Andrés Lasagni

• PhD
• Professor at TUD Dresden University of Technology

In this work, anisotropic line‐like textures with gradually increasing spatial periods from 2.0 to 4.8 µm are fabricated on stainless steel by two‐beam Direct Laser Interference Patterning using a ps‐laser source. Three manufacturing strategies are developed to fabricate these so‐called gradient structures achieving different surface roughness Rz a...

Direct laser interference patterning (DLIP) is a promising technique for fabricating periodic surface structures on large areas, but controlling process quality can be challenging due to laser power fluctuations. This study presents a novel monitoring approach using acoustic and optical emissions to diagnose and correct these fluctuations during DL...

Transparent electrodes with high conductivity and mechanical robustness are essential for flexible opto‐electronic applications. Indium tin oxide (ITO) single layers have long been considered as unsuitable for flexible applications due to their brittleness. Here, it is shown that their mechanical stability can be substantially enhanced by texturing...

The development of new materials and surface functionalization processes has been extensively studied to further improve the performance of implants. This work explores the direct laser writing method as a potential alternative to produce controlled textures on the surface of traditional 3Y‐TZP and a novel high‐toughness composite (Ce‐TZP/Al2O3/SrA...

Laser-structuring techniques like Direct Laser Interference Patterning show great potential for optimizing electrodes for water electrolysis. Therefore, a systematic experimental study is performed to analyze the influence of the spatial period and the aspect ratio between spatial period and structure depth on the electrode performance for pure Ni...

Direct Laser Interference Patterning (DLIP) is an emerging manufacturing technology for creating functional surfaces. To integrate DLIP into industrial processes, reliable and rapid methods for determining the quality of the produced microstructures are essential. Surface roughness evaluation methods are typically designed to quantify variations in...

The increasing bacterial resistance to antibiotics is prompting research into new approaches to design bacterial repellent surfaces. This work investigated the hot embossing of sub-micron direct laser interference patterning (DLIP) and laser-induced periodic surface structures (LIPSS) textures from stainless steel onto polypropylene samples to achi...

Improving light‐trapping capabilities through surface microstructuring of transparent conductive oxides is a promising approach to enhance solar cell efficiency. This study focuses on treating fluorine‐doped tin oxide (FTO) thin films using four‐beam direct laser interference patterning (DLIP) to create dot‐like periodic surface microstructures. Th...

Laser-structuring techniques like Direct Laser Interference Patterning show great potential for optimizing electrodes for water electrolysis. Therefore, a systematic experimental study based on statistical design of experiments is performed to analyze the influence of the spatial period and the aspect ratio between spatial period and structure dept...

We present preliminary results on the fabrication of patterned surfaces by Direct Laser Interference Patterning and the characterization and theoretical interpretation of their infrared emissivities. The upgraded experimental method is capable of studying the full directional emission of samples under a controlled atmosphere at high temperatures. T...

Microstructured hollow-core fibers enable a flexible integration of high-power ultrafast lasers, offering the advantages of fiber-based beam delivery to ultrafast laser applications. For widespread industrial utilization of this technology, ever-increasing demands need to be fulfilled by adapting the beam delivery to new laser systems and process p...

Fibre-reinforced thermoplastic composites (TPC) provide an automated and cost-effective solution for their usein lightweight structures in series production. The combination of different material configurations allows thedesign of highly stress tolerant components. Previous studies demonstrated that the combination of TPC sheets,TPC hollow profiles...

The functionalization of zirconia surfaces by accurate and fast printing of periodical patterns embedding sub‐micrometric features is of great interest to many engineering fields and is yet to be explored. This study aims to assess the influence of the Direct Laser Interference Patterning processing parameters on the morphology and microstructure o...

The use of ultrashort pulse lasers opens up a wide range of possibilities for processing dielectric materials. The present study focuses on the investigation of the ablation‐free microscopic surface modification of borosilicate glass using femtosecond laser radiation (350 fs at 515 nm wavelength) in a scanning machining process. Furthermore, its ai...

Surface roughness measurement is an integral part of the characterization of microtextured surfaces. Multiple established software packages offer the calculation of roughness parameters according to ISO 25178. However, these packages lack a specific set of features, which we hope to address in this work. Firstly, they often lack or have limited cap...

Vacuum and air atmospheres impose very different requirements on tribological-loaded contacts, which usually require different surface materials. While hard tetrahedral amorphous carbon (ta-C) coatings provide good tribological properties in air, soft coatings such as molybdenum disulfide (MoS2) work well in a vacuum. Tribological performance in th...

Improved understandings of two-phase transport in electrochemical gas-evolving systems are increasingly demanded, while high-performance imaging techniques using simplified instrumentations are not readily available. This work presents volumetric scanning acoustic microscopy (SAM) imaging for quantifying the dynamics of gas bubbles and electrolyte...

In this work, the fabrication of gradient periodic line‐like structures with continuously changing spatial period on stainless steel by means of two‐beam direct laser interference patterning (DLIP) is studied. A 70 ps (picosecond [ps]) pulsed laser operating at 532 nm wavelength and 0.64 J cm⁻² laser fluence is used to produce the gradient microstr...

Direct Laser Interference Patterning (DLIP) stands out as a versatile and cost-effective method for functionalizing material surfaces at high throughputs. Monitoring the dynamics of the structure formation can lead to a deeper understanding of the interplay between the main factors governing the process and ultimately to optimize the final texture....

The present work utilizes direct laser interference patterning in conjunction with a polygon scanner system to fabricate micro‐ and nanostructures on the surface of nickel foils. A picosecond pulsed laser source with an average power of ≈470 W is used to pattern line‐like structures having spatial periods of 11.0 and 25.0 μm and a maximum structure...

Boron doping of diamond-like carbon coatings has multiple effects on their tribological properties. While boron typically reduces wear in cutting applications, some B-doped coatings show poor tribological performance compared with undoped films. This is the case of the tribological tests presented in this work in which an alumina ball is placed in...

Thermoplastic matrix composites are a viable option to reduce the carbon footprint during the life of an aircraft due to their ability to be molten and resolidified again. Tape-based layup processes, such as automated tape placement, are well-examined but have not seen extensive use in large-scale joining applications, since they have to be process...

In this study, the ablation efficiency of single ultra-short laser pulses having different burst modes was evaluated on three types of stainless steel (AISI 420, AISI 304, and AISI 316Ti). The experiments are performed using an infrared ultra-short pulsed laser (1032 nm, 250 fs). The investigation focused on analyzing the morphology of the ablated...

The nucleation of bubbles on solid surfaces is an important phenomenon in nature and technological processes like electrolysis. During proton-exchange membrane electrolysis, the nucleation and separation of the electrically nonconductive oxygen in the anodic cycle plays a crucial role to minimize the overpotential it causes in the system. This incr...

Thermoplastic matrix composites are a viable option to reduce the carbon footprint during the life of an aircraft due to their ability to be molten and resolidified again. Tape‐based layup processes, such as automated tape placement, are well‐examined but have not seen extensive use in large‐scale joining applications, since they have to be process...

This study explores the enhancement of biocompatible titanium‐based implants through surface functionalization for improved bone healing. Specifically, a near‐beta type Ti‐13Nb‐13Zr alloy is 3D printed using laser powder bed fusion and subsequently textured using nanosecond (ns) and picosecond (ps) direct laser interference patterning (DLIP) to cre...

This study investigates the influence of processing parameters when applying direct laser interference patterning (DLIP) on the morphology and microstructure of zirconia surfaces using a 10 ps‐pulsed laser source with 1064 nm wavelength. An experimental testing matrix is built with different values of laser fluence (5.7–18.2 J cm⁻²) and pulse overl...

In this work, the mechanism of the corrosion behavior of laser‐treated aluminum is studied. Two different laser techniques are used to fabricate the samples, direct laser interference patterning (DLIP) and direct laser writing (DLW), using nanosecond laser sources. The DLIP treatment uses a two‐beam optical configuration producing line‐like periodi...

With the increasing processing power of micro-electronic components and increasing spatial limitations, ensuring sufficient heat dissipation has become a crucial task. This work presents a microscopic approach to increasing the surface area through periodic surface structures. Microstructures with a periodic distance of 8.5 µm are fabricated via Di...

In recent years, the combination of hydrophobic and corrosion resistance properties on metallic surfaces has gained increasing interest due to its great applicability in industry [1]. These properties have been enhanced by the presence of air pockets generated by hierarchical microstructures on the metal surface [2]. For generating those surfaces,...

The aim of this work was to evaluate the feasibility of the fabrication of microtextures in zirconia using the direct laser interference patterning (DLIP) technique. A green ultra‐short pulsed laser (532 nm, 10 ps) with a two‐beam interference setup was used to produce line‐like structures with a spatial period of 3 µm. For a fixed set of fluence a...

Nowadays, lightweight materials become more important in diverse industrial applications, such as automotive and aeronautics. Innovative surface features like superhydrophobicity enable further fields of applications. In this context, aluminium Al 2024-T351 alloy is structured using direct laser writing (DLW) to achieve a superhydrophobic surface....

Due to its high corrosion resistance and mechanical properties, stainless steel is commonly used in various industrial applications. Although different types of stainless steel are similar in their chemical composition, they can differ significantly in their thermal diffusivity. This property is relevant in the ability of a material to conduct heat...

An emerging laser-based surface structuring technology (DLIP) uses the interference of light to transfer to materials well-defined periodic features for the large-scale production of novel bio-inspired multifunctional surfaces. In this text, we describe briefly some fundamental aspects of laser-based materials processing, describe the different cap...

In this work, the technique of Direct Laser Interference Patterning (DLIP) was used to fabricate micrometric structures at the surface of Cobalt-Chromium-Molybdenum and AZ91D magnesium alloys. Line-like patterns with spatial periods of 5 μm were textured using an ultra-short pulsed laser (10 ps pulse duration and 1064 nm wavelength) with a two-beam...

Near-beta titanium alloys are promising bone implant materials due to their low elastic modulus and good corrosion resistance. To optimize their surface properties, we apply direct laser interference patterning (DLIP) microtextures using nano (ns)-and picosecond (ps) pulses to an additively manufactured Ti-13Nb-13Zr alloy. It was observed that both...

Near-beta titanium alloys are increasingly gaining importance in the biomedical application as bone implants due to their low elastic modulus and corrosion resistance. Moreover, implant surfaces are commonly post-processed using conventional techniques such as sandblasting in order to increase surface roughness. Using laser powder bed fusion (LBPF)...

A route to increase the efficiency of thin film solar cells is improving the light-trapping capacity by texturing the top Transparent Conductive Oxide (TCO) so that the sunlight reaching the solar absorber scatters into multiple directions. In this study, Indium Tin Oxide (ITO) thin films are treated by infrared sub-picosecond Direct Laser Interfer...

With an increasing demand for lower fuel consumption of different means of transportation, the demand for lightweight construction materials is rising. In this frame, usually metallic parts can be replaced by components consisting of fiberreinforced plastics. On the other hand, the components lose their electromagnetic field (EMF) shielding propert...

Direct laser interference patterning (DLIP) is applied on additively manufactured near-beta Ti-13Nb-13Zr using nanosecond (ns) and picosecond (ps) pulses to tune its surface properties. Multiscale surface chemical and microstructural analyses (AES, XPS, XRD, SEM, TEM, GD-OES, contact angle) of those DLIP states are performed for understanding the c...

Surface modification of yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) using lasers for adhesion enhancement with resin-matrix cement has been increasingly explored. However, Y-TZP is chemically inert and non-reactive, demanding surface modification using alternative approaches to enhance its bond strength to resin-matrix cements. The m...

Fabrication of two- and three-dimensional structures in the micro- and nano-range allows a new degree of freedom for the design of materials by tailoring desired material properties and, thus, obtaining enhanced functionalities. Such complex designs are only possible using novel fabrication techniques with high resolution, even in the nanoscale ran...

Emerging manufacturing technologies make it possible to design the morphology of electrocatalysts on the nanoscale in order to improve their efficiency in electrolysis processes. The current work investigates the effects of electrode-attached hydrogen bubbles on the performance of electrodes depending on their surface morphology and wettability. Ni...

In this study, the wetting behavior of microstructured polyethylene tereph-thalate (PET) foils for polar and nonpolar liquids produced by plate-to-plate hot embossing is investigated. For the embossing step, stainless steel plates are used as stamps, which are microstructured with single-scaled and hierarchical textures using direct laser writing a...

Graphene oxide (GO) and reduced graphene oxide (rGO) have outstanding qualities that could be exploited as reinforcement and antibacterial agents in a plethora of biomedical applications. In this contribution, it is reported the deployment of a polyacrylamide GO-hydrogel composite (GO@pAAm) which was photo-converted and structured by ultra-short la...

Process monitoring in laser‐based manufacturing has become a forward‐looking strategy for industrial‐scale laser machines to increase process reliability, efficiency, and economic profit. Moreover, monitoring techniques are successfully used in laser surface texturing workstations to improve and guarantee the quality of the produced workpieces by a...

Functional laser surface texturing (LST) arose in recent years as a very powerful tool for tailoring the surface properties of parts and components to their later application. As a result, self-cleaning surfaces with an improved wettability, efficient engine components with optimized tribological properties, and functional implants with increased b...

Internal combustion engines are increasingly regulated in regard to efficiency and environmental impact, which requires advanced optimization strategies of engine components. The contact between the top ring and the cylinder liner is critical to the efficiency of an internal combustion engine. As shown in a previous study, an amorphous carbon coati...

A route to increase the efficiency of thin film solar cells is improving the light-trapping capacity by texturing the top Transparent Conductive Oxide (TCO) so that the sunlight reaching the solar absorber scatters into multiple directions. In this study, Indium Tin Oxide (ITO) thin films are treated by infrared sub-picosecond Direct Laser Interfer...

Surface structuring using nano-second lasers can be used to enhance certain properties of a material or even to introduce new ones. One way to create these structures efficiently is direct laser interference patterning using different polarization vector orientations of the interfering beams. However, experimentally measuring the fabrication proces...

Thermoelectric (TE) films, which are normally fabricated by MicroElectroMechanical‐Systems (MEMS) technology, are crucial for the development of micro‐TE devices (e.g., Peltier coolers for hot‐spot cooling, TE generators). However, achieving a significant TE property (e.g., high power factor) of TE films and a low‐cost fabrication process is challe...

In this study, a scatterometry-based monitoring system designed for tracking the quality and reproducibility of laser-textured surfaces in industrial environments was validated in off-line and real-time modes. To this end, a stainless steel plate was structured by direct laser interference patterning (DLIP) following a set of conditions with artifi...

Transparent conductive oxides (TCOs) are used in solar cells not only to extract photogenerated carriers but also to allow sunlight to reach the photoactive material. Therefore, controlling the electrical and optical properties of such oxides is crucial for the optimization of the efficiency of solar cells. Herein, direct laser interference pattern...

In times of societal development, sustainability has become a major concern for many manufacturers in the metal industries. In this context, surface texturing of cutting tools offers a promising approach in terms of reducing energy consumption and material waste. In this work, direct laser interference patterning is utilized for producing periodic...

Increasingly compact and powerful light emitting diodes require the development of efficient optical diffusers to manage their lighting capability according to the required application. In this study, a cost‐effective strategy is demonstrated for fabricating micro‐structured polymethylmethacrylate (PMMA) diffusers for white light sources. By combin...

Direct laser interference patterning (DLIP) employing sub-picosecond IR irradiation allows for the ultrafast processing of polyaniline surfaces polymerized onto a poly(methyl methacrylate) substrate (PANI@PMMA) achieving excellent quality features. The patterning shows high levels of precision regarding control of width and height in micro/nanoarra...

Aluminum foils are commonly used in food and pharmaceutical packaging due to their outstanding combination of malleability, low cost, oxygen barrier and light reflectivity. Extra functionalities, like hydrophobicity or structural coloration, can be added to them by engineering topographical surfaces microstructures. In this work, cold embossing met...

Functionalization of surfaces by engraving micro or nano-textures using laser-based methods has become a broad field of research with potential for large-scale manufacturing. Particularly, Direct Laser Interference Patterning (DLIP) is a surface structuring method that allows the fabrication of periodic structures with resolutions down to the micro...

To obtain a good adhesive bonding quality between aluminum parts it is necessary to remove contaminations and to define the chemical composition and topographic status of the corresponding surfaces. Hence, a surface pre-treatment is needed which simultaneously guarantees environmental concerns, industrial safety, efficiency, and reproducibility of...

Micropatterning of metal oxides is of high interest for structuring electrodes in optoelectronic devices. In this work, the impact of infrared (IR) sub-picosecond Direct Laser Interference Patterning (DLIP) on the surface morphology, surface chemistry, optical and electrical properties of Fluorine-doped Tin Oxide (FTO) is studied. The topography ch...

The combination of direct laser interference patterning (DLIP) with laser-induced periodic surface structures (LIPSS) enables the fabrication of functional surfaces reported for a wide spectrum of materials. The process throughput is usually increased by applying higher average laser powers. However, this causes heat accumulation impacting the roug...

Recently, monitoring systems have become crucial components in industrial-scale laser machines to increase process reliability and efficiency. Particularly, monitoring methods have the potential to optimize and ensure the quality of laser surface patterning by indirectly characterizing the surface topography. Here, a diffraction measurement system,...

In recent years, the demand for highly integrated and lightweight components has been rising sharply, especially in plastics processing. One strategy for weight-saving solutions is the development of conductive tracks and layouts directly on the polymer housing parts in order to be able to dispense with the system integration of additional printed...

Microtextures generated by pulsed lasers allow for changing the surface properties of a wide palette of materials by replicating nature's most effective topographies. In the case of laser-induced microtextures, the surface's wetting properties evolve over time and eventually stabilize. The size of the fabricated features and the initial surface rou...

In this study, the wetting behavior of micro-structured poly(methyl methacrylate) (PMMA) surfaces produced by plate-to-plate hot embossing is investigated. The embossing tools used consist of stainless steel plates, which were previously processed by different laser methods, namely Direct Laser Engraving (DLE), Direct Laser Writing (DLW) and Direct...