Rapid construct superhydrophobic microcracks on the open-surface platform for droplet manipulations

Abstract

Droplet-based transport driven by surface tension has been explored as an automated pumping source for several biomedical applications. This paper presented a simple and fast superhydrophobic modify and patterning approach to fabricate various open-surface platforms to manipulate droplets to achieve transport, mixing, concentration, and rebounding control. Several commercial reagents were tested in our approach, and the Glaco reagent was selected to create a superhydrophobic layer; laser cutters are utilized to scan on these superhydrophobic surface to create gradient hydrophilic micro-patterns. Implementing back-and-forth vibrations on the predetermined parallel patterns, droplets can be transported and mixed successfully. Colorimetry of horseradish peroxidase (HRP) mixing with substrates also reduced the reaction time by more than 5-times with the help of superhydrophobic patterned chips. Besides, patterned superhydrophobic chips can significantly improve the sensitivity of colorimetric glucose-sensing by more than 10 times. Moreover, all bioassays were distributed homogeneously within the region of hydrophilic micropatterns without the coffee-ring effect. In addition, to discuss further applications of the surface wettability, the way of controlling the droplet impacting and rebounding phenomenon was also demonstrated. This work reports a rapid approach to modify and patterning superhydrophobic films to perform droplet-based manipulations with a lower technical barrier, higher efficiency, and easier operation. It holds the potential to broaden the applications of open microfluidics in the future.

Multiple-Droplet Selective Manipulation Enabled by Laser-Textured Hydrophobic Magnetism-Responsive Slanted Micropillar Arrays with an Ultrafast Reconfiguration Rate

“…Subsequently, the effect of the surface chemical composition on the wettability of MSMA was also investigated. As a commercial superhydrophobic spray, Glaco is widely used in surface treatment, which is made of an alkyl-modified silica nanoparticle (particle size: 30–50 nm) suspension in isopropyl alcohol. − After Glaco modification, a superhydrophobic film with alkyl functional groups can be formed on the surface of the MSMA. As shown in Figure c,f, the WSA on the surface of the Glaco-modified MSMA, both in the anterograde and retrograde states, is reduced compared to the previous one (except for an S of 500 μm).…”

Point‐of‐Care Testing (POCT) Devices for DNA Detection: A Comprehensive Review

“…Alternatively, capillary force is one of the most widely used systems in microfluidic to provide a successful method of passive-driven micro-pumping for effective fluid regulation. Lin et al [33] described the development of a passively driven microfluidic device for detecting nucleic acids by loop-mediated isothermal amplification (LAMP) assay with simultaneous monitoring under a fluorescence microscope (Figure 1B). The microfluidic chip used in this system is free of pumps and valves and allows users to control the droplet on a nanoliter scale through micropipette regulation.…”

Laser-Induced Fast Assembly of Wettability-Finely-Tunable Superhydrophobic Surfaces for Lossless Droplet Transfer

“…Superhydrophobic surfaces inspired by animals and plants are recently explored seeking advanced liquid manipulation. − The surface wettability is determined by surface energy and topographic features. − For example, rose-petal and lotus-leaf effects exhibit two distinct natural superhydrophobic characteristics, leading to “water pinning” and “water rolling” effects, respectively. The rose-petal-like super-hydrophobicity has proven to play an important role in the manipulation of microdroplets. , A variety of efforts have been made to achieve “rose-petal-like” superhydrophobic surfaces with controlled wettability characteristics for liquid droplet handling. ,− Zhang et al prepared biomimetic films with multilayers of microstructures by a template method, the adhesive forces of which were adjusted from 8.3 up to 57 μN.…”