Inkjet Printing Controllable Polydopamine Nanoparticle Line Array for Transparent and Flexible Touch‐Sensing Application

Abstract

A cost‐effective and environmentally benign inkjet‐printing technique is reported for fabrication of ultra‐fine polydopamine (PDA) nanoparticle line arrays (NPLAs) with controllable line‐to‐line spacing (pitch size). The narrowest single line width achieved is 4.7 μm, and tunable pitch size ranging from 77 to 380 μm is also achieved by exploitation of the evaporation‐driven convective particle self‐assembly mechanism. Controllable pitch size is accomplished by printing on hydrophobically recovered polyethylene terephthalate (PET) substrates after oxygen plasma treatment. A theoretical model is developed to investigate the NPLA growth mechanism, which shows good agreement with experimental measurements. Conversion of the NPLA to electrically conductive structure is achieved by a subsequent silver electroless metallization process. The fabrication of a transparent capacitive touch sensor as an application of this approach is also demonstrated. This technique offers manufacturing of conductive narrow lines by additive means with the advantages of low cost, low process temperature, and minimal environmental impact.

Strategic Advances in Spatiotemporal Control of Bioinspired Phenolic Chemistries in Materials Science

“…Adding to this, PDA micropatterns further allow for site-specific immobilization of metal particles, chemical molecules, proteins, and cells, thus advancing applications, including but not limited to, biochips and biosensors. In this section, we summarize the repertoire of micro-/nanofabrication technologies for spatially controlled mussel-inspired patterning (Figure 12A), including photolithography, [27,46,100,[218][219][220] microcontact printing, [47,[221][222][223] inkjet printing, [48,224] electropolymerization, [225,226] microfluidics, [105,227] colloidal lithography, [228] and atomic force microscopy (AFM)-assisted lithography. [229]…”

“…Fine lines of PDA can be created by inkjet printing of aqueous PDA nanoparticles inks. [48,224] Recently, Liu et al reported the fabrication of evenly-spaced and ultrafine PDA line arrays ( Figure 12D). [48] Assisted by evaporation-driven convective particle self-assembly ( Figure 12D, a-c), as well as control of the surface energy of substrate, patterns of defined single line width and line-to-line spacing could be attained ( Figure 12D, d).…”

“…[48,224] Recently, Liu et al reported the fabrication of evenly-spaced and ultrafine PDA line arrays ( Figure 12D). [48] Assisted by evaporation-driven convective particle self-assembly ( Figure 12D, a-c), as well as control of the surface energy of substrate, patterns of defined single line width and line-to-line spacing could be attained ( Figure 12D, d). After electroless metallization of silver, conductive patterns were readily generated to suit applications as fatigue-tolerant flexible transparent touch sensors ( Figure 12D, e,f).…”

“…[42] Moreover, the preferential growth of PDA has been well exemplified recently to potentiate Janus nano-sheets/particles with anisotropic surface properties, [43][44] as well as to control the folding of reprogrammable DNA origami. [45] Aided by cutting-edge microfabrication technologies, such as photolithography, [46] microcontact printing, [47] and 3D printing, [48] spatially and/or temporally controlled phenolic polymerization/assembly has also become a reality, enabling functional phenolic micropatterns/nanocoatings that are indispensable to fabricate microelectronics, photonics, microdevices, and tissue niches with extensive utilities. Finally, the postpolymerization control of phenolic chemistries offers a second opportunity for tailoring material properties.…”

Morphological Control of Linear Particle Deposits from the Drying of Inkjet-Printed Rivulets

“…20-80 µm), w can be further minimized by increasing the drop spacing to the limit of 'stable' coalescence, 13 increasing the temperature to speed up evaporation 17 and/or increasing the advancing contact angle. 18 Surprisingly, past studies have given little consideration to the effect of particle concentration and have been only focused on the formation of twin lines resulting from an evaporation process where the contact line is always pinned. The purpose of the present work is to show that the morphology and dimensional characteristics of linear solid deposits can be modified by changing the evaporation mode.…”