Conception et fabrication d'un biocapteur à haute sensibilité pour la détection des neurotransmetteurs

Dans ce mémoire, nous présentons de nouvelles architectures de différents biocapteurs électrochimiques discrets et intégrés appelés potentiostats. Tous les potentiostats développés sont basés sur une structure entièrement différentielle pour une meilleure sensibilité et une meilleure précision. Deux conceptions discrètes à un et quatre canaux ont été proposées. La conception discrète à un canal détecte la molécule de dopamine avec un courant de l’ordre du nA et une consommation électrique de 120 mW. Cette architecture a été développée sur une carte de circuit imprimé (PCB) de 20 mm x 35 mm. L’architecture discrète à quatre canaux est la version améliorée de la précédente en termes de superficie, de sensibilité et de consommation électrique. Une autre version du potentiostat, implémentée sur un PCB de 15 mm x 15 mm, peut mesurer les courants d’oxydoréduction dans la plage du pA avec une consommation de puissance de 60 mW. L’avantage de la structure à multicanaux est qu’elle offre des sensibilités différentes allant du pA au mA pour chaque canal. Une chambre microfluidique de 7,5 mm x 5 mm avec deux entrées et une sortie a été déposée sur le PCB. Une solution saline tampon au phosphate (PBS) avec une solution de ferrocyanure a été utilisée pour tester la fonctionnalité du système réalisé. La voltampérométrie cyclique a été utilisée comme technique de détection. Un comportement linéaire a été observé lorsque la concentration des neurotransmetteurs change. De plus, un potentiostat intégré a été proposé et fabriqué en technologie CMOS 180 nm, basé sur une structure entièrement « différentiel de différence » (Fully Differential Diffrence Amplifier FDDA) pour une faible consommation de puissance et un système à haute sensibilité. Cette nouvelle configuration a été conçue pour la détection des neurotransmetteurs en très faible concentration avec un faible bruit et une plage dynamique élevée. Cette architecture intégrée peut détecter les courants dans une plage inférieure au pA avec un bruit d’entrée faible de 6,9 μVrms tout en consommant seulement 53,9 μW. Le potentiostat proposé est dédié aux dispositifs implantables à faible consommation de puissance et à sensibilité et linéarité élevées.In this thesis, we present different discrete and integrated electrochemical biosensors. All these designed potentiostats are based on fully-differential architecture to enhance sensitivity and accuracy. Two complete single channel and four-channel discrete designs were fabricated. The single channel discrete design imaged the dopamine neurotransmitter with the sensed current of approximately low nano-ampere and power consumption of 120 mW implemented on a 20 x 35 mm PCB. The four-channel discrete design was the improved version of previous one in terms of area, sensitivity and power consumption. The 15 x 15 mm PCB was able to measure the reduction-oxydation currents in the range of high pico-ampere while consuming 60 mW. The advantage of the multichannel architecture is to provide a system with different sensitivity going from pA to mA for each channel. A microfluidic 7.5 x 5 mm chamber with two inlets and one outlet was bonded to the PCB. A phosphate buffered saline (PBS) with ferrocyanide solution was used to test the functionality of the implemented system. Cyclic voltammetry has been used as a detection technique. A linear behavior had been observed when the neurotransmitter concentration changed. An integrated CMOS potentiostat was designed and fabricated in 180 nm technology based on a fully-differential-difference architecture for a low power consumption and also high sensitivity system. This new architecture was designed in order to sense ultra-low concentration of neurotransmitters with low noise and high dynamic range. This integrated design was able to image currents in the range of sub-pA with low input-referred noise of 6.9 µVrms while consuming only 53.9 µW. The proposed potentiostat is dedicated for implantable devices with low power consumption and high sensitivity and linearity

Biosensor system with an integrated CMOS microelectrode array for high spatio-temporal electrochemical imaging, A

2019 Fall.Includes bibliographical references.The ability to view biological events in real time has contributed significantly to research in life sciences. While optical microscopy is important to observe anatomical and morphological changes, it is equally important to capture real-time two-dimensional (2D) chemical activities that drive the bio-sample behaviors. The existing chemical sensing methods (i.e. optical photoluminescence, magnetic resonance, and scanning electrochemical), are well-established and optimized for existing ex vivo or in vitro analyses. However, such methods also present various limitations in resolution, real-time performance, and costs. Electrochemical method has been advantageous to life sciences by supporting studies and discoveries in neurotransmitter signaling and metabolic activities in biological samples. In the meantime, the integration of Microelectrode Array (MEA) and Complementary-Metal-Oxide-Semiconductor (CMOS) technology to the electrochemical method provides biosensing capabilities with high spatial and temporal resolutions. This work discusses three related subtopics in this specific order: improvements to an electrochemical imaging system with 8,192 sensing points for neurotransmitter sensing; comprehensive design processes of an electrochemical imaging system with 16,064 sensing points based on the previous system; and the application of the system for imaging oxygen concentration gradients in metabolizing bovine oocytes. The first attempt of high spatial electrochemical imaging was based on an integrated CMOS microchip with 8,192 configurable Pt surface electrodes, on-chip potentiostat, on-chip control logic, and a microfluidic device designed to support ex vivo tissue experimentation. Using norepinephrine as a target analyte for proof of concept, the system is capable of differentiating concentrations of norepinephrine as low as 8µM and up to 1,024 µM with a linear response and a spatial resolution of 25.5×30.4μm. Electrochemical imaging was performed using murine adrenal tissue as a biological model and successfully showed caffeine-stimulated release of catecholamines from live slices of adrenal tissue with desired spatial and temporal resolutions. This system demonstrates the capability of an electrochemical imaging system capable of capturing changes in chemical gradients in live tissue slices. An enhanced system was designed and implemented in a CMOS microchip based on the previous generation. The enhanced CMOS microchip has an expanded sensing area of 3.6×3.6mm containing 16,064 Pt electrodes and the associated 16,064 integrated read channels. The novel three-electrode electrochemical sensor system designed at 27.5×27.5µm pitch enables spatially dense cellular level chemical gradient imaging. The noise level of the on-chip read channels allow amperometric linear detection of neurotransmitter (norepinephrine) concentrations from 4µM to 512µM with 4.7pA/µM sensitivity (R=0.98). Electrochemical response to dissolved oxygen concentration or oxygen partial pressure (pO2) was also characterized with deoxygenated deionized water containing 10µM to 165 µM pO2 with 8.21pA/µM sensitivity (R=0.89). The enhanced biosensor system also demonstrates selectivity to different target analytes using cyclic voltammetry to simultaneously detect NE and uric acid. In addition, a custom-designed indium tin oxide and Au glass electrode is integrated into the microfluidic support system to enable pH measurement, ensuring viability of bio-samples in ex vivo experiments. Electrochemical images confirm the spatiotemporal performance at four frames per second while maintaining the sensitivity to target analytes. The overall system is controlled and continuously monitored by a custom-designed user interface, which is optimized for real-time high spatiotemporal resolution chemical bioimaging. It is well known that physiological events related to oxygen concentration gradients provide valuable information to determine the state of metabolizing biological cells. Utilizing the CMOS microchip with 16,064 Pt MEA and an improved three-electrode system configuration, the system is capable of imaging low oxygen concentration with limit of detection of 18.3µM, 0.58mg/L, or 13.8mmHg. A modified microfluidic support system allows convenient bio-sample handling and delivery to the MEA surface for sensing. In vitro oxygen imaging experiments were performed using bovine cumulus-oocytes-complexes cells with custom software algorithms to analyze its flux density and oxygen consumption rate. The imaging results are processed and presented as 2D heatmaps, representing the dissolved oxygen concentration in the immediate proximity of the cell. The 2D images and analysis of oxygen consumption provide a unique insight into the spatial and temporal dynamics of cell metabolism

Advanced Electrochemical Biosensors

With the progress of nanoscience and biotechnology, advanced electrochemical biosensors have been widely investigated for various application fields. Such electrochemical sensors are well suited to miniaturization and integration for portable devices and parallel processing chips. Therefore, advanced electrochemical biosensors can open a new era in health care, drug discovery, and environmental monitoring. This Special Issue serves the need to promote exploratory research and development on emerging electrochemical biosensor technologies while aiming to reflect on the current state of research in this emerging field

Development of In Vitro Point of Care Diagnostics (IVPCD) Based on Aptamers integrated Biosensors

The global market for the medical diagnostic industry is worth 25 billion dollars in the United States and is expected to grow exponentially each year. Presently available methods for biodetection, such as immunoassays, chemiluminescence and fluorescent based assays are expensive, time consuming and require skilled labor with high-end instruments. Therefore, development of novel, passive colorimetric sensors and diagnostic technologies for detection and surveillance is of utmost importance especially in resource constrained communities. The present work focusses on developing novel and advanced in vitro biodiagnostic tools based on aptamer integrated biosensors for an early detection of specific viral proteins or small biomolecules used as potential markers for deadly diseases. Aptamers are short single stranded deoxyribonucleic acid (DNA) which are designed to bind to a specific target biomolecule. These are readily synthesized in laboratory and offers several advantages over antibodies/enzymes such as stable in harsh environment, easily functionalized for immobilization, reproducibility etc. These undergo conformational changes upon target binding and produces physical or chemical changes in the system which are measured as colorimetric or electrochemical signals. Here, we have explored the aptamer-analyte interaction on different platforms such as microfluidic channel, paper based substrate as well as organic electrochemical transistor to develop multiple compact, robust and self-contained diagnostic tools. These testing tools exhibit high sensitivity (detection limit in picomolar) and selectivity against the target molecule, require no sophisticated instruments or skilled labor to implement and execute, leading a way to cheaper and more consumer driver health care. These innovative platforms provide flexibility to incorporate additional or alternative targets by simply designing aptamers to bind to the specific biomolecule

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

Micro- and nano-devices for electrochemical sensing

Electrode miniaturization has profoundly revolutionized the field of electrochemical sensing, opening up unprecedented opportunities for probing biological events with a high spatial and temporal resolution, integrating electrochemical systems with microfluidics, and designing arrays for multiplexed sensing. Several technological issues posed by the desire for downsizing have been addressed so far, leading to micrometric and nanometric sensing systems with different degrees of maturity. However, there is still an endless margin for researchers to improve current strategies and cope with demanding sensing fields, such as lab-on-a-chip devices and multi-array sensors, brain chemistry, and cell monitoring. In this review, we present current trends in the design of micro-/nano-electrochemical sensors and cutting-edge applications reported in the last 10 years. Micro- and nanosensors are divided into four categories depending on the transduction mechanism, e.g., amperometric, impedimetric, potentiometric, and transistor-based, to best guide the reader through the different detection strategies and highlight major advancements as well as still unaddressed demands in electrochemical sensing

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

Nanostructured biosensors with DNA-based receptors for real-time detection of small analytes

In zahlreichen lebenswichtigen Bereichen haben sich Biosensoren als unverzichtbare Messgeräte erwiesen. Der Nachweis von spezifischen Molekülen im Körper für eine frühzeitige Krankheitserkennung erfordert empfindliche und zugleich zuverlässige Messmethoden. Ein rasantes Fortschreiten im Bereich der Nanotechnologie führt dabei zur Entwicklung von Materialien mit neuen Eigenschaften, und damit verbunden, auch zu innovativen Anwendungsmöglichkeiten im Bereich der Biosensorik. Das Zusammenspiel von Nanotechnologie und Sensortechnik gewährleistet die Konstruktion von Sensoren mit empfindlicheren Nachweisgrenzen und kürzeren Reaktionszeiten. Die Option zur Integration und Miniaturisierung stellen daher einen erfolgreichen Einsatz in direkter Patientennähe in Aussicht, sodass Nanobiosensoren die Brücke zwischen Laborddiagnostik und Standardanwendungen schließen können. Die folgende Arbeit widmet sich der Anwendung von nanostrukturierten Biosensoren für einen empfindlichen und markierungsfreien Nachweis von Zielmolekülen. Ein Hauptaugenmerk liegt dabei auf der kontinuierlichen Messung von Biomarkern mit kompakten Auslesesystemen, die eine direkte Signalmeldung und somit eine Detektion in Echtzeit ermöglichen. Dies erfordert zunächst die sorgfältige Funktionalisierung von Sensoroberflächen mit geeigneten DNA-basierten Rezeptoren. Infolgedessen werden beispielhaft verschiedene Sensorsysteme, Analyten und Charakterisierungsmethoden vorgestellt sowie universelle Strategien für die erfolgreiche Konfiguration von Nanobiosensorplattformen präsentiert. Das erste Anwendungsbeispiel widmet sich einem plasmonischen Biosensor, bei dem vertikal ausgerichtete Gold-Nanoantennen Signale mittels sog. lokalisierter Oberflächenplasmonenresonanz (LSPR) erzeugen. Mit dem Sensor konnte erfolgreich die Immobilisierung, das nachträgliche Blocken sowie die anschließende Hybridisierung von DNA nachgewiesen werden. Mithilfe des LSPR-Sensors wurden gleichzeitig grundlegende Hybridisierungsmechanismen auf nanostrukturierten und planaren Oberflächen verglichen und damit verbunden die einzigartigen optischen Eigenschaften metallischer Nanostrukturen betont. In einem zweiten Anwendungsbeispiel misst ein elektrischer Biosensor kontinuierlich die Konzentration des Stressmarkers Cortisol im menschlichen Speichel. Der direkte, markierungsfreie Nachweis von Cortisol mit Silizium-Nanodraht basierten Feldeffekttransistoren (SiNW FET) wurde anhand zugrunde liegender Ladungsverteilungen innerhalb des entstandenen Rezeptor-Analyte-Komplexes bewertet, sodass ein Nachweis des Analyten innerhalb der sog. Debye-Länge ermöglicht wird. Die erfolgreiche Strategie zur Oberflächenfunktionalisierung im Zusammenspiel mit dem Einsatz von SiNW FETs auf einem tragbaren Messgerät wurde anhand des Cortisolnachweises im Speichel belegt. Ein übereinstimmender Vergleich der gemessenen Corisolkonzentrationen mit Werten, die mit einer kommerziellen Alternative ermittelt wurden, verdeutlichen das Potential der entwickelten Plattform. Zusammenfassend veranschaulichen beide vorgestellten Nanobiosensor-Plattformen die vielseitige und vorteilhafte Leistungsfähigkeit der Systeme für einen kontinuierlichen Nachweis von Biomarkern in Echtzeit und vorzugsweise in Patientennähe.:Kurzfassung I Abstract III Abbreviations and symbols V Content VII 1 Introduction 1 1.1 Scope of the thesis 4 1.2 References 6 2 Fundamentals 9 2.1 Biosensors 9 2.2 Influence of nanotechnology on sensor development 10 2.3 Biorecognition elements 12 2.3.1 Biorecognition element: DNA 13 2.3.2 Aptamers 14 2.3.3 Immobilization of receptors 15 2.4 Transducer systems 17 2.4.1 Optical biosensors - surface plasmon resonance 17 2.4.2 Electric Biosensors – Field-effect transistors (FETs) 21 2.5 Metal oxide semiconductor field-effect transistor - MOSFET 21 2.6 Summary 26 2.7 References 27 3 Materials and methods 33 3.1 Plasmonic biosensors based on vertically aligned gold nanoantennas 33 3.1.1 Materials 33 3.1.2 Manufacturing of nanoantenna arrays 34 3.1.3 Surface modification and characterization 35 3.1.4 Measurement setup for detection of analytes 38 3.2 SiNW FET-based real-time monitoring of cortisol 40 3.2.1 Materials 40 3.2.2 Manufacturing of silicon nanowire field effect transistors (SiNW FETs) 42 3.2.3 Integration of SiNW FETs into a portable platform 42 3.2.4 Biomodification and characterization of electronic biosensors SiNW FETs 42 3.2.5 Electric characterization of FETs 47 3.3 References 50 4 Plasmonic DNA biosensor based on vertical arrays of gold nanoantennas 51 4.1 Introduction - Optical biosensors operating by means of LSPR 53 4.2 Biosensing with vertically aligned gold nanoantennas 56 4.2.1 Sensor fabrication, characterization, and integration 56 4.2.2 Integration of microfluidics 58 4.2.3 Immobilization of probe DNA and backfilling 58 4.2.4 Hybridization of complementary DNA strands 62 4.2.5 Surface coverage and hybridization efficiency of DNA 69 4.2.6 Refractive index sensing 72 4.2.7 Backfilling and blocking 73 4.3 Summary 75 4.4 References 77 5 Label-free detection of salivary cortisol with SiNW FETs 83 5.1 Introduction 85 5.2 Design, integration, and performance of SiNW FETs into a portable platform 89 5.2.1 Structure and electrical characteristics of honeycomb SiNW FETs 89 5.2.2 Integration of SiNW FET into a portable measuring unit 91 5.2.3 Performance of SiNW FET arrays 93 5.3 Detection of biomolecules with SiNW FETs 102 5.3.1 General considerations for biodetection with FETs 102 5.3.2 Sensing aptamers with FETs 103 5.3.3 Biodetection of the analyte cortisol with SiNW FETs 104 5.3.4 Detection of cortisol with SiNW FETs 112 5.4 Summary 119 5.5 References 121 6 Summary and outlook 131 6.1 Summary 131 6.2 Perspectives – toward multiplexed biosensing applications 134 6.3 References 137 Appendix i A.1 Protocols i A.1.1 Functionalization of gold antennas with thiolated DNA i A.1.2 Functionalization of SiO2 with TESPSA and amino-modified receptors i A.1.3 Functionalization with APTES and carboxyl-modified receptors ii A.1.4 Preparation of microfluidic channels via soft lithography ii A.2 Predicted secondary structures iv A.2.1 Secondary structures of 100base pair target without probe-strands iv A.2.2 Secondary structures of 100base pair target with 25 base pair probe-strand x Versicherung xvii Acknowledgments xix List of publications xxi Peer-reviewed publications xxi Publications in preparation xxi Selected international conferences xxii Curriculum Vitae xxiiiBiosensors have proven to be indispensable in numerous vital areas. For example, detecting the presence and concentration of specific biomarkers requires sensitive and reliable measurement methods. Rapid developments in the field of nanotechnology lead to nanomaterials with new properties and associated innovative applications. Thus, nanotechnology has a far-reaching impact on biosensors' development, e.g., delivery of biosensing devices with greater sensitivity, shorter response times, and precise but cost-effective sensor platforms. In addition, nanobiosensors hold high potential for integration and miniaturization and can operate directly at the point of care - serving as a bridge between diagnostics and routine tests. This work focuses on applying nanostructured biosensors for the sensitive and label-free detection of analytes. A distinct aim is the continuous monitoring of biomarkers with compact read-out systems to provide direct, valuable feedback in real-time. The first step in achieving this goal is the adequate functionalization of nanostructured sensor surfaces with suitable receptors to detect analytes of interest. Due to their thermal and chemical stability with the possibility for customizable functionalization, DNA-based receptors are selected. Thereupon, universal strategies for confining nanobiosensor platforms are presented using different sensor systems, analytes, and characterization methods. As a first application, a plasmonic biosensor based on vertically aligned gold nanoantennas tracked the immobilization, blocking, and subsequent hybridization of DNA by means of localized surface plasmon resonance (LSPR). At the same time, the LSPR sensor was used to evaluate fundamental hybridization mechanisms on nanostructured and planar surfaces, emphasizing the unique optical properties of metallic nanostructures. In a second application, an electric sensor based on silicon nanowire field-effect transistors (SiNW FET) monitored the level of the stress marker cortisol in human saliva. Based on evaluating the underlying charge distributions within the resulting receptor-analyte complex of molecules, the detection of cortisol within the Debye length is facilitated. Thus, direct, label-free detection of cortisol in human saliva using SiNW FET was successfully applied to the developed platform and compared to cortisol levels obtained using a commercial alternative. In summary, both presented platforms indicate a highly versatile and beneficial performance of nanobiosensors for continuous detection of biomarkers in real-time and preferably point-of-care (POC).:Kurzfassung I Abstract III Abbreviations and symbols V Content VII 1 Introduction 1 1.1 Scope of the thesis 4 1.2 References 6 2 Fundamentals 9 2.1 Biosensors 9 2.2 Influence of nanotechnology on sensor development 10 2.3 Biorecognition elements 12 2.3.1 Biorecognition element: DNA 13 2.3.2 Aptamers 14 2.3.3 Immobilization of receptors 15 2.4 Transducer systems 17 2.4.1 Optical biosensors - surface plasmon resonance 17 2.4.2 Electric Biosensors – Field-effect transistors (FETs) 21 2.5 Metal oxide semiconductor field-effect transistor - MOSFET 21 2.6 Summary 26 2.7 References 27 3 Materials and methods 33 3.1 Plasmonic biosensors based on vertically aligned gold nanoantennas 33 3.1.1 Materials 33 3.1.2 Manufacturing of nanoantenna arrays 34 3.1.3 Surface modification and characterization 35 3.1.4 Measurement setup for detection of analytes 38 3.2 SiNW FET-based real-time monitoring of cortisol 40 3.2.1 Materials 40 3.2.2 Manufacturing of silicon nanowire field effect transistors (SiNW FETs) 42 3.2.3 Integration of SiNW FETs into a portable platform 42 3.2.4 Biomodification and characterization of electronic biosensors SiNW FETs 42 3.2.5 Electric characterization of FETs 47 3.3 References 50 4 Plasmonic DNA biosensor based on vertical arrays of gold nanoantennas 51 4.1 Introduction - Optical biosensors operating by means of LSPR 53 4.2 Biosensing with vertically aligned gold nanoantennas 56 4.2.1 Sensor fabrication, characterization, and integration 56 4.2.2 Integration of microfluidics 58 4.2.3 Immobilization of probe DNA and backfilling 58 4.2.4 Hybridization of complementary DNA strands 62 4.2.5 Surface coverage and hybridization efficiency of DNA 69 4.2.6 Refractive index sensing 72 4.2.7 Backfilling and blocking 73 4.3 Summary 75 4.4 References 77 5 Label-free detection of salivary cortisol with SiNW FETs 83 5.1 Introduction 85 5.2 Design, integration, and performance of SiNW FETs into a portable platform 89 5.2.1 Structure and electrical characteristics of honeycomb SiNW FETs 89 5.2.2 Integration of SiNW FET into a portable measuring unit 91 5.2.3 Performance of SiNW FET arrays 93 5.3 Detection of biomolecules with SiNW FETs 102 5.3.1 General considerations for biodetection with FETs 102 5.3.2 Sensing aptamers with FETs 103 5.3.3 Biodetection of the analyte cortisol with SiNW FETs 104 5.3.4 Detection of cortisol with SiNW FETs 112 5.4 Summary 119 5.5 References 121 6 Summary and outlook 131 6.1 Summary 131 6.2 Perspectives – toward multiplexed biosensing applications 134 6.3 References 137 Appendix i A.1 Protocols i A.1.1 Functionalization of gold antennas with thiolated DNA i A.1.2 Functionalization of SiO2 with TESPSA and amino-modified receptors i A.1.3 Functionalization with APTES and carboxyl-modified receptors ii A.1.4 Preparation of microfluidic channels via soft lithography ii A.2 Predicted secondary structures iv A.2.1 Secondary structures of 100base pair target without probe-strands iv A.2.2 Secondary structures of 100base pair target with 25 base pair probe-strand x Versicherung xvii Acknowledgments xix List of publications xxi Peer-reviewed publications xxi Publications in preparation xxi Selected international conferences xxii Curriculum Vitae xxii

Textile sensors platform for the selective and simultaneous detection of chloride ion and pH in sweat

open7noAcknowledgements. Te National Operation Program (PON) of the Ministry of Education, University and Research supported this work (Project PON-MIUR 2018 (Italy) ARS01_00996: “TEX-STYLE—Nuovi tessuti intelligenti e sostenibili multi-settoriali per design creativo e stile made-in-Italy”). Te authors wish to thank Dr. Nicola Patelli and Dr. Alberto Piccioni for the SEM images.The development of wearable sensors, in particular fully-textile ones, is one of the most interesting open challenges in bioelectronics. Several and significant steps forward have been taken in the last decade in order to achieve a compact, lightweight, cost-effective, and easy to wear platform for healthcare and sport activities real-time monitoring. We have developed a fully textile, multi-thread biosensing platform that can detect different bioanalytes simultaneously without interference, and, as an example, we propose it for testing chloride ions (Cl−) concentration and pH level. The textile sensors are simple threads, based on natural and synthetic fibers, coated with the conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate) (PEDOT:PSS) and properly functionalized with either a nano-composite material or a chemical sensitive dye to obtain Cl− and pH selective sensing functionality, respectively. The single-thread sensors show excellent sensitivity, reproducibility, selectivity, long term stability and the ability to work with small volumes of solution. The performance of the developed textile devices is demonstrated both in buffer solution and in artificial human perspiration to perform on-demand and point-of-care epidermal fluids analysis. The possibility to easily knit or sew the thread sensors into fabrics opens up a new vision for a textile wearable multi-sensing platform achievable in the near future.openPossanzini L.; Decataldo F.; Mariani F.; Gualandi I.; Tessarolo M.; Scavetta E.; Fraboni B.Possanzini L.; Decataldo F.; Mariani F.; Gualandi I.; Tessarolo M.; Scavetta E.; Fraboni B