Electrophoretically Guided micro Additive Manufacturing – EPuAM

Pritchet, David

doi:https://doi.org/10.21985/n2-dj97-dz94

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Electrophoretically Guided micro Additive Manufacturing – EPuAM

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Over the last several decades, market-driven needs created a vast assortment of products with micron-sized features. To achieve the necessary levels of precision and accuracy, a synergistic approach was undertaken, where both material addition and subtraction was employed in the creation of the desired parts. However, currently employed micromanufacturing processes suffer from lack of flexibility and scalability, where the user has to make the tradeoffs between accuracy and productivity. This problem is emphasized through the use of complex, high maintenance equipment, and convoluted process operations that result in a situation where new product designs necessitate a partial, or complete redesign of the production lines. This work reports on the development of a new micromanufacturing process, motivated by the perceived shortcomings of the existing methods, namely lack of multi-material processability and part scalability. The new process is based on additive manufacturing principle, where the desired part geometry is gradually built by depositing the material in the desired location, layer by layer. The multi-material processability is ensured with the use of the electrophoretic deposition process (EDP) as a primary way of depositing material. The EDP uses uniform electric fields to deposit suspended particles – this process is enhanced with the dielectrophoresis phenomenon (DEP), where nonuniform electric fields create nonuniform polarization on the surface of a particle or a micron-sized object, and subsequently enable finer manipulation and sorting capabilities of said objects. The nonuniform electric field is generated via (micro)electrode array, which ensures highly flexible and scalable processing. Because the new process uses electric fields to control the particle deposition and manipulation, it is named Electrophoretically Guided micro Additive Manufacturing (EPµAM). Relevant literature search on the topics of EDP, DEP, and particle self-assembly, used in the new process conceptualization, is presented for reference purposes. Initial modeling efforts, developed control paradigm, and hardware and software testbed implementations precede preliminary EPμAM device and process characterization efforts. The developed models of the EPμAM process were used in various stages of the process and device design. Force balance analysis and governing equations of the EPμAM process facilitated the development of a novel open-loop control paradigm, which was implemented as a prototype control system on the EPμAM hardware platform. On one side, finite element analysis was used for the determination of optimized electrode geometry and the most efficient actuating waveforms for the generation of non-uniform electric fields. On the other side, a 2D multiphysics model of the EPμAM process was developed where particle trajectories and deposition locations were successfully predicted and validated with empirical results. The equivalent electric circuit model is presented as a means for the determination of initial process parameters for the EPμAM process and further EPμAM process planning. The current EPμAM platform is presented from the system design and integration standpoints, where iterative design approach was used to create solutions for all system requirements. Proof of principle goals for the EPμAM process, where the achieved nonuniform and localized particle depositions are presented alongside the developed process characterization procedures and relevant, physics-based process metrics. In summary, a new micro-additive manufacturing process was developed. Necessary, physics-related theories are explained through modeling efforts that covered several aspects of the EPμAM process. Hardware and software implementations of the basic EPμAM functionality are reported. Preliminary empirical characterization efforts demonstrated the EPμAM process viability and stability. This was followed by a discussion of the future application potential of the developed process.

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