20 research outputs found
Advanced Sensors for Real-Time Monitoring Applications
It is impossible to imagine the modern world without sensors, or without real-time information about almost everything—from local temperature to material composition and health parameters. We sense, measure, and process data and act accordingly all the time. In fact, real-time monitoring and information is key to a successful business, an assistant in life-saving decisions that healthcare professionals make, and a tool in research that could revolutionize the future. To ensure that sensors address the rapidly developing needs of various areas of our lives and activities, scientists, researchers, manufacturers, and end-users have established an efficient dialogue so that the newest technological achievements in all aspects of real-time sensing can be implemented for the benefit of the wider community. This book documents some of the results of such a dialogue and reports on advances in sensors and sensor systems for existing and emerging real-time monitoring applications
Recent Application in Biometrics
In the recent years, a number of recognition and authentication systems based on biometric measurements have been proposed. Algorithms and sensors have been developed to acquire and process many different biometric traits. Moreover, the biometric technology is being used in novel ways, with potential commercial and practical implications to our daily activities. The key objective of the book is to provide a collection of comprehensive references on some recent theoretical development as well as novel applications in biometrics. The topics covered in this book reflect well both aspects of development. They include biometric sample quality, privacy preserving and cancellable biometrics, contactless biometrics, novel and unconventional biometrics, and the technical challenges in implementing the technology in portable devices. The book consists of 15 chapters. It is divided into four sections, namely, biometric applications on mobile platforms, cancelable biometrics, biometric encryption, and other applications. The book was reviewed by editors Dr. Jucheng Yang and Dr. Norman Poh. We deeply appreciate the efforts of our guest editors: Dr. Girija Chetty, Dr. Loris Nanni, Dr. Jianjiang Feng, Dr. Dongsun Park and Dr. Sook Yoon, as well as a number of anonymous reviewers
Sensing at nanostructures for agri-food and enviromental applications
With a predicted population increase of 2.3 billion people, by 2050, agricultural productivity must be vastly improved and made sustainable. Globally, agriculture must deliver a 60% increase in food production to cope with the population demand. Moreover, this needs to be achieved against a changing climate, an exploitation of natural resources, and growing water and land scarcities. New digital technologies can optimise production efficiency and ensure food security and safety while also minimising waste within the production systems and the supply chain. To this end, new sensor technologies are being developed for applications in animal health diagnostics and environmental issues related to the global population, such as food & crop protection, pathogen and toxin detection, and environmental remediation. In this thesis, two new nanosensing diagnostic devices are developed and presented; surface enhanced Raman sensing and electrochemical sensing. Surface-enhanced Raman spectroscopy (SERS) substrates were fabricated by templating a flexible thermoplastic polymer against an aluminium drinks can followed by coating with a silver film, to produce a rough nanostructured metallic surface. SERS is used for both qualitative (molecular fingerprint) and quantitative detection of dye molecules and food toxins. In addition, the SERS technique is also applied in combination with nanoelectrochemical square wave voltammetry to detect nano-concentrations of neonicotinoid pesticides. The enhanced sensitivity and minimum sample preparation requirements provide tremendous opportunities for food safety and security sectors. An impedimetric immunosensor device (with a micro SD style pin-out) was also developed for the serological diagnosis of viruses and antibodies associated with bovine respiratory disease and bovine liver fluke. The silicon chip devices consist of six on-chip nanoband electrodes which can be independently modified with a polymer layer for covalent immobilisation of capture and target biomolecules. This electrochemical biosensor technology provides label-free and cost-efficient sensing capability in a compact size, and demonstrates the potential development of immunoassay-based point-of-use devices for on-farm diagnosis or therapeutic monitoring in animal health applications
Self-contained microfluidic platform for general purpose lab-on-chip using pcb-mems technology.
El presente trabajo está centrado en la investigación de una nueva plataforma
microfluídica autónoma para propósito general fabricada en PCBMEMS. En la
vista de la proliferación en los últimos años de los sistemas microfluídicos Lab
on Chip (LoC) y la multitud de aplicaciones en las que tienen cabida, surge la
necesidad de creación de un sistema portable, autónomo y con una fabricación orientada hacia la producción masiva.
En este contexto, se presenta el trabajo de esta tesis dentro de los proyectos
de investigación de financiación nacional ISILAB (TEC2011-29045-C04-02) y
BIOLOP (TEC2014-54449-C3-2- R). La tesis se encuentra organizada para cubrir los aspectos previamente propuestos. Primeramente, se presenta una introducción donde se explican los motivos para el desarrollo de este trabajo y cuáles son los objetivos específicos que se quieren cumplir. Seguidamente, se hace un breve estudio del arte. En este estudio se presenta la tecnología MEMS, los principios básicos de la microfluídica, que son los fundamentos de los sistemas LOCs y por último, se detalla un estudio de los principales elementos activos en la literatura que componen una plataforma microfluídica.
Después de la introducción y revisión literaria del marco de esta tesis, se explican los resultados obtenidos. Esta tesis está desarrollada en dos fases principales: el desarrollo de todos los componentes que hacen un lab on chip autónomo de propósito general y el desarrollo de una tecnología basada en estándares para una producción masiva. En la primera fase se detallan los principales componentes que forman parte de una plataforma autónoma multifunción: microválvula, sistema de impulsión, circuito microfluídico y plataforma de sensado. Todos estos componentes son diseñados como un prototipo y están fabricados en SU-8 y PCBMEMS. El PCB permanece como sustrato y los canales y cámaras microfluídicas están fabricados en SU-8. La microválvula diseñada presenta una activación termoeléctrica,
es de un solo uso y tiene una rápida activación y un consumo bajo
de energía. Además, el diseño está pensado para ser altamente integrable en una plataforma microfluídica. El siguiente componente descrito es una sistema de impulsión basado en cámaras presurizadas, este sistema está integrado con la microválvula y su principal característica es la activación en el momento de uso, asegurando la ausencia de pérdidas. Para probar la validez de los componentes anteriores, se desarrolla un circuito microfluídico de propósito general. El circuito está diseñado para mezclar dos muestras y transportarlas a una cámara de detección. Finalmente, se desarrolla una plataforma para la detección de glucosa, integrable en el circuito microfluídico. Una vez desarrollado el prototipo, el siguiente objetivo de la tesis es el paso de la tecnología de prototipado hacía una de producción masiva. Para ello los materiales utilizados son el PMMA y el PCB. La tecnología PCBMEMS es conocida por su versatilidad para la integración de la electrónica, por lo que lo hace idóneo para la conexión con el exterior. El PMMA es un material también muy extendido en las aplicaciones microfluídicas, debido a su transparencia, bio compatibilidad
y su fácil modelado. La unión de los dos componentes representa un desafío en el desarrollo de la tesis, debido a sus diferentes propiedades químicas. El proceso de fabricación se desarrolla integrando la microválvula y el sistema de impulsión, como partes de una plataforma microfluídica. Para terminar, se ha diseñado un pequeño circuito microfluídico para probar la viabilidad del sistema propuesto hacia una tecnología de gran escala.
Finalmente, se exponen las conclusiones de la investigación, las posibles líneas futuras de este trabajo y los apéndices que complementan el trabajo de la tesis.The work presented is focused on the investigation of a new autonomous microfluidic platform manufactured using PCBMEMS technology for general purpose. With the proliferation of the microfluidic platforms, Lab on Chip (LoC), and the multitude of applications which have placed in the market, there is a need to create a self-contained microfluidic platform for general purpose with mass production-oriented manufacturing. Within this framework, the work of this thesis is presented. This is part of two national research project ISILAB (TEC2011-29045-C04-02) and BIOLOP (TEC2014-54449-C3-2- R). The thesis is organized to cover the aspects previously explained. Firstly, an introduction is presented with the motivation and objectives of this work. Subsequently, a study of the art is done. This study presents theMEMS technology, the basics principles of microfluidics, which are the pillars of the lab on chips and finally, a study of the main active elements presented in
the literature. After the introduction and the literary revision of the framework of this thesis, the results obtained are presented. This thesis is developed in two main phases: the development of all components that make an autonomous general purpose lab on chip and the development of a standards-based technology for mass production.
The first phase details the main components of an autonomous multifunction platform: microvalve, impulsion system, microfluidic circuit and sensing platform. All of these components are designed as a prototype and are manufactured in SU- 8 and PCBMEMS. The PCB remains as a substrate, and the microfluidic channels and chambers are manufactured in SU-8. The microvalve developed is a single use thermoelectrical microvalve with fast activation and low power consumption. In addition, the design is thought to be highly integrable in a microfluidic plat-form. The next component is a impulsion system based on pressurized chambers.
The system is integrated with the microvalve and its main characteristic is the activation at the moment of use, ensuring the absence of losses. To test the validity of the above components, a general purpose microfluidic circuit is developed. The circuit is designed to mix two samples and transport those to a detection chamber.
Finally, a platform for the detection of glucose, integrable in the microfluidic
circuit, is developed. Once the prototype is achieved, the next objective of the thesis is the migration from prototyping technology to mass production. To this end, the materials used are PMMA and PCB. PCBMEMS technology is known for its versatility for the integration of electronics, making it suitable for electrical connection. PMMA is also widely used in microfluidic applications due to its transparency, bio compatibility and easy modeling. The union of the two components represents a challenge in the development of the thesis due to its different chemical properties. The manufacturing process is developed by integrating the microvalve and the drive system, as parts of a microfluidic platform. In conclusion, a small microfluidic circuit is designed by testing the feasibility of the proposed system towards large-scale technology.
Finally, the conclusions of the research, the possible future lines of this work
and the appendices that complement the work of the thesis are presented
Cationic polymers made from poly(2-oxazoline)s for biomedical applications
The present thesis deals with the convenient modification of cationic polymers based on poly(2-oxazoline)s to enhance their biological properties and introduce targeting sites, while maintaining the efficiency for biomedical applications. Besides enhancing the biocompatibility, the biodegradability and the transport of genetic material, the specific drug targeting using poly(ethylene imine) derivatives is a major challenge. The presented modification approaches enable, among others, the selective transport of genetic material into a human breast cancer cell line or the successful transport through a highly selective blood-brain barrier model. This work will be the basis for further tailor-made polymer systems and encourage researchers to continue the investigation of modified cationic polymers. In particular, the combination of drug delivery and cell specific targeting is of tremendous interest for the future treatment of human diseases and has to take the next step from bench to bedside
Towards a smartphone-connected point-of-care test for HIV
The devastation caused by HIV is driving the development of new point-of-care diagnostics. The work presented in this thesis aims to help develop a new generation of smartphone- connected HIV tests designed to address the very high levels of undiagnosed HIV-infected individuals, by widening access to HIV testing to doctors surgeries, pharmacies and developing countries. The biosensor is based on mass manufacturable surface acoustic wave (SAW) devices, and uses piezoelectricity to transduce the binding of biomarkers on the surface of the device into a measurable electric signal, making the test low cost, easy to use and reliable. In addition, the SAW biosensor presented here has the ability to wirelessly and securely transmit results to healthcare providers to potentially offer follow-up appointments at local clinics, or virtually. This thesis begins with the theory behind SAW biosensors. A more focussed characterisation of the specific device developed is then presented, followed by the details of the work done to optimise the biosensor in order to make it a good candidate for a point-of-care test for HIV. Key results include the proof of concept detection of different biomarkers of HIV infection, as well as a demonstration of the ability of the SAW biosensor to deliver a fast response. Different pilot studies are then presented, demonstrating the performance of the device as a diagnostic test, highlighting 100% sensitivity and 100% specificity. These were conducted with more than 30 confirmed HIV positive patient samples and more than 100 healthy volunteers. The following chapter then examines the fundamental mechanisms underpinning the SAW biosensor output and an empirical method to ultimately design more sensitive devices in future antigen detection. This thesis concludes with a summary of the main results and future work, including the potential for larger clinical studies, and field trials in developing countries
A Design of Digital Microfluidic Biochip along with Structural and Behavioural Features in Triangular Electrode Based Array
AbstractDigital microfluidic based biochip manoeuvres on the theory of microfluidic technology, having a broad variety of applications in chemistry, biology, environmental monitoring, military etc. Being concerned about the technological advancement in this domain, we have focused on equilateral triangular electrodes based DMFB systems. Accepting the associated design issues, here, we have addressed many facets of such electrodes regarding their structural and behavioural issues in comparison to the existing square electrodes. As the requisite voltage reduction is a key challenging design issues, to implement all the tasks using triangular electrodes that are possible in square electrode arrays as well, is a tedious job. Furthermore, to deal with this new design deploying triangular electrodes, we have analyzed all the necessary decisive factors including fluidic constraints to ensure safe droplet movements and other modular operations together with mixing and routing. Moreover, an algorithm has been developed to find a route for a given source and destination pair in this newly designed DMFB. Finally, we have included a comparative study between this new design and the existing one while encountering the above mentioned issues
Silicone microspheres and disposable separation technology for gaseous analytes
Part I of this dissertation describes the synthesis and characterization of solid, copolymeric, magnetic, fluorescent, core-shell, and hollow or foamed micron-sized silicone spheres prepared via ultrasonic spray pyrolysis (USP). Silicones are found in an amazing number of commercial products including cosmetics, sealants, adhesives, lubricants, medical devices, and even food. Despite the prevalence of bulk silicones in today’s society, the synthesis of silicone micromaterials has remained elusive. The same chemical and material characteristics that make silicones ideal for many commercial applications, namely hydrophobicity and low surface tension, cause the droplets in silicone-precursor emulsions to coalesce and aggregate upon curing. Conveniently, the aerosol created in USP, an industrially-scalable synthetic technique used to make relatively monodisperse sub-micron and micron-sized spheres, isolates silicone oligomers into individual droplets during curing.
These USP prepared silicone microspheres range from ~500 nm to 2 µm in diameter and are prepared from commercial silicone kits and commercially available oligomers. Synthetic control over size, crosslinking density, composition, and swelling is shown. The solid USP PDMS microspheres are shown to be highly bioinert, are found to be taken into cell cytosol, and show impressive drug loading capacities (as high as 36% by weight). Functional silicone microspheres are obtained by simply adding the appropriate dopant (e.g., fluorescent dye, colloidal Fe3O4, polymeric or ionic salt core material) or changing the silicone oligomers of the precursor solution prior to nebulization. These results demonstrate the versatility and generalizability of this synthetic method and serve as a road-map for the fabrication of silicone microspheres with nearly any desired functionality.
Part II of this dissertation describes our efforts in the development of a fully integrated, disposable, and portable gas chromatography column and detector. There is a pressing need for rapid, portable, and inexpensive technology for the on-site detection of gaseous analytes. Significant progress has been made towards this goal through the miniaturization of gas chromatographs (GC), the most widely used method for analyzing complex gas mixtures. Typical GC microcolumns are made through a multi-step fabrication process, which requires hazardous reagents, complex equipment, and problematic stationary phase coating procedures. This section of the thesis explores, as an alternative: a microcolumn made from a single microtextured polymer composite that acts as both the structural support and stationary phase. This work marks the first molded gas chromatography microcolumn capable of separating mixtures of VOCs in minutes with baseline resolution (N > 1800 plates m-1) and contributes significantly to understanding which factors (e.g., polymer permeability, phase-separated structure) must be considered in the design of such microcolumns.
Finally, this work also describes advancements in realizing colorimetric sensor arrays as microdetectors for gas chromatography. Because GC miniaturization necessitates extremely short columns (often < 3 m in total length), micro-GC systems suffer from incomplete separations and frequently have analytes which coelute. Sensor arrays have been proposed as microdetectors for micro-GC analysis in an attempt to ameliorate this problem. Described here are initial studies on optimization of colorimetric sensor arrays for use with GC including the development of a solvatochromic array for sensing organic solvents, an analysis of the effects of secondary factors on sensor array kinetics, and a proof of concept study sensing amines as they elute from a microcolumn. These advances provide a basis for further development of colorimetric sensor array microdetectors for use with GC