Engineering Commons^™

Low Temperature Flexible Perovskite Solar Cell With Mesoporous Tio2 Electron Transport Layer In High Humidity Environment, Felipe De La Torre

Theses and Dissertations

Perovskite solar cells are the fastest advancing solar technology to date with efficiencies increasing from 3.9% to more than 21% within a few years. They have emerged as a possible alternative to silicon photovoltaics due to their exceptional photovoltaic performance, light absorbing properties, and low-cost fabrication with methylammonium lead iodide (CH3NH 3PbI3) getting considerable interest in research and development. However, there are still many challenges that must be addressed for perovskite solar cells to replace contemporary solar cells, such as improving their stability, making them nonhazardous, further increasing their efficiency, and developing better techniques for large scale fabrication. In this …

Wearable Piezotronic Devices For Heart Rate Monitoring, Adam J. Miller, Wenzhuo Wu Dr.

The Summer Undergraduate Research Fellowship (SURF) Symposium

Self-powered multifunctional wearable devices that are capable of human-device interfacing are highly desired. Piezotronic devices utilize piezoelectricity and semiconductor properties to enable devices to have seamless interaction between human and device. One important use for piezotronic devices is for pressure sensing. Pressure sensing devices have been employed in smart skins, biomonitoring, gesture recognition, and many more applications. This study aims to create a flexible piezotronic device, specifically for use in pressure sensing to monitor heart rate. ZnO nanowires are grown on a flexible polymer substrate so that they can be made into wearable devices. A p-n heterojunction is formed by …

The Effect Of Flexibility On Interaction Of Two Fibers Settling In Moderate Reynolds Numbers, Ahmed Alhasan

Masters Theses

The behavior of solid particles in a fluid has become an important topic. The need to improve our understanding of the mechanisms of fluid-particle interaction is the motivation for the present work. The characteristics of fibers suspensions depend on the many variables such as flexibility, Reynolds numbers, density and aspect ratio. The aim of this work is to probe effects of these variables on sedimentation behavior by using a fiber-level simulation technique. In this techniques, a D3Q15 model in a lattice Boltzmann equation with a Bhatnagar-Gross-Krook (BGK) approximation is used to simulate motion of fluids, where Navier-Stokes equations are solved …

Development Of Strain And Pressure Sensors On Flexible And Stretchable Platforms, Mohammed Mudher Mohammed Ali

Masters Theses

The capability of the human brain to operate in conjunction with human senses and muscles enables us to become powerful autonomous beings. By using these organs, humans can interact with the surrounding environment. Similarly, the combination of sensors with the signal processing of modern electronics enables the interaction with the non-electrical environment.

In this thesis, the work focuses on the design and fabrication of flexible and stretchable sensors which have been receiving an increased interest for applications such as human body movement, tracking in the biomedical industry, object detection, fingerprint sensor as well as for monitoring deformations or structural changes …

Transfer Printed Semiconductor Nanomembranes For Heterogeneously Integrated Multi-Band Imager Arrays, Laxmy Menon

Electrical Engineering Dissertations

The electronics industry is ruled by silicon which is realized as the solution to meet the requirements of higher bandwidth and low cost high density monolithic integration. However, silicon has its limitations when it comes to high frequency or optoelectronic applications. Fusion of several functionalities on one chip can be obtained by heterogeneous integration of materials that have optimized performance for a specific application. The ability to tailor heterogeneous materials to be able to integrate them with each other, in rigid or flexible form, can lead to novel and superior functionalities, with impact in multitude of areas like electronics, optoelectronics, …

Comparison Of Different Metals As Electrodes For A Flexible Micro Ph Sensor, Pavan Kumar Kota

Electrical Engineering Theses

pH can be explained in general terms as a numerical scale used to state the acidity or basicity of an aqueous solution. Keeping track of pH is very useful in many applications like medicine, civil engineering, chemical engineering, biology, water purification etc. Most commonly used pH sensors employ glass electrodes but there are some disadvantages associated with these kinds of pH sensors. Glass is a rigid, chemically reactive and fragile material. Also, glass electrodes, owing to the size require significant quantity of solution to test for pH which makes it difficult to use in cases where we have very little …

Separation Of Organic Liquid Mixture By Flexible Nanofibrous Membranes With Precisely Tunable Wettability, Lanlan Hou, Li Wang, Nu Wang, Fengyun Guo, Jing Liu, Yuee Chen, Jingchong Liu, Yong Zhao, Lei Jiang

Australian Institute for Innovative Materials - Papers

Separation of liquid mixtures, especially organic liquid mixtures, is widely used in industrial processes but still faces challenges with respect to separation in a high-efficiency, low-energy mode. In this work, we report a flexible wettability-tunable nanofibrous membrane composed of a high-performance fluoro-polymer as the matrix and fluorosilane as a surface energy regulator that can be successfully applied in immiscible organic liquid mixture separation. The separation is achieved by tuning the surface energy of a membrane to a value between the surface tensions of two organic liquids. Moreover, for use in different mixed liquid systems, we programmatically designed nanofibrous membranes with …

A Strategy For Configuration Of An Integrated Flexible Sulfur Cathode For High-Performance Lithium-Sulfur Batteries, Hongqiang Wang, Wenchao Zhang, Hua-Kun Liu, Zaiping Guo

Faculty of Engineering and Information Sciences - Papers: Part A

Lithium-sulfur batteries are regarded as promising candidates for energy storage devices owing to their high theoretical energy density. The practical application is hindered, however, by low sulfur utilization and unsatisfactory capacity retention. Herein, we present a strategy for configuration of the sulfur cathode, which is composed of an integrated carbon/sulfur/carbon sandwich structure on polypropylene separator that is produced using the simple doctor-blade technique. The integrated electrode exhibits excellent flexibility and high mechanical strength. The upper and bottom carbon layers of the sandwich-structured electrode not only work as double current collectors, which effectively improve the conductivity of the electrode, but also …

Finite Element Method Analysis Of Surface Roughness Transfer In Micro Flexible Rolling, Feijun Qu, Haibo Xie, Zhengyi Jiang

Faculty of Engineering and Information Sciences - Papers: Part A

Micro flexible rolling aims to fabricate submillimeter thick strips with varying thickness profile, where the surface quality of products is mainly determined by initial workpiece surface roughness and subsequent surface asperity flattening process, which is affected by process parameters during rolling. This paper shows a 3D finite element model for flexible rolling of a 250 μm thick workpiece with reduction of 20 to 50%, and rolling phase with thinner thickness indicates a better ability to decrease the surface roughness. Four types of initial workpiece surface roughness are studied in the simulation, and the influences of process parameters, such as friction …

Analysis Of Micro Flexible Rolling With Consideration Of Material Heterogeneity, Feijun Qu, Zhengyi Jiang, Haina Lu

Faculty of Engineering and Information Sciences - Papers: Part A

This paper establishes a finite element model to numerically study the springback in thickness direction during micro flexible rolling process, in which 3D Voronoi tessellation has been applied to describe grain boundary and generation process of grain in the workpiece. To reflect material heterogeneity, nine kinds of mechanical properties defined by nine types of heterogeneity coefficients are selected and assigned to Voronoi polyhedrons as per the statistical distribution of hardness of grains identified by micro hardness testing. Initial workpiece thicknesses of 100, 250 and 500 μm with reduction changing from 20% to 50% are respectively considered in the numerical simulation …

Flexible Analysis Of Digital Pcr Experiments Using Generalized Linear Mixed Models, Matthijs Vynck, J Vandesompele, Nele Nijs, Björn Menten, Ariane De Ganck, Olivier Thas

Faculty of Engineering and Information Sciences - Papers: Part A

The use of digital PCR for quantification of nucleic acids is rapidly growing. A major drawback remains the lack of flexible data analysis tools. Published analysis approaches are either tailored to specific problem settings or fail to take into account sources of variability. We propose the generalized linear mixed models framework as a flexible tool for analyzing a wide range of experiments. We also introduce a method for estimating reference gene stability to improve accuracy and precision of copy number and relative expression estimates. We demonstrate the usefulness of the methodology on a complex experimental setup.