Automatic magnetic manipulation of droplets on an open surface using a superhydrophobic electromagnet needle

Yang, Chao; Ning, Yongfeng; Ku, Xiaoyong; Zhuang, Guisheng; Li, Gang

doi:10.1016/j.snb.2017.10.118

Cited by 37 publications

(30 citation statements)

References 37 publications

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“…By comparison, open-surface microfluidics mainly controls dispersed droplets on the open-surface device by adjusting surface structures and wettability 6 – 8 . In addition, open surface microfluidics offers several advantages over the conventional counterpart, including simple monolithic construction, direct environmental accessibility, no cavitation/interfacial obstruction, clear optical path, and compatibility with biological experiments 9 . In recent years, open-surface microfluidics has attracted much attention due to several advantages, such as reduced consumption of reagents and samples 10 ; a simplified integration processes and controlled system (i.e., no bonding is required); and most importantly, no channels exist, thereby avoiding trapped bubbles and eliminating the risk of the microchannel clogging 11 – 13 .…”

Section: Introductionmentioning

confidence: 99%

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

Wan

Chen

Wang

et al. 2021

Sci Rep

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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.

show abstract

Section: Introductionmentioning

confidence: 99%

“…One of the latest developments is patterned superhydrophobic open-surface microfluidics, which offers an alternative means to manipulate droplets with the “Lotus effect” 9 , 25 . Meanwhile, the behavior of droplets on superhydrophobic surfaces 26 – 28 and related analytical methods 29 , 30 have been studied.…”

Section: Introductionmentioning

confidence: 99%

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

Wan

Chen

Wang

et al. 2021

Sci Rep

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show abstract

“…One of the latest developments is patterned superhydrophobic open-surface microfluidics, which offers an alternative means to manipulate droplets with the "Lotus effect". 24,25 Open surface microfluidics offers several advantages over the conventional counterpart, including simple monolithic construction, direct environmental accessibility, no cavitation/interfacial obstruction, clear optical path, and compatibility with biological experiments. 24 Surface roughness and low surface energy materials are important factors affecting surface wettability.…”

Section: Introductionmentioning

confidence: 99%

“…24,25 Open surface microfluidics offers several advantages over the conventional counterpart, including simple monolithic construction, direct environmental accessibility, no cavitation/interfacial obstruction, clear optical path, and compatibility with biological experiments. 24 Surface roughness and low surface energy materials are important factors affecting surface wettability. Various surface modification techniques are used to fabricate superhydrophobic surface, including UV irradiation, plasma polymerization, polymer coating, electrospinning, chemical vapor deposition, and photolithography.…”

Section: Introductionmentioning

confidence: 99%

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

Lin

Chen

Wang

et al. 2021

Preprint

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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 pattering 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.

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“…These ferrofluid droplets can be displaced and deformed by controlling the magnetic field amplitude and gradient 7 . Additionally, recent articles present the use of superhydrophobic magnetic needle to handle magnetic droplets 8 . Here we propose a new route to use superhydrophobic surfaces as platforms for of milli/microfluidic using ferrofluids not only as mobile droplets but also as reactive ones.…”

Section: Introductionmentioning

confidence: 99%

New Platform for Gravitational Microfluidic Using Ferrofluids

et al. 2019

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Among the large variety of microfluidic platforms, surface devices are a world apart. Electrowetting systems are used to control the displacement of droplets among predetermined pathways. More confidential, superhydrophobic surfaces are more and more described as new elements to guide spherical droplet reactors. As such, they can exhibit confinement properties analog to channel-based microfluidics. In this article, we describe a new strategy to use superhydrophobic surfaces as permanently-tilted microfluidic platform, on which droplets containing iron oxide nanoparticles are guided with permanent magnets. These droplets are fed with water through a capillary tube until their weight exceeds the magnetic field force. Thus, the volume at which the droplet rolls off the surface is only governed by the initial quantity of magnetic nanoparticles and the tilting angle of the surface. This phenomenon provides a strategy for droplet dilution in a simple and reproducible manner, which is not that easy in micro-channels, and a key advantage of open systems. As a proof of concept, we used this platform to prepare magnetic filaments by a salting-out process already described in large batches. By reducing salt concentration on the platform, we are able to control the electrostatic attractive interactions between iron oxide nanoparticles coated with poly(acrylic acid) and a positively charged polyelectrolyte (poly(diallyldimethylammonium chloride)). The formation of nanostructured filaments was conducted in two minutes while more than 30 minutes were required by dialysis. Our results also illustrate the power of microfluidic reaction processes since such magnetic filaments could not be obtained through direct batch dilution due to mixing issues. Such microfluidic platforms could be useful for the efficient and simple dilution of systems where reactivity is controlled by concentration.

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Automatic magnetic manipulation of droplets on an open surface using a superhydrophobic electromagnet needle

Cited by 37 publications

References 37 publications

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

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

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

New Platform for Gravitational Microfluidic Using Ferrofluids

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