Laser Induced Nano-Droplet Ejection for the Construction of Nano-Inkjets

To achieve precise nano-droplet ejection, the existing microscale inkjet module could be scaled down to nanoscale, including both the fluidic channel and the pressure driver. While 2D/3D nanoscale fluidic channels are currently available, a nanoscale pressure driver providing high enough power intensity to overcome surface tension for nano-droplet ejection is still lacking. In this study, laser induced nanoscale confined heating with nano-nozzles are constructed and demonstrated as a simple and robust approach to achieve the required pressure driver. For the heating with continuous laser, micro spray composed with nano-droplets can be induced from the nano-nozzles. For the heating with nanosecond laser of adequate pulse energy, drop-on-demand ejection of droplets with similar diameter as the apertures of the nano-nozzle can be achieved.

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Deformation characteristics of a single droplet driven by a piezoelectric nozzle of the drop-on-demand inkjet system

Journal of Fluid Mechanics ◽

10.1017/jfm.2019.242 ◽

2019 ◽

Vol 869 ◽

pp. 634-645 ◽

Cited By ~ 3

Author(s):

Shangkun Wang ◽

Yonghong Zhong ◽

Haisheng Fang

Keyword(s):

Surface Tension ◽

Pressure Wave ◽

Deformation Process ◽

Deformation Characteristics ◽

Single Droplet ◽

Computational Simulations ◽

Droplet Deformation ◽

On Demand ◽

Drop On Demand ◽

Maximum Value

In the drop-on-demand (DOD) inkjet system, deformation process and the direct relations between the droplet motions and the liquid properties have been seldom investigated, although they are very critical for the printing accuracy. In this study, experiments and computational simulations regarding deformation of a single droplet driven by a piezoelectric nozzle have been conducted to address the deformation characteristics of droplets. It is found that the droplet deformation is influenced by the pressure wave propagation in the ink channel related to the driven parameters and reflected in the subsequent droplet motions. The deformation extent oscillates with a certain period of $T$ and a decreasing amplitude as the droplet moves downwards. The deformation extent is found strongly dependent on the capillary number ($Ca$), first ascending and then descending as the number increases. The maximum value of the deformation extent is surprisingly found to be within range of 0.068–0.082 of the $Ca$ number regardless of other factors. Furthermore, the Rayleigh’s linear relation of the oscillation frequency of the droplet to the parameter, $\sqrt{\unicode[STIX]{x1D70E}/\unicode[STIX]{x1D70C}r^{3}}$ (where $\unicode[STIX]{x1D70E}$ is the surface tension coefficient, $\unicode[STIX]{x1D70C}$ is the density and $r$ is the droplet’s radius), is updated with a smaller slope shown both by experiment and simulation.

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Effect of viscosity, electrical conductivity, and surface tension on direct-current-pulsed drop-on-demand electrohydrodynamic printing frequency

Applied Physics Letters ◽

10.1063/1.4902241 ◽

2014 ◽

Vol 105 (21) ◽

pp. 214102 ◽

Cited By ~ 30

Author(s):

Seongpil An ◽

Min Wook Lee ◽

Na Young Kim ◽

Changmin Lee ◽

Salem S. Al-Deyab ◽

...

Keyword(s):

Electrical Conductivity ◽

Surface Tension ◽

Direct Current ◽

On Demand ◽

Drop On Demand ◽

Electrohydrodynamic Printing

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Deposition of Molten Eutectic Solder using Jet Printing Techniques

MRS Proceedings ◽

10.1557/proc-390-201 ◽

1995 ◽

Vol 390 ◽

Cited By ~ 2

Author(s):

Michael D. Snyder ◽

Ronald Lasky

Keyword(s):

Surface Tension ◽

Circuit Boards ◽

Eutectic Solder ◽

On Demand ◽

Drop On Demand ◽

Single Feature ◽

Ink Jet ◽

Jet Printing ◽

Printing Techniques ◽

Large Spherical

ABSTRACTThis paper discusses the use of Ink Jet printing techniques to dispense small (50 to 75 micrometer diameter) particles of molten eutectic solder individually at programmable dispense rates from drop on demand to several thousand per second. Alternative jet dispensing techniques are discussed. The technology could allow the selective application of programmable amounts of solder on precision circuit boards and wafer substrates, while avoiding the high cost and flexibility limits associated with hard tooling. Large solder features can be constructed by dispensing individual droplets and relying on surface tension to draw them together to form a large single feature. Alternatively, columnar features can be created by successively dispensing solder droplets at the same site, allowing time between successive droplets to avoid forming a single large spherical feature.Several potential application areas in industry are discussed along with some of the issues associated with the projected performance of the method in the accuracy and speed domains.

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One Dimensional Simulation of Droplet Ejection of Drop-on-Demand Inkjet

Volume 10: Micro- and Nano-Systems Engineering and Packaging ◽

10.1115/imece2017-71190 ◽

2017 ◽

Author(s):

Huicong Jiang ◽

Hua Tan

Keyword(s):

Method Of Lines ◽

Driving Pressure ◽

Navier Stokes ◽

Drop Breakup ◽

Nozzle Orifice ◽

On Demand ◽

2D Simulation ◽

Drop On Demand ◽

Droplet Ejection ◽

Fluid Properties

In this study, we present a 1D method to predict the droplet ejection of a drop-on-demand (DoD) inkjet which includes the drop breakup, coalescence, and the meniscus movement at nozzle orifice. A simplified 1D slender-jet analysis based on the lubrication approximation is used to study the drop breakup. In this model, the free-surface (liquid-air interface) is represented by a shape function so that the full Navier-Stokes (NS) equations can be linearized into a set of simple partial differential equations (PDEs) which are solved by method of lines (MOL). The shape-preserving piecewise cubic interpolation and third-order polynomial curve are employed to merge approaching droplets smoothly. The printhead is simplified into a circular tube, and a 2D axisymmetric unsteady Poiseuille flow model is adopted to acquire the relationship between the time-dependent driving pressure and velocity profile of the meniscus. Drop breakup and meniscus movement are coupled together by a threshold of meniscus extension to complete a full simulation of droplet ejection. These algorithms and simulations are carried out using MATLAB code. The result is compared with a high fidelity 2D simulation which was previously developed [10], and good agreement is found. This demonstrates that the proposed method enables rapid parametric analysis of DoD inkjet droplet ejection as a function of nozzle dimensions, driving pressure and fluid properties.

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Relevant Influencing Factors on Droplet Characteristics for a Piezoelectrically Driven Drop-on-Demand Printhead

Volume 7: Fluids Engineering Systems and Technologies ◽

10.1115/imece2014-36199 ◽

2014 ◽

Author(s):

Markus Kagerer ◽

Arne Meeuw ◽

Jan Berger ◽

Dominik Rumschoettel ◽

Tim C. Lueth ◽

...

Keyword(s):

Surface Tension ◽

Formation Process ◽

Droplet Formation ◽

Electrical Excitation ◽

Fluid Mixture ◽

Nozzle Length ◽

On Demand ◽

Drop On Demand ◽

Fluid Properties

Dispensing minute amounts of fluid is used in many industries, such as in life science, bioengineering, 3D printing, or in electronics manufacturing. Each application for drop-on-demand (DoD) printheads requires different drop volumes and drop velocities. Furthermore, it is necessary to eject droplets made of fluids with different fluid properties, like viscosity, surface tension, or density. Due to this wide range of different applications and demands on printheads it is important to investigate the influence of relevant factors on the droplet formation process. Therefore, the influence of the fluid properties, the printhead geometry, and the electrical excitation form on the droplet formation process are described in this project. In detail, the influence of the surface tension as well as the viscosity of the fluid, the nozzle length and its width, and the amplitude of the applied voltage at different pulse widths on the droplet characteristics are investigated. The used printhead consists of a silicon chip, which includes the fluidic components, and of a bimorph piezoelectric actuator. The printhead is manufactured with rapid manufacturing techniques, such as laser micromachining. The advantage of this method is that the printhead is adaptable to new boundary conditions in a time- and cost-saving manner. In this project, the nozzles have a square shape with a sidelength between 50 and 100 μm and the nozzle length varies between 50 and 200 μm. A fluid mixture is provided which can be varied in its fluid properties. Therefore, the possibility for the independent adjustment of its viscosity and its surface tension is given. The mixture consists of glycerin, distilled water, and isopropanol. An analytical description for each amount of its substances enables to provide a fluid with defined properties. Three kinds of experiments are carried out in order to determine the influence of the fluid properties, the printhead geometry, and the electrical excitation on the droplet formation process. The determination of the minimum excitation voltage needed for droplet ejection and the determination of the droplet volume and its velocity. The main results are: The higher the surface tension, viscosity, and nozzle length, the higher is the minimum excitation voltage. Furthermore, the droplet velocity decreases for an increased surface tension, viscosity, and nozzle length. On the other hand, the droplet velocity increases with an enlarged amplitude of the voltage and pulse width. The droplet volume increases for an increased surface tension, nozzle width, pulse width, and amplitude of the voltage. In general, the reasons for these correlations are the interaction between the strength of the pressure pulse, friction forces, fluidic resistances, and fluid properties. Overall, the possibility to achieve microdroplets made of different fluids and with a specific velocity and volume is described. Furthermore, a fluid mixture, which can be varied in its fluid properties, is presented.

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Drop-on-demand cell bioprinting via Laser Induced Side Transfer (LIST)

Scientific Reports ◽

10.1038/s41598-020-66565-x ◽

2020 ◽

Vol 10 (1) ◽

Cited By ~ 1

Author(s):

Hamid Ebrahimi Orimi ◽

Sayadeh Sara Hosseini Kolkooh ◽

Erika Hooker ◽

Sivakumar Narayanswamy ◽

Bruno Larrivée ◽

...

Keyword(s):

Repetition Rate ◽

Laser Energy ◽

Umbilical Vein ◽

Intercellular Junctions ◽

Laser Wavelength ◽

Nanosecond Laser ◽

Satellite Droplet ◽

On Demand ◽

Drop On Demand ◽

Umbilical Vein Endothelial Cells

Abstract We introduced and validated a drop-on-demand method to print cells. The method uses low energy nanosecond laser (wavelength: 532 nm) pulses to generate a transient microbubble at the distal end of a glass microcapillary supplied with bio-ink. Microbubble expansion results in the ejection of a cell-containing micro-jet perpendicular to the irradiation axis, a method we coined Laser Induced Side Transfer (LIST). We show that the size of the deposited bio-ink droplets can be adjusted between 165 and 325 µm by varying the laser energy. We studied the corresponding jet ejection dynamics and determined optimal conditions for satellite droplet-free bioprinting. We demonstrated droplet bio-printing up to a 30 Hz repetition rate, corresponding to the maximum repetition rate of the used laser. Jet ejection dynamics indicate that LIST can potentially reach 2.5 kHz. Finally, we show that LIST-printed human umbilical vein endothelial cells (HUVECs) present negligible loss of viability and maintain their abilities to migrate, proliferate and form intercellular junctions. Sample preparation is uncomplicated in LIST, while with further development bio-ink multiplexing can be attained. LIST could be widely adapted for applications requiring multiscale bioprinting capabilities, such as the development of 3D drug screening models and artificial tissues.

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