Minxuan Kuang

Controllable Printing Droplets for High-Resolution Patterns

Inkjet printing has attracted wide attention due to the important applications in fabricating biological, optical, and electrical devices. During the inkjet printing process, the solutes prefer to deposit along the droplet periphery and form an inhomogeneous morphology, known as the coffee-ring effect. Besides, the feature size of printed dots or lines of conventional inkjet printing is usually limited to tens or even hundreds of micrometers. The above two issues greatly restrict the extensive application of printed patterns in high-performance devices. This paper reviews the recent advances in precisely controlling the printing droplets for high-resolution patterns and three-dimensional structures, with a focus on the development to suppress the coffee-ring effect and minimize the feature size of printed dots or lines. A perspective on the remaining challenges of the research is also proposed.

Inkjet printed colloidal photonic crystal microdot with fast response induced by hydrophobic transition of poly(N-isopropyl acrylamide)

This paper presents rapid response colloidal photonic crystal (PC) microdots fabricated by inkjet printing, which demonstrate a fastest response of ca. 1.2 s to water vapor. This remarkable improvement of response rate could be attributed to the combined effects of the intrinsic small size of the inkjet microdots and the hydrophobic transition of poly(N-isopropyl acrylamide) (PNIPAm) above its lower critical solution temperature (LCST). The reversible phase transition of PNIPAm modifies the hydrophilic–hydrophobic balance of the polymer interface, which leads to the modulation of wetting states/adhesion properties of adsorbed water on the polymer segments, resulting in the remarkable improvement of response rate. Moreover, the optimal response performance (including signal strength and response sensitivity) of the printed PC microdot is achieved by the coordination of a well-ordered latex assembly and full infiltration of the responsive polymer in the latex interstices. This simple fabrication of functional colloidal PC microdots opens new avenues for the construction of advanced microanalysis and microsensing devices. In addition, improving the response rate by the phase transition of the polymer segments is promising for the creation of high-performance sensors.

Bio-inspired photonic crystals with superwettability

Photonic crystals (PCs) have attracted enormous research interest due to their unique light manipulation and potential applications in sensing, catalysts, detection, displays, solar cells and other fields. In particular, many novel applications of PCs are derived from their surface wettability. Generally, the wettability of PCs is determined by a combination of its surface geometrical structures and surface chemical compositions. This review focuses on the recent developments in the mechanism, fabrication and application of bio-inspired PCs with superwettability. It includes information on constructing superwetting PCs based on designing the topographical structure and regulating the surface chemical composition, and information on extending the practical applications of superwetting PCs in humidity/oil/solvent sensing, actuating, anti-fouling and liquid-impermeable surface, chemical detection, etc.

Direct-Writing Multifunctional Perovskite Single Crystal Arrays by Inkjet Printing

Perovskite single-crystalline microplate arrays are directly achieved in large scale by inkjet printing, which present high performance lasing property with quality factors up to 863 and RGB (red-green-blue) emission. This facile, nonlithographic method makes its promising applications on multi-integrated coherent light sources and other high-performance integrated optoelectronic applications.

Sliding three-phase contact line of printed droplets for single-crystal arrays

Controlling the behaviours of printed droplets is an essential requirement for inkjet printing of delicate three-dimensional (3D) structures or high-resolution patterns. In this work, molecular deposition and crystallization are regulated by manipulating the three-phase contact line (TCL) behaviour of the printed droplets. The results show that oriented single-crystal arrays are fabricated based on the continuously sliding TCL. Owing to the sliding of the TCL on the substrate, the outward capillary flow within the evaporating droplet is suppressed and the molecules are brought to the centre of the droplet, resulting in the formation of a single crystal. This work provides a facile strategy for controlling the structures of printed units by manipulating the TCL of printed droplets, which is significant for realizing high-resolution patterns and delicate 3D structures.