Piezoelectric Drop‐On‐Demand Inkjet Printing of High‐Viscosity Inks

Abstract

Drop‐on‐demand inkjet printing of highly viscous fluids represents a highly attractive emerging technology for advanced material deposition. The jetting of viscous inks, such as concentrated polymer solutions and nanoparticle suspensions, is a key enabling technology for many industrial applications, ranging from microelectronics to biomedicine and ceramics manufacturing. Currently available standard inkjet printers typically operate in a relatively narrow viscosity range (up to 16 mPa s), and alternative drop‐on‐demand printing techniques (such as laser‐induced forward transfer) present limited industrial applicability. In this context, the development of a piezoelectric‐driven printhead capable of jetting high‐viscosity fluids is of great interest. Herein, a prototype of such a device is presented and its performance is evaluated using model fluids at increasing viscosities. Specifically, the dependence of emitted droplets’ properties on jetting parameters is evaluated and linked to the physical characteristics of the system. In optimal conditions, piezoelectric jetting of solutions characterized by viscosities in excess of 200 cP is achieved. Finally, as an applicative example, the jetting of functional inks is attempted. A ZnO suspension and a poly(3,4‐ethylenedioxythiophene) (PEDOT) based solution are successfully jetted to demonstrate the applicability of the developed printhead to the deposition of ceramic suspensions and concentrated polymer solutions.

Mayer Rod‐Coated Organic Light‐Emitting Devices: Binary Solvent Inks, Film Topography Optimization, and Large‐Area Fabrication

“…[ 7–9 ] Solution‐based deposition methods are proven to be reliable techniques in realizing high‐performance and large‐area mass production of flexible/wearable optoelectronic devices, especially printing techniques. [ 10–14 ] A variety of printing methods have been developed, such as inkjet printing, [ 15–18 ] spraying, [ 19,20 ] gravure printing, [ 21–23 ] roll to roll, [ 24,25 ] and Mayer rod coating. [ 26–28 ]…”

“…[7][8][9] Solution-based deposition methods are proven to be reliable techniques in realizing high-performance and large-area mass production of flexible/wearable optoelectronic devices, especially printing techniques. [10][11][12][13][14] A variety of printing methods have been developed, such as inkjet printing, [15][16][17][18] spraying, [19,20] gravure printing, [21][22][23] roll to roll, [24,25] and Mayer rod coating. [26][27][28] Nevertheless, these printing techniques suffer from inherent restrictions, for example, a specific viscosity or surface tension window, which is required for printing functional inks to construct highperformance printed electronics.…”

Cyber‐Physical Watermarking with Inkjet Edible Bioprinting

“…To fabricate safe edible watermarked taggants for on‐dose applications, we use commercially available FDA‐approved food coloring dyes formulated in a food‐grade laboratory (see the Experimental Section). These edible dyes have the appropriate physical properties (e.g., viscosity < 16 mPa∙s) to be compatible to inkjet printer ink [ 48 ] (Table S1 and Figure S5, Supporting Information). Indeed, inkjet printing is an attractive option to ensure the scalable printing of edible taggants and can potentially be integrated into an additive pharmaceutical manufacturing process.…”

Nanometric Hydroxyapatite Particles as Active Ingredient for Bioinks: A Review

“…Inkjet printing based on drop-on demand is classified into thermal, piezoelectric, and electrostatic, where such a division is made based on droplet motivation mechanisms [35,36]. This technology has enabled applications in industry ranging from microelectronics to the manufacturing of ceramics and biomedicine [37,38]. Another type of droplet bioprinting is thermal inkjet bioprinting where the thermal actuator is heated by a manageable impulsive voltage which leads to partial vaporization and formation of small bubbles [38].…”