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Laser-induced periodic surface structures (LIPSS, ripples) are a universal phenomenon and can be generated on almost any material upon irradiation with linearly polarized radiation. With the availability of ultrashort laser pulses, LIPSS have gained an increasing attraction during the past decade, since these structures can be generated in a simple single-step process, which allows a surface nanostructuring for tailoring optical, mechanical, and chemical surface properties. In this study, the current state in the field of LIPSS is reviewed. Their formation mechanisms are analyzed in ultrafast time-resolved scattering, diffraction, and polarization constrained double-pulse experiments. These experiments allow us to address the question whether the LIPSS are seeded via ultrafast energy deposition mechanisms acting during the absorption of optical radiation or via self-organization after the irradiation process. Relevant control parameters of LIPSS are identified, and technological applications featuring surface functionalization in the fields of optics, fluidics, medicine, and tribology are discussed.
Laser-induced periodic surface structures (LIPSS, ripples) are a universal phenomenon that can be observed on almost any material after the irradiation by linearly polarized laser beams, particularly when using ultrashort laser pulses with durations in the picosecond to femtosecond range. During the past few years significantly increasing research activities have been reported in the field of LIPSS, since their generation in a single-step process provides a simple way of nanostructuring and surface functionalization towards the control of optical, mechanical or chemical properties. In this contribution current applications of LIPSS are reviewed, including the colorization of technical surfaces, the control of surface wetting, the tailoring of surface colonization by bacterial biofilms, and the improvement of the tribological performance of nanostructured metal surfaces.
Ultrashort laser pulses with durations in the fs- to ps-range were used for large area surface processing of steel aimed at mimicking the morphology and extraordinary wetting behaviour of bark bugs (Aradidae) found in nature. The processing was performed by scanning the laser beam across the surface of initially polished flat sample surfaces. A systematic variation of the laser processing parameters (peak fluence, scan velocity, line overlap) allowed the identification of different regimes associated with characteristic surface morphologies (laser-induced periodic surface structures (LIPSS), grooves, spikes, etc.). Additionally, we show that different laser processing strategies, varying laser wavelength, pulse duration and repetition rates, allowed to achieve a range of morphologies that resemble different structures found in bark bugs. For identifying the ideal combination of parameters for mimicking bug-like structures, the surfaces were inspected by optical and scanning electron microscopy.
Complementary to the morphology study, the wetting behaviour of the surface structures for water and oil was examined intensively in terms of philic/-phobic nature and fluid transport. With these results in hand, tribological tests were carried out investigating the wear resistance of the laser-induced nano- and microstructures. Our results demonstrate a route towards reproducing complex structures inspired by nature and their functional response in technologically relevant materials.
Applications of laser-induced periodic surface structures (LIPSS, ripples) upon irradiation of solid materials by fs-laser pulses are reviewed. This includes the colorization of technical surfaces, the control of surface wetting, the mimicry of the natural texture of animal integuments for realizing specific fluid transport functionalities, the tailoring of surface colonization by bacterial biofilms, and the improve-ment of the tribological performance of nanostructured metal surfaces.
Laser-induced periodic surface structures (LIPSS) can be generated by irradiation of almost any material with linearly polarized laser beams, particularly when using ultrashort laser pulses.
Within this work, different types of steel were irradiated at optimized conditions for the processing of large surface areas. For these nanostructured surfaces, the coefficient of friction (COF) using different lubricants was determined and the corresponding wear tracks were characterized by scanning electron microscopy (SEM). Our experiments provide a qualification of the tribologicalperformance of the fs-LIPSS on different steel surfaces, which are relevant for technical applications.
Laser-induced Nanostructures as Biomimetic Model of Fluid Transport in the Integument of Animals”, aims on laser-fabrication of biomimetic surfaces with unique wetting properties, which are inspired by the hierarchical micro- and/or nano- structures of animal body surfaces. LiNaBioFluid is a Research and Innovation Action funded by the European Commissions’ Horizon 2020 - FET Open Programme, which supports early-stage research on any idea for a new technology (Grant Agreement no: 665337). It brings together 7 partners from 4 different countries and is strongly interdisciplinary combining renowned experts from the fields of zoology, physics, mechatronics, life sciences, materials sciences, laser-matter interaction, production technology, tribology, and biomimetics. www.laserbiofluid.eu/
Applications of femtosecond laser processed surfaces are reviewed. This includes the colorization of technical surfaces, the control of surface wetting, the tailoring of surface colonization by bacterial biofilms, the reduction of cell adhesion on novel pacemakers, and the improvement of the tribological performance of nanostructured metal surfaces.
Nature provides countless examples of surface structures featuring extraordinary properties such as directional fluid transport. In order to mimic the morphology and outstanding wetting behaviour of bark bugs, ultrashort laser pulses with durations in the fs- to ps-range were employed for large area surface processing of steel. By scanning the laser beam across the surface of initially polished flat sample surfaces and systematically varying the laser processing parameters (peak fluence, scan velocity, line overlap), different regimes associated with characteristic surface morphologies (laser-induced periodic surface structures (LIPSS), grooves, spikes, etc.) could be identified. Additionally, different laser processing strategies were applied, varying laser wavelength, pulse duration and repetition rates, which allowed to achieve a range of morphologies that resemble different structures found on bark bugs. For identifying the ideal combination of parameters for mimicking such bug-like structures, the surfaces were inspected by means of optical and scanning electron microscopy.
Complementary to the morphology study, the wetting behaviour of the surface structures for water and oil was examined intensively in terms of fluid transport and philic/-phobic nature. Additionally, with these results in hand, tribological tests investigating the wear resistance of the laser-induced nano- and microstructures were carried out. Our results demonstrate that the functionality of surface structures found in nature could be transferred to technologically relevant materials, such as steel, providing a huge potential for industrial applications for instance in friction and wear reduction.
Ultrashort laser pulses with durations in the fs-to-ps range were used for large area surface processing of steel aimed at mimicking the morphology and extraordinary wetting behaviour of bark bugs (Aradidae) found in nature. The processing was performed by scanning the laser beam over the surface of polished flat sample surfaces. A systematic variation of the laser processing parameters (peak fluence and effective number of pulses per spot diameter) allowed the identification of different regimes associated with characteristic surface morphologies (laser-induced periodic surface structures, i.e., LIPSS, grooves, spikes, etc.). Moreover, different laser processing strategies, varying laser wavelength, pulse duration, angle of incidence, irradiation atmosphere, and repetition rates, allowed to achieve a range of morphologies that resemble specific structures found on bark bugs. For identifying the ideal combination of parameters for mimicking bug-like structures, the surfaces were inspected by scanning electron microscopy. In particular, tilted micrometre-sized spikes are the best match for the structure found on bark bugs. Complementary to the morphology study, the wetting behaviour of the surface structures for water and oil was examined in terms of philic/ phobic nature and fluid transport. These results point out a route towards reproducing complex surface structures inspired by nature and their functional response in technologically relevant materials.