Increasing the Writing Resolution for Electro-hydrodynamic 3D-Printing : by Active Steering of e-jet

Abstract: Additive manufacturing has grown considerably during the last couple of decades, whether it comes to the printing of metal structure or living cells. Additive manufacturing techniques relays on the successive addition of material to create the wanted structure. Among the diversity of these many printing techniques, electrohydrodynamic 3D-printing is of particular interest, as the technique has a promising outlook for high-resolution printing on the microscale. The technique is compatible with a myriad of thermoplastics, but its writing resolution is limited due to the inherent affect the manufacturing process has on the material. Electrostatic forces between already deposited fibres and the fibre in light affect the final position of printed fibre. This thesis evaluates the possibility to increase the writing resolution in melt electrohydrodynamic 3D printing by a closed-loop feedback system. Components were built and added to an already existing printing setup to implement in-situ measurements of the fibres position as well as active electrostatic guiding of the fibre. The setup consisted of a camera that determined the position of the fibre; the position was then used in a PID controller to calculate an appropriate potential. The potential was forwarded to a high voltage amplifier, connected to a steering electrode, mounted in the vicinity of the jet. The setup built for one-dimensional steering of the fibre improved the printing accuracy by ten times through suppressing the repulsive/attractive forces, where the process variable of the PID controller was measured. However, the precision decreased roughly four times as it was deposited on the substrate. The limitations of the system have been evaluated, and possible improvements for the two-dimensional control of the fibre are further discussed.