Abstract
Ink-jet printing is a non-impact printing technology in which drops jetted from an orifice onto a designated position. This technology can digitally transport fluids containing cells precisely onto desired substrates to construct three-dimensional organs. In order to obtain the stable uniform droplets, a stream is the key point of this technology. However, there are so many factors that affect the uniform droplet stream construction process: print parameters, material parameters, control method, etc. A good understanding of the various coupled transport processes that occur during bio-ink impact and spreading on bio-structure can improve the success of print-ability. This paper aims to obtain a good linear bio-structure with ink-jet printing technology. First, a typical droplet deposition process model is constructed; including droplet dynamics impact models and droplet diffusion cap models. Second, a model of successive droplet overlap, to form linear bio-structures, is constructed. Third, the finite element method is used to simulate the droplet impact, collision, and fusion process. Finally, the main influencing factors of the continuous injection printing process, namely the time interval between consecutive droplets and the droplet contact angles, are discussed. Sodium alginate is selected as bio-ink to verify the theory, and it is found that a good linear bio-structure could be obtained if the printing parameters are controlled optimally, i.e., if the initial contact angle is set as 60 degrees and the trigger frequency is set as 150 kHz. With a proper printing speed and gel coating, a good survival rate of printed cells could be obtained.
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Abbreviations
- \(R_{\text{droplet}}\) :
-
The radius of the initial droplet
- \(R\) :
-
The droplet spreading radius
- \(r\) :
-
The radius of the gap
- \(h\) :
-
The height of the cap
- \(\theta\) :
-
The contact angle
- \(\theta_{\text{a}}\) :
-
The contact angle when spreading to the maximum area
- \(U_{0}\) :
-
The dropping speed
- \(D_{0}\) :
-
The diameter of the droplet
- \(\rho\) :
-
The density of fluid
- \(\sigma\) :
-
The surface tension
- \(E_{{{\text{K}}1}}\) :
-
The kinetic energy
- \(E_{{{\text{S}}1}}\) :
-
The surface energy of the droplet
- \(E_{{{\text{S}}2}}\) :
-
The surface energy of droplets falling on the substrate and spreading to the maximum area
- \(W\) :
-
The viscous dissipated energy
- \(t_{c}\) :
-
The spreading time
- \(\varOmega\) :
-
The volume of viscous fluid
- \(\varphi\) :
-
The dissipation function
- \(\delta\) :
-
The thickness of the spreading boundary layer
- \(R{\text{e}}\) :
-
The Reynolds number of fluid
- \(U_{R}\) :
-
The droplet spreading speed
- \(d\) :
-
The spreading diameter of the base plate when the droplet impacts
- D :
-
The diameter of the wetted surface area
- H :
-
The thickness of liquid when spreading to maximum diameter
- \(\beta\) :
-
The original spread factor computation formula
- \(\beta_{\text{new}}\) :
-
The new spread factor computation formula
- \(v\) :
-
The nozzle moving speed
- \(f\) :
-
The transmission frequency
- \(\Delta x\) :
-
The center distance between the prints
- \(L\) :
-
The length of linear bio-structure
- \(N\) :
-
The droplet number of printed
- \(r_{\text{e}}\) :
-
The equilibrium wetting radius
- \(U\) :
-
The moving speed of the base plate
- \(W_{f}\) :
-
The maximum width of linear bio-structure
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Funding
The work is financially supported by the National Natural Science Foundation of China (51805475, 51675148)
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Conceptualization, Youping Gong and Xiangjuan Bian; Data curation, Zhikai Bi, Jingyang He, and Guojin Chen; Formal analysis, Youping Gong, Xiangjuan Bian and Xiang Zhang; Funding acquisition, Youping Gong, Huifeng Shao and Guojin Chen; Investigation, Jingyang He; Methodology, Youping Gong, Xiangjuan Bian; Project administration, Youping Gong; Resources, Anlei Ge; Software, Youping Gong, Zhikai Bi, Wenxin Li and Jingang He; Supervision, Youping Gong; Validation, Xiangjuan Bian; Writing – original draft, Youping Gong, Zhikai Bi, Xiangjuan Bian and Anlei Ge; Writing – review & editing, Xiangjiuan Bian.
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This study does not contain any studies with human or animal subjects performed any of the authors.
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Gong, Y., Bi, Z., Bian, X. et al. Study on linear bio-structure print process based on alginate bio-ink in 3D bio-fabrication. Bio-des. Manuf. 3, 109–121 (2020). https://doi.org/10.1007/s42242-020-00065-9
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DOI: https://doi.org/10.1007/s42242-020-00065-9