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Dynamic Magnetic Responsive Wall Array with Droplet Shedding-off Properties.

Wang L, Zhang M, Shi W, Hou Y, Liu C, Feng S, Guo Z, Zheng Y - Sci Rep (2015)

Bottom Line: The walls can easily tilt through the effect of the external magnet because of the magnetic material in the DMRW.It offers an insight into design of dynamic interface for water repellency.This strategy realizes the preparation of multifunctional, tunable and directional drive functions.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry and Environment, Beihang University, Beijing, 100191 (P. R. China).

ABSTRACT
Directional control of droplets on a surface is an important issue for tasks of long-range liquid-transport, self-cleaning and water repellency. However, it is still challenging to control the structure motions in orientations so as to control the shedding-off of droplets. Herein, we report a novel dynamic magnetic responsive wall (DMRW) array on PDMS (polydimethylsiloxane)-based surface. The walls can easily tilt through the effect of the external magnet because of the magnetic material in the DMRW. The droplets can be shed off directionally on the surface. Particularly, with the shape recovery and flexible properties, it achieves simultaneous control of the tilt angles (0-60°) of DMRW for shedding-off of droplets with different volumes (1-15 μL) under magnetic action on DMRW. The mechanism of droplet shedding-off on DMRW is elucidated by theory of interfaces. It offers an insight into design of dynamic interface for water repellency. This strategy realizes the preparation of multifunctional, tunable and directional drive functions.

No MeSH data available.


The illustration of the neodymium iron boron magnet used to tilt the DMRWs.a, The schematic of the magnetic effect on the tilt angle of DMRW. With the increasing magnetic field by getting closer magnet, the tilt angles βtilt of DMRWs increase. Im and ΔIm are intensity of magnetic field and the increased intensity of magnetic field, respectively. βtilt is the tilt angle of DMRW, the red arrow indicates the dynamic direction of DMRW. Y, X are the vertical and horizontal coordinates, respectively. b, c and d, The top view (the left) and the side view (the right) of the wall array tilt angle process. For observations of magnetic-driven, two directions are defined: direction 1 represents the direction towards the tilt direction; direction 2 indicates the direction against direction 1. e, The relationship between magnetic intensity (Im) and tilt angles (βtilt) of DMRWs. The insets are the sequent photos of DMRWs with change of βtilt from 0° to 60° with the increase of Im from 0 to 1 Tesla.
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f2: The illustration of the neodymium iron boron magnet used to tilt the DMRWs.a, The schematic of the magnetic effect on the tilt angle of DMRW. With the increasing magnetic field by getting closer magnet, the tilt angles βtilt of DMRWs increase. Im and ΔIm are intensity of magnetic field and the increased intensity of magnetic field, respectively. βtilt is the tilt angle of DMRW, the red arrow indicates the dynamic direction of DMRW. Y, X are the vertical and horizontal coordinates, respectively. b, c and d, The top view (the left) and the side view (the right) of the wall array tilt angle process. For observations of magnetic-driven, two directions are defined: direction 1 represents the direction towards the tilt direction; direction 2 indicates the direction against direction 1. e, The relationship between magnetic intensity (Im) and tilt angles (βtilt) of DMRWs. The insets are the sequent photos of DMRWs with change of βtilt from 0° to 60° with the increase of Im from 0 to 1 Tesla.

Mentions: The motion of DMRWs is induced via an externally applied magnetic field generated by neodymium-iron-boride permanent magnet1819. In our experiment, the magnetism acts on Fe micro-particles in the DMRWs, and makes the DMRWs tilt into angles. As known, Iron (Fe) as paramagnetic material is used for structure-driven. With the increase of external magnetic field strength (magnet moved from infinity in towards the DMRWs), Fe will be magnetized and attracted by the neodymium iron boron magnet. Fe shows magnetism when external magnet gets close to it. The structures will tilt and the tilt angle depends on the intensity of magnetic field. When the external magnetic field decrease or vanished, the structure will recover to the initial state due to the elastic property of PDMS. The tilt degree of the DMRWs is recorded by a high-speed CCD camera (Phantom v 9.1, America). We can observe the tilt angles (βtilt ) of DMRWs versus the magnetic intensity (Im) as shown in Fig. 2. Figure 2a show the schematic of driven motion. (As distance between magnet and substrate decreases, the strength of magnetic fields increase and the tilt angle of DMRWs becomes larger, see Frame 2a1–a3). Figure 2b–d shows the optical images from the top view (the left) and the side view (the right) on the tilt degree of DMRW. For observations of magnetic-driven, two directions are defined: direction 1 represents the direction towards the tilt direction; direction 2 indicates the direction against direction 1. Figure 2e shows the sequent photos of DMRWs with tilt angles, βtilt, ranging from 0° to 60° from side view. The relationship diagram of magnetic strength to tilt angles of DMRWs is recorded, and the tilt angles increase with the gradually increase of magnetic strength (Fig. 2e). The magnetic strength ranging from 0 to 1 Tesla, generates different tilt angle on DMRWs, e.g., when the strength reach to 0.5 Tesla, the tilt angle increases to 30°. With the tilt effect of DMRWs, the anisotropic strategy trend is more distinct. The tilt angle (βtilt) of DMRW increases with the magnetic field strength (Im) based on the measurements. (Figure S3). This investigation realizes the dynamic structure array surface controlled by magnetic action, where magnetic strength can be in direct proportion to tilt angle of DMRWs.


Dynamic Magnetic Responsive Wall Array with Droplet Shedding-off Properties.

Wang L, Zhang M, Shi W, Hou Y, Liu C, Feng S, Guo Z, Zheng Y - Sci Rep (2015)

The illustration of the neodymium iron boron magnet used to tilt the DMRWs.a, The schematic of the magnetic effect on the tilt angle of DMRW. With the increasing magnetic field by getting closer magnet, the tilt angles βtilt of DMRWs increase. Im and ΔIm are intensity of magnetic field and the increased intensity of magnetic field, respectively. βtilt is the tilt angle of DMRW, the red arrow indicates the dynamic direction of DMRW. Y, X are the vertical and horizontal coordinates, respectively. b, c and d, The top view (the left) and the side view (the right) of the wall array tilt angle process. For observations of magnetic-driven, two directions are defined: direction 1 represents the direction towards the tilt direction; direction 2 indicates the direction against direction 1. e, The relationship between magnetic intensity (Im) and tilt angles (βtilt) of DMRWs. The insets are the sequent photos of DMRWs with change of βtilt from 0° to 60° with the increase of Im from 0 to 1 Tesla.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4462108&req=5

f2: The illustration of the neodymium iron boron magnet used to tilt the DMRWs.a, The schematic of the magnetic effect on the tilt angle of DMRW. With the increasing magnetic field by getting closer magnet, the tilt angles βtilt of DMRWs increase. Im and ΔIm are intensity of magnetic field and the increased intensity of magnetic field, respectively. βtilt is the tilt angle of DMRW, the red arrow indicates the dynamic direction of DMRW. Y, X are the vertical and horizontal coordinates, respectively. b, c and d, The top view (the left) and the side view (the right) of the wall array tilt angle process. For observations of magnetic-driven, two directions are defined: direction 1 represents the direction towards the tilt direction; direction 2 indicates the direction against direction 1. e, The relationship between magnetic intensity (Im) and tilt angles (βtilt) of DMRWs. The insets are the sequent photos of DMRWs with change of βtilt from 0° to 60° with the increase of Im from 0 to 1 Tesla.
Mentions: The motion of DMRWs is induced via an externally applied magnetic field generated by neodymium-iron-boride permanent magnet1819. In our experiment, the magnetism acts on Fe micro-particles in the DMRWs, and makes the DMRWs tilt into angles. As known, Iron (Fe) as paramagnetic material is used for structure-driven. With the increase of external magnetic field strength (magnet moved from infinity in towards the DMRWs), Fe will be magnetized and attracted by the neodymium iron boron magnet. Fe shows magnetism when external magnet gets close to it. The structures will tilt and the tilt angle depends on the intensity of magnetic field. When the external magnetic field decrease or vanished, the structure will recover to the initial state due to the elastic property of PDMS. The tilt degree of the DMRWs is recorded by a high-speed CCD camera (Phantom v 9.1, America). We can observe the tilt angles (βtilt ) of DMRWs versus the magnetic intensity (Im) as shown in Fig. 2. Figure 2a show the schematic of driven motion. (As distance between magnet and substrate decreases, the strength of magnetic fields increase and the tilt angle of DMRWs becomes larger, see Frame 2a1–a3). Figure 2b–d shows the optical images from the top view (the left) and the side view (the right) on the tilt degree of DMRW. For observations of magnetic-driven, two directions are defined: direction 1 represents the direction towards the tilt direction; direction 2 indicates the direction against direction 1. Figure 2e shows the sequent photos of DMRWs with tilt angles, βtilt, ranging from 0° to 60° from side view. The relationship diagram of magnetic strength to tilt angles of DMRWs is recorded, and the tilt angles increase with the gradually increase of magnetic strength (Fig. 2e). The magnetic strength ranging from 0 to 1 Tesla, generates different tilt angle on DMRWs, e.g., when the strength reach to 0.5 Tesla, the tilt angle increases to 30°. With the tilt effect of DMRWs, the anisotropic strategy trend is more distinct. The tilt angle (βtilt) of DMRW increases with the magnetic field strength (Im) based on the measurements. (Figure S3). This investigation realizes the dynamic structure array surface controlled by magnetic action, where magnetic strength can be in direct proportion to tilt angle of DMRWs.

Bottom Line: The walls can easily tilt through the effect of the external magnet because of the magnetic material in the DMRW.It offers an insight into design of dynamic interface for water repellency.This strategy realizes the preparation of multifunctional, tunable and directional drive functions.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry and Environment, Beihang University, Beijing, 100191 (P. R. China).

ABSTRACT
Directional control of droplets on a surface is an important issue for tasks of long-range liquid-transport, self-cleaning and water repellency. However, it is still challenging to control the structure motions in orientations so as to control the shedding-off of droplets. Herein, we report a novel dynamic magnetic responsive wall (DMRW) array on PDMS (polydimethylsiloxane)-based surface. The walls can easily tilt through the effect of the external magnet because of the magnetic material in the DMRW. The droplets can be shed off directionally on the surface. Particularly, with the shape recovery and flexible properties, it achieves simultaneous control of the tilt angles (0-60°) of DMRW for shedding-off of droplets with different volumes (1-15 μL) under magnetic action on DMRW. The mechanism of droplet shedding-off on DMRW is elucidated by theory of interfaces. It offers an insight into design of dynamic interface for water repellency. This strategy realizes the preparation of multifunctional, tunable and directional drive functions.

No MeSH data available.