Time-Resolved Imaging Study of Jetting Dynamics during Laser Printing of Viscoelastic Alginate Solutions

Abstract

Matrix-assisted pulsed-laser evaporation direct-write (MAPLE DW) has been successfully implemented as a promising laser printing technology for various fabrication applications, in particular, three-dimensional bioprinting. Since most bioinks used in bioprinting are viscoelastic, it is of importance to understand the jetting dynamics during the laser printing of viscoelastic fluids in order to control and optimize the laser printing performance. In this study, MAPLE DW was implemented to study the jetting dynamics during the laser printing of representative viscoelastic alginate bioinks and evaluate the effects of operating conditions (e.g., laser fluence) and material properties (e.g., alginate concentration) on the jet formation performance. Through a time-resolved imaging approach, it is found that when the laser fluence increases or the alginate concentration decreases, the jetting behavior changes from no material transferring to well-defined jetting to well-defined jetting with an initial bulgy shape to jetting with a bulgy shape to pluming/splashing. For the desirable well-defined jetting regimes, as the laser fluence increases, the jet velocity and breakup length increase while the breakup time and primary droplet size decrease. As the alginate concentration increases, the jet velocity and breakup length decrease while the breakup time and primary droplet size increase. In addition, Ohnesorge, elasto-capillary, and Weber number based phase diagrams are presented to better appreciate the dependence of jetting regimes on the laser fluence and alginate concentration.

Laser-assisted bioprinting at different wavelengths and pulse durations with a metal dynamic release layer: A parametric study

“…One aspect of the printing process, which is influenced by these parameters, is the velocity of the hydrogel jet that might affect the vitality of printed cells. Zhang et al [16] demonstrated printing with jet velocities down to 10 m/s, while the jet velocities in our study have been about 50 m/s so far. Therefore, printing of alginate droplets with three different focal spot sizes (3000, 4000, and 7500 µm²) and the generated jet velocities have been investigated for different laser pulse energies ( Figure 9A).…”

Study of extrudability and standoff distance effect during nanoclay-enabled direct printing

“…3c-1 and c-2. For comparison, a high-concentration viscous NaAlg, which has a zero-shear-rate viscosity of approximately 3.1 Pa·s [27] but is not a yield-stress fluid, was extruded to examine the effect of viscosity on the extrudability. NaAlg filament formation is illustrated in Fig.…”

Single cell isolation process with laser induced forward transfer

“…The cavitation resulting from the ablation of titanium expanded with the energy converting to deformation of the sacrificed layer if any, viscous dissipation energy, surface energy, and potentially the kinetic energies to forming jets root from Rayleigh or Plateau-Rayleigh instability [30]. In Newtonian fluids, the jettability significantly depends on the Ohnesorge number Oh  =  η /( ρ l σR ) 1/2 and Weber number We  =  ρ l RU 2 / σ where η is the zero-shear viscosity, σ is the surface tension, R is the characteristic length that could be considered as the radius of the laser spot, and ρ l is the density of medium.…”