Microfluidics in Haemostasis: a Review

Haemostatic disorders are both complex and costly in relation to both their treatment and subsequent management. As leading causes of mortality worldwide, there is an ever-increasing drive to improve the diagnosis and prevention of haemostatic disorders. The field of microfluidic and Lab on a Chip (LOC) technologies is rapidly advancing and the important role of miniaturised diagnostics is becoming more evident in the healthcare system, with particular importance in near patient testing (NPT) and point of care (POC) settings. Microfluidic technologies present innovative solutions to diagnostic and clinical challenges which have the knock-on effect of improving health care and quality of life. In this review, both advanced microfluidic devices (R&D) and commercially available devices for the diagnosis and monitoring of haemostasis-related disorders and antithrombotic therapies, respectively, are discussed. Innovative design specifications, fabrication techniques, and modes of detection in addition to the materials used in developing micro-channels are reviewed in the context of application to the field of haemostasi

Development of a new biosensor array and lab-on-a-chip for portable applications using a label-free detection method

The detection and quantification of cardiac biomarkers in serum is crucial to diagnose patients in the early stage of a disease. The recent advances in microfluidics technology can improve diagnostics by reducing the application time and integrating several clinical analysis into a single, portable device called lab-on-a-chip (LOC). The development of such immunosensing LOC is a major thrust of the rapidly growing bionanotechnology industry. It involves a multidisciplinary research effort encompassing microfluidics, microelectronics and biochemistry. This thesis work focused on the development of immunoassays on microfabricated gold inter-digitated transducers (IDT) on silica and glass substrates. The concept of label-free, affinity-based biosensing is introduced with a special emphasis to impedance spectroscopy. Different protocols involving the covalent immobilization of cancer risk marker (human epidermal growth factor, hEGFR) and cardiac risk marker proteins C reactive protein (CRP), interleukin (IL6) and nicotinamide phosphoribosyltransferase (Nampt) single stranded deoxyribonucleic acid were investigated. For this, IDTs were fabricated using integrated circuit (IC) fabrication processes providing compatibility for the integration of electronic circuits, for single-chip and lab-on-a-chip biosensing applications. The thesis also involves development of a poly dimethylsiloxane (PDMS)-based fluidic system comprising on-chip actuated mechanism for multi-target immunosensing applications. The fluidic flow is controlled by an applied hydraulic pressure on the micropump. Label-free affinity type sensing was carried out using two different biological recognition elements (a) immunosensing approach using antibodies for hEGFR and IL-6 was employed and the function of the LOC was analyzed for detection of hEGFR and IL-6 as model analytes. A detection limit of 0.1ng/ml of hEGFR and IL-6 in serum was obtained without any signal amplification. (b) label-free affinity-based methodology using ssDNA aptamers specific for Nampt to develop an aptasensor and obtained a detection limit of 1 ng/ml in serum for Nampt, which is the most sensitive detection range with the application of the aptamer for Nampt

Immunosensors

Immunosensors are solid-state devices in which the immunochemical reaction is coupled to a transducer. They form one of the most important classes of affinity biosensors based on the specific recognition of antigens by antibodies to form a stable complex, in a similar way to immunoassay. Depending on the type of transducer there are four types of immunosensor: electrochemical, optical, microgravimetric and thermometric. The most commonly used bioelements for the development of electrochemical immunosensors are antibodies (Ab), followed by aptamers (Apt) and, in the last five years, microRNA (miRNA). In order to perform an early diagnosis, a method that is able to measure peptides and proteins directly in a sample, without any sample pre-treatment or any separation, is preferred. This direct detection can be performed with methods making use of the specific interaction of proteins with Ab, Apt and miRNA. The recent developments made in the immunosensor field, regarding the incorporation of nanomaterials for increased sensitivity, multiplexing or microfluidic-based devices, may have potential for promising use in industry and clinical analysis. Some examples of assays for several commercially available biomarkers will be presented. The main application fields, beside biomedical analysis, are drug abuse control, food analysis and environmental analysis

Development of an autonomous lab-on-a-chip system with ion separation and conductivity detection for river water quality monitoring

This thesis discusses the development of a lab on a chip (LOC) ion separation for river water quality monitoring using a capacitively coupled conductivity detector (C⁴D) with a novel baseline suppression technique.Our first interest was to be able to integrate such a detector in a LOC. Different designs (On-capillary design and on-chip design) have been evaluated for their feasibility and their performances. The most suitable design integrated the electrode close to the channel for an enhanced coupling while having the measurement electronics as close as possible to reduce noise. The final chip design used copper tracks from a printed circuit board (PCB) as electrodes, covered by a thin Polydimethylsiloxane (PDMS) layer to act as electrical insulation. The layer containing the channel was made using casting and bonded to the PCB using oxygen plasma. Flow experiments have been conduced to test this design as a detection cell for capacitively coupled contactless conductivity detection (C⁴D).The baseline signal from the system was reduced using a novel baseline suppression technique. Decrease in the background signal increased the dynamic range of the concentration to be measured before saturation occurs. The sensitivity of the detection system was also improved when using the baseline suppression technique. Use of high excitation voltages has proven to increase the sensitivity leading to an estimated limit of detection of 0.0715 μM for NaCl (0.0041 mg/L).The project also required the production of an autonomous system capable of operating for an extensive period of time without human intervention. Designing such a system involved the investigation of faults which can occur in autonomous system for the in-situ monitoring of water quality. Identification of possible faults (Bubble, pump failure, etc.) and detection methods have been investigated. In-depth details are given on the software and hardware architecture constituting this autonomous system and its controlling software

Microfluidics for Biosensing and Diagnostics

Efforts to miniaturize sensing and diagnostic devices and to integrate multiple functions into one device have caused massive growth in the field of microfluidics and this integration is now recognized as an important feature of most new diagnostic approaches. These approaches have and continue to change the field of biosensing and diagnostics. In this Special Issue, we present a small collection of works describing microfluidics with applications in biosensing and diagnostics

Biomedical Sensing and Imaging

This book mainly deals with recent advances in biomedical sensing and imaging. More recently, wearable/smart biosensors and devices, which facilitate diagnostics in a non-clinical setting, have become a hot topic. Combined with machine learning and artificial intelligence, they could revolutionize the biomedical diagnostic field. The aim of this book is to provide a research forum in biomedical sensing and imaging and extend the scientific frontier of this very important and significant biomedical endeavor

Biosensors for Diagnosis and Monitoring

Biosensor technologies have received a great amount of interest in recent decades, and this has especially been the case in recent years due to the health alert caused by the COVID-19 pandemic. The sensor platform market has grown in recent decades, and the COVID-19 outbreak has led to an increase in the demand for home diagnostics and point-of-care systems. With the evolution of biosensor technology towards portable platforms with a lower cost on-site analysis and a rapid selective and sensitive response, a larger market has opened up for this technology. The evolution of biosensor systems has the opportunity to change classic analysis towards real-time and in situ detection systems, with platforms such as point-of-care and wearables as well as implantable sensors to decentralize chemical and biological analysis, thus reducing industrial and medical costs. This book is dedicated to all the research related to biosensor technologies. Reviews, perspective articles, and research articles in different biosensing areas such as wearable sensors, point-of-care platforms, and pathogen detection for biomedical applications as well as environmental monitoring will introduce the reader to these relevant topics. This book is aimed at scientists and professionals working in the field of biosensors and also provides essential knowledge for students who want to enter the field

An Exploration of Paul Bowles\u27 Piano-Solo Pieces

This research paper provides a general overview of the piano-solo literature by the American composer Paul Frederic Bowles (1910-1999). Thanks to recent contributions, this repertoire is now available in recordings and musical scores as it has never been before.;This paper is divided into two sections. The first covers the biography of Paul Bowles and his musical achievements as a composer, along with his research into the folk music of Morocco and his literary writings as a music critic for the journal Modern Music and for The New Herald Tribune. The second part is about Bowles\u27 piano-solo output, divided thematically into pieces with similar forms and structures.;For Bowles\u27 solo piano music, theoretical analysis and a review of existing literature help to reveal style traits; these include his preference for short character pieces, in which Bowles employs neoclassical elements, such as melodies with classical harmonies that display bitonal and pandiatonal tendencies, along with ostinato patterns and Alberti-bass accompaniments. Bowles\u27 music often displays ternary or free structures, with motivic development techniques through which themes or passages are derived from previous motives. Jazz and folk idioms are also an important aspect of Bowles\u27 piano music, particularly in his dancelike pieces, many of which display a Latin-American flavor

Development of Microwave/Droplet-Microfluidics Integrated Heating and Sensing Platforms for Biomedical and Pharmaceutical Lab-on-a-Chip Applications

Interest in Lab-on-a-chip and droplet-based microfluidics has grown recently because of their promise to facilitate a broad range of scientific research and biological/chemical processes such as cell analysis, DNA hybridization, drug screening and diagnostics. Major advantages of droplet-based microfluidics versus traditional bioassays include its capability to provide highly monodispersed, well-isolated environment for reactions with magnitude higher throughput (i.e. kHz) than traditional high throughput systems, as well as its low reagent consumption and elimination of cross contamination. Major functions required for deploying droplet microfluidics include droplet generation, merging, sorting, splitting, trapping, sensing, heating and storing, among which sensing and heating of individual droplets remain great challenges and demand for new technology. This thesis focuses on developing novel microwave technology that can be integrated with droplet-based microfluidic platforms to address these challenges. This thesis is structured to consider both fundamentals and applications of microwave sensing and heating of individual droplets very broadly. It starts with developing a label-free, sensitive, inexpensive and portable microwave system that can be integrated with microfluidic platforms for detection and content sensing of individual droplets for high-throughput applications. This is, indeed, important since most droplet-based microfluidic studies rely on optical imaging, which usually requires expensive and bulky systems, the use of fluorescent dyes and exhaustive post-imaging analysis. Although electrical detection systems can be made inexpensive, label-free and portable, most of them usually work at low frequencies, which limits their applications to fast moving droplets. The developed microwave circuitry is inexpensive due to the use of off-the-shelf components, and is compact and capable of detecting droplet presence at kHz rates and droplet content sensing of biological materials such as penicillin antibiotic, fetal bovine serum solutions and variations in a drug compound concentration (e.g., for Alzheimer’s Disease). Subsequently, a numerical model is developed based on which parametrical analysis is performed in order to understand better the sensing and heating performance of the integrated platform. Specifically, the microwave resonator structure, which operates at GHz frequency affecting sensing performance significantly, and the dielectric properties of the microfluidic chip components that highly influence the internal electromagnetic field and energy dissipation, are studied systematically for their effects on sensing and heating efficiency. The results provide important findings and understanding on the integrated device operation and optimization strategies. Next, driven by the need for on-demand, rapid mixing inside droplets in many applications such as biochemical assays and material synthesis, a microwave-based microfluidic mixer is developed. Rapid mixing in droplets can be achieved within each half of the droplet, but not the entire droplet. Cross-center mixing is still dominated by diffusion. In this project, the microwave mixer, which works essentially as a resonator, accumulates an intensive, nonuniform electromagnetic field into a spiral capacitive gap (around 200 μm) over which a microchannel is aligned. As droplets pass by the gap region, they receive spatially non-uniform energy and thus have non-uniform temperature distribution, which induces non-uniform Marangoni stresses on the interface and thus three-dimensional (3D) chaotic motion inside the droplet. The 3D chaotic motion inside the droplet enables fast mixing within the entire droplet. The mixing efficiency is evaluated by varying the applied power, droplet length and fluid viscosity. In spite of various existing thermometry methods for microfluidic applications, it remains challenging to measure the temperature of individual fast moving droplets because they do not allow sufficient exposure time demanded by both fluorescence based techniques and resistance temperature detectors. A microwave thermometry method is thus developed here, which relies on correlating fluid temperature with the resonance frequency and the reflection coefficient of the microwave sensor, based on the fact that liquid permittivity is a function of temperature. It is demonstrated that the sensor can detect the temperature of individual droplets with ±1.2 °C accuracy. At the final part of the thesis, I extend my platform technology further to applications such as disease diagnosis and drug delivery. First, I develop a microfluidic chip for controlled synthesis of poly (acrylamide-co-sodium acrylate) copolymer hydrogel microparticles whose structure varies with temperature, chemical composition and pH values. This project investigates the effects of monomer compositions and cross-linker concentrations on the swelling ratio. The results are validated through the Fourier transform infrared spectra (FTIR), SEM and swelling test. Second, a preliminary study on DNA hybridization detection through microwave sensors for disease diagnosis is conducted. Gold sensors and biological protocols of DNA hybridization event are explored. The event of DNA hybridization with the immobilized thiol-modified ss-DNA oligos and complimentary DNA (c-DNA) are monitored. The results are promising, and suggests that microwave integrated Lab-on-a-chip platforms can perform disease diagnosis studies