Alternating Force Based Drop-on-Demand Microdroplet Formation and Three-Dimensional Deposition

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Long Zhao ◽  
Karen Chang Yan ◽  
Rui Yao ◽  
Feng Lin ◽  
Wei Sun
Keyword(s):  
Process Parameters ◽  
Droplet Diameter ◽  
Three Dimensional ◽  
Inertial Force ◽  
Deposition Process ◽  
Droplet Formation ◽  
Solution Viscosity ◽  
Cell Printing ◽  
On Demand ◽  
Drop On Demand

Drop-on-demand (DOD) microdroplet formation and deposition play an important role in additive manufacturing, particularly in printing of three-dimensional (3D) in vitro biological models for pharmacological and pathological studies, for tissue engineering and regenerative medicine applications, and for building of cell-integrated microfluidic devices. In development of a DOD based microdroplet deposition process for 3D cell printing, the droplet formation, controlled on-demand deposition and at the single-cell level, and most importantly, maintaining the viability and functionality of the cells during and after the printing are all remaining to be challenged. This report presents our recent study on developing a novel DOD based microdroplet deposition process for 3D printing by utilization of an alternating viscous and inertial force jetting (AVIFJ) mechanism. The results include an analysis of droplet formation mechanism, the system configuration, and experimental study of the effects of process parameters on microdroplet formation. Sodium alginate solutions are used for microdroplet formation and deposition. Key process parameters include actuation signal waveforms, nozzle dimensional features, and solution viscosity. Sizes of formed microdroplets are examined by measuring the droplet diameter and velocity. Results show that by utilizing a nozzle at a 45 μm diameter, the size of the formed microdroplets is in the range of 52–72 μm in diameter and 0.4–2.0 m/s in jetting speed, respectively. Reproducibility of the system is also examined and the results show that the deviation of the formed microdroplet diameter and the droplet deposition accuracy is within 6% and 6.2 μm range, respectively. Experimental results demonstrate a high controllability and precision for the developed DOD microdroplet deposition system with a potential for precise cell printing.

Modeling on Microdroplet Formation for Cell Printing Based on Alternating Viscous-Inertial Force Jetting

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Long Zhao ◽  
Karen Chang Yan ◽  
Rui Yao ◽  
Feng Lin ◽  
Wei Sun
Keyword(s):  
Inertial Force ◽  
Droplet Formation ◽  
Experimental Results ◽  
Viscous Force ◽  
Drop Diameter ◽  
Maximum Difference ◽  
Engineering Model ◽  
Cell Printing ◽  
Cylindrical Nozzle ◽  
Drop On Demand

Drop-on-demand (DOD) microdroplet jetting technology has diverse applications ranging from additive manufacturing (AM) and the integrated circuit (IC) industry to cell printing. An engineering model of droplet formation can provide insights for optimizing the process and ensuring its controllability and reproducibility. This paper reports a development of an engineering model on the fluid outflow and microdroplet formation based on alternating viscous-inertial force jetting (AVIFJ). The model provides a fundamental understanding on the mechanism of droplet formation driven by the alternating viscous force and inetial force. Furthermore, the model studies the fluid acceleration, velocity, and displacement under the conditions of a uniform cylindrical nozzle and a nonuniform cylindrical nozzle. In conjunction with an energy-based criterion for droplet formation, the model is applied to predict the formability of single microdroplets and the volume and velocity of formed microdroplets. A series of experiments was conducted to validate the developed model. The results show that the model predictions agree well with the experimental results. Specifically, comparing the model prediction and experimental results, the maximum difference of drop diameter is 4 μm, and the maximum difference of drop velocity is 0.3 m/s. These results suggest that the developed theoretical model will provide guidance to the subsequent cell printing applications.

scholarly journals On-demand Ferrofluid Droplet Formation With Non-linear Magnetic Permeability in the Presence of a Non-uniform Magnetic Field

2021 ◽  
Author(s):  
Mohamad Ali Bijarchi ◽  
Mohammad Yaghoobi ◽  
Amirhossein Favakeh ◽  
Mohammad Behshad Shafii
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
Uniform Magnetic Field ◽  
Maxwell Equations ◽  
Droplet Diameter ◽  
Droplet Formation ◽  
Bond Number ◽  
On Demand ◽  
Drop On Demand ◽  
The Magnetic Field

Abstract The magnetic actuation of ferrofluid droplets offers an inspiring tool in widespread engineering and biological applications. In this study, the dynamics of ferrofluid droplet generation with a Drop-on-Demand feature under a non-uniform magnetic field is investigated by multiscale numerical modeling. Langevin equation is assumed for ferrofluid magnetic susceptibility due to the strong applied magnetic field. Large and small computational domains are considered. In the larger domain, the magnetic field is obtained by solving Maxwell equations. In the smaller domain, a coupling of continuity, Navier Stokes, two-phase flow, and Maxwell equations are solved by utilizing the magnetic field achieved by the larger domain for the boundary condition. The Finite volume method and coupling of level-set and Volume of Fluid methods are used for solving equations. The droplet formation is simulated in a two-dimensional axisymmetric domain. The method of solving fluid and magnetic equations is validated using a benchmark. Then, ferrofluid droplet formation is investigated experimentally and the numerical results are in good agreement with the experimental data. The effect of 12 dimensionless parameters including the ratio of magnetic, gravitational, and surface tension forces, the ratio of the nozzle and magnetic coil dimensions, and ferrofluid to continuous-phase properties ratios are studied. The results showed that by increasing the magnetic Bond number, gravitational Bond number, Ohnesorge number, dimensionless saturation magnetization, initial magnetic susceptibility of ferrofluid, the generated droplet diameter reduces, whereas the formation frequency increases. The same results were observed when decreasing the ferrite core diameter to outer nozzle diameter, density, and viscosity ratios.

Learning-Based Cell Injection Control for Precise Drop-on-Demand Cell Printing

2018 ◽  
Vol 46 (9) ◽  
pp. 1267-1279 ◽  
Author(s):  
Jia Shi ◽  
Bin Wu ◽  
Bin Song ◽  
Jinchun Song ◽  
Shihao Li ◽  
...  
Keyword(s):  
Cell Injection ◽  
Cell Printing ◽  
On Demand ◽  
Drop On Demand ◽  
Injection Control

Finite Element Simulation of Localized Electrochemical Deposition for Maskless Electrochemical Additive Manufacturing

2015 ◽  
Vol 137 (1) ◽  
Author(s):  
Anne M. Brant ◽  
Murali M. Sundaram ◽  
Abishek B. Kamaraj
Keyword(s):  
Additive Manufacturing ◽  
Process Parameters ◽  
Three Dimensional ◽  
Deposition Process ◽  
Specific Process ◽  
Manufacturing Technique ◽  
Element Simulation ◽  
Interelectrode Gap ◽  
Linear And Nonlinear ◽  
High Control

Localized electrodeposition (LED) was explored as an additive manufacturing technique with high control over process parameters and output geometry. The effect of variation of process parameters and changing boundary conditions during the deposition process on the output geometry was observed through simulation and experimentation. Trends were found between specific process parameters and output geometries in the simulations; trends varied between linear and nonlinear, and certain process parameters such as voltage and interelectrode gap were found to have a greater influence on the output than others. The simulations were able to predict the output width of deposition of experiments in an error of 8–30%. The information gained from this research allows for greater understanding of LED output, so that it can potentially be applied as an additive manufacturing technique of complex three-dimensional (3D) parts on the microscale.

Effect of process parameters on copper droplet ejecting by pneumatic drop-on-demand technology

2014 ◽  
Vol 214 (12) ◽  
pp. 3089-3097 ◽  
Author(s):  
Song-yi Zhong ◽  
Le-hua Qi ◽  
Jun Luo ◽  
Han-song Zuo ◽  
Xiang-hui Hou ◽  
...  
Keyword(s):  
Process Parameters ◽  
On Demand ◽  
Drop On Demand

Direct Inkjet Deposition of Ceramic Green Bodies: II – Jet Behaviour and Deposit Formation

1998 ◽  
Vol 542 ◽  
Author(s):  
N. Reis ◽  
K. A. M. Seerden ◽  
B. Derby ◽  
J. W. Halloran ◽  
J. R. G. Evans
Keyword(s):  
Pulse Shape ◽  
Three Dimensional ◽  
Jet Formation ◽  
Deposit Formation ◽  
On Demand ◽  
Drop On Demand ◽  
Material Systems ◽  
Hot Melt ◽  
Feature Resolution ◽  
Deposition Conditions

AbstractIn order to successfully build three-dimensional shapes by hot-melt inkjet deposition it is essential to control the building block characteristics, i.e., the deposit geometry, dimensions and fine feature resolution. The deposit formation is mainly dependent on the material systems and their jetting behaviour. It is therefore crucial to understand how the jet formation is affected by the inks 'rheological properties and how to manipulate the jet-head driving parameters to achieve optimum deposition conditions. This paper reports our investigations with a model jet firing station, about the influence of driving parameters of hot-melt drop-on-demand print-heads (e.g., pulse shape and frequency) on the jet and deposit formation characteristics, for both unfilled and powder loaded vehicles.

scholarly journals Rheological Investigation of Collagen, Fibrinogen, and Thrombin Solutions for Drop-on-Demand 3D Bioprinting

2020 ◽  
Author(s):  
Hemanth Gudapati ◽  
Daniele Parisi ◽  
Ralph H. Colby ◽  
Ibrahim Ozbolat
Keyword(s):  
Bulk Viscosity ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Protein Solutions ◽  
Ionic Surfactant ◽  
3D Bioprinting ◽  
Rheological Measurements ◽  
On Demand ◽  
Drop On Demand ◽  
Air Interface

<p>Collagen, fibrinogen, and thrombin proteins in aqueous buffer solutions are widely used as precursors of natural biopolymers for three-dimensional (3D) bioprinting applications. The proteins are sourced from animals and their quality may vary from batch to batch, inducing differences in the rheological properties of such solutions. In this work, we investigate the rheological response of collagen, fibrinogen, and thrombin protein solutions in bulk and at the solution/air interface. Interfacial rheological measurements show that fibrous collagen, fibrinogen and globular thrombin proteins adsorb and aggregate at the solution/air interface, forming a viscoelastic solid film at the interface. The viscoelastic film corrupts the bulk rheological measurements in rotational rheometers by contributing to an apparent yield stress, which increases the apparent bulk viscosity up to shear rates as high as 1000 s<sup>-1</sup>. The addition of a non-ionic surfactant, such as polysorbate 80 (PS80) in small amounts between 0.001 and 0.1 v/v%, prevents the formation of the interfacial layer, allowing the estimation of true bulk viscosity and viscoelastic properties of the solutions. The estimation of viscosity not only helps in identifying those protein solutions that are potentially printable with drop-on-demand (DOD) inkjet printing but also detects inconsistencies in flow behavior among the batches.</p>

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