TY - JOUR A1 - Bonse, Jörn A1 - Höhm, S. A1 - Kirner, Sabrina V. A1 - Rosenfeld, A. A1 - Krüger, Jörg T1 - Laser-induced periodic surface structures — a scientific evergreen N2 - 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. KW - Laser ablation KW - Nanostructures KW - Surface functionalization KW - Surface texture KW - Laser-induced periodic surface structures (LIPSS) PY - 2017 U6 - https://doi.org/10.1109/JSTQE.2016.2614183 SN - 1077-260X SN - 1558-4542 VL - 23 IS - 3 SP - 9000615 PB - IEEE AN - OPUS4-38633 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Höhm, S. A1 - Rosenfeld, A. A1 - Krüger, Jörg A1 - Bonse, Jörn T1 - Laser-induced periodic surface structures on zinc oxide crystals upon two-colour femtosecond double-pulse irradiation N2 - In order to study the temporally distributed energy deposition in the formation of laser-induced periodic surface structures (LIPSS) on single-crystalline zinc oxide (ZnO), two-colour double-fs-pulse experiments were performed. Parallel or cross-polarised double-pulse sequences at 400 and 800 nm wavelength were generated by a Mach–Zehnder interferometer, exhibiting inter-pulse delays up to a few picoseconds between the sub-ablation 50-fs-pulses. Twenty two-colour double-pulse sequences were collinearly focused by a spherical mirror to the sample surface. The resulting LIPSS periods and areas were analysed by scanning electron microscopy. The delay-dependence of these LIPSS characteristics shows a dissimilar behaviour when compared to the semiconductor silicon, the dielectric fused silica, or the metal titanium. A wavelength-dependent plasmonic mechanism is proposed to explain the delay-dependence of the LIPSS on ZnO when considering multi-photon excitation processes. Our results support the involvement of nonlinear processes for temporally overlapping pulses. These experiments extend previous two-colour studies on the indirect semiconductor silicon towards the direct wide band-gap semiconductor ZnO and further manifest the relevance of the ultrafast energy deposition for LIPSS formation. KW - Laser-induced periodic surface structures, LIPSS KW - Laser ablation KW - Surface plasmon polariton PY - 2017 U6 - https://doi.org/10.1088/1402-4896/aa5578 SN - 1402-4896 SN - 0031-8949 VL - 92 IS - 3 SP - Article 034003, 1 EP - 7 PB - IOP CY - Bristol, UK AN - OPUS4-39082 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heitz, J. A1 - Plamadeala, C. A1 - Muck, M. A1 - Habidzadeh, H. A1 - Baumgartner, W. A1 - Weth, A. A1 - Steinwender, C. A1 - Blessberger, H. A1 - Kellermair, J. A1 - Kirner, Sabrina V. A1 - Krüger, Jörg A1 - Bonse, Jörn A1 - Guntner, A. S. A1 - Hassel, A. W. T1 - Laser-induced microstructures on Ti substrates for reduced cell adhesion N2 - The abstract summarizes the poster presented at the "Kardiologie im Zentrum - Fortbildung der Klinik für Kardiologie und Intensivmedizin Kepler Universitätsklinikum Linz", held between October 20th and 31st in Linz, Austria. The poster has been awarded the 2nd place of the "Best Poster Award". T2 - Kardiologie im Zentrum - Fortbildung der Klinik für Kardiologie und Intensivmedizin Kepler Universitätsklinikum Linz CY - Linz, Austria DA - 20.10.2017 KW - Femtosecond laser processing KW - Titanium alloy KW - Cell adhesion KW - Pacemaker PY - 2017 UR - http://www.kup.at/kup/pdf/14098.pdf SN - 1024-0098 VL - 24 IS - 11-12 SP - 292 EP - 292 PB - Krause & Pachernegg GmbH CY - Gablitz, Austria AN - OPUS4-43160 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Rosenfeld, A. A1 - Höhm, S. A1 - Krüger, Jörg A1 - Bonse, Jörn ED - Reedijk, J. T1 - Dynamics of ultrashort double-pulse laser ablation of solid surfaces N2 - Given their unique properties, ultrashort laser pulses with durations in the femtosecond to picosecond range currently open new avenues in the field of laser materials processing, resulting in groundbreaking new applications based on laser-induced surface functionalization. This article reviews the usability of temporally distributed energy deposition via double-pulse irradiation in applications based on laser ablation. This includes simple new techniques for surface nanostructuring and improved sensitivities in spectroscopic material analyses. KW - Carrier excitation KW - Double-pulse KW - Interferometer KW - Laser ablation KW - Femtosecond PY - 2017 UR - https://www.sciencedirect.com/science/article/pii/B9780124095472141277 SN - 978-0-12-409547-2 U6 - https://doi.org/10.1016/B978-0-12-409547-2.14127-7 SP - 1 EP - 10 PB - Elsevier AN - OPUS4-43594 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Andree, Stefan A1 - Heidmann, B. A1 - Ringleb, F. A1 - Eylers, K. A1 - Bonse, Jörn A1 - Boeck, T. A1 - Schmid, M. A1 - Krüger, Jörg T1 - Femtosecond laser pulses for photovoltaic bottom-up strategies N2 - A promising technology in photovoltaics is based on micro-concentrator solar cells, where the photovoltaic active area is realized as an array of sub-millimeter sized cells onto which the incident light is focused via microlenses. This approach allows to increase the cell efficiency and to realize much more compact modules compared to macroscopic concentrator devices. At the same time, expensive raw materials can be saved, which is of interest, for example, with respect to indium in the case of copper-indium-gallium-diselenide (CIGSe) thin film solar cells. Two methods to produce micro-sized precursors of CIGSe absorbers on molybdenum are presented using 30-fs laser pulses at 790 nm wavelength. On the one hand, a multi pulse surface structuring of the molybdenum film or the underlying glass substrate and a subsequent physical vapor deposition were used for a site-selective aggregation of indium droplets. On the other hand, a single pulse laser-induced forward transfer was utilized to selectively deposit combined copper-indium precursor pixels on the molybdenum back contact of the solar cell. Post-processing (selenization, isolation, contacting) of the laser-generated micro-sized precursors results in functional CIGSe solar cells. T2 - 10. Mittweidaer Lasertagung CY - Mittweida, Germany DA - 16.11.2017 KW - Copper indium gallium diselenide (CIGSe) KW - Micro solar cell KW - Femtosecond laser KW - Laser ablation KW - Laser-induced forward transfer (LIFT) PY - 2017 SN - 1437-7624 VL - 2 SP - 1 EP - 4 PB - Hochschule Mittweida CY - Mittweida AN - OPUS4-42988 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn A1 - Hermens, U. A1 - Kirner, Sabrina V. A1 - Emonts, C. A1 - Comanns, P. A1 - Skoulas, E. A1 - Mimidis, A. A1 - Mescheder, H. A1 - Winands, K. A1 - Krüger, Jörg A1 - Stratakis, E. T1 - Mimicking lizard-like surface structures and their fluid transport upon ultrashort laser pulse irradiation of steel N2 - The wetting behavior of material surfaces can be controlled by surface structures. We functionalized case-hardened alloyed carbon steel to modify the wetting behavior using ultrashort laser pulses (fs- to ps-range). The laser processing was performed by scanning the laser beam across the surface of initially polished flat sample material. An experimental study of the laser processing parameters (peak fluence, scan velocity, line overlap) rendered an assignment of different regimes associated with characteristic surface morphologies (laser-induced periodic surface structures, grooves, micro cones, etc.) possible. Analyzing the surface using optical as well as scanning electron microscopy allowed the identification of morphologies providing the optimum similarity to the natural skin of non-moisture havesting lizards. For mimicking skin structures of moisture-harvesting lizards, additionally a two-step laser processing strategy was established for realizing hierarchical microstructures. In this approach, micrometer-scaled capillaries (step 1) were superimposed by a laser-generated regular array of small dimples (step 2). Optical focus variation imaging measurements finally revealed the three dimensional topography of the laser processed surfaces derived from lizard skin structures. The functionality of these surfaces was analyzed in view of wetting and directional fluid transport properties. The results suggest possible applications of the laser-structured surfaces. T2 - European Materials Research Society (EMRS) Spring Meeting 2017, Symposium K “Bioinspired and biointegrated materials as new frontiers nanomaterials VII” CY - Strasbourg, France DA - 22.05.2017 KW - Lizards KW - Laser processing KW - Steel KW - Fluid transport KW - Wetting PY - 2017 AN - OPUS4-40421 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Seuthe, T. A1 - Mermillod-Blondin, A. A1 - Grehn, M. A1 - Bonse, Jörn A1 - Wondraczek, L. A1 - Eberstein, M. T1 - Structural relaxation phenomena in silicate glasses modifed by irradiation with femtosecond laser pulses N2 - Structural relaxation phenomena in binary and multicomponent lithium silicate glasses were studied upon irradiation with femtosecond (fs) laser pulses (800 nm central wavelength, 130 fs pulse duration) and subsequent thermal annealing experiments. Depending on the annealing temperature, micro-Raman spectroscopy analyses evidenced different relaxation behaviours, associated to bridging and non-bridging oxygen structures present in the glass network. The results indicate that the mobility of lithium ions is an important factor during the glass modification with fs-laser pulses. Quantitative phase contrast imaging (spatial light interference microscopy) revealed that these fs-laser induced structural modifications are closely related to local changes in the refractive index of the material. The results establish a promising strategy for tailoring fs-laser sensitivity of glasses through structural mobility. KW - Femtosecond laser KW - Silicate glasses KW - Raman spectroscopy KW - Structural relaxation KW - Refractive index PY - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-393045 SN - 2045-2322 VL - 7 SP - 43815, 1 EP - 43815, 10 PB - Nature Publishing Group CY - London, UK AN - OPUS4-39304 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn A1 - Kirner, Sabrina V. A1 - Höhm, S. A1 - Epperlein, Nadja A1 - Spaltmann, Dirk A1 - Rosenfeld, A. A1 - Krüger, Jörg T1 - Applications of laser-induced periodic surface structures (LIPSS) N2 - 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. T2 - SPIE Photonics West Conference, Laser-based Micro- and Nanoprocessing XI CY - San Francisco, USA DA - 27.01.2017 KW - Laser-induced periodic surface structures (LIPSS) KW - Laser processing KW - Surface functionalization KW - Application PY - 2017 SN - 978-1-5106-0625-8 SN - 978-1-5106-0626-5 U6 - https://doi.org/10.1117/12.2250919 SN - 0277-786X SN - 1996-756X VL - 10092 SP - Article UNSP 100920N, 100920N-1 EP - 100920N-9 PB - SPIE CY - Bellingham, USA AN - OPUS4-39305 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Kirner, Sabrina A1 - Koter, Robert A1 - Pentzien, Simone A1 - Spaltmann, Dirk A1 - Krüger, Jörg T1 - Femtosecond laser-induced periodic surface structures on titanium nitride coatings for tribological applications N2 - Titanium nitride (TiN) was coated on different substrate materials, namely pure titanium (Ti), titanium alloy (Ti6Al4V) and steel (100Cr6), generating 2.5 μm thick TiN layers. Using femtosecond laser pulses (30 fs, 790 nm, 1 kHz pulse repetition rate), large surface areas (5 mm × 5 mm) of laser-induced periodic surface structures (LIPSS) with sub-wavelength periods ranging between 470 nm and 600 nm were generated and characterized by optical microscopy (OM), white light interference microscopy (WLIM) and scanning electron microscopy (SEM). In tribological tests, coefficients of friction (COF) of the nanostructured surfaces were determined under reciprocating sliding conditions (1 Hz, 1.0 N normal load) against a 10-mm diameter ball of hardened 100Cr6 steel during 1000 cycles using two different lubricants, namely paraffin oil and engine oil. It turned out that the substrate material, the laser fluence and the lubricant are crucial for the tribological performance. However, friction and wear could not be significantly reduced by LIPSS on TiN layers in comparison to unstructured TiN surfaces. Finally, the resulting wear tracks on the nanostructured surfaces were investigated with respect to their morphology (OM, SEM), depth (WLIM) and chemical composition by energy dispersive X-ray spectroscopy (EDX) and, on one hand, compared with each other, on the other hand, with non-structured TiN surfaces. KW - Laser-induced periodic surface structures (LIPSS) KW - Femtosecond laser ablation KW - Titanium nitride films KW - Friction KW - Wear PY - 2017 UR - http://www.sciencedirect.com/science/article/pii/S0169433216322486 U6 - https://doi.org/10.1016/j.apsusc.2016.10.132 SN - 0169-4332 SN - 1873-5584 VL - 418 IS - Part B SP - 572 EP - 579 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-40507 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hermens, U. A1 - Kirner, Sabrina A1 - Emonts, C. A1 - Comanns, P. A1 - Skoulas, E. A1 - Mimidis, A. A1 - Mescheder, H. A1 - Winands, K. A1 - Krüger, Jörg A1 - Stratakis, E. A1 - Bonse, Jörn T1 - Mimicking lizard-like surface structures upon ultrashort laser pulse irradiation of inorganic materials N2 - Inorganic materials, such as steel, were functionalized by ultrashort laser pulse irradiation (fs- to ps-range) to modify the surface’s wetting behavior. The laser processing was performed by scanning the laser beam across the surface of initially polished flat sample material. A systematic experimental study 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, grooves, spikes, etc.). Analyses of the surface using optical as well as scanning electron microscopy revealed morphologies providing the optimum similarity to the natural skin of lizards. For mimicking skin structures of moisture-harvesting lizards towards an optimization of the surface wetting behavior, additionally a two-step laser processing strategy was established for realizing hierarchical microstructures. In this approach, micrometer-scaled capillaries (step 1) were superimposed by a laser-generated regular array of small dimples (step 2). Optical focus variation imaging measurements finally disclosed the three dimensional topography of the laser processed surfaces derived from lizard skin structures. The functionality of these surfaces was analyzed in view of wetting properties. KW - Femtosecond laser ablation KW - Laser-induced periodic surface structures KW - Lizard KW - Surface wetting KW - Fluid transport KW - Steel PY - 2017 UR - http://www.sciencedirect.com/science/article/pii/S0169433216328306 U6 - https://doi.org/10.1016/j.apsusc.2016.12.112 SN - 0169-4332 SN - 1873-5584 VL - 418 IS - Part B SP - 499 EP - 507 PB - Elsevier, North-Holland CY - Amsterdam AN - OPUS4-40509 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ringleb, F. A1 - Eylers, K. A1 - Teubner, T. A1 - Schramm, H.-P. A1 - Symietz, Christian A1 - Bonse, Jörn A1 - Andree, Stefan A1 - Heidmann, B. A1 - Schmid, M. A1 - Krüger, Jörg A1 - Boeck, T. T1 - Growth and shape of indium islands on molybdenum at micro-roughened spots created by femtosecond laser pulses N2 - Indium islands on molybdenum coated glass can be grown in ordered arrays by surface structuring using a femtosecond laser. The effect of varying the molybdenum coated glass substrate temperature and the indium deposition rate on island areal density, volume and geometry is investigated and evaluated in a physical vapor deposition (PVD) process. The joined impact of growth conditions and spacing of the femtosecond laser structured spots on the arrangement and morphology of indium islands is demonstrated. The results yield a deeper understanding of the island growth and its precise adjustment to industrial requirements, which is indispensable for a technological application of such structures at a high throughput, for instance as precursors for the preparation of Cu(In,Ga)Se2 micro concentrator solar cells. KW - Indium islands KW - Femtosecond laser patterning KW - Diffusion KW - CIGSe micro solar cells PY - 2017 UR - http://www.sciencedirect.com/science/article/pii/S0169433216325764 U6 - https://doi.org/10.1016/j.apsusc.2016.11.135 SN - 0169-4332 SN - 1873-5584 VL - 418 SP - 548 EP - 553 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-40551 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Epperlein, Nadja A1 - Menzel, Friederike A1 - Schwibbert, Karin A1 - Koter, Robert A1 - Bonse, Jörn A1 - Sameith, Janin A1 - Krüger, Jörg A1 - Toepel, Jörg T1 - Influence of femtosecond laser produced nanostructures on biofilm growth on steel N2 - Biofilm formation poses high risks in multiple industrial and medical settings. However, the robust nature of biofilms makes them also attractive for industrial applications where cell biocatalysts are increasingly in use. Since tailoring material properties that affect bacterial growth or its inhibition is gaining attention, here we focus on the effects of femtosecond laser produced nanostructures on bacterial adhesion. Large area periodic surface structures were generated on steel surfaces using 30-fs laser pulses at 790 nm wavelength. Two types of steel exhibiting a different corrosion resistance were used, i.e., a plain structural steel (corrodible) and a stainless steel (resistant to corrosion). Homogeneous fields of laser-induced periodic surface structures (LIPSS) were realized utilizing laser fluences close to the ablation threshold while scanning the sample under the focused laser beam in a multi-pulse regime. The nanostructures were characterized with optical and scanning electron microscopy. For each type of steel, more than ten identical samples were laser-processed. Subsequently, the samples were subjected to microbial adhesion tests. Bacteria of different shape and adhesion behavior (Escherichia coli and Staphylococcus aureus) were exposed to laser structures and to polished reference surfaces. Our results indicate that E. coli preferentially avoids adhesion to the LIPSS-covered areas, whereas S. aureus favors these areas for colonization. KW - Laser-induced periodic surface structures KW - Femtosecond laser KW - Steel KW - Biofilms KW - Microbial adhesion tests PY - 2017 UR - http://www.sciencedirect.com/science/article/pii/S0169433217305470 U6 - https://doi.org/10.1016/j.apsusc.2017.02.174 SN - 0169-4332 SN - 1873-5584 VL - 418 IS - Part B SP - 420 EP - 424 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-40565 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn T1 - Laser-induzierte periodische Oberflächenstrukturen N2 - Der Vortrag gibt einen Überblick zu aktuellen Projekt- und Publikationsaktivitäten im BAM-Fachbereich 6.4 Technologien mit Nanowerkstoffen zum Thema “Laser-induzierte periodische Oberflächenstrukturen”. Die Herstellung solcher Mikro- und Nanostrukturen mittels ultrakurzer Laserpulse wird beschrieben, wodurch optische, chemische, mechanische oder biologische Oberflächenfunktionalsierungen vorgenommen werden können. Beispiele aus den Bereichen der Farbwirkung, der Benetzbarkeit mit Flüssigkeiten und der Reibungs- und Verschleissminderung werden erläutert. T2 - IFSW-Kolloquium CY - Universität Stuttgart, Stuttgart, Germany DA - 15.02.2017 KW - Femtosekundenlaser KW - Laser-Materialbearbeitung KW - Oberflächenfunktionalisierung KW - Nanostrukturen PY - 2017 AN - OPUS4-39215 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn A1 - Kirner, Sabrina A1 - Höhm, S. A1 - Epperlein, Nadja A1 - Spaltmann, Dirk A1 - Rosenfeld, A. A1 - Krüger, Jörg T1 - Applications of laser-induced periodic surface structures (LIPSS) N2 - 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 mimicry of the natural texture of animal integuments, the tailoring of surface colonization by bacterial biofilms, and the improvement of the tribological performance of nanostructured metal surfaces. T2 - SPIE Photonics West Conference, Symposium "Laser-Based Micro- and Nanoprocessing XI" CY - San Francisco, USA DA - 28.01.2017 KW - Laser-induced periodic surface structures KW - Surface functionalization KW - Femtosecond laser PY - 2017 AN - OPUS4-39216 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kirner, Sabrina V. A1 - Hermens, U. A1 - Mimidis, A. A1 - Skoulas, E. A1 - Florian, C. A1 - Hischen, F. A1 - Plamadeala, C. A1 - Baumgartner, W. A1 - Winands, K. A1 - Mescheder, H. A1 - Krüger, Jörg A1 - Solis, J. A1 - Siegel, J. A1 - Stratakis, E. A1 - Bonse, Jörn T1 - Mimicking bug-like surface structures and their fluid transport produced by ultrashort laser pulse irradiation of steel N2 - 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. KW - Biomometics KW - Surface wetting KW - Steel KW - Bug KW - Laser-induced periodic surface structures KW - Fluid transport KW - Femtosecond laser ablation PY - 2017 U6 - https://doi.org/10.1007/s00339-017-1317-3 SN - 0947-8396 SN - 1432-0630 VL - 123 IS - 12 SP - 754, 1 EP - 13 AN - OPUS4-42817 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heitz, J. A1 - Plamadeala, C. A1 - Muck, M. A1 - Armbruster, O. A1 - Baumgartner, W. A1 - Weth, A. A1 - Steinwender, C. A1 - Plessberger, H. A1 - Kellermair, J. A1 - Kirner, Sabrina V. A1 - Krüger, Jörg A1 - Bonse, Jörn A1 - Guntner, A. S. A1 - Hassel, A. W. T1 - Femtosecond laser-induced microstructures on Ti substrates for reduced cell adhesion N2 - Miniaturized pacemakers with a surface consisting of a Ti alloy may have to be removed after several years from their implantation site in the heart and shall, therefore, not be completely overgrown by cells or tissue. A method to avoid this may be to create at the surface by laser-ablation self-organized sharp conical spikes, which provide too little surface for cells (i.e., fibroblasts) to grow on. For this purpose, Ti-alloy substrates were irradiated in the air by 790 nm Ti:sapphire femtosecond laser pulses at fluences above the ablation threshold. The laser irradiation resulted in pronounced microstructure formation with hierarchical surface morphologies. Murine fibroblasts were seeded onto the laser-patterned surface and the coverage by cells was evaluated after 3–21 days of cultivation by means of scanning electron microscopy. Compared to flat surfaces, the cell density on the microstructures was significantly lower, the coverage was incomplete, and the cells had a clearly different morphology. The best results regarding suppression of cell growth were obtained on spike structures which were additionally electrochemically oxidized under acidic conditions. Cell cultivation with additional shear stress could reduce further the number of adherent cells. KW - Laser Processing KW - Femtosecond laser KW - Titanium alloy KW - Cell adhesion KW - Anodic oxidation KW - Pacemaker PY - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-427681 UR - https://link.springer.com/article/10.1007/s00339-017-1352-0 SN - 0947-8396 SN - 1432-0630 VL - 123 IS - 12 SP - 734, 1 EP - 9 PB - Springer-Verlag CY - Berlin AN - OPUS4-42768 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heidmann, B. A1 - Ringleb, F. A1 - Eylers, K. A1 - Levcenko, S. A1 - Bonse, Jörn A1 - Andree, Stefan A1 - Krüger, Jörg A1 - Unold, T. A1 - Boeck, T. A1 - Lux-Steiner, M. C. A1 - Schmid, M. T1 - Local growth of CuInSe2 micro solar cells for concentrator application N2 - A procedure to fabricate CuInSe2 (CISe) micro-absorbers and solar cells for concentrator applications is presented. The micro-absorbers are developed from indium precursor islands, which are deposited on a molybdenum coated glass substrate (back contact), followed by deposition of copper on top and subsequent selenization as well as selective etching of copper selenides. In order to compare the properties of the locally grown absorbers to those of conventional large area CISe films, we systematically examine the compositional and morphological homogeneity of the micro absorbers and carry out photoluminescence measurements. Preliminary devices for micro-concentrator solar cell applications are fabricated by optimizing the copper to indium ratio and the size of the indium precursor islands. The resulting micro solar cells provide a characteristic I–V curve under standard illumination conditions (1 sun). KW - Micro solar cells KW - Light concentration KW - CuInSe2 KW - Absorber optimization KW - Chalcopyrite PY - 2017 UR - https://www.sciencedirect.com/science/article/pii/S2468606917300953 U6 - https://doi.org/10.1016/j.mtener.2017.10.010 SN - 2468-6069 VL - 6 IS - December 2017 SP - 238 EP - 247 PB - Elsevier Ltd. AN - OPUS4-42801 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Andree, Stefan A1 - Heidmann, B. A1 - Ringleb, F. A1 - Eylers, K. A1 - Bonse, Jörn A1 - Boeck, T. A1 - Schmid, M. A1 - Krüger, Jörg T1 - Production of precursors for micro-concentrator solar cells by femtosecond laser-induced forward transfer N2 - Single-pulse femtosecond laser-induced forward transfer (LIFT, 30 fs, 790 nm) is used to deposit micron-sized dots of copper and/or indium onto a molybdenum layer on glass. Such systems can serve as precursors for the bottom-up manufacturing of micro-concentrator solar cells based on copper-indium-gallium-diselenide. The influence of the thickness of the copper, indium and combined copper-indium donor layers on the quality of the transferred dots was qualified by scanning electron microscopy, energy-dispersive X-ray analysis, and optical microscopy. The potential for manufacturing of a spatial arrangement adapted to the geometry of micro-lens arrays needed for micro-concentrator solar cells is demonstrated. T2 - EMRS Spring Meeting 2017, Symposium X “New frontiers in laser interaction: from hard coatings to smart materials" CY - Strasbourg, France DA - 22.05.2017 KW - Laser-induced forward transfer (LIFT) KW - Femtosecond laser KW - Micro-concentrator solar cell KW - Copper-indium-gallium-diselenide KW - CIGSe PY - 2017 U6 - https://doi.org/10.1007/s00339-017-1282-x SN - 1432-0630 SN - 0947-8396 VL - 123 SP - Article 670, 1 EP - 8 AN - OPUS4-42273 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn A1 - Kirner, Sabrina A1 - Slachciak, Nadine A1 - Elert, Anna Maria A1 - Griepentrog, Michael A1 - Hertwig, Andreas A1 - Sahre, Mario A1 - Weise, Matthias A1 - Sturm, Heinz A1 - Pentzien, Simone A1 - Koter, Robert A1 - Spaltmann, Dirk A1 - Krüger, Jörg T1 - Tribological performance of titanium samples oxidized by fs-laser radiation, thermal heating, or electrochemical anodization N2 - Commercial grade-1 titanium samples (Ti, 99.5% purity) were treated using three alternative methods, i.e., fs-laser processing in air, thermal heat treatment in an oven, or anodization in an electrochemical bath, all resulting in the formation of differently conditioned superficial oxide layers. The laser processing was carried out by a Ti:sapphire laser (pulse duration 30 fs, central wavelength 790 nm, pulse repetition rate 1 kHz) in a regime of generating laser-induced periodic surface structures (LIPSS). The experimental conditions (laser fluence, spatial spot overlap) were optimized in a sample-scanning geometry for the processing of several square-millimetres large surface areas covered homogeneously by these nanostructures. The thermal processing in the oven was done at two different temperatures, while the electrochemical anodization was performed at room temperature, aiming to generate different polymorphs of titanium oxide at similar oxide layer thickness. The irradiated surface regions were characterized by optical and scanning electron microscopy, and micro Raman spectroscopy. The tribological performance of the differently treated titanium surfaces was characterized in the regime of mixed friction by reciprocating sliding tests against a sphere of hardened steel in un-additivated paraffin oil and fully formulated engine oil as lubricants. The specific tribological performance of the differently treated surfaces is discussed on the basis of possible physical and chemical mechanisms. T2 - International Conference on Laser Ablation, COLA 2017 CY - Marseille, France DA - 03.09.2017 KW - Femtosecond laser KW - Oxidation KW - Laser-induced periodic surface strcutures, LIPSS KW - Friction KW - Wear PY - 2017 AN - OPUS4-42032 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn T1 - Scattering on scattering N2 - Ultrafast experiments can reveal the spatiotemporal dynamics of nanostructure formation via scattering in background-free optical dark-field microscopy. KW - Ultrafast microscopy KW - Scattering KW - Darkfield microscopy KW - Laser ablation PY - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-411596 SN - 2047-7538 VL - 6 SP - e17088, 1 EP - 2 PB - Springer Nature AN - OPUS4-41159 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -