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Lookup NU author(s): Dr Zi Jie Choong, Dr Dehong Huo, Dr Nilhil Ponon, Rachael Savidis, Professor Patrick Degenaar, Professor Anthony O'Neill
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND).
© 2020 Elsevier B.V. This paper introduces a new hybrid microfabrication technique which combines ultra-precision micro-milling and a ductile sacrificial material deposition process to fabricate a silicon-based implant for neuroprosthetics applications with near defect-free quality at several hundreds of micrometres in thickness. The sacrificial materials can influence the quality of silicon during machining. The cutting mechanism and feasibility of the hybrid technique are studied by molecular dynamics (MD) simulations and experiments. Due to the complexity of modelling PMMA and SU-8 structures in MD environment, only copper was modelled as the simulation is intended to understand the performance of using a ductile sacrificial layer structure in silicon machining. MD analysis shows that the reduced stress intensity and subsurface damage were mainly attributed to workpiece plasticity enhancement, where its mechanism was contributed by better deformability of the ductile sacrificial layer and enhanced thermal softening from the heat generated by the high interfacial stress between the sacrificial layer and silicon substrate. Despite the MD simulation and experiment having different machining scale in terms of cutting parameters, phenomenal behaviours of the cutting performance when observed under the experimental conditions are in good agreement with simulation. Experimental verification shows that near defect-free quality was achieved at large cutting depth of 150 μm when silicon is coated either with PMMA or SU-8. An exemplary implant structure was also fabricated to better demonstrate the hybrid technique's capability. In addition, the hybrid technique will be beneficial for low volume high customisation applications as it is a serial process.
Author(s): Choong ZJ, Huo D, Ponon N, Savidis R, Degenaar P, O'Neill A
Publication type: Article
Publication status: Published
Journal: Materials Science and Engineering C
Year: 2020
Volume: 110
Print publication date: 01/05/2020
Online publication date: 10/02/2020
Acceptance date: 09/02/2020
Date deposited: 26/03/2020
ISSN (print): 0928-4931
ISSN (electronic): 1873-0191
Publisher: Elsevier Ltd
URL: https://doi.org/10.1016/j.msec.2020.110737
DOI: 10.1016/j.msec.2020.110737
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