Microfluidics-Enabled Soft Manufacture of Materials with Tailorable Wettability

Abstract

Microfluidics and wettability are interrelated and mutually reinforcing fields, experiencing synergistic growth. Surface wettability is paramount in regulating microfluidic flows for processing and manipulating fluids at the microscale. Microfluidics, in turn, has emerged as a versatile platform for tailoring the wettability of materials. We present a critical review on the microfluidics-enabled soft manufacture (MESM) of materials with well-controlled wettability and their multidisciplinary applications. Microfluidics provides a variety of liquid templates for engineering materials with exquisite composition and morphology, laying the foundation for precisely controlling the wettability. Depending on the degree of ordering, liquid templates are divided into individual droplets, one-dimensional (1D) arrays, and two-dimensional (2D) or three-dimensional (3D) assemblies for the modular fabrication of microparticles, microfibers, and monolithic porous materials, respectively. Future exploration of MESM will enrich the diversity of chemical composition and physical structure for wettability control and thus markedly broaden the application horizons across engineering, physics, chemistry, biology, and medicine. This review aims to systematize this emerging yet robust technology, with the hope of aiding the realization of its full potential.

Controlled Thin Polydimethylsiloxane Membrane with Small and Large Micropores for Enhanced Attachment and Detachment of the Cell Sheet

“…as the spin-coating speed increased, and many surface microstructures with hydrophobic properties were created. These results caused an increase in the hydrophobic specific surface area of the porous PDMS membrane, which resulted in an increase in the contact angle [33,34]. Figure 3a shows the surface morphologies of the PDMS membranes (control, 2000, 3000, 4000, and 5000 rpm) visualized by AFM analysis.…”

“…In the case of porosity-free PDMS, the contact angle was reported to be about 120 degrees [ 32 ], but in our experiment, the number of pores increased as the spin-coating speed increased, and many surface microstructures with hydrophobic properties were created. These results caused an increase in the hydrophobic specific surface area of the porous PDMS membrane, which resulted in an increase in the contact angle [ 33 , 34 ].…”

Overflow Control for Sustainable Development by Superwetting Surface with Biomimetic Structure

“…Biomimicry, namely, revealing and learning these functional principles from the diversity of life and applying them to solve economic and sociocultural matters, is a crucial component to address all kinds of sustainable issues. In recent years, with the emergence of biomimetic interface research, bioinspired materials with superwettabilities and topological structures were fabricated and used to control liquid–solid interfacial action. ,,− Superwettability as a new scientific discovery and a fully commercialized technology has been listed as one of the top ten emerging technologies of chemistry projects in 2021, which possesses a great capacity to contribute to the well-being of society and the sustainability of the earth, and open new opportunities in chemistry and beyond . Research on fundamental interface problems has gradually shifted from static to dynamic ,, such as liquid impact, transport, breakup and dripping, bursting, etc., − from kinetic processes to thermodynamic processes such as icing and melting, , frosting, dewing, thermal cooling, evaporation and crystallization, ,,,, cooling crystallization, and boiling. , In nature, many organisms can survive under harsh conditions via skillfully manipulating liquid overflow using their unique surface structures.…”

Patterning Wettability for Open-Surface Fluidic Manipulation: Fundamentals and Applications

“…Microfluidic flows also lend to the development of novel materials with distinct surface properties, e.g., spinning of microfibers and nonwoven materials, , or leveraging microscale spray and film spreading to develop slippery liquid-infused porous (SLIP) surfaces . Often, microfluidic approaches are employed to make interfacial-property measurements − and wettability tuning is adopted to gain insight into microfluidic-flow behavior. , For a comprehensive review on the role of microfluidics on the synthesis of functional surfaces and characterizing surface properties, the reader is referred to two excellent articles , and a book . The present review article highlights the complementary attributes of the interrelationship between microfluidics and wettability, focusing on the origin of wettability induced flows on open-surface microfluidic platforms.…”