Laser Inscription of Microfluidic Devices for Biological Assays

Abstract

A rapid and direct CO2 laser ablation method was developed to create superhydrophilic surfaces and arrays of hydrophobic–superhydrophilic patterns for application in bioassays. Here, a combination of superhydrophilic and hemiwicking wetting characteristics was exploited to create microfluidic slides that were used as biological assays that prevented cell aggregation. This feature allowed microscopic analyses to be carried out at the individual cell level. This bioassay enabled control of cell population in localized areas (15 cells cm–2). The device had 84% transparency, allowing direct fluorescence microscopy measurements in transmission mode. High adhesion of aqueous fluids on superhydrophilic areas surrounded by superhydrophobic boundaries provided selective retention and confinement. The adhered droplets maintained retention under 180° substrate tilt. These architectures provided rapid self-partitioning of the liquid into an array of droplets. The hydrophobic–superhydrophilic patterned arrays may have applications in microfluidic bioassays, high-throughput screening, and medical diagnostics.

Air Plasma-Enhanced Covalent Functionalization of Poly(methyl methacrylate): High-Throughput Protein Immobilization for Miniaturized Bioassays

“…The development of coupled microarray and microfluidic technology has boosted the creation of miniaturized and disposable high-throughput screening chips that enable parallel analyses of biochemical compounds with limited reagent quantities and short detection times. − The robust mechanical and optical properties of PMMA has made this thermoplastic a popular candidate for the fabrication of these chips . However, the lack of scalable and reproducible chemical modification techniques that enable controlled immobilization of proteins with preserved functionalities has hindered the development of PMMA-based microfluidic-microarray chips.…”

Highly Flexible, Stretchable, and Tunable Optical Diffusers with Mechanically Switchable Wettability Surfaces

“…It is well-known that liquid wetting on solids depends on both surface chemistry and physical factors, whereas this work focused on physical factors. 28−30 For the two diffuser elements, the surfaces were decorated with identical cylindrical lenslet arrays but separated with different tip widths. Both tip width and lenslet depth play an important role in liquid wetting behavior.…”

Laser-Engraved Textiles for Engineering Capillary Flow and Application in Microfluidics

“…Therefore, textile-based microfluidics are promising to achieve the concept of portable, low-cost, and field-based diagnostic technology . Previous studies have focused on creating patterned wettability by selectively hydrophobic modification of the porous substrate to manipulate capillary flow, − which changes the intrinsic chemical properties of the porous materials; moreover, the hydrophobic layer could be thermally or chemically instable . The assembly of yarns from the bottom up is another attempt to guide capillary flow, , for example, integrating yarn-based microfluidics into a simple network for branching and mixing liquids or weaving hydrophobic and hydrophilic yarns as fabrics to create directional flow path. , However, it is a great challenge to construct sophisticated capillary interconnections through yarn assemblies for a precise capillary filling front.…”