Filtern
Dokumenttyp
- Vortrag (34)
- Zeitschriftenartikel (8)
- Beitrag zu einem Tagungsband (6)
- Buchkapitel (5)
- Posterpräsentation (4)
- Monografie (1)
- Video (1)
Referierte Publikation
- nein (59) (entfernen)
Schlagworte
- Laser-induced periodic surface structures (LIPSS) (32)
- Surface functionalization (20)
- Femtosecond laser (14)
- Applications (9)
- Laser-induced periodic surface structures, LIPSS (9)
- Femtosecond laser ablation (6)
- Laser processing (6)
- Microstructures (6)
- Nanostructures (6)
- Laser ablation (5)
- Oxidation (5)
- Electromagnetic scattering (4)
- Tribology (4)
- Capillary waves (3)
- Hard X-ray photoelectron spectroscopy (HAXPES) (3)
- Laser-induced X-ray emission (3)
- Ultrafast laser processing (3)
- Femtosecond laser processing (2)
- Free electron laser (2)
- Friction (2)
- Industrial applications (2)
- Oberflächenfunktionalisierung (2)
- Radiation protection (2)
- Ti6Al4V alloy (2)
- Time-of-flight secondary ion mass spectrometry (ToF-SIMS) (2)
- Time-resolved scattering (2)
- Wear (2)
- Additive (1)
- Additives (1)
- Anodization (1)
- Antiadhesive surfaces (1)
- Antibakterielle Oberflächen (1)
- Antimicrobial (1)
- Atomic force microscopy (1)
- Bacteria (1)
- Bacteria-repellent surfaces (1)
- Bacterial adhesion tests (1)
- Bessel-Strahlen (1)
- Biofilm growth (1)
- Biofilme (1)
- Biofilms (1)
- Bone screws (1)
- Cell-repellent surfaces (1)
- Chalcopyrite (1)
- Chemical analyses (1)
- Chemical analysis (1)
- Cribellate spiders (1)
- Electrochemical treatment (1)
- Electromagnetic radiation (1)
- Femtosecond (1)
- Femtosecond laser-processing (1)
- Femtosekunden-Laserablation (1)
- Finite-difference time-domain calculations (1)
- Force distance curve (1)
- Free electron laser (FEL) (1)
- Glow-discharge optical emission spectroscopy (1)
- Hydrodynamics (1)
- Implant material (1)
- LIFT (1)
- LIPSS (1)
- Laser nanostructuring (1)
- Laser technology (1)
- Laser-Materialbearbeitung (1)
- Laser-induced Periodic Surface Structures (LIPSS) (1)
- Laser-induced amorphization (1)
- Laser-induced micro- and nanostructures (1)
- Laser-induzierte periodische Oberflächen-Nanostrukturen (1)
- Laser-induzierte periodische Oberflächenstrukturen (1)
- Laserschutz (1)
- Light concentration (1)
- Materialbearbeitung (1)
- Matter reorganization (1)
- Medical implants (1)
- Metals (1)
- Micro solar cells (1)
- Mikrostrukturen (1)
- Modelling (1)
- Nanostrcutures (1)
- Nanostrukturen (1)
- Native oxide layer (1)
- Nonlinear lithography (1)
- Oberflächenmodifikation (1)
- Optical scattering (1)
- Pump-probe (1)
- Pump-probe experiments (1)
- Quarzglas (1)
- Reactive oxygen species (1)
- Reibung (1)
- Reibungsreduktion (1)
- Röntgenemission (1)
- Saphir (1)
- Secondary hazard (1)
- Sekundärstrahlung (1)
- Self-organization (1)
- Spectroscopic imaging ellipsometry (1)
- Surface engineering (1)
- Surface structures (1)
- Theoretical modelling (1)
- Time-offlight secondary ion mass spectrometry (ToF-SIMS) (1)
- Time-resolved analysis (1)
- Time-resolved coherent scattering (1)
- Titanium (1)
- Titanium alloy (1)
- Titanium alloys (1)
- ToF-SIMS (1)
- Transmission electron microscopy (1)
- Tribologie (1)
- Ultra-short pulse laser processing (1)
- Ultrafast scattering (1)
- Ultrakurze Laserpulse (1)
- Ultrakurzpuls-Laser (1)
- Ultrakurzpuls-Laserbearbeitung (1)
- Ultrashort (1)
- Ultrashort laser material interaction (1)
- Ultrashort laser processing (1)
- Ultrashort laser pulses (1)
- Ultrashort pulse laser processing (1)
- Verschleiß (1)
- Verschleißreduktion (1)
- Wetting (1)
- X-ray (1)
- XUV scattering (1)
Organisationseinheit der BAM
- 6 Materialchemie (59) (entfernen)
Paper des Monats
- ja (1)
The invention of new miniaturized and smart medical implants continues in all medical fields, including miniaturized heart pacemakers. These implants often come with a titanium (Ti) casing, which may have to be removed after several months or years and shall therefore not be completely overgrown by cells or scar tissue after implantation. Scar tissue is mainly formed by fibroblast cells and extracellular matrix proteins like collagen produced by them. Suppression of fibroblast growth at Ti surfaces could be achieved by 800 nm femtosecond laser-ablation creating self-organized sharp spikes with dimensions in the 10 μm-range which are superposed by fine sub-μm parallel ripples. On flat Ti control samples, the best results regarding suppression of cell growth were obtained on spike-structures which were additionally electrochemically anodized under acidic conditions. When Ti cylinders with a diameter of 8 mm (similar as the pacemakers) were placed upright in a culture of murine fibroblasts, a multi-layer cell growth up to a height of at least 1.5 mm occurred within 19–22 days. We have demonstrated that a laser-structured and anodized ring around the Ti cylinder surface is an effective way to create a barrier that murine fibroblasts were not able to overgrow within this time.
Titanium and its alloys are known to allow the straightforward laser-based manufacturing of ordered surface nanostructures, so-called high spatial frequency laser-induced periodic surface structures (HSFL). These structures exhibit sub-100 nm spatial periods – far below the optical diffraction limit. The resulting surface functionalities are usually enabled by both, topographic and chemical alterations of the nanostructured surfaces. For exploring these effects, multi-method characterizations were performed here for HSFL processed on Ti–6Al–4V alloy upon irradiation with near-infrared ps-laser pulses (1030 nm, ≈1 ps pulse duration, 1–400 kHz) under different laser scan processing conditions, i.e., by systematically varying the pulse repetition frequency and the number of laser irradiation passes. The sample characterization involved morphological and topographical investigations by scanning electron microscopy (SEM), atomic force microscopy (AFM), tactile stylus profilometry, as well as near-surface chemical analyses hard X-ray photoelectron spectroscopy (HAXPES) and depth-profiling time-of-flight secondary ion mass spectrometry (ToF-SIMS). This provides a quantification of the laser ablation depth, the geometrical HSFL characteristics and enables new insights into the depth extent and the nature of the non-ablative laser-induced near-surface oxidation accompanying these nanostructures. This allows to answer the questions how the processing of HSFL can be industrially scaled up, and whether the latter is limited by heat-accumulation effects.
Laser-induced Periodic Surface Structures (LIPSS, ripples) are a universal phenomenon and can be generated in a contactless, single-step process on almost any material upon irradiation of solids with intense laser radiation. Nowadays processing rates of up to m^2/min are enabling new industrial applications in medicine, optics, tribology, biology, etc. Depending on the specific type of LIPSS, their structural sizes typically range from several micrometers down to less than 100 nanometers – far beyond the optical diffraction limit – while their orientations exhibit a clear correlation with the local polarization direction of the laser radiation. From a theoretical point of view, however, a vivid, controversial, and long-lasting debate has emerged during the last two decades, whether LIPSS originate from electromagnetic effects (seeded already during the laser irradiation) – or whether they emerge from matter reorganization processes (distinctly after the laser irradiation). This presentation reviews the currently existent theories of LIPSS. A focus is laid on the historic development of the fundamental ideas, their corresponding mathematical descriptions and numerical implementations, along with a comparison and critical assessment of the different approaches.
Advances in ultrafast laser manufacturing: nanostructures, thin films, and scaling perspectives
(2024)
Advanced ultrafast laser technology is a rapidly growing field that currently enables many new industrial and scientific applications. During the last decades, this has been significantly driven by the availability of high-repetition-rate laser sources and novel beam delivery concepts. At the laser side, Moore’s law equally manifests for ultrafast laser technologies, since the average output power of such lasers doubles approximately every two years. This development is mainly driven by the increase of the pulse repetition rates of energetic laser pulses, currently enforcing the development of smart beam control and novel scanning strategies for preventing heat-accumulation and plasma-shielding effects during laser-based materials processing. This keynote presentation addresses the advantages, recent developments, and perspectives of laser processing with ultrashort laser pulses. A special focus is laid on the tailored structuring of thin films as well as the manufacturing and probing of sub-diffraction surface nanostructures – an ongoing race to extreme scales. Current limitations are identified and an outlook to future scaling perspectives will be provided.
A laser-based bottom-up technique for the fabrication of Cu(In,Ga)Se2 (CIGSe) micro solar cells is presented.
We use femtosecond laser-induced forward transfer (LIFT) to transport a metallic precursor composed of copper, indium, and gallium onto a molybdenum back contact layer on a glass substrate. A CIGSe absorber forms by subsequent selenization. An array of micro absorbers with defined spacing is fabricated to solar cells and characterized under concentrated light illumination. The solar cell array exhibited a conversion efficiency of 1.4‰ at 1 sun as well as a significant efficiency enhancement of 68% rel. under 20-fold concentration. This work demonstrates the possibility of directly grown micrometer-sized solar cells based on chalcogenide absorber layers, enabling effective material usage.
Laser-Induced Periodic Surface Structures (LIPSS, ripples) are a universal phenomenon and can be generated in a contactless, single-step process on almost any material upon irradiation of solids with intense laser radiation. Nowadays, processing rates of up to m^2/min are enabling new industrial applications in medicine, optics, tribology, biology, etc. Depending on the specific type of LIPSS, their structural sizes typically range from several micrometers down to less than 100 nanometers – far beyond the optical diffraction limit – while their orientations exhibit a clear correlation with the local polarization direction of the laser radiation. From a theoretical point of view, however, a controversial and vivid debate has emerged during the last two decades, whether LIPSS originate from electromagnetic effects (seeded already during the laser irradiation) – or whether they emerge from matter reorganization processes, i.e. distinctly after the laser irradiation. This presentation reviews the currently existent theories of LIPSS. A focus is laid on the historic development of the fundamental ideas, their corresponding mathematical descriptions and numerical implementations, along with a comparison and critical assessment of the different approaches.
Antibiotic resistance is a growing global problem which poses a massive threat to human health. Although human activity contributes to the acceleration of the process, bacteria have a self-driven stabilisation mechanism to protect themselves from such and other external threats: biofilm formation. Nonetheless, it is the adhesion of a single bacterial cell to a surface that triggers the formation of such network of biomolecules and microorganisms, as well as its hazardous consequences. The main objective of this work was to quantify the adhesion force of a single E. coli cell on a Ti substrate via the AFM-related single-cell force spectroscopy, with both the cell and the substrate material being of high clinical relevance. A set of 25 x 25 force displacement curves was acquired with a maximum force of 3.2 nN without dwell time, yielding a topography map and an adhesion force map that showed to be correlated. A mean adhesion force of 0.85 ± 0.175 nN was measured and the presence of cell appendages on the bacterial cell wall was verified through individual force-displacement curves. Bacterial viability was assessed after the measurements via live/dead staining.
This presentation reviews current and expected developments in the field of laser-induced periodic surface structures (LIPSS, ripples). These surface nanostructures are a universal phenomenon and can be generated on almost any material by irradiation with intense linearly polarized radiation. LIPSS are formed in a “self-ordered” way and are often accompanying laser material processing applications. The structures can be produced in a single-step process and enable surface functionalization through the adaption of optical, mechanical and chemical surface properties. Their spatial periods typically range from several micrometers down to less than 100 nanometers, exhibiting a clear correlation with the polarization direction of the laser radiation used. Various types of LIPSS have been classified, relevant control parameters were identified, and material specific formation mechanisms are analyzed for different types of inorganic solids, i.e., metals, semiconductors, and dielectrics, through time-resolved optical experiments and theoretical simulations. Special attention will be paid to a comparison of the currently available formation theories for LIPSS with a discussion of their respective strengths and weaknesses. Currrently explored applications featuring surface functionalization in the fields of optics, surface wetting, medicine, and tribology will be discussed.
During the past few years significantly increasing research activities in the field of laser-induced periodic surface structures (LIPSS, ripples) have been reported since the generation of LIPSS in a single-step process provides a simple way of surface nanostructuring towards a control of optical, mechanical or chemical surface properties. In this contribution the current research state in this field is reviewed. The formation of LIPSS upon irradiation of metals, semiconductors and dielectrics by multiple linearly polarized Ti:sapphire fs-laser pulses (30-150 fs) is studied experimentally and theoretically. Different types of LIPSS with periods even below 100 nm can be generated. Their dynamics and formation mechanisms are analyzed and identified in ultrafast optical experiments. Complementing theoretical calculations of the laser-induced carrier dynamics address transient changes of the optical properties of the irradiated materials and reveal the importance of surface plasmon polaritons in the early stage of LIPSS formation. Various applications of these nanostructures are outlined.