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Controllable assembly of silver nanoparticles induced by femtosecond laser direct writing

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ABSTRACT

We report controllable assembly of silver nanoparticles (Ag NPs) for patterning of silver microstructures. The assembly is induced by femtosecond laser direct writing (FsLDW). A tightly focused femtosecond laser beam is capable of trapping and driving Ag NPs to form desired micropatterns with a high resolution of ∼190 nm. Taking advantage of the ‘direct writing’ feature, three microelectrodes have been integrated with a microfluidic chip; two silver-based microdevices including a microheater and a catalytic reactor have been fabricated inside a microfluidic channel for chip functionalization. The FsLDW-induced programmable assembly of Ag NPs may open up a new way to the designable patterning of silver microstructures toward flexible fabrication and integration of functional devices.

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SEM images of silver micropatterns fabricated by FsLDW-induced controllable assembly of Ag NPs. (a) Ag microwires with different widths. From right to left, the width is 190, 290, 400, 510, 630, and 710 nm, respectively. (b) SEM image of a ‘Chinese knot’ pattern. (c), (d) Magnified SEM images of the ‘Chinese knot’ pattern.
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Figure 3: SEM images of silver micropatterns fabricated by FsLDW-induced controllable assembly of Ag NPs. (a) Ag microwires with different widths. From right to left, the width is 190, 290, 400, 510, 630, and 710 nm, respectively. (b) SEM image of a ‘Chinese knot’ pattern. (c), (d) Magnified SEM images of the ‘Chinese knot’ pattern.

Mentions: Note that the pulse width of our femtosecond laser is only 120 fs, so thermal relaxation could be effectively suppressed within a small area near the focus. Taking advantage of this feature, high-resolution silver patterns could be fabricated. Figure 3 shows SEM images of the resulting silver micropatterns. The narrowest width of a continuous silver microwire was only ∼190 nm, which is much smaller than the light diffraction limit. The improved resolution could be mainly attributed to the use of an ultrafast laser, which induces nonlinear effects such as multiphoton absorption [63]. In addition to simple microwires, any desired micropatterns could be readily fabricated through FsLDW. As an example, we fabricated a ‘Chinese knot’ structure on a glass substrate (figure 3(b)). A magnified SEM image (figure 3(c)) showed that the line width of the ‘Chinese knot’ was ∼2 μm. By further magnifying the SEM images, we found that the silver micropattern was constructed by close-packed silver particles whose size grew to tens of nanometers. As compared with the TEM image of the pristine Ag NPs, whose size is below 5 nm, the significant increase in particle size in the silver micropattern could be attributed to the laser-induced sintering.


Controllable assembly of silver nanoparticles induced by femtosecond laser direct writing
SEM images of silver micropatterns fabricated by FsLDW-induced controllable assembly of Ag NPs. (a) Ag microwires with different widths. From right to left, the width is 190, 290, 400, 510, 630, and 710 nm, respectively. (b) SEM image of a ‘Chinese knot’ pattern. (c), (d) Magnified SEM images of the ‘Chinese knot’ pattern.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5036472&req=5

Figure 3: SEM images of silver micropatterns fabricated by FsLDW-induced controllable assembly of Ag NPs. (a) Ag microwires with different widths. From right to left, the width is 190, 290, 400, 510, 630, and 710 nm, respectively. (b) SEM image of a ‘Chinese knot’ pattern. (c), (d) Magnified SEM images of the ‘Chinese knot’ pattern.
Mentions: Note that the pulse width of our femtosecond laser is only 120 fs, so thermal relaxation could be effectively suppressed within a small area near the focus. Taking advantage of this feature, high-resolution silver patterns could be fabricated. Figure 3 shows SEM images of the resulting silver micropatterns. The narrowest width of a continuous silver microwire was only ∼190 nm, which is much smaller than the light diffraction limit. The improved resolution could be mainly attributed to the use of an ultrafast laser, which induces nonlinear effects such as multiphoton absorption [63]. In addition to simple microwires, any desired micropatterns could be readily fabricated through FsLDW. As an example, we fabricated a ‘Chinese knot’ structure on a glass substrate (figure 3(b)). A magnified SEM image (figure 3(c)) showed that the line width of the ‘Chinese knot’ was ∼2 μm. By further magnifying the SEM images, we found that the silver micropattern was constructed by close-packed silver particles whose size grew to tens of nanometers. As compared with the TEM image of the pristine Ag NPs, whose size is below 5 nm, the significant increase in particle size in the silver micropattern could be attributed to the laser-induced sintering.

View Article: PubMed Central - PubMed

ABSTRACT

We report controllable assembly of silver nanoparticles (Ag NPs) for patterning of silver microstructures. The assembly is induced by femtosecond laser direct writing (FsLDW). A tightly focused femtosecond laser beam is capable of trapping and driving Ag NPs to form desired micropatterns with a high resolution of ∼190 nm. Taking advantage of the ‘direct writing’ feature, three microelectrodes have been integrated with a microfluidic chip; two silver-based microdevices including a microheater and a catalytic reactor have been fabricated inside a microfluidic channel for chip functionalization. The FsLDW-induced programmable assembly of Ag NPs may open up a new way to the designable patterning of silver microstructures toward flexible fabrication and integration of functional devices.

No MeSH data available.


Related in: MedlinePlus