conclusion, since our low-cost, time-saving, user-friendly, and minimized-electricity-comsumed hand-powered CMF detected the target antibody precisely, we believed that another similar assays can be feasible as well. Therefore, we were firmly convinced that this alternative POCT device was going to lead the trend of next-generation healthcare diagnosis.

Micro-total analysis systems (æTAS) have enabled the miniaturization and simplification of environmental contaminant detection methods. Reduced reagent and sample consumption, speed of analysis, and field portability are only a few of the advantages æTAS systems provide. Centrifugal microfluidics have the added advantages of using centrifugal force for moving liquids, thereby avoiding solvent and filtration problems encountered with the electroosmotic flow typically used in æTAS manifolds. These properties suggest that centrifugal æTAS systems may offer many advantages as analysis platforms for the on-site analyses of a variety of important environmental pollutants. A model instrument has been developed and characterized for rapid, classical spectrochemical reactions. The system is designed for the determination of nitrite, nitrate and hexavalent chromium, three common pollutants. The system uses a single disc that requires 100æl of sample per analyte using a centrifugal disc that filters the water sample which is then mixed with the appropriate reagents in one or two steps using capillary valves, and is detected on-disc with a pathlength of 1.04 mm. Using a multi-wavelength technique for the precise determination of the reference signal, the detection limits for these three systems are 0.008, 0.6, and 0.03 mg*L -1 for NO 2 - -N, NO 3 - -N, and Cr 6+ respectively. A comparison between this technique and several conventional techniques highlights the strengths and limitations of the system.

碩士
長庚大學
醫療機電工程研究所
94
There is currently great interest in combining the functional components that are necessary for performing complex chemical and biochemical analyses into small, integrated units and Micro-Electro-Mechanical Systems (MEMS) are developed quickly in the field of biomedical devices and lab test for the miniaturization of object, which stands for faster reaction, higher efficiency, less specimen and less space. Microfluidic devices, from single element to integrated micro-total-analysis-system (μTAS) or lab-on-a-chip are under development and are expected to speed up and simplify important biological operations. However, the pumping and valving designs of biochip are fabricated by semi-conductor or LIGA process so that the processes not only are complicated but also cost a lot of money. In order to overcome the short- comings of the conventional lab-on-a-chip fabrication, depending on the pumps and valves, this research utilizes centrifugal propulsion to actuate fluid flow in the microfluidic channels and proposes a new lab-on-a-chip fabrication method, “microfluidic biochip fabrication technology with centrifugal force actuation and thermal control mechanism”, and the new fabrication technology will be verified by biomedical applications to test its feasibility. This research comprises of three different stages. The first stage is the microfluidic design of the biochip system. The microfluidic design includes analysis of microfluidic propulsion theory, thermal Conductivity theory, design of functional microfluidic patterns, incision of microfluidic and evaluation of microfluidic quality. The working solution includes using SolidWorks for pattern design, ANSYS for pattern simulation, PowerMill and Visual Basic to design the software window platform for computer numerical control (CNC) programming profile and CNC machine for pattern engraving. FRT and FTA machines are also used to evaluate the microfluidic surface quality. The second stage is the platform design of microfluidic biochip fabrication including capability study and design guideline and hardware design. The hardware design of microfluidic platform includes heat press device to seal the lab-on-a-CD (compact disk), temperature control device, centrifugal actuation device and electronic stroboscopes device. The heat press device with temperature feedback control is designed to seal the biochip. A servo motor within the centrifugal actuation device is used to generate centrifugal force which will lead the sample move through the microfluidic channel instead of pumps and valves. The temperature control device is designed to provide constant temperature for microfluidc channels. The electronic stroboscopes device is mainly used to observe fluid routes in high-speed rotation. The third stage is the clinical biomedical applications. The protocol of clinical test is pre-process and preservation of specimen, quantitative and qualitative biochemical reaction of specimen, and post-process of specimen or sewage. The separation, mixing and heating of specimen are so common in the clinical test that our biochip fabrication technology is verified by blood separation test, hexokinase method and BCG method. Hexokinase method is the measurement of blood sugar and BCG is the measurement of albumin. Seven cases are involved in either control or test group. Each case needs 10 c.c. of blood sample. The microfluidic biochip is applied in the test group and the conventional method offered by Chang Gung Memorial Hospital was applied in the control group. The statistical method, SPSS, was used to verify the value of this technique. In the statistical results of our microfluidic biochip and clinical data, the P-value is 0.115 in the blood sugar test, and 0.075 in the albumin test. To sum up, there is no remarkable different between our novel biochip and clinical test method. Our centrifugal microfluidic fabrication technology with temperature controlled developed in this study is a desk-top device and can use in laboratory or clinical biomedical tests. Furthermore, this biochip can also be used in other clinical tests in near future.