This experiment investigated the effect of infill pattern shape on structural stiffness for 3D printed components made out of carbon fiber reinforced nylon. In order to determine the natural frequency of each specimen, nondestructive vibrational testing was conducted and processed using data acquisition software. After obtaining the acceleration information of each component, in response to ambient vibrational conditions and excitation, frequency response functions were generated. These functions provided the natural frequency of each component, making it possible to calculate their respective stiffness values. The four infill patterns investigated in this experiment were: Zig Zag, Tri-Hex, Triangle, and Concentric. Results of the experiment showed that changing the infill pattern of a 3D printed component, while maintaining a constant geometry and density, could increase mechanical stiffness properties by a factor of two. Comprehensively, the experiment showed that infill pattern geometry directly attributes to the mechanical stiffness of 3D printed components. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection

abstract: BioMEMS has the potential to provide many future tools for life sciences, combined with microfabrication technologies and biomaterials. Especially due to the recent corona 19 epidemic, interest in BioMEMS technology has increased significantly, and the related research has also grown significantly. The field with the highest demand for BioMEMS devices is in the medical field. In particular, the implantable device field is the largest sector where cutting-edge BioMEMS technology is applied along with nanotechnology, artificial intelligence, genetic engineering, etc. However, implantable devices used for brain diseases are still very limited because unlike other parts of human organs, the brain is still unknow area which cannot be completely replaceable.To date, the most commercially used, almost only, implantable device for the brain is a shunt system for the treatment of hydrocephalus. The current cerebrospinal fluid (CSF) shunt treatment yields high failure rates: ~40% within first 2 years and 98% within 10 years. These failures lead to high hospital admission rates and repeated invasive surgical procedures, along with reduced quality of life. New treatments are needed to improve the disease burden associated with hydrocephalus. In this research, the proposed catheter-free, completely-passive miniaturized valve is designed to alleviate hydrocephalus at the originating site of the disorder and diminish failure mechanisms associated with current treatment methods. The valve is composed of hydrogel diaphragm structure and polymer or glass outer frame which are 100% bio-compatible material. The valve aims to be implanted between the sub-arachnoid space and the superior sagittal sinus to regulate the CSF flow substituting for the obstructed arachnoid granulations. A cardiac pacemaker is one of the longest and most widely used implantable devices and the wireless technology is the most widely used with it for easy acquisition of vital signs and rapid disease diagnosis without clinical surgery. But the conventional pacemakers with some wireless technology face some essential complications associated with finite battery life, ultra-vein pacing leads, and risk of infection from device pockets and leads. To solve these problems, wireless cardiac pacemaker operating in fully-passive modality is proposed and demonstrates the promising potential by realizing a prototype and functional evaluating. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2020

Electronic skin (e-skin) materials have gained a wide range of attention due to their multiple applications in different areas, including soft robotics, skin attachable electronics, prosthetics, and health care. These materials are required to emulate tactile perceptions and sense the surrounding environments while maintaining properties such as flexibility and stretchability. Current e-skin fabrication techniques, such as photolithography, screen printing, lamination, and laser reducing, have limitations in terms of costs and manufacturing scalability, which ultimately preventing e-skin widespread usage. In this work, we introduce conductive stretchable 3D printable skin-like nanocomposite material. Our nanocomposite is easily 3D printed, cost-effective, and actively senses physical stimuli, such as strain and pressure, which gave them the potential to be used in prosthetics, skin-attachable electronics, and soft robotics applications. Using the conductive properties of carbon nanofibers, alongside a polymeric matrix based on Smooth-on platinum cured silicone and crosslinked PDMS, we can obtain a flexible and stretchable material that resembles human skin and can conduct electricity. A great advantage in our composite is the ability to tune its mechanical properties to fit the desired application area through varying PDMS's chain lengths and composition ratios in the nanocomposite. Also, the interconnecting network of micrometer-long nanofibers allows the measurement of resistivity changes upon physical stimuli, granting the nanocomposite sensing abilities. Moreover, we explored and optimized 3D printing of the nanocomposite material, which offering simplicity and versatility for fabricating complex 3D structures at lower costs.

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The ability to generate a range of concentrations of various solutions rapidly and conveniently is an ongoing need in biotechnology. In this thesis we demonstrate how we took advantage of the full process control afforded by our recent custom high resolution 3D printer and resin advances to realize highly integrated and miniaturized microfluidic components for simultaneous on-chip serial dilution for dose-response assays. With judicious selection of mixed layer thicknesses and pixel-by-pixel dose control, we show that the diameter of 3D printed membrane valves can be reduced from 300 µm to 46 µm. We further introduce an entirely new kind of 3D printed valve, termed a squeeze valve, in which the active area is reduced still further to 15 µm x 15 µm. We demonstrate and characterize pumps based on each type of valve and introduce a short (<1 mm long) high aspect ratio channel that enables rapid diffusion-based mixing. We show that combining two pumps with this diffusion mixing channel results in a highly compact 1:1 mixer component. Connecting 10 of these components in series yields a miniature 10 stage 2-fold microfluidic serial dilution module that from two solution inputs simultaneously generates 10 output concentrations that cover three orders of magnitude. We show the efficacy of our serial dilution approach by demonstrating an assay for dose-dependent permeabilization of A549 cells in different concentrations of digitonin integrated into a single device. Our demonstration of component miniaturization in conjunction with a high degree of integration illustrates the promise of 3D printing to enable highly functional and compact microfluidic devices for a variety of biomolecular applications.

The aim of my diploma thesis was engineering design of 4x4 chassis dynamometer model at 1:10 scale for presentation purpose and for testing RC cars models. The first part describes the current types of chassis dynamometers. The main goal of the thesis was designed the model itself in order to produce some parts of the dynamometer using 3D printing. The work also includes production drawings of individual parts and economic estimate of the entire production.

This work is focused on solving the problems of delta 3d printer frame rigidity and impact of rigidity on final quality of 3d printing. A variant of a 3d printer on a classic Kossel-shaped frame has designed and built. Further, frame strength analysis and improvement design is performed, with subsequent production of a new variant and comparison of the 3d printing results of both variants. The result of this work is to show how the frame construction really affects the print quality.

This thesis deals with properties of austenitic stainless steel 304L processed by SLM technology and tested at room and cryogenics temperatures. Result is description of mechanical properties and microstructure. First step was to develop processing parameters to achieve porosity of prints fell below 0,01 %. Following tensile test showed higher yield and ultimate tensile strength than conventionally fabricated parts, even at temperature -80 °C, but at cost of reduced ductility. Due to deformation and low temperature austenite transformed into martensite. This transformation also occurred in Charpy toughness test, that resulted in ductile to brittle behaviour.

Sandwich panels serve many purposes in engineering applications. Additive manufacturing opened the door for easy fabrication of the sandwich panels with different core structures. In this study, additive manufacturing technique, experiments, and numerical analysis are combined to evaluate the mechanical properties of sandwich panels with different cellular core structures. The sandwich panels having honeycomb, re-entrant honeycomb, diamond, square core topologies are printed with the vat photopolymerization technique. Uniaxial compression testing is performed to determine the compressive modulus, strength, and specific strength of these lightweight panels. Elasto-plastic finite element analysis having good similarities with the experimental results provided a preview of the stress distribution of the sandwich panels under applied loading. The imaging of the tested samples showed the fractured regions of the cellular cores. Dynamic mechanical analysis of the panels provided scope to compare the performance of panels and solid materials with the variation of temperature. Sandwich panels with the diamond structure exhibit better compressive properties and specific strength while the re-entrant structure offers high energy absorption capacity. The sandwich structures provided better thermo-mechanical properties than the solid material. The findings of this study offer insights into the mechanical properties of sandwich panels printed with vat photopolymerization technique which can benefit a wide range of engineering applications.