Electric Field Guided Micro Additive Manufacturing Process

Northwestern University, Evanston IL

Investigators

Abstract

Products with micron- and sub-micron-sized features find widespread applications in the electronic, biomedical, aeronautics, and energy industries for enhanced efficiency and functionality, yet existing techniques are limited in their ability to generate complex structures with the required features. The goal of this project is to enable a new micro-additive manufacturing process in which an electric field guides the deposition of particles into three-dimensional structures. The process is characterized by micron-level resolution, wide material selection, and superior processing time. The scientific findings of this work can also potentially contribute to overcoming challenges related to contact handling of micro-components and offer a new tool for contactless micro-assembly. This interdisciplinary research will promote the training of new generations of engineers and scientists with broad and deep knowledge in modern micro-manufacturing science and technology, which will have derivative effects on the US economy. The technical approach is based on the use of electrophoretic deposition in which an externally applied electric field governs the movement, agglomeration, and deposition of dispersed particles in a solvent, without requiring expensive and complex tooling and processing equipment. This research will provide the knowledge needed to establish the new micro additive manufacturing technology by completing the following tasks: creating reliable models for force field control of particle trajectories in a dielectrophoretic deposition process with arrays of micro electrodes; understanding the underlying physics behind the guided self-assembly of the particles in the deposition phase of the dielectrophoretic deposition; establishing a numerical model to characterize the influence of the electric field on the already deposited structure's stability; and verifying the developed model on a laboratory-scale prototyping system. The control of the force field will be based on an extended effective field method that is based on the modified Nernst-Planck equations to account for particle and particle charge concentration. Particle adhesion to the substrate surface and consecutive self-organization mechanics will be modeled as an electric charge redistribution and energy minimization problem, respectively. A streamlined numerical model for structural stability of the particle layer during new layer deposition will be implemented to characterize the deposited layer as a new deposition surface. The numerical models will facilitate the optimization of the electrode geometry and electrode array topology with respect to process accuracy, repeatability of the builds, and electrode durability.