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- All Subjects: Perchlorates--Electric properties.
- Genre: Masters Thesis
- Resource Type: Text
Description
Electronic devices based on various stimuli responsive polymers are anticipated to have great potential for applications in innovative electronics due to their inherent intelligence and flexibility. However, the electronic properties of these soft materials are poor and the applications have been limited due to their weak compatibility with functional materials. Therefore, the integration of stimuli responsive polymers with other functional materials like Silicon is strongly demanded. Here, we present successful strategies to integrate environmentally sensitive hydrogels with Silicon, a typical high-performance electronic material, and demonstrate the intelligent and stretchable capability of this system. The goal of this project is to develop integrated smart devices comprising of soft stimuli responsive polymeric-substrates with conventional semiconductor materials such as Silicon, which can respond to various external stimuli like pH, temperature, light etc. Specifically, these devices combine the merits of high quality crystalline semiconductor materials and the mechanical flexibility/stretchability of polymers. Our innovative system consists of ultra-thin Silicon ribbons bonded to an intelligently stretchable substrate which is intended to interpret and exert environmental signals and provide the desired stress relief. As one of the specific examples, we chose as a substrate the standard thermo-sensitive poly(N-isopropylacrylamide) (PNIPAAm) hydrogel with fast response and large deformation. In order to make the surface of the hydrogel waterproof and smooth for high-quality Silicon transfer, we introduced an intermediate layer of poly(dimethylsiloxane) (PDMS) between the substrate and the Silicon ribbons. The optical microscope results have shown that the system enables stiff Silicon ribbons to become adaptive and drivable by the soft environmentally sensitive substrate. Furthermore, we pioneered the development of complex geometries with two different methods: one is using stereolithography to electronically control the patterns and build up their profiles layer by layer; the other is integrating different multifunctional polymers. In this report, we have designed a bilayer structure comprising of a PNIPAAm hydrogel and a hybrid hydrogel of N-isopropylacrylamide (NIPAAm) and acrylic acid (AA). Typical variable curvatures can be obtained by the hydrogels with different dimensional expansion. These structures hold interesting possibilities in the design of electronic devices with tunable curvature.
ContributorsPan, Yuping (Author) / Dai, Lenore (Thesis advisor) / Jiang, Hanqing (Thesis advisor) / Lind, Mary Laura (Committee member) / Arizona State University (Publisher)
Created2012
Description
In recent years, a new type of ionic salt based solid propellant, considered inert until the application of an electric current induces an electro-chemical reaction, has been under investigation due to its broad range of possible uses. However, while many electric propellant formulations and applications have been explored over the years, a fundamental understanding of the operational mechanisms of this propellant is necessary in order to move forward with development and implementation of this technology. It has been suggested that the metallic additive included in the formulation studied during this investigation may be playing an additional, currently unknown role in the operation and performance of the propellant. This study was designed to examine variations of an electric propellant formulation with the purpose of investigating propellant bulk volume electrical resistivity in order to attempt to determine information regarding the fundamental science behind the operation of this material. Within a set of fractional factorial experiments, variations of the propellant material made with tungsten, copper, carbon black, and no additive were manufactured using three different particle size ranges and three different volume percentage particle loadings. Each of these formulations (a total of 21 samples and 189 specimens) were tested for quantitative electrical resistivity values at three different pulse generator input voltage values. The data gathered from these experiments suggests that this electric propellant formulation’s resistivity value does change based upon the included additive. The resulting data has also revealed a parabolic response behavior noticeable in the 2D and 3D additive loading percentage versus additive particle size visualizations, the lowest point of which, occurring at an approximately 2.3% additive loading percentage value, could be indicative of the effects of the percolation phenomena on this material. Finally, the investigation results have been loosely correlated to power consumption testing results from previous work that may indicate that it is possible to relate propellant electrical resistivity and operating requirements. Throughout this study, however, it is obvious based on the data gathered that more information is required to be certain of these conclusions and in order to fully understand how this technology can be controlled for future use.
ContributorsBrunacini, Lauren (Author) / Middleton, James (Thesis advisor) / Dai, Lenore (Committee member) / Langhenry, Mark T (Committee member) / Arizona State University (Publisher)
Created2019