scholarly journals Functionalization of Plastic Parts by Replication of Variable Pitch Laser-Induced Periodic Surface Structures

Micromachines ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 429 ◽  
Author(s):  
Leonardo Piccolo ◽  
Marco Sorgato ◽  
Afif Batal ◽  
Stefan Dimov ◽  
Giovanni Lucchetta ◽  
...  
Keyword(s):  
Contact Angle ◽  
Laser Ablation ◽  
Injection Molding ◽  
Femtosecond Laser Ablation ◽  
Cost Effective ◽  
Surface Structures ◽  
Periodic Surface ◽  
Wetting Behavior ◽  
Static Contact ◽  
Plastic Parts

Surface functionalization of plastic parts has been studied and developed for several applications. However, demand for the development of reliable and profitable manufacturing strategies is still high. Here we develop and characterize a new process chain for the versatile and cost-effective production of sub-micron textured plastic parts using laser ablation. The study includes the generation of different sub-micron structures on the surface of a mold using femtosecond laser ablation and vario-thermal micro-injection molding. The manufactured parts and their surfaces are characterized in consideration of polymer replication and wetting behavior. The results of the static contact angle measurements show that replicated Laser-Induced Periodic Surface Structures (LIPSSs) always increase the hydrophobicity of plastic parts. A maximum contact angle increase of 20% was found by optimizing the manufacturing thermal boundary conditions. The wetting behavior is linked to the transition from a Wenzel to Cassie–Baxter state, and is crucial in optimizing the injection molding cycle time.

scholarly journals Fabrication of Diamond Membranes by Femtosecond Laser Ablation for MEMS Sensor Applications

Proceedings ◽  
2020 ◽  
Vol 56 (1) ◽  
pp. 13
Author(s):  
Johann Zehetner ◽  
Alexander Kromka ◽  
Tibor Izsák ◽  
Gabriel Vanko ◽  
Lenka Gajdošová ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Femtosecond Laser ◽  
Surface Chemistry ◽  
Membrane Surface ◽  
Femtosecond Laser Ablation ◽  
Surface Structures ◽  
Ablation Process ◽  
Periodic Surface ◽  
Sensor Applications ◽  
Mems Sensor

We present the feasibility in fabricating membranes and cantilevers made of diamond grown on Si/SiO2 substrates by femtosecond laser ablation. In the ablation process, we generated nano- and microstructures on the membrane surface. Such laser-induced periodic surface structures (LIPSS) are useful in tailoring the surface chemistry. In combination with wet or reactive ion etching, smooth membranes were generated.

scholarly journals Multiscale Hierarchical Micro/Nanostructures Created by Femtosecond Laser Ablation in Liquids for Polarization-Dependent Broadband Antireflection

Nanomaterials ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1573
Author(s):  
Dongshi Zhang ◽  
Bikas Ranjan ◽  
Takuo Tanaka ◽  
Koji Sugioka
Keyword(s):  
Laser Ablation ◽  
Femtosecond Laser ◽  
Light Trapping ◽  
Femtosecond Laser Ablation ◽  
Surface Structures ◽  
Mid Infrared ◽  
Periodic Surface ◽  
Broadband Antireflection ◽  
20 Nm ◽  
Light Absorbance

In this work, we present the possibility of producing multiscale hierarchical micro/nanostructures by the femtosecond laser ablation of transition metals (i.e., Ta and W) in water and investigate their polarization-dependent reflectance. The hierarchical micro/nanostructures are composed of microscale-grooved, mountain-like and pit-rich structures decorated with hybrid laser-induced periodic surface structures (LIPSSs). The hybrid LIPSSs consist of low/high and ultrahigh spatial frequency LIPSSs (LSFLs/HSFLs and UHSFLs). LSFLs/HSFLs of 400–600 nm in a period are typically oriented perpendicular to the direction of the laser polarization, while UHSFLs (widths: 10–20 nm and periods: 30–50 nm) are oriented perpendicular to the curvatures of LSFLs/HSFLs. On the microstructures with height gradients, the orientations of LSFLs/HSFLs are misaligned by 18°. On the ablated W metasurface, two kinds of UHSFLs are observed. UHSFLs become parallel nanowires in the deep troughs of LSFLs/HSFLs but result in being very chaotic in shallow LSFLs, turning into polygonal nanonetworks. In contrast, chaotic USFLs are not found on the ablated Ta metasurfaces. With the help of Fourier transform infrared spectroscopy, it is found that microgrooves show an obvious polarization-dependent reflectance at wavelengths of 15 and 17.5 μm associated with the direction of the groove, and the integration of microstructures with LSFs/HSFLs/UHSFLs is thus beneficial for enhancing the light absorbance and light trapping in the near-to-mid-infrared (NIR-MIR) range.

scholarly journals Biomimetic Approach for the Elaboration of Highly Hydrophobic Surfaces: Study of the Links between Morphology and Wettability

Biomimetics ◽  
2021 ◽  
Vol 6 (2) ◽  
pp. 38
Author(s):  
Quentin Legrand ◽  
Stephane Benayoun ◽  
Stephane Valette
Keyword(s):  
Contact Angle ◽  
Ginkgo Biloba ◽  
Contact Angle Hysteresis ◽  
Contact Angles ◽  
Textured Surfaces ◽  
Replication Process ◽  
Wetting Behavior ◽  
Static Contact ◽  
Biomimetic Approach ◽  
Highly Hydrophobic

This investigation of morphology-wetting links was performed using a biomimetic approach. Three natural leaves’ surfaces were studied: two bamboo varieties and Ginkgo Biloba. Multiscale surface topographies were analyzed by SEM observations, FFT, and Gaussian filtering. A PDMS replicating protocol of natural surfaces was proposed in order to study the purely morphological contribution to wetting. High static contact angles, close to 135∘, were measured on PDMS replicated surfaces. Compared to flat PDMS, the increase in static contact angle due to purely morphological contribution was around 20∘. Such an increase in contact angle was obtained despite loss of the nanometric scale during the replication process. Moreover, a significant decrease of the hysteresis contact angle was measured on PDMS replicas. The value of the contact angle hysteresis moved from 40∘ for flat PDMS to less than 10∘ for textured replicated surfaces. The wetting behavior of multiscale textured surfaces was then studied in the frame of the Wenzel and Cassie–Baxter models. Whereas the classical laws made it possible to describe the wetting behavior of the ginkgo biloba replications, a hierarchical model was developed to depict the wetting behavior of both bamboo species.

scholarly journals Evolution of Microstructures on Stainless Steel induced by Ultra-Short Laser Ablation

2019 ◽  
Author(s):  
Norbert Ackerl ◽  
Gabriela Fisch ◽  
Janko Auerswald ◽  
Konrad Wegener
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Laser Ablation ◽  
Grain Orientation ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Surface Structures ◽  
Periodic Surface ◽  
Processing Window ◽  
Grain Orientations

Ultra-short pulsed laser ablation of stainless steel is accompanied by the evolution of different microstructures. Depending on the fuence, accumulated energy and number of laser passes cones from impurities, laser induced periodic surface structures and conelike protrusion (CLP) evolve at the surface. These often unwanted morphologies can be inhibited by carefully choosing the strategy and laser parameters. Here, the identifed region shows a small processing window fordesigned 515nm sub 1 ps ablation leading to low surface roughness. CLP are still not well understood and here a pre-cursor structure is reported. Subsequently, the CLP growth is grain orientation and polarization dependent and studied in more depth. Preferentially, CLP start to evolve at the (101) grain orientations with linear polarized laser radiation. Moreover, a nanoindentation study reveals robust mechanical properties, which could be beneficial for tribology applications in the hydrodynamic regime.

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