Süsinikmaterjalist elektroodidega ioonsed ja mahtuvuslikud elektroaktiivsed laminaadid sensorite ning energiakogumisseadmetena

Väitekirja elektrooniline versioon ei sisalda publikatsioone.Kaasaegses elektroonika- ja robootikatööstuses valitseb suundumus miniatuursete, autonoomsete ja läbinisti pehmete seadmete väljatöötamisele, mis ühtlasi tingib huvi sobivate materjalide arenduse vastu. Käesolevas töös käsitletakse antud valdkonnale huvipakkuvat pehmet ioonset elektroaktiivset polümeerset laminaatmaterjali (IEAP), mis koosneb suure-eripinnalistest süsinikelektroodidest, poorsest polümeermembraanist ning ioonvedelikust, mis täidab nii elektroodi kui polümeermembraani poore. Antud laminaatmaterjal on väga multifunktsionaalne – varasemalt on tuntud selle energiasalvestus- ja täituriomadused. Käesolevas töös uuritakse antud materjaliklassi uudset omadust – elektrilaengu genereerimise võimet. Esmalt rakendati IEAP laminaati konfiguratsioonis, mis vastab selle kasutamisele elektromehaanilise täiturina, kuid seda painutati välise jõuga. Painutamise tulemusena genereeris IEAP elektrilaengut proportsionaalselt painutuse ulatusega. Seega on võimalik sama IEAP-i kasutada vaheldumisi nii pehme täituri kui liigutussensorina. IEAP-d iseloomustab suur tundlikkus õhuniiskuse suhtes, sest IEAP koosneb ülihügroskoopsetest koostisosadest. Elektrokeemilise impedantsspektroskoopia meetodil selgus, et õhuniiskuse pöörduva absorptsiooni tõttu võivad IEAP elektrilised omadused muutuda enam kui ühe suurusjärgu ulatuses. Antud töös rakendati IEAP materjali kõrget niiskustundlikkust uudses, ootamatus konfiguratsioonis – hügroelektrilise rakuna. Kui IEAP paigutada kahe erineva suhtelise õhuniiskusega keskkonna eralduspiirile, tekib IEAP elektroodidel elektrilaeng. IEAP hügroelektriline rakk võimaldab koguda elektrienergiat ümbritsevast õhuniiskusest, kusjuures õhuniiskusest genereeritav elektrilaeng ületab enam kui suurusjärgu võrra painutussensorit. Siinkohal on määrava tähtsusega ka IEAP-i energiasalvestiomadused – IEAP hügroelektriline rakk ei vaja välist energiasalvestuselementi, vaid genereeritud elektrilaeng salvestatakse samasse materjaliossa, mis antud laengu genereeris.The modern electronics and robotics industry is interested in development of miniature, autonomous, and fully soft devices; consequently, the research on compatible materials is promoted. This work considers one class of materials – ionic electroactive polymer laminate (IEAP), perspective for the given field. An IEAP consists of carbonaceous electrodes with high specific surface area, a porous polymeric separator, and ionic liquid, which fills the pores in electrode and separator. IEAP is a multifunctional material – it is known for its energy storage and actuation capability. The work at hand explores a novel property of IEAP – generation of electric charge. First, an IEAP laminate was employed in a configuration that corresponds to its use as an electromechanical actuator, but it was bent using an external force. The IEAP generated electric charge proportional to the bending magnitude. Consequently, the same IEAP could be used intermittently as a soft actuator and as a motion sensor. IEAP consists of highly hygroscopic materials, which is expressed in its high sensitivity to ambient humidity. Electrochemical impedance spectroscopy revealed that reversible absorption of ambient humidity changes the electrical properties of IEAP over one order of magnitude. In this work, humidity-sensitive IEAP is employed in a novel, unexpected configuration – as a hygroelectrical cell. If an IEAP is placed between environments with unequal relative humidities, electric charge is formed between the IEAP’s electrodes. An IEAP can be used to harvest electric energy from the ambient humidity, whereas the magnitude of the generated charge is more than one order of magnitude higher than in the case of the same material as a motion sensor. At this point, the energy storage properties of IEAP are essential – an IEAP hygroelectrical cell does not require additional energy storage units; instead, the generated electric charge is stored in the same part of the material, where it was generated

MEMS Technology for Biomedical Imaging Applications

Biomedical imaging is the key technique and process to create informative images of the human body or other organic structures for clinical purposes or medical science. Micro-electro-mechanical systems (MEMS) technology has demonstrated enormous potential in biomedical imaging applications due to its outstanding advantages of, for instance, miniaturization, high speed, higher resolution, and convenience of batch fabrication. There are many advancements and breakthroughs developing in the academic community, and there are a few challenges raised accordingly upon the designs, structures, fabrication, integration, and applications of MEMS for all kinds of biomedical imaging. This Special Issue aims to collate and showcase research papers, short commutations, perspectives, and insightful review articles from esteemed colleagues that demonstrate: (1) original works on the topic of MEMS components or devices based on various kinds of mechanisms for biomedical imaging; and (2) new developments and potentials of applying MEMS technology of any kind in biomedical imaging. The objective of this special session is to provide insightful information regarding the technological advancements for the researchers in the community

Nanoelectronics in Oxides and Semiconductors

The success of silicon industry lies on three major properties of silicon, an easily formed oxide layer to allow field effect operation, tunability of carrier density and high device scalability. All these features exist in oxides, together with some novel properties such as ferroelectricity, magnetic effects and metal-insulator transition. With the recent development in material growth method including molecular beam epitaxy (MBE), pulsed laser deposition (PLD) and reflection high energy electron diffraction (REED), atomically engineered oxide interfaces become available, thus opening the door to the novel oxide nanoelectronics. In this dissertation we create and study nanoelectronics in oxides, semiconductors and hybrid of these two. We used a conductive atomic force microscope tip to write single electron transistors in the 3-unit-cell-LaAlO3/SrTiO3 heterostructure and observed ferroelectric tunneling behaviors. We also fabricated ferroelectric field transistors directly on silicon using strained SrTiO3 ferroelectric film and further confirmed the ferroelectric properties of this device. Meanwhile, we developed an ultrasensitive microwave capacitance sensor to study the electronic properties of self-assembled quantum dots and the switching mechanism of memristive devices. The integration of this sensor to a home made atomic force microscope provides an important tool to study the dielectric properties at nanoscale

A Label Free CMOS-Based Smart Petri Dish for Cellular Analysis

RÉSUMÉ Le dépistage de culture cellulaire à haut débit est le principal défi pour une variété d’applications des sciences de la vie, y compris la découverte de nouveaux médicaments et le suivi de la cytotoxicité. L’analyse classique de culture cellulaire est généralement réalisée à l’aide de techniques microscopiques non-intégrées avec le système de culture cellulaire. Celles-ci sont laborieuses spécialement dans le cas des données recueillies en temps réel ou à des fins de surveillance continue. Récemment, les micro-réseaux cellulaires in-vitro ont prouvé de nombreux avantages dans le domaine de surveillance des cellules en réduisant les coûts, le temps et la nécessité d’études sur des modèles animaux. Les microtechniques, y compris la microélectronique et la microfluidique,ont été récemment utilisé dans la biotechnologie pour la miniaturisation des systèmes biologiques et analytiques. Malgré les nombreux efforts consacrés au développement de dispositifs microfluidiques basés sur les techniques de microscopie optique, le développement de capteurs intégrés couplés à des micropuits pour le suivi des paramètres cellulaires tel que la viabilité, le taux de croissance et cytotoxicité a été limité. Parmi les différentes méthodes de détection disponibles, les techniques capacitives offrent une plateforme de faible complexité. Celles-ci ont été considérablement utilisées afin d’étudier l’interaction cellule-surface. Ce type d’interaction est le plus considéré dans la majorité des études biologiques. L’objectif de cette thèse est de trouver des nouvelles approches pour le suivi de la croissance cellulaire et la surveillance de la cytotoxicité à l’aide d’un réseau de capteurs capacitifs entièrement intégré. Une plateforme hybride combinant un circuit microélectronique et une structure microfluidique est proposée pour des applications de détection de cellules et de découverte de nouveaux médicaments. Les techniques biologiques et chimiques nécessaires au fonctionnement de cette plateforme sont aussi proposées. La technologie submicroniques Standard complementary metal-oxide-Semiconductor (CMOS) (TSMC 0.35 μm) est utilisée pour la conception du circuit microélectronique de cette plateforme. En outre, les électrodes sont fabriquées selon le processus CMOS standard sans la nécessité d’étapes de post-traitement supplémentaires. Ceci rend la plateforme proposée unique par rapport aux plateformes de dépistage de culture cellulaire à haut débit existantes. Plusieurs défis ont été identifiés durant le développement de cette plateforme comme la sensibilité, la bio-compatibilité et la stabilité et les solutions correspondantes sont fournies.----------ABSTRACT High throughput cell culture screening is a key challenge for a variety of life science applications, including drug discovery and cytotoxicity monitoring. Conventional cell culture analysis is widely performed using microscopic techniques that are not integrated into the target cell culture system. Additionally, these techniques are too laborious in particular to be used for real-time and continuous monitoring purposes. Recently, it has been proved that invitro cell microarrays offer great advantages for cell monitoring applications by reducing cost, time, and the need for animal model studies. Microtechnologies, including microelectronics and microfluidics, have been recently used in biotechnology for miniaturization of biological and analytical systems. Despite many efforts in developing microfluidic devices using optical microscopy techniques, less attention have been paid on developing fully integrated sensors for monitoring cell parameters such as viability, growth rate, and cytotoxicity. Among various available sensing methods, capacitive techniques offer low complexity platforms. This technique has significantly attracted attentions for the study of cell-surface interaction which is widely considered in biological studies. This thesis focuses on new approaches for cell growth and cytotoxicity monitoring using a fully integrated capacitive sensor array. A hybrid platform combining microelectronic circuitry and microfluidic structure is proposed along with other required biological and chemical techniques for single cell detection and drug discovery applications. Standard submicron complementary metal–oxide–semiconductor (CMOS) technology (TSMC 0.35 μm) is used to develop the microelectronic part of this platform. Also, the sensing electrodes are fabricated in standard CMOS process without the need for any additional post processing step, which makes the proposed platform unique compared to other state of the art high throughput cell assays. Several challenges in implementing this platform such as sensitivity, bio-compatibility, and stability are discussed and corresponding solutions are provided. Specifically, a new surface functionalization method based on polyelectrolyte multilayers deposition is proposed to enhance cell-electrode adherence and to increase sensing electrodes’ life time. In addition, a novel technique for microwell fabrication and its integration with the CMOS chip is proposed to allow parallel screening of cells. With the potential to perform inexpensive, fast, and real-time cell analyses, the proposed platform opens up the possibility to transform from passive traditional cell assays to a smart on-line monitoring system