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

2019 ◽  
Vol 869 ◽  
pp. 634-645 ◽  
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.

Push-Mode Printhead Using Magnetic Linear Actuator

2014 ◽  
Vol 931-932 ◽  
pp. 1280-1284
Author(s):  
Mana Saedan ◽  
Manatpong Mangkrai
Keyword(s):  
Pressure Wave ◽  
Drop Size ◽  
Piezo Actuator ◽  
Manufacturing Processes ◽  
Linear Actuator ◽  
Linear Motion ◽  
Single Droplet ◽  
On Demand ◽  
Drop On Demand ◽  
Wide Range

A magnetic linear actuator drop-on-demand printhead with interchangeable components is designed and fabricated. The manufacturing processes of all parts are carried out with simple techniques. A droplet generation relies on a linear motion from a piston inside a printhead chamber that causes a pressure wave to push an ink out from a nozzle-aperture. The motion is actuated by a voice coil liked actuator. The voltage applied across the actuator is significantly lower than the piezo actuator. The interchangeable components enable rapid configuration of a printhead to suit wide range of ink-materials. The prototype of our printhead was tested with inks prepared from glycerin-water solutions. The operability of the printhead was evaluated at actuated time ranging from 2 100 milliseconds. Our printhead was able to jet a single droplet of ink with viscosity up to 35 mPa.s. The drop size is comparable to other types of printheads.

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

2012 ◽  
Author(s):  
Yu Yang ◽  
Vijay M. Sundaram ◽  
Alok Soni ◽  
Sy-Bor Wen
Keyword(s):  
Surface Tension ◽  
Pulse Energy ◽  
Nanosecond Laser ◽  
Continuous Laser ◽  
Fluidic Channel ◽  
Robust Approach ◽  
Power Intensity ◽  
On Demand ◽  
Drop On Demand ◽  
Droplet Ejection

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.

scholarly journals Drop-on-demand microdroplet generation: a very stable platform for single-droplet experimentation

RSC Advances ◽  
2016 ◽  
Vol 6 (65) ◽  
pp. 60215-60222 ◽  
Author(s):  
Bartholomew S. Vaughn ◽  
Phillip J. Tracey ◽  
Adam J. Trevitt
Keyword(s):  
Fluorescence Spectroscopy ◽  
Single Droplet ◽  
Enhanced Fluorescence ◽  
On Demand ◽  
Drop On Demand

This paper reports the performance of drop-on-demand piezo-activated microdroplet generation, investigated using microdroplet cavity enhanced fluorescence spectroscopy.

Drop-by-drop Polymer Deposition by Acoustic Picoliter Droplet Generators for Applications in Semiconductor Industry and Biotechnology

2006 ◽  
Vol 954 ◽  
Author(s):  
Grace C. Lee ◽  
Jeremiah R Cohen ◽  
Utkan Demirci
Keyword(s):  
Silicon Wafer ◽  
Semiconductor Industry ◽  
Wafer Surface ◽  
Single Droplet ◽  
On Demand ◽  
Drop On Demand ◽  
Silicon Wafer Surface ◽  
Polymer Deposition ◽  
Picoliter Droplet ◽  
Single Droplets

ABSTRACTPhotoresist droplets are ejected onto a wafer surface by an acoustic two dimensional micromachined ejector array. The spread of single droplets on a silicon wafer surface at varying droplet speeds is studied. Series of photoresist droplets are printed periodically drop-on-demand on a silicon wafer surface and profiles of a single droplet and two droplets overlapping with varying distances of 25 μm and 1 μm on a silicon wafer are demonstrated. Moreover, 3.4 μm thick spinless full coverage of a 4 inch wafer with photoresist is demonstrated which indicates a potential for coating wafers in less than a few seconds.

scholarly journals Flexible Piezoelectric Drop-On-Demand Droplet Generation

2017 ◽  
Author(s):  
Norbert Riefler ◽  
Thomas Wriedt ◽  
Udo Fritsching
Keyword(s):  
Pressure Wave ◽  
Droplet Generation ◽  
Pulse Excitation ◽  
Generation Process ◽  
Two Phase ◽  
On Demand ◽  
Drop On Demand ◽  
Order Of Magnitude ◽  
Droplet Sizes ◽  
Phase Fluid

The size of droplets generated by piezoelectric drop-on-demand (DOD) droplet generators can be varied to a cer-tain degree within one order of magnitude. This variation means that the droplet size is not solely determined by the nozzle diameter, and the droplet generation process is not restricted to drops extruded through a nozzle in conven- tional operation. By varying the electronic driving pulse, different droplet sizes can be obtained. To investigate the interaction of piezoelectric pulse excitation and the finally produced droplets, different approaches are applied. A comparison of a modal analysis of a pure piezo based on mechanical admittance calculations proofs the usability of electrical impedance measurements. This kind of measurements are then compared to finite-element simulations of a coupled piezo system – one as actuator, the other as pressure sensor – to extend the usable methods with the result that the fluid is of minor influence on the modal frequencies. Last, two phase fluid flow simulations with consequent pressure wave evaluations of the fluid show different pressure wave frequency specta than the modalanalysis.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4846

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

2014 ◽  
Vol 105 (21) ◽  
pp. 214102 ◽  
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

Deposition of Molten Eutectic Solder using Jet Printing Techniques

1995 ◽  
Vol 390 ◽  
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.

Experimental Studies of Meniscus Dynamic Behaviors in a Squeeze-Mode Piezoelectric Inkjet Printhead

2008 ◽  
Vol 594 ◽  
pp. 155-162 ◽  
Author(s):  
Tzong Shyng Leu ◽  
Jan Hua Lin
Keyword(s):  
Pressure Wave ◽  
Experimental Studies ◽  
Dynamic Behaviors ◽  
Dwelling Time ◽  
Meniscus Shape ◽  
On Demand ◽  
Drop On Demand ◽  
Inkjet Printhead ◽  
Later Phase ◽  
Driving Signal

Meniscus dynamic behaviors, as well as its optimal waveform of driving signal, in a squeeze mode piezoelectric inkjet device are studied in this paper. To use the squeeze mode piezoelectric inkjet device as a drop-on-demand dispenser, the driving signal is trapezium waveform. The parameters in a trapezium waveform of the driving signal include rise time (trise), dwelling time (tdwell), fall time (tfall) and voltage (Vp). Among these parameters, the most important parameter of driving signal is the dwelling time. To demonstrate the importance of dwelling time, a LED signal synchronized with the driving signal is used to visualize the instantaneous meniscus shape under a microscope. Experimental results show the meniscus oscillation at beginning and droplet ejection at the later phase. It is found there is an optimal dwelling time. At the optimal dwelling time, droplet ejects in a minimum time and its ejection velocity reaches the maximum. The optimal dwelling time can be further identified it relates to a pressure wave oscillation within the device. The optimal dwelling time can be approximated as the length (L) of the piezoelectric inkjet device divide by the speed of sound (c) in the dispensed fluid.

Dominant factors to produce single droplet per cycle using drop-on-demand technology driven by pulse electromagnetic force

Vacuum ◽  
2018 ◽  
Vol 156 ◽  
pp. 128-134 ◽  
Author(s):  
Tongju Wang ◽  
Jian Lin ◽  
Yongping Lei ◽  
Xingye Guo ◽  
Hanguang Fu ◽  
...  
Keyword(s):  
Electromagnetic Force ◽  
Single Droplet ◽  
On Demand ◽  
Drop On Demand

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

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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