Origami-based design is increasing in popularity as its benefits and advantages become better understood and explored. However, many opportunities still exist for the application of origami principles to engineered designs, especially in the use of non-paper, thick sheet materials. One specific area utilizing thick sheet materials that is especially promising is origami-based mechanisms that require electrical power transfer applications. Many of these opportunities can be met by the use of surrogate folds. This thesis provides methods and frameworks that can be used by engineers to efficiently select and design surrogate folds for use in origami-based mechanisms and products. Surrogate folds are a means of achieving fold-like behavior, offering a simple method for achieving folding motions in thicker materials. A surrogate fold is a localized reduction in stiffness in a given direction allowing the material to function like a fold. A family of surrogate folds is reviewed, and the respective behaviors of the folds discussed. For a specified fold configuration, the material thickness is varied to yield different sizes of surrogate folds. Constraint assumptions drive the design, and the resultant configurations are compared for bending motions. Finite element and analytical models for the folds are also compared. Prototypes are made from different materials. This work creates a base for creating design guidelines for using surrogate folds in thick sheet materials. As mechanisms with origami-like movement increase in popularity, there is a need for conducting electrical power across folds. Surrogate folds can be used to address this need. Current methods and opportunities for conducting across folds are reviewed. A framework for designing conductive surrogate folds that can be adapted to fit specific applications is presented. Equations for calculating the electrical resistance in single surrogate folds as well as arrays are given. Prototypes of several conductive joints are presented and discussed. The framework is then followed in the design and manufacture of a conductive origami-inspired mechanism.

Neuro-engineering is an emerging multi-disciplinary domain which investigates the electrophysiological activities of the nervous system. It provides procedures and techniques to explore, analyze and characterize the functions of the different components comprising the nervous system. Neuro-engineering is not limited to research applications; it is employed in developing unconventional therapeutic techniques for treating different neurological disorders and restoring lost sensory or motor functions. Microelectrodes are principal elements in functional electric stimulation (FES) systems used in electrophysiological procedures. They are used in establishing an interface with the individual neurons or in clusters to record activities and communications, as well as modulate neuron behaviour through stimulation. Microelectrode technologies progressed through several modifications and innovations to improve their functionality and usability. However, conventional electrode technologies are open to further development, and advancement in microelectrodes technology will progressively meliorate the neuro-interfacing and electrotherapeutic techniques. This research introduced design methodology and fabrication processes for intra-cortical microelectrodes capable of befitting a wide range of design requirements and applications. The design process was employed in developing and implementing an ensemble of intra-cortical microelectrodes customized for different neuro-interfacing applications. The proposed designs presented several innovations and novelties. The research addressed practical considerations including assembly and interconnection to external circuitry. The research was concluded by exhibiting the Waterloo Array which is a high channel count flexible 3-D neuro-interfacing array. Finally, the dissertation was concluded by demonstrating the characterization, in vitro and acute in vivo testing results of the Waterloo Array. The implemented electrodes were tested and benchmarked against commercial equivalents and the results manifested improvement in the electrode performance compared to conventional electrodes. Electrode testing and evaluation were conducted in the Krembil Neuroscience Centre Research Lab (Toronto Western Hospital), and the Neurosciences & Mental Health Research Institute (the Sick Kids hospital). The research results and outcomes are currently being employed in developing chronic intra-cortical and electrocorticography (ECoG) electrode arrays for the epilepsy research and rodents nervous system investigations. The introduced electrode technologies will be used to develop customized designs for the clinical research labs collaborating with CIRFE Lab.

Les transistors organiques à effet de champ (OFETs) ont aujourd’hui des performances qui permettent d’envisager la réalisation de circuits électroniques plus ou moins complexes. Cependant, ces dispositifs doivent encore être améliorés en termes de performance et de stabilité sous air avant d’être commercialisés. Le premier objectif de cette thèse est de réaliser des OFETs stables à l’air avec des performances atteignant l’état de l’art, tout en simplifiant leur procédé de fabrication. Le dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (DNTT),petite molécule référence, a été choisie comme couche active des dispositifs pour chaque étude. En insérant une couche interfaciale d’oxyde entre le matériau de contact et le SCO de nos OFETs, une étude a été menée sur la réduction de la résistance de contact, qui affecte la mobilité effective des porteurs de charge mais peut également compliquer l’élaboration de circuits. Dans le but de réaliser des OFETs sur substrats flexibles opérant à de faibles tensions,un travail a été réalisé sur le dépôt d’un diélectrique à forte capacité dont la surface a ensuite été passivée et lissée par un polymère. Les transistors de type p obtenus présentent des performances hautes en termes de mobilité (2,4 cm2.V-1.s-1) et de ratio des courant On/Off (>106) avec une faible tension de seuil et aucune hystérésis. Le second objectif a été de réaliser des simulations sur ces OFETs optimisés avec le logiciel GoldenGate dans l’environnement Cadence Virtuoso®, pour obtenir les paramètres nécessaires à l’élaboration d’un circuit amplificateur. Enfin, des composants passifs (résistances) ont été développés et un circuit détecteur d’amplitude sur substrat flexible a été élaboré et testé. / Organic field effect transistors (OFETs) have huge potential in the applications of future electronics, such as flexible circuits and displays or medical application. However, stability and performances of OFETs need to be improved, so as to reach the real market applications.First objective of this work is to realize air stable OFETs with state of the art performance. To that end, several approaches have been applied with special focus on process simplification. Small molecule, dinaphtho[2,3-b:2',3‘-f]thieno[3,2-b]thiophene (DNTT) has been chosen as the active layer for all devices studies. Metal electrodes in combination with oxide interfacial layers were investigated to decrease the contact resistance, which not only affects eventual mobility that can be achieved but also complicates circuit design. A systematic study was carried out to fabricate high capacitance dielectric layer and passivating the surface with proper interfacial layers. These approaches allowed to obtain high performance OFET on plastic substrate with high mobility (2.4cm2.V-1.s-1), high current on/off ratio (> 106), low threshold voltage and no hysteresis As the second objective, OFET devices were simulated using GoldenGate (with Cadence Virtuoso® environment) to derive relevant parameters, which helped to design amplifier circuit. Finally, passive component (resistance) has been developed and final circuit was realized and characterized.