Additive Manufacturing (AM) is a unique method of fabrication that, in contrast to traditional manufacturing methods, builds objects layer by layer. The ability of AM (when partnered with 3D scanning) to “clone” physical objects has raised concerns in the area of intellectual property (IP). To address this issue, the goal of this dissertation is to characterize and model a method to incorporate unique security features within AM builds. By adding optically detectable nanoparticles into transparent AM media, Physical Unclonable Function (PUFs) can be embedded into AM builds and serve as an anticounterfeiting measure. The nanoparticle selected for this work is a Quantum Dot (QD), which absorbs UV light and emits light in the visible spectrum. This unique interaction with light makes the QDs ideal for a security system since the “challenge” (UV light) is a different signal from the “response” (the visible light emitted by the QDs).
PolyJet, the AM process selected for this work, utilizes inkjet to deposit a photopolymer into layers, which are then cured with a UV light. An investigation into the visibility of the QDs within the printed PolyJet media revealed that the QDs produce PUF patterns visible via fluorescent microscopy. Furthermore, rheological data shows that the ink-jetting properties of the printing media are not significantly affected by QDs in sufficient concentrations to produce PUFs.
The final objective of this study is to characterize the effects of the QDs on photocuring. The mathematical model to predict the critical exposure of the QD-doped photopolymer utilizes light scattering theory, QD characterization results, and photopolymer-curing characterization results. This mathematical representation will contribute toward the body of knowledge in the area of Additive Manufacturing of nanomaterials in photopolymers.
Overall, this work embodies the first investigations of the effects of QDs on rheological characteristics of ink-jetted media, the effects of QDs on curing of AM photopolymer media, visibility of nanoparticles within printed AM media, and the first attempt to incorporate security features within AM builds. Finally, the major scientific contribution of this work is the theoretical model developed to predict the effects of QDs on the curing properties of AM photopolymers.
|Advisor:||Williams, Christopher B.|
|School:||Virginia Polytechnic Institute and State University|
|School Location:||United States -- Virginia|
|Source:||DAI-B 78/09(E), Dissertation Abstracts International|
|Subjects:||Polymer chemistry, Civil engineering|
|Keywords:||Additive manufacturing, Inkjet, Photopolymers, Physical unclonable functions, Polyjets, Quantum dots|
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