Characterization of Individual Microneedles Formed on Alloy Surfaces by Femtosecond Laser Ablation

Bhattacharya, Sudip; Kam, Dong-Hyuck; Song, Lijun; Mazumder, J.

doi:10.1007/s11661-012-1152-2

Cited by 10 publications

(13 citation statements)

References 21 publications

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“…These surface cones, first discovered by Dyer et al [37] in 1986, bear a striking resemblance to the ellipsoidal cones discussed in this work and others [11,19,20,35], in terms of morphology, spatial distribution, and trends with respect to experimental conditions. Krajnovich and Vázquez [36] proposed a "radiation hardening" theory which states that, as more laser pulses are applied, the target polyimide surface becomes increasingly enriched in carbon, leading to an elevated ablation threshold.…”

Section: Chemical Analysissupporting

confidence: 78%

“…At low fluence (approximately F Σline,max < 130 J/cm 2 ), ellipsoidal cones -composed of unablated steel concealed within several distinct layers of nanoparticles -appear randomly distributed over the irradiated area. In this first regime, deposition dominates over ablation due to the low pulse energies utilized [35]. Nanoparticles that deposit on the machined surface agglomerate and form clusters that serve as precursors for ellipsoidal cones.…”

Section: Resultsmentioning

confidence: 99%

“…In this study, we investigate the formation and growth of ellipsoidal cones ( Figure 1a and 2) using a series of chemical, crystallographic, and topographical analyses. While several authors [11,19,20,[35][36][37][38][39][40] have already observed the formation of ellipsoidal cones via laser processing, this work focuses on elucidating the mechanisms behind the formation and growth of ellipsoidal cones by multiple laser raster scans.…”

Section: Model Computationsmentioning

confidence: 99%

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Investigating and understanding the effects of multiple femtosecond laser scans on the surface topography of stainless steel 304 and titanium

Ling

Saïd

Brodusch

et al. 2015

Applied Surface Science

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The majority of studies performed on the formation of surface features by femtosecond laser radiation focuses on single scan procedures, i.e. solely manipulating the laser beam once over the target area to fabricate different surface topographies. In this work, the effect of scanning stainless steel 304 multiple times with femtosecond laser pulses is thoroughly investigated over a wide range of fluences. The resultant laserinduced surface topographies can be categorized into two different regimes. In the low fluence regime (F Σline,max < 130 J/cm 2 ), ellipsoidal cones (randomly distributed surface protrusions covered by several layers of nanoparticles) are formed. Based on chemical, crystallographic, and topographical analyses, we conclude that these ellipsoidal cones are composed of unablated steel whose conical geometry offers a significant degree of fluence reduction (35-52%). Therefore, the rest of the irradiated area is preferentially ablated at a higher rate than the ellipsoidal cones. The second, or high fluence regime (F Σline,max > 130 J/cm 2 ) consists of laser-induced surface patterns such as columnar and chaotic structures. Here, the surface topography showed little to no change even when the target was scanned repeatedly. This is in stark contrast to the ellipsoidal cones in the first regime, which evolve and grow continuously as more laser passes are applied. Keywords

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Section: Chemical Analysissupporting

confidence: 78%

Section: Resultsmentioning

confidence: 99%

Section: Model Computationsmentioning

confidence: 99%

See 1 more Smart Citation

Investigating and understanding the effects of multiple femtosecond laser scans on the surface topography of stainless steel 304 and titanium

Ling

Saïd

Brodusch

et al. 2015

Applied Surface Science

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“…for multi-scale structuring of surfaces, involving both LIPSS and CLP, to create super-hydrophobic properties [24]. However, for the targeted application, CLP is unwanted, since it makes it impossible to machine flat surfaces and sharp edges at high precision [17,21,22,[25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Ultrashort pulsed laser ablation of stainless steels

Villerius

Kooiker

Post

et al. 2019

International Journal of Machine Tools and Manufacture

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This research investigated the ablation process of commercial stainless steels with ultrashort pulsed laser. Square hollows were ablated on stainless steel sheets using a picosecond laser with pulse duration of 0.25, 1 and 10 ps, respectively, and fluence ranging from 0.125 J/cm 2 to 5 J/cm 2 . For each setting the surface quality and ablation efficiency were determined by optical microscopy and scanning electron microscopy (SEM). Processing windows producing high quality surfaces at high ablation efficiency were found at a fluence around 0.75 J/cm 2 for the two shorter pulse lengths tested. Individual cones and periodic cone-like protrusions were found in the low fluence regime (< 0.625 J/cm 2 ) and high fluence regime (> 0.875 J/cm 2 ), respectively, both of which make the ablated surface rough. Emphasizing on the individual cones, it is found that the cones are caused by inclusions in the base materials, attributed to a higher fluence threshold required for ceramic-like inclusions. This novel theory explaining the creation mechanism is verified by multiple analysis methods like SEM and energy dispersive X-ray spectroscopy and stop-motion SEM imaging. current hypotheses are self-organization as suggested by Reif et al. [14]

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“…Other methods have been employed to control the wetting properties of surfaces for preparing (a) hydrophilic surfaces via hydrophilic coatings [21,22], plasma treatments [23,24], or chemical treatments [25] and (b) hydrophobic surfaces via hydrophobic coatings [27,[30][31][32][33]. However, these methods are generally expensive, complicated, and time consuming.…”

Section: Introductionmentioning

confidence: 99%

Permeability Study of Austenitic Stainless Steel Surfaces Produced by Selective Laser Melting

Segura-Cárdenas

Ramírez-Cedillo

Sandoval-Robles

et al. 2017

Metals

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Selective laser melting (SLM) is emerging as a versatile process for fabricating different metal components with acceptable mechanical properties and geometrical accuracy. The process has been used in the manufacturing of several parts (e.g., aerospace or biomedical components), and offers the capability to tailor the performance of several surface and mechanical properties. In this work, permeability properties and surface roughness of stainless steel (SS316L) surfaces were evaluated through experimentation with three different laser scanning patterns (chessboard, meander, and stripe), and different sloping angles between the fabricated surface and the laser beam incident on the process. Results showed that for each scanning pattern, the roughness decreased as the sloping angle increased consistently in all experimental trials. Furthermore, in the case of the permeability evaluation, the manufactured surfaces showed changes in properties for each series of experiments performed with different scanning patterns. The chessboard pattern showed a change of 67 • to 107 • in contact angle, while the meander and stripe patterns showed a variation in contact angle in a range of 65 • to 85 • . The different scanning strategies in the SLM process resulted in an alternative method for surface enhancement with different hydrophobicity properties, valuable for designing the most appropriate permeability characteristics for specific applications.

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Characterization of Individual Microneedles Formed on Alloy Surfaces by Femtosecond Laser Ablation

Cited by 10 publications

References 21 publications

Investigating and understanding the effects of multiple femtosecond laser scans on the surface topography of stainless steel 304 and titanium

Investigating and understanding the effects of multiple femtosecond laser scans on the surface topography of stainless steel 304 and titanium

Ultrashort pulsed laser ablation of stainless steels

Permeability Study of Austenitic Stainless Steel Surfaces Produced by Selective Laser Melting

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