Three-Dimensional Metal Microprinting Based on Controlled Removal of Self-Assembled Monolayers

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The development of micro electromechanical systems (MEMS), optical precision systems, micro total analysis system and other similar systems increased the demand for the efficient manufacture of micro/nano metallic components. Currently, 3D metal printing is mainly achieved by thermal based processes, such as selective laser sintering (SLS), electron beam melting (EBM) and liquid metal droplet-based manufacturing. These thermal based techniques involve melt and solidification processes of metal material which always lead to lots of defects in the components (coarse grain, concentration of residual stress, existence of micro holes and cracks). Those defects result in very poor mechanical property of the component and hindered their industrial application. Furthermore, these techniques are incapable for fabrication of micro metal component. This proposal presents unique approaches for three-dimensional (3D) metal microprinting based on controlled removal of self-assembled monolayers (SAMs) and electrodeposition. The fact that has hindered the application of electrodepostion for 3D metal printing to date, is the incapacity of temporal and site-selectively control of the electrodeposition, a problem that is expected to be conquered by this project. Insulating SAMs, which can hinder the electrodepostion, will be used as the mask. Micro meniscus or light beam will be used to site-selectively remove the insulating SAM and trigger the in situ electrodepostion. Upon stop of illumination, the SAM will re-form and terminate the metal deposition. The key aims are to: (i) develop the experimental set up which combines the electrochemical system and micro meniscus manipulation system (or optical system); (ii) reveal the site-selective removal mechanism of SAMs in liquid environments by meniscus and light and establish the corresponding techniques; (iii) reveal the metal ions transfer mechanism at interface when meniscus is used for removing the SAMs; (iv) ultimately develop a novel meniscus or optical controlled 3D metal microprinting technique which is capable for fabrication of micro metal component at unprecedented efficiency. Compared to the thermal based techniques, the proposed technique is based on thermal less electrodeposition process, therefore, defect-free components are expected to be printed. By this research, theoretical and technical foundation will be laid for the ultimate invention of a new 3D metal microprinting technology with both huge scientific and industry applications.