Microfluidic Systems for Pathogen Sensing: A Review

Rapid pathogen sensing remains a pressing issue today since conventional identification methodsare tedious, cost intensive and time consuming, typically requiring from 48 to 72 h. In turn, chip based technologies, such as microarrays and microfluidic biochips, offer real alternatives capable of filling this technological gap. In particular microfluidic biochips make the development of fast, sensitive and portable diagnostic tools possible, thus promising rapid and accurate detection of a variety of pathogens. This paper will provide a broad overview of the novel achievements in the field of pathogen sensing by focusing on methods and devices that compliment microfluidics

BioMEMS

As technological advancements widen the scope of applications for biomicroelectromechanical systems (BioMEMS or biomicrosystems), the field continues to have an impact on many aspects of life science operations and functionalities. Because BioMEMS research and development require the input of experts who use different technical languages and come from varying disciplines and backgrounds, scientists and students can avoid potential difficulties in communication and understanding only if they possess a skill set and understanding that enables them to work at the interface of engineering and biosciences. Keeping this duality in mind throughout, BioMEMS: Science and Engineering Perspectives supports and expedites the multidisciplinary learning involved in the development of biomicrosystems. Divided into nine chapters, it starts with a balanced introduction of biological, engineering, application, and commercialization aspects of the field. With a focus on molecules of biological interest, the book explores the building blocks of cells and viruses, as well as molecules that form the self-assembled monolayers (SAMs), linkers, and hydrogels used for making different surfaces biocompatible through functionalization. The book also discusses: Different materials and platforms used to develop biomicrosystems Various biological entities and pathogens (in ascending order of complexity) The multidisciplinary aspects of engineering bioactive surfaces Engineering perspectives, including methods of manufacturing bioactive surfaces and devices Microfluidics modeling and experimentation Device level implementation of BioMEMS concepts for different applications. Because BioMEMS is an application-driven field, the book also highlights the concepts of lab-on-a-chip (LOC) and micro total analysis system (μTAS), along with their pertinence to the emerging point-of-care (POC) and point-of-need (PON) applications

Test analysis & fault simulation of microfluidic systems

This work presents a design, simulation and test methodology for microfluidic systems, with particular focus on simulation for test. A Microfluidic Fault Simulator (MFS) has been created based around COMSOL which allows a fault-free system model to undergo fault injection and provide test measurements. A post MFS test analysis procedure is also described.A range of fault-free system simulations have been cross-validated to experimental work to gauge the accuracy of the fundamental simulation approach prior to further investigation and development of the simulation and test procedure.A generic mechanism, termed a fault block, has been developed to provide fault injection and a method of describing a low abstraction behavioural fault model within the system. This technique has allowed the creation of a fault library containing a range of different microfluidic fault conditions. Each of the fault models has been cross-validated to experimental conditions or published results to determine their accuracy.Two test methods, namely, impedance spectroscopy and Levich electro-chemical sensors have been investigated as general methods of microfluidic test, each of which has been shown to be sensitive to a multitude of fault. Each method has successfully been implemented within the simulation environment and each cross-validated by first-hand experimentation or published work.A test analysis procedure based around the Neyman-Pearson criterion has been developed to allow a probabilistic metric for each test applied for a given fault condition, providing a quantitive assessment of each test. These metrics are used to analyse the sensitivity of each test method, useful when determining which tests to employ in the final system. Furthermore, these probabilistic metrics may be combined to provide a fault coverage metric for the complete system.The complete MFS method has been applied to two system cases studies; a hydrodynamic “Y” channel and a flow cytometry system for prognosing head and neck cancer.Decision trees are trained based on the test measurement data and fault conditions as a means of classifying the systems fault condition state. The classification rules created by the decision trees may be displayed graphically or as a set of rules which can be loaded into test instrumentation. During the course of this research a high voltage power supply instrument has been developed to aid electro-osmotic experimentation and an impedance spectrometer to provide embedded test

BioMEMS

As technological advancements widen the scope of applications for biomicroelectromechanical systems (BioMEMS or biomicrosystems), the field continues to have an impact on many aspects of life science operations and functionalities. Because BioMEMS research and development require the input of experts who use different technical languages and come from varying disciplines and backgrounds, scientists and students can avoid potential difficulties in communication and understanding only if they possess a skill set and understanding that enables them to work at the interface of engineering and biosciences. Keeping this duality in mind throughout, BioMEMS: Science and Engineering Perspectives supports and expedites the multidisciplinary learning involved in the development of biomicrosystems. Divided into nine chapters, it starts with a balanced introduction of biological, engineering, application, and commercialization aspects of the field. With a focus on molecules of biological interest, the book explores the building blocks of cells and viruses, as well as molecules that form the self-assembled monolayers (SAMs), linkers, and hydrogels used for making different surfaces biocompatible through functionalization. The book also discusses: Different materials and platforms used to develop biomicrosystems Various biological entities and pathogens (in ascending order of complexity) The multidisciplinary aspects of engineering bioactive surfaces Engineering perspectives, including methods of manufacturing bioactive surfaces and devices Microfluidics modeling and experimentation Device level implementation of BioMEMS concepts for different applications. Because BioMEMS is an application-driven field, the book also highlights the concepts of lab-on-a-chip (LOC) and micro total analysis system (μTAS), along with their pertinence to the emerging point-of-care (POC) and point-of-need (PON) applications

Microfluidic Organ/Body-on-a-Chip Devices at the Convergence of Biology and Microengineering

Recent advances in biomedical technologies are mostly related to the convergence of biology with microengineering. For instance, microfluidic devices are now commonly found in most research centers, clinics and hospitals, contributing to more accurate studies and therapies as powerful tools for drug delivery, monitoring of specific analytes, and medical diagnostics. Most remarkably, integration of cellularized constructs within microengineered platforms has enabled the recapitulation of the physiological and pathological conditions of complex tissues and organs. The so-called organ-on-a-chip technology, which represents a new avenue in the field of advanced in vitro models, with the potential to revolutionize current approaches to drug screening and toxicology studies. This review aims to highlight recent advances of microfluidic-based devices towards a body-on-a-chip concept, exploring their technology and broad applications in the biomedical field.European Regional Development Fund-Project FNUSA-ICRC [CZ.1.05/1.1.00/02.0123]; Fundacao para a Ciencia e a Tecnologia (FCT), Portugal [UID/BIM/04773/2013]; Internal Research Grant Program, Universita Campus Bio-Medico di Romainfo:eu-repo/semantics/publishedVersio

Review: Biosensors for the detection of Escherichia coli

The supply of safe potable water, free from pathogens and chemicals, requires routine  analyses and the application of several diagnostic techniques. Apart from being  expensive, many of the detection methods require trained personnel and are often time-consuming. With drastic climate changes, severe droughts, increases in  population and pollution of natural water systems, the need to develop ultrasensitive, low-cost and hand-held, point-of-use detection kits to monitor water quality is critical. Although Escherichia coli is still considered the best indicator of water quality, cell numbers may be below detection limits, or the cells may be non-culturable and thus only detected by DNA amplification. A number of different biosensors have been developed to detect viable, dead or non-culturable microbial cells and chemicals in water. This review discusses the differences in these biosensors and evaluates the application of microfluidics in the design of ultra-sensitive nano-biosensors.Keywords: Biosensors, microfluidics, nano-biosensors, E. coli detectio

Development of electrochemical platforms for DNA sensing

[eng] The present doctoral thesis is framed in the research and development (R & D) project between a private biotechnology company of molecular diagnostics Genomica SAU, the Institute for Bioengineering of Catalonia (IBEC), the University of Barcelona, and the Microfluidics ChipShop Company. The main objective of the project is making, implementation and marketing of a diagnostic device for early detection of DNA sequences involved with cancer. The multi device, or lab-on-chip (LOC), consists of a central automation unit (CAU), a system in miniature of DNA amplification or chain reaction polymerase (mini-PCR), and a biosensing platform (DNA chip) that consisting of a matrix or electrochemical array. The three elements are integrated by a microfluidic system in sandwich format cartridge. For this purpose, the aim of this thesis was the creation, characterization and optimization of the biochemical recognition platform between two single strands of DNA of dissimilar lengths but with some complementary sequences for the subsequent electrochemical detection of a hybridization event between them. Then, the integration into the cartridge of above platform was done. For the creation of this platform, we chose to use a self-assembled monolayer (SAM) of thiols as biorecognition interface of the 14 DNA sequences that are part of the project. During optimization of the interface chips individual gold and various molecules were used being chosen the molecule with two arms disulfide of polyethylene glycol (PEG) and a malaimida group at the end of one of them. This linker (or MalPEG linker) reacts with the gold surface due to the dative interaction between the sulfur atoms of the disulfide and the gold atoms from the surface of the chips. At the same time, the malaimida group reacts with the thiol group of the capture probes, joining. The PEG groups function as anti-adhesion molecules. Surface plasmon resonance (SPR) and cyclic voltammetry (CV) were techniques used to characterize the substrate and the hybridization event. For the manufacture of the cartridge, this was divided into two main blocks, the biosensing or electrochemical block and PCR block. The electrochemical block is composed of 4 layers, one of 64 working electrodes and gold paths for contact with the potentiostat, another layer that defines the area of the sensors must be functionalized gold and isolating the gold surface of the tracks. The third layer is a double-sided adhesive that has a hexagonal hole working as hybridization chamber, and the last layer is a screen printing layer with the reference electrode (RE) and counter electrodes. The above layers form an electrochemical cell wherein the hybridization will occurs. Regarding the PCR block, this is a system of two layers with a type microfluidic channel kind loop and its function is to contain the solutions during the process of DNA amplification by the mini-PCR. During the integration of the optimized SAM into an electrochemical cartridge a manual and automated ways were used to immobilize the capture probes. Several tests were performed in order to obtain the best conditions and ratios between the molecules to maximize the hybridization signal during the electrochemical detection.[spa] El presente trabajo de tesis está enmarcado en un proyecto de investigación y desarrollo (I+D) entre la empresa privada Genomica S.A.U., el Instituto de Bioingeniería de Cataluña (IBEC), la Universidad de Barcelona y la empresa alemana ChipShop Microfluidics. El objetivo principal es el desarrollo, puesta a punto y comercialización de un dispositivo electroquímico de diagnóstico médico para etapas tempranas de cáncer. El objetivo de la tesis es la creación, optimización y posterior integración de una interfaz de biosensado de ADN en el dispositivo de diagnóstico, siendo pieza fundamental en el desarrollo de éste. La interfaz escogida fue una monocapa autoensamblada (SAM) que hace las veces de biosensor y que es capaz de anclar secuencias de ADN como sondas de captura y así poder detectar, selectivamente, las secuencias objetivo complementarias. El dispositivo también cuenta con un sistema microfluídico y un sistema de amplificación de ADN de reacción en cadena de la polimerasa en miniatura. La SAM esta inmovilizada en un array electroquímico que consta de 64 electrodos de trabajo que funcionan como elemento transductor de la señal electroquímica redox de los eventos de hibridación que ocurren sobre ellos. La funcionalización y puesta a punto del dispositivo se llevó a cabo inmovilizando múltiples sondas de captura después de una optimización de las concentraciones entre las diferentes partes constituyentes de la monocapa. Técnicas ópticas y electroquímicas fueron utilizadas para la caracterización de cada etapa y técnicas de fotolitografiado y de impresión por pantalla fueron utilizadas para la fabricación de los componentes del dispositivo. Finalmente, y después de algunos cambios surgidos durante el desarrollo del dispositivo, se llega a un diseño final y a las pruebas con muestras reales, proceso que aún está en etapa experimental

Micro- and Nanofluidics for Bionanoparticle Analysis

Bionanoparticles such as microorganisms and exosomes are recoganized as important targets for clinical applications, food safety, and environmental monitoring. Other nanoscale biological particles, includeing liposomes, micelles, and functionalized polymeric particles are widely used in nanomedicines. The recent deveopment of microfluidic and nanofluidic technologies has enabled the separation and anslysis of these species in a lab-on-a-chip platform, while there are still many challenges to address before these analytical tools can be adopted in practice. For example, the complex matrices within which these species reside in create a high background for their detection. Their small dimension and often low concentration demand creative strategies to amplify the sensing signal and enhance the detection speed. This Special Issue aims to recruit recent discoveries and developments of micro- and nanofluidic strategies for the processing and analysis of biological nanoparticles. The collection of papers will hopefully bring out more innovative ideas and fundamental insights to overcome the hurdles faced in the separation and detection of bionanoparticles

Application of functionalized graphene oxide based biosensors for health monitoring: Simple graphene derivatives to 3D printed platforms

Biosensors hold great potential for revolutionizing personalized medicine and environmental monitoring. Their construction is the key factor which depends on either manufacturing techniques or robust sensing materials to improve efficacy of the device. Functional graphene is an attractive choice for transducing material due to its various advantages in interfacing with biorecognition elements. Graphene and its derivatives such as graphene oxide (GO) are thus being used extensively for biosensors for monitoring of diseases. In addition, graphene can be patterned to a variety of structures and is incorporated into biosensor devices such as microfluidic devices and electrochemical and plasmonic sensors. Among biosensing materials, GO is gaining much attention due to its easy synthesis process and patternable features, high functionality, and high electron transfer properties with a large surface area leading to sensitive point-of-use applications. Considering demand and recent challenges, this perspective review is an attempt to describe state-of-the-art biosensors based on functional graphene. Special emphasis is given to elucidating the mechanism of sensing while discussing different applications. Further, we describe the future prospects of functional GO-based biosensors for health care and environmental monitoring with a focus on additive manufacturing such as 3D printing

Methods for immobilizing receptors in microfluidic devices: A review

In this review article, we discuss state-of-the-art methods for immobilizing functional receptors in microfluidic devices. Strategies used to immobilize receptors in such devices are essential for the development of specific, sensitive (bio)chemical assays that can be used for a wide range of applications. In the first section, we review the principles and the chemistry of immobilization techniques that are the most commonly used in microfluidics. We afterward describe immobilization methods on static surfaces from microchannel surfaces to electrode surfaces with a particular attention to opportunities offered by hydrogel surfaces. Finally, we discuss immobilization methods on mobile surfaces with an emphasis on both magnetic and non-magnetic microbeads, and finally, we highlight recent developments of new types of mobile supports