Inkjet Printing Humidity Sensing Pattern Based on Self-Organizing Polystyrene Spheres

Abstract

This study is devoted to the development of photonic patterns based on polystyrene spheres (PSS) incorporated in chitosan hydrogels by inkjet printing. Using this method, high-resolution encrypted images that became visible only in high humidity were obtained. Inks based on PSS with carboxylic groups on the surface were made, and their rheological parameters (viscosity, surface tension, and ζ-potential) were optimized according to the Ohnesorge theory. The obtained value of the ζ-potential indicated the stability of the synthesized colloidal inks. The dependences of the printing parameters on the concentration of ethylene glycol in PSS dispersion, the drop spacing, the shape of the printed pattern, waveform, the temperature of the printing process, and the degree of ordering of the PSS-based photonic crystal were investigated. The scanning electronic microscope (SEM) images confirmed that the optimal self-organization of PSS was achieved at the following values of 0.4% weight fraction (wt%) carboxylic groups, the drop spacing of 50 μm, and the temperature of the printing table of 25 °C. High-resolution microstructures were obtained by drop-on-demand printing with a deposited drophead diameter of 21 μm and an accuracy of ±2 μm on silicon and glass substrates. The deposition of chitosan-based hydrogels on the obtained polystyrene photonic crystals allowed reversibly changing the order of the diffraction lattice of the photonic crystal during the swelling of the hydrogel matrix, which led to a quick optical response in the daylight. The kinetics of the appearance of the optical response of the obtained coating were discussed. The simplicity of production, the speed of image appearance, and the ability to create high-resolution patterns determine the potential applications of the proposed systems as humidity sensors or anticounterfeiting coatings.

An Experimental and Theoretical Determination of Oscillatory Shear-Induced Crystallization Processes in Viscoelastic Photonic Crystal Media

“…This is particularly the case in striving for large scale assembly methods, that are sufficiently cost effective to facilitate widespread application. Widely studied strategies for assembling bulk-ordered optical materials have conventionally relied upon the self-assembly of high and low refractive index components [9][10][11][12][13][14][15]. However, the resultant structures lack the mechanical tractability and robustness needed for many practical applications and, critically, any reproducible bulk-scaling remains very limited.…”

Challenges, Prospects, and Emerging Applications of Inkjet‐Printed Electronics: A Chemist's Point of View

“…Neterebskaia et al. also described the self‐assembly of polystyrene spheres into photonic crystal arrangements and underlined that the printed pattern, drop spacing, and temperature regime of drop‐drying have to be carefully chosen to obtain high‐dimension photonic crystals [98] . They evaluated the close‐packing of equal spheres of PSS by the Fourier method and showed a higher degree of ordering at the edge of the drop due to Marangoni flows.…”

Challenges, Prospects, and Emerging Applications of Inkjet‐Printed Electronics: A Chemist's Point of View

“…Neterebskaia et al also described the self-assembly of polystyrene spheres into photonic crystal arrangements and underlined that the printed pattern, drop spacing, and temperature regime of drop-drying have to be carefully chosen to obtain highdimension photonic crystals. [98] They evaluated the closepacking of equal spheres of PSS by the Fourier method and showed a higher degree of ordering at the edge of the drop due to Marangoni flows. Another interesting system was reported by Kang et al, who printed a photonic crystals based on a block copolymer (poly(styrene-block-quater- nized 2-vinylpyridine)) to achieve a rewritable display (over 50 printing/erasing cycles).…”

“…Inkjet printing is considered to be an adequate solution to pattern macroscopic surfaces with such optically active crystals, provided that a very uniform and thin (ideally a monolayer) deposit is achieved. [96][97][98][99][100] Liu et al developed this approach using poly(styrenemethacrylic acid) colloidal inks that led to the fabrication of brilliant-color photonic devices. [96,97] Strong attention was devoted to the formulation of the ink in order to suppress the coffee-ring effect and to achieve thin and uniform deposition (see Section 3.2).…”