Drop on demand inkjet

Drop-on-Demand Inkjet (DOD) is a broad classification of inkjet technology where drops are ejected only when required. In general, the drops are formed by the creation of a pressure pulse. " The... 

An inkjet printing of colloidal crystals was proposed by Frese et describing inkjet printing processes of monodispersed particles which are able to form two- or three-dimensional photonic crystals on the substrate surface by arranging in a closely packed lattice structure on the surface. The particle size was selected so that it will diffract light in the visible spectral region, i.e., particle size of 200-500 nanometers. In this work drop-on-demand inkjet printing techniques are utilized. 

Biehl et al. demonstrated a method to fabricate microlenses from hybrid organic-inorganic materials on glass using drop-on-demand inkjet printing with 50 /xm nozzles driven by piezoelectric... 

R.L. Adams and X Roy. A one-dimensional numerical model of a drop-on-demand inkjet. Journal of Applied Mechanics, 53 (1986) 193-197. 

J. Krestschmer, C. Tille, and I. Ederer A drop-on demand inkjet printhead for a wide range of applications, IS Ts NIP 14 International Conference on Digital printing technologies, Seattle, pp. 343-347 (1997). 

D. B. Bogy and P. E. Talke Experimental and theoretieal study of wave propagation phenomena in drop-on-demand inkjet devices, IBM Journal of Research and Development, 28(3), 314-321 (1984). 

In a drop-on-demand inkjet printer, the fluid is maintained at ambient pressure, and a transducer is used to create a drop only when needed. The transducer creates a volumetric change in the fluid which creates pressure waves. The pressure waves travel to an orifice and are converted to fluid velocity, which results in a drop being ejected from the orifice. Figure 8 shows a schematic of a drop-(Mi-demand-type inkjet system which can generate 60 pm diameter drops of butyl carbitol (an organic solvent) from a device with a 50 pm orifice at 4,000 drops per second. 

Chen, L., Bao, J., Gao, C. Combinatorial synthesis of insoluble oxide library from ultrafine/ nanoparticle suspension using a drop on demand inkjet delivery system. J. Comb. Chem. 6, 699 (2004)... 

Planar lithography techniques are not effective for precise fabrication of microdevices with hemispherical shapes (17). Drop-on-demand inkjet printing of a photocurable ink is a more appropriate approach as it takes advantage of the surface tension as well as of the delivery of a well-defined ink volume. 

Recently, a method for forming polymer microspheres has been described that consists of dispensing a polymeric material from an orifice of a drop-on-demand inkjet printhead while the orifice is immersed in a solvent extraction media (34). Pol5maers that can be used for polymer microspheres are summarized in Table 7.2. 

There are at least three types of drop-on-demand inkjet systems (47) ... 

Droplet radius, in polymer blends, 20 333 Droplet size correlations, 23 190-191 Droplet size distribution, in polymer blends, 20 332-333 Droplet sizes, in sprays, 23 185 Drop-on-demand (DOD) inkjet printing, 9 222... 

In many processes (such as oil recovery, blood flow, underground water), one encounters liquid flow through thin (micrometer diameter), noncircular-shaped tubes, or pores. In the literature, one finds studies that address these latter systems. In another context of liquid drop formation, for example, in an inkjet nozzle, this technique falls under a class of scientifically challenging technology. The inkjet printer demands such quality that this branch of drop-on-demand technology is much in the realm of industrial research. All combustion engines are controlled by oil drop formation and evaporation characteristics. The important role of capillary forces is obvious in such systems. 

Drop-on-demand (DOD) inkjet is the method that is universally adopted in the printers used in the home and the office environments. It takes its generic name from the fact that ink is delivered from the ink head directly to the substrate only as demanded by the printing information supplied by the software. 

Generally, ink dyes for ink jet applications and writing, drawing, or marking materials are selected from food, acid, direct, sulfur, and reactive dyes. The choice of dye depends on the application and the ink used, whether it is aqueous, solvent based, or hot melt, and on the printer type continuous ink jet or drop-on-demand, piezo or thermal inkjet. 

While all inkjet technologies can fundamentally be described as the digitally controlled ejection of drops of fluid from a print head onto a substrate, this is accomplished in a variety of ways. Industrial inkjet is broadly and most typically classified as either continuous (CIJ) or drop-on-demand (DOD), with variants within each classification. 

As the name implies, continuous inkjet technology ejects drops continuously (Fig. lA). These drops are then either directed to the substrate or to a collector for recirculation and reuse. Drop-on-demand technology ejects drops only when required " (Fig. IB). 

A further distinction, when referring to inkjet inks, is the printing mechanism. Solvent inks are used widely in drop-on-demand piezo inkjet printing (DOD PIJ) and in continuous inkjet (CIJ). To a lesser extent there is an effort to introduce solvents into thermal inkjet drop-on-demand (DOD TIJ). 

Several types of fluids may be jetted via inkjet heads, which can be of the continuous inkjet variety (CIJ, primarily aqueous or solvent-based), thermal inkjet (TIJ, primarily aqueous, but some solvent and UV/aqueous hybrids exist), or piezoelectric drop-on-demand (DOD, aqueous, solvent, oil, UV curable). While there are advantages and disadvantages for each type of hardware and fluid, a clear leader in growth has emerged from the list. UV curable inkjet... 

Inkjet is a non-contact additive process that delivers metered amounts of a variety of fluids at a precise location in time and space. It requires low viscosity liquid phase inks that must successfully be fired through a nozzle. Inkjet has broad appeal due to its seemingly simple nature. Although all inkjet processes share basic features, the ways in which inkjet technology can be configured are endless. For the most part, drop-on-demand printers have been used in inkjet printing of electronics. ... 

Derived from standard desktop printers, drop-on-demand techniques, such as electrohydrodynamic jet (e-jet) printing, solid freeform fabrication (SFF), or piezoelectric inkjet printing, are among a few notable examples of rapid prototyping techniques that have been developed to pattern biomaterials. With the incorporation of a user friendly computer interface, these techniques have been employed to process a number of multiplexed, biomaterial constructs without the use of masks, stamps, or any other time consuming processing equipment. The design of such constructs with minimal feature sizes in the microliter to picoliter resolution has been demonstrated and will be discussed below. 

Fabrication of 3D Microfluidic Structures, Fig. 8 Schematic of a drop-on-demand-type inkjet system... 

The later developed thermal inkjet technology has the advantage of being able to position a drop on demand. Ink drops are not emitted continuously but only when needed for printing. This property eliminates the need for additional systems to capture and recirculate... 

When printing in the drop-on-demand mode employing certain inkjet ink compositions on substrates which retain high static electric charges, such as in poly(ethylene) and poly(vinyl chloride) shrink wrap packaging materials, the printer nozzle tends to clog up more frequently than normal (52). 

The transfer process of ink jet printing is one of removing a drop of liquid ink from the bulk and giving it a velocity of sufficient precision and magnitude to place it on a substrate in close proximity to but not touching the printhead. There are three broad techniques continuous, electrostatic, and drop on demand. Continuous inkjet printing, because of its intrinsic high drop rate, has tended to find more applications... 

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