Ultrafast electrohydrodynamic 3D printing with submicrometer resolutio

Ievgenii Liashenko

Rosell Llompart, Joan Cabot Codina, Andreu

Additive manufacturing (AM) technologies based on layer-by-layer deposition of material ejected from a nozzle provide unmatched versatility but are limited in terms of printing speed and resolution. Electrohydrodynamic (EHD) jetting uniquely allows generating submicrometer jets that can reach speeds above 1 m/s, but such jets cannot be deposited on a moving substrate with submicron accuracy even when using state-of-the-art mechanical stages, which are limited to accelerations below ~30 m/s^2. Here, we demonstrate a new printing approach in which the EHD jet trajectory can be continuously adjusted with lateral accelerations up to 10^6 m/s^2 via controlling voltages applied to electrodes positioned around the jet. Using high-speed imaging we have conducted a parametric analysis of how the deflection signal parameters and setup configurations influence the jet deflection. Custom-made software has been developed to generate jet-deflecting signals which control the jet to print 2D patterns, as well as 3D objects with submicrometer features. Such 3D objects have been printed by stacking nanofibers at layer-by-layer frequencies as high as 2000 Hz. The high jet speeds and layer-by-layer frequencies achieved translate into printing speeds up to 0.5 m/s in-plane and 0.4 mm/s in the vertical direction, which is three to four orders of magnitude faster than for other AM techniques providing equivalent feature sizes. We have also used electrostatic jet deflection to develop a novel method for determining the speed of EHD jets. Unlike all previous approaches, which rely on ex-situ high-resolution microscopy analysis of the printed fiber, our method is based on image recognition of predefined printed patterns, allowing in-situ monitoring of the jet speed. Finally, in an additional study on stage-based printing of slow EHD jets of polymer melts, we show that updating the printing path for each deposited layer enables to significantly expand the range of printable structures and thus manipulate their mechanical properties.

3D printing will be a highly disruptive force within the global manufacturing industry. The current global 3D printing market is above 5 billion Euros and it is foreseen to reach above 20 billion by 2025. With its unprecedented printing speed and resolution, our technology is ideally positioned for manufacturing very small objects, such as those frequently used in microelectronics and biotechnology industries. 3.1. Our vision is to fabricate a commercial desktop-scale 3D printer based on our jet-deflection technology to validate and demonstrate it in relevant applications. In parallel, we will develop additional inks to prove the versatility of the technology and to develop it toward specific applications. We foresee that it will take 2-3 years to have our first product in the market, most probably targetted to research institutions for R&D purposes. We will aim entering markets with high volume and high margin potential. 3.2. Main goals towards commercialization are (1) the design, fabrication and validation of a compact printer prototype, (2) the creation of a spin-off company to commercialize the technology, and (3) the identification and consolidation of additional partners, customers and funding sources. To accomplish these general goals, we have designed a work plan divided in 11 workpackages (WP) that include 5 technological WPs devoted to the fabrication and validation of the prototype and the development of inks and applications, and 6 exploitation WPs focused on the active identification of partners, clients and end users, the promotion of our technology by different means, and the development of a business plan and creation of the spin off company. 3.3. Product/service definition. Based on our disruptive 3D printing technology, several products and services can be brought to the market (with associated potential revenue streams): • The most obvious is an ultrafast and high-resolution 3D printer – desktop scale. • A related product is the inks of a wide range of materials adapted to this printer. • A possible complementary business model is the leasing of the printers. • Another is commercialization of the printed products (printing-as-a-service). • Licensing of the technology for niche applications (based on our 2 patents protecting the technology). 3.4. Possible business exit strategy. At some point the developed technology could also be sold to a large company already operating in the additive manufacturing business, either a developer of systems or a supplier of additive manufacturing services for a range of applications, such as: Voxeljet AG, Materialise N.V., Stratasys, ExOne, 3D Systems, Hewlett-Packard Inc., Nano Dimension, Organovo, etc.

Additive Manufacturing (AM) Technologies; Layer-by-Layer Deposition; Nozzle Ejection; Printing Speed; Resolution; Electrohydrodynamic (EHD) Jetting; Submicrometer Jets; High Speeds; Moving Substrate; Submicron Accuracy; Mechanical Stages; Jet Trajectory Adjustment; Lateral Accelerations; Controlling Voltages; Electrodes; High-Speed Imaging; Parametric Analysis; Deflection Signal Parameters; Setup Configurations; Jet Deflection; Custom-Made Software; 2D Patterns; 3D Objects; Submicrometer Features; Stacking Nanofibers; Layer-by-Layer Frequencies; Printing Speeds; In-plane Printing; Vertical Direction; Feature Sizes; Electrostatic Jet Deflection; Novel Method; EHD Jet Speed Determination; Ex-situ High-Resolution Microscopy; Printed Fiber Analysis; Image Recognition; Predefined Printed Patterns; In-situ Monitoring; Stage-Based Printing; Slow EHD Jets; Polymer Melts; Printing Path Update; Printable Structures; Mechanical Properties Manipulation.