A Thesis submitted to The University of Arizona College of Medicine - Phoenix in partial fulfillment of the requirements for the Degree of Doctor of Medicine.

Nitrocellulose is currently the most common porous material used in commercially available lateral flow assays. It is, however, unsafe to manufacture and time consuming to incorporate into multi-component assay devices. Precipitated calcium carbonate is a material produced from naturally occurring lime that can be suspended in a binder and extruded onto a surface. This extruded suspension forms a porous coating through which a solution can be wicked. The physical characteristics of three different types of calcium carbonate types were investigated to determine differences that may yield better lateral flow. The capillary flow rate through the coating was found to be largely affected by the calcium carbonate type used, the binder concentration and whether any post-printing treatment was applied, specifically heating the print. Calcium carbonate has a high specific surface area, which results in a high protein binding capacity. To prevent protein binding, pre-treating calcium carbonate particles prior to forming the suspension in a binder was attempted. Pre-treatment with bovine serum albumin, casein or methoxy-PEG phosphate did not show prevention of protein binding. Furthermore, by treating the calcium carbonate particles with a protein before suspension formulation, the wicking rate after printing was found to be diminished. / Thesis / Master of Applied Science (MASc)

In this study, we explore ultra-thin insulators of organic and inorganic composition and their potential role as high-speed rectifiers. Typical applications for these structures include IR sensing, chemical detection, high speed logic circuits, and MEMS enhancements. While there are many elements in the functional group required to create a rectifying antenna (rectenna), the primary thrust of this work is on the rectifier element itself. To achieve these research goals, a very good understanding of quantum tunneling was required to model the underlying phenomenon of charge conduction. The development of a multi-variable optimization routine for tunneling prediction was required. MATLAB was selected as the programming language for this application because of its flexibility and relative ease of use for simulation purposes. Modeling of physical processes, control of electromechanical systems, and simulation of ion implantation were also to be undertaken. To advance the process science, a lithographic mask set was made which utilized the information gleaned from the theoretical simulations and initial basic experiments to create a number of diode test structures. This came to include the creation of generations of mask sets--each optimizing various parameters including testability, alignment, contact area, device density, and process ease. Following this work, a complete toolset for the creation of "soft" contact top metals was required and needed to be developed. Ultra-flat substrates were needed to improve device reliability and measurement consistency. The final phase of research included measurement and characterization of the resultant structures. Basic DC electrical characterization of the organic monolayers would be accomplished using metal probes. Statistical studies of reliability and process yield could then easily be carried out. The rectification ratio (ratio of forward over reverse current at a given voltage magnitude) was found to be a reliable indicator of diode performance in the low frequency ranges. This would mean writing additional code in MATLAB to assist in the automatic analysis for the acquired IV curves. Progression to AC / RF measurements of tunneling performance was to be accomplished using relatively low frequencies (below 100 MHz). Finally, the organic films themselves would be studied for consistency, impedance characteristics, incidence of defects, and thickness by a variety of metrology techniques. This project resulted in a number of advances to the state-of-the-art in nanofabrication using organic monolayers. A very detailed review of the state of alkanethiol research was presented and submitted for publication. A single pot technique was developed to softly deposit metal nanoparticles onto a charged surface with a high degree of control. A temporary contact method using pure, sub-cooled gallium liquid metal was used to probe organic monolayers and plot IV curves with better understanding of surface states than before. An inkjet printer solution was devised for top contact printing which involved the development and production of a work-up free insulator ink which is water soluble and printable to resolutions of about 25 um. Localized selective chemical crosslinking was found to reduce printed ink solubility following deposition. Future work will likely include additional exploration of crosslinkable Langmuir-Blodgett films as MIM insulators. Stability and testing will hinge on the fabrication of enclosures or packages for environmental isolation.

Thermal constraints and the quantum limit will soon put a boundary on the scale of new micro and nano magnetoelectronic devices. This necessitates a push into the limits of harnessable natural phenomena to facilitate a post-Moore’s era of design. Requirements for thermodynamic stability at room temperature, fast (Ghz) switching, and low energy cost narrow the list of candidates. Molecular electronic frontier orbital structure of some d-block transition metal ions in crystal fields will deform in response to their local energetic environment, giving rise to the eg and t2g suborbitals. More specifically, in an mononuclear Fe(II) complex, the energetic scale between these two orbitals yields an S=0 low spin diamagnetic state and an S=2 high spin paramagnetic state. Spin crossover complex [Fe{H2B (pz) 2 }2 (bipy)] will show locking of its spin state well above the transition temperature, with an accompanied change of conductivity, when placed in a polar environment. Here we show voltage controllable, room temperature, stable locking of the spin state, and the corresponding conductivity change, when molecular thin films of [Fe{H2B (pz) 2 }2 (bipy)] are deposited on a ferroelectric polyvinylidene fluoride hexafluropropylene substrate. This opens the door to the creation of a thermodynamically stable, room temperature, molecular multiferroic gated voltage device.

Conducting polymers entered the research field in late 70´s and efforts aimed at achieving printed electronics started a decade later. This thesis treats printable organic electrochemical transistors (OECT). Some conjugated polymers can be switched between a high conducting and a low conducting state in an electrochemical cell. In this thesis, the work carried out using poly(3,4-ethylenedioxythiophene) (PEDOT) as the active material in an electrochemical transistor is reported. The electrochemical transistors, presented, can be designed into a bi-stable and dynamic mode of operation. These transistors operates at voltages below 2V and current on/off ratios are typically 5000, but 105 have been reached. The transistor device can be built up from all-organic materials using common printing techniques such as with screen-printing. The bi-stable transistor can be combined with an electrochromic (EC) display cell to form a smart pixel circuit. Combining several of these smart pixels yield an actively addressed cross-point matrix display. From this an all-organic active matrix display printable on paper has been achieved. The OECT, combined with a resistor network was successfully used in inverter and logic circuits. One important feature of these organic electrochemical devices is that both ions and electrons are used as the charge (signal) carriers. This is of particular interest and importance for chemical sensors. By combining a proton-conducting electrolyte (Nafion®) that changes its conductivity upon exposure to humidity, a simple OECT humidity sensor was achieved. This proves the use of this OECT as the ion-to-electron transducer.

<p>The 2020 pandemic emphasized the need for accessible and accurate point-of-care diagnostic tests. With the continued development of isothermal nucleic acid amplification tests, this can be achieved. A requirement of these tests includes heating and holding a specific temperature, in this case, 65C for 30 minutes, for amplification to occur. To achieve this, heaters often require external feedback to control the temperature; bringing up the device’s cost. Several self-regulating heaters have been made with materials having a positive thermal coefficient of resistance eliminating the need for complex circuitry. With this property, point-of-care diagnostic tests can be simplified and made more accessible. In this study, ink-based positive thermal coefficient of resistance heaters are developed and characterized using the scalable method of screen printing to achieve 65C and aid in the detection of SARS-CoV-2. Various curing methods and screen-printing parameters were evaluated to improve the stability and understanding of the reproducibility of the heaters. The longevity of the heaters was evaluated with oxidation studies and a COMSOL model was created to study the heat transfer within the device. Furthermore, the heaters were successfully implemented into a second-generation electronic point-of-care diagnostic device. Detection of SARS-CoV-2 using a self-regulating heater removes the need for complex circuitry, improving the accessibility of point-of-care tests with the potential to be expanded to a wide range of pathogen detection. </p>

<p dir="ltr">Origami has emerged as a design paradigm to realize morphing structures with rich kinematic and mechanical properties. Biological examples augment the potential folding design space by suggesting intriguing routes for achieving and expanding crease patterns which traditional origami laws are unable to capture. Specifically, spring origami theory exploits the material system architecture and energy storage mechanism of the earwig wing featuring one of the highest folding ratios in the animal kingdom (1:18), minimal energy required for deployment and collapse of the wing, and bistability locking the wing in closed, and open configurations for crawling through tunnels, and flight, respectively. The central mechanism responsible for bistability in the wing features a non-developable crease pattern with a non-zero Gaussian curvature. Reconfiguring, or even flattening a structure with such an intrinsic property requires stretching or tearing; soft, rubbery material found in the creases of the central mechanism allows for stretching enabling shape transformations between open and closed states without tearing. In the first part of this thesis, such characteristics are transferred to a synthetic bistable soft robotic gripper leveraging the shape adaptability and conformability exhibited by the biological organism to minimize actuation energy. This is achieved by integrating soft, flexible material in the bioinspired gripper that allows kinematically driven geometries to grasp and manipulate objects without continuous actuation. Secondly, the stiffening effect from spring origami is utilized in a bioinspired wing for an aerial--aquatic robot. Transitions between air and sea in multimodal robots is challenging, however, a structurally efficient and multifunctional membrane is developed to increase locomotive capabilities and longer flights. This is motivated by the flying fish's locomotive modules and origami design principles for deployment and folding. Additionally, to keep the wing in a stiff state while gliding, spring origami bistable units are integrated into the membrane inducing self-stiffening and a global curvature reducing energy expenditure while generating lift. While the previous examples present solutions to adaptive manipulation and membrane multifunctionality, once programmed, their shapes are fixed. In the third application, a class of multistable self-folding origami architectures that are reprogrammable post fabrication are presented. This is achieved by encoding prestrain in bilayer creases with anisotropic shrinkage that change shape and induce a local curvature in the creases in response to external stimuli. The topology of the energy landscapes can thus be tuned as a function of the stimulation time and adaptable post fabrication. The proposed method and model allows for converting flat sheets with arranged facets and prestrained mountain-valley creases into self-folding multistable structures. Lasty, encoding crease prestrain is leveraged to manufacture a biomimetic earwig wing featuring the complex crease pattern, structural stability, and rapid closure of the biological counterpart. The presented method provides a route for encoding prestrain in self-folding origami, the multistability of which is adaptable after fabrication.</p>

<div>Glutamate is the principal excitatory neurotransmitter in the central nervous system. As one of the most abundant neurotransmitters, glutamate plays an essential role in many processes of the central nervous system and beyond. As a result, any disruption that causes an abnormal glutamate level can significantly impact the central nervous system's neurological functions. Glutamate excitotoxicity is a neuropathology that persists in many neurodegenerative disorders such as Parkinson's and Alzheimer's disease as well as in the traumatic brain and spinal cord injuries. Thus, the ability to obtain precise information about the extracellular glutamate level in the living brain and spinal cord tissue may provide new insights into the fundamental understanding of glutamate in neurological disorders and neurophysiological phenomena.</div><div><br></div><div>Conventional bioanalytical techniques that characterize glutamate levels <i>in vivo</i> have a low spatiotemporal resolution that has impeded our understanding of this dynamic event. The electrochemical sensor has emerged as a promising solution that can satisfy the requirement for highly reliable and continuous monitoring methods with an excellent spatiotemporal resolution for the characterization of extracellular glutamate concentration. In this thesis, I present various amperometric biosensors fabricated using a simple direct ink writing technique for<i> ex vivo </i>and <i>in vivo</i> glutamate monitoring.</div><div><br></div><div>The amperometric biosensor is fabricated by immobilizing glutamate oxidase on nanocomposite electrodes made of platinum nanoparticles, multiwalled carbon nanotubes, and a conductive polymer. The biosensors demonstrate good sensitivity and selectivity that can be inserted into a spinal cord and measure extracellular glutamate concentration. Additionally, another type of glutamate biosensor is fabricated from commercially available activated carbon with platinum microparticles. We utilize astrocyte cell culture to demonstrate our biosensor's ability to monitor the glutamate uptake process. We also present a direct measurement of glutamate release from optogenetic stimulation in mouse primary visual cortex brain slides. </div><div><br></div><div>Moreover, we explore a new type of material, perovskite nickelate-Nafion heterostructure, to fabricate biosensors and measure glutamate inside the mouse brain. Finally, by utilizing the nanocomposite ink and direct ink writing technique, we also fabricate the gold-ruthenium non-enzymatic glucose biosensor. We apply a modified Butler-Volmer non-linear model to evaluate the impact of geometrical and chemical design parameters of non-enzymatic biosensor performance. </div><div><br></div>

Angetrieben von vielversprechenden Effizienzsteigerungen wird der Beton-3D-Druck stetig weiterentwickelt. Um die gewonnenen Erkenntnisse niederschwellig in die Baupraxis zu überführen, empfehlen sich druckbare Betone im Rahmen des geltenden Regelwerks. Dabei stellt die Limitierung des Mehlkorngehalts eine Herausforderung dar. Um diese zu meistern, wird eine verallgemeinerbare, numerisch unterstützte Anwendung der Korngrößenverteilung nach Andreasen und Andersen als Basis für den Betonentwurf vorgeschlagen. Experimentelle Untersuchungen haben eine gute Verbaubarkeit und hinreichende Extrudierbarkeit eines Betons mit einem 16 mm Größtkorn und einem Mehlkorngehalt von 500 kg/m³ demonstriert.

This thesis addresses the development of materials, technologies and circuits applied for the fabrication of a new class of microelectronic devices that are relying on a three-dimensional shape variation namely shapeable microelectronics. Shapeable microelectronics has a far-reachable future in foreseeable applications that are dealing with arbitrarily shaped geometries, revolutionizing the field of neuronal implants and interfaces, mechanical prosthetics and regenerative medicine in general. Shapeable microelectronics can deterministically interface and stimulate delicate biological tissue mechanically or electrically. Applied in flexible and printable devices shapeable microelectronics can provide novel functionalities with unmatched mechanical and electrical performance. For the purpose of shapeable microelectronics, novel materials based on metallic multilayers, photopatternable organic and metal-organic polymers were synthesized. Achieved polymeric platform, being mechanically adaptable, provides possibility of a gentle automatic attachment and subsequent release of active micro-scale devices. Equipped with integrated electronic the platform provides an interface to the neural tissue, confining neural fibers and, if necessary, guiding the regeneration of the tissue with a minimal impact. The self-assembly capability of the platform enables the high yield manufacture of three-dimensionally shaped devices that are relying on geometry/stress dependent physical effects that are evolving in magnetic materials including magentostriction and shape anisotropy. Developed arrays of giant magnetoimpedance sensors and cuff implants provide a possibility to address physiological processes locally or distantly via magnetic and electric fields that are generated deep inside the organism, providing unique real time health monitoring capabilities. Fabricated on a large scale shapeable magnetosensory systems and nanostructured materials demonstrate outstanding mechanical and electrical performance. The novel, shapeable form of electronics can revolutionize the field of mechanical prosthetics, wearable devices, medical aids and commercial devices by adding novel sensory functionalities, increasing their capabilities, reducing size and power consumption.