Date of Graduation

8-2019

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Engineering (PhD)

Degree Level

Graduate

Department

Mechanical Engineering

Advisor/Mentor

Zhou, Wenchao

Committee Member

Wejinya, Uche C.

Second Committee Member

Tung, Chao-Hung Steve

Third Committee Member

Leylek, James H.

Fourth Committee Member

Jensen, Hanna A.

Keywords

3D printed optics; Micro 3D printing; microeheaters; Microextrusion; Molybednum disilicide; Waveguides

Abstract

The drive for smaller and more compact devices presents several challenges in materials and fabrication strategies. Although photolithography is a well-developed method for creating microdevices, the disparate requirements in fabrication strategies, material choices, equipment and process complexities have limited its applications. Microextrusion printing (μEP) provides a promising alternative for microfabrication. Compared to the traditional techniques, the attractions lie in the wide range of printable material choice, greater design freedom, fewer processing steps, lower cost for customized production, and the plurality of compatible substrates. However, while extrusion-based 3D printing processes have been successfully applied at the macroscale, this seeming simplicity belies the dynamic complexities needed for consistent, repeatable, and cost-effective printing at the microscale. The fundamental understanding of the microextrusion printing process is still lacking.

One primary goal of this dissertation, therefore, is to develop the fundamental understanding of μEP. This study elucidates the underlying principles of this printing technique, offering an overall roadmap - stepwise guide for successful printing based on both results in the literature and our experimental tests. The primary motivation is to provide users at both the research and industrial platforms with the requisite knowledge base needed for adapting μEP for microfabrication. Ultimately, this understanding, optimization of materials properties, and process parameters dictate the resolution and quality of the printed features.

Following the improved understanding of microextrusion printing, two complementary goals were set. First, in order to test and validate the applicability the framework, a high-resolution microextrusion 3D printer was designed and implemented to enable high precision printing of microdevices and microstructures. Second, taking advantage of the guiding framework and printing platform, printing of novel materials and devices including flexible optics and a high-temperature microheater were explored and demonstrated. One common thread is observed throughout this work, that is, the development of the fundamental understanding of microextrusion 3D printing and its application for creating functional microdevices and structures. This work opens new possibilities and versatile approach for low-cost patterning of materials and functional devices.

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