Ultrafast electrohydrodynamic 3D printing with in situ jet speed monitoring

Patterning with Aligned Electrospun Nanofibers by Electrostatic Deflection of Fast Jets

“…We recently demonstrated that electrostatic deflection of the jet in its travel toward the substrate allows an unprecedented degree of control over the geometrical parameters of the printed object. [ 26,27 ] In the present work, we further demonstrate that the jet deflection enables to accurately align and pattern fast EHD jets into well‐defined fiber tracks. Using this strategy, fiber tracks with preset width, fiber alignment, and directionality, as well as with easily quantifiable and controlled fiber density, can be produced.…”

“…The fiber density can be adjusted by changing the translation speed, which does not affect the track's width (Figure 2a and S2, Supporting Information), or the deflection frequency or the deflection amplitude, which do modify the width of the fiber track (Figure 2b,e). As shown in Figure 2, within a proper parameter range, [ 27 ] the fiber density decreases in inverse proportion to the speed of the translation stage and the deflection signal amplitude (Figure 2a and S2, Supporting Information), and it increases linearly with signal frequency (Figure 2e).…”

“…A schematic of the printer elements, as well as the photographs of electrode design and high-speed imaging of deflected jets, were previously demonstrated and can be found in other studies. [26,27] The voltages applied to the jet-deflecting electrodes were obtained from two amplifiers with a high slew rate (max. AE 2000 V, Matsusada AMJ-2B10 and Trek 677B) controlled by the two synchronized analog signals (AE10 V) generated by a data acquisition card (National Instruments, USB-6259).…”

“…Laminar flow of dry nitrogen gas was supplied around the jet from a side tube to establish a reproducible solvent evaporation rate while room temperature and relative humidity slightly fluctuated between 17–19 ºC and 40–65 %. Under these printing conditions (see Table S1, Supporting Information, for further details), the arriving fiber diameters ranged from as low as 85 to 420 nm, [ 27 ] but typically were 250 ± 50 nm. Fibers with diameters on the extremes of this range are shown in Figure 1c–d, demonstrating the impact of fiber diameter on the width of the buckled fiber track.…”

“…Similarly, the feasibility of jet-deflection printing over a stationary collector was demonstrated in our previous works. [26,27] Figure 2. Fiber track width and density.…”