Article
Optics
Julia Brand, Andrei Rode, Steve Madden, Alison Wain, Penelope L. King, Ludovic Rapp
Summary: This paper investigates the ultrashort pulsed laser ablation of a high heritage value Australian granite and determines the ablation threshold and efficiency of different mineral components. It is relevant to laser cleaning and maintenance of heritage stone surfaces.
OPTICS AND LASER TECHNOLOGY
(2022)
Article
Chemistry, Physical
Farkhod Babadjanov, Uwe Specht, Thomas Lukasczyk, Bernd Mayer
Summary: In this study, femtosecond laser pulses with high repetition rates were utilized to create unique microstructures on the surface of Ti6Al4V. The impact of pulse overlap and laser repetition rates on structure formation was investigated. Laser texturing with significant overlap led to material melting and the formation of specific microstructures suitable for drug delivery cavities. Heat accumulation at high repetition rates was identified as the cause of the melting effect. These structures can be fabricated on materials with low thermal conductivity, including steel.
Article
Chemistry, Physical
Daniel Franz, Tom Haefner, Tim Kunz, Gian-Luca Roth, Stefan Rung, Cemal Esen, Ralf Hellmann
Summary: In this study, a comprehensive investigation on laser percussion microvia drilling of FR-4 printed circuit board material using ultrashort pulse lasers is carried out. The effects of different laser parameters on the quality of microvias are analyzed, and the optimal conditions are identified.
Article
Materials Science, Multidisciplinary
Andreas Tuennermann, Carsten Momma, Stefan Nolte
Summary: Ultrashort pulse lasers have been widely used in precise micromachining. This article presents a brief perspective on the development of this innovative technology from the 1990s until today.
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
(2023)
Article
Optics
Feng Yang, Zhigang Dong, Renke Kang, Cheng Liu, Dongjiang Wu, Guangyi Ma
Summary: Reaction-bonded silicon carbide composites exhibit a complex ablation mechanism under femtosecond laser irradiation. The ablation threshold decreases with increasing pulse number and stabilizes. Photochemical ablation dominates at low fluence and low pulse number, while photothermal ablation dominates at higher fluence and pulse number. A preliminary model of the ablation mechanism was established based on surface morphology, microstructure, and physical phase analysis.
Article
Optics
Kang Xu, Lingyu Huang, Shaolin Xu
Summary: We developed a far-field laser nanofabrication method called line-shaped laser lithography, which can efficiently create multiple subwavelength nanogratings on substrates. The use of separated line-shaped ultrafast laser pulses and high-speed scanning ensures high fabrication efficiency. Furthermore, nanogratings with a sub-100 nm line width were generated based on the Marangoni effect. Diversified nanogratings, such as moire, blaze-like, Dammann, and 2D nanogratings, can be obtained by designing scanning strategies, showing light modulation effects in diffraction and beam splitting.
Article
Optics
Chong Chen, Chong Kuong Ng, Fan Zhang, Xin Xiong, Bing-Feng Ju, Yang Zhang, Hans Norgaard Hansen, Yuan-Liu Chen
Summary: This study used femtosecond laser ablation to achieve surfaces with nanometric finish. Different parameters were investigated, and a mathematical model was established to study the formation mechanism of ablated surface characteristics. Experiments verified the effectiveness of this method.
OPTICS AND LASER TECHNOLOGY
(2022)
Article
Polymer Science
Kay Bischoff, Dominik Muecke, Gian-Luca Roth, Cemal Esen, Ralf Hellmann
Summary: In this study, we report on the laser ablation of cyclic olefin copolymer using an amplified ultrashort pulsed laser in the ultraviolet spectral range. The results demonstrate high ablation depth, excellent surface roughness, and increasing ablation efficiencies with increasing fluence. Comparing with an infrared laser wavelength, UV ablation shows significant advantages in terms of ablation efficiency, surface roughness, and quality. This study provides an efficient and qualitative tool for the laser machining of cyclic olefin copolymer using high-power UV ultrashort pulsed lasers.
Article
Optics
Sunderlal Singh Sanasam, G. l. Samuel
Summary: This paper reports on the application of femtosecond laser for modifying surface wettability without significant chemical modification, by tuning the surface morphology. The study shows the ability to achieve both hydrophilicity and hydrophobicity.
OPTICS AND LASER TECHNOLOGY
(2024)
Article
Optics
Hee-Lak Lee, Arif Hussain, Yoon Jae Moon, Jun Young Hwang, Seung Jae Moon
Summary: The conditions for obtaining a completely connected ablated line were investigated, and it was found that a higher fluence was needed to form the ablated line properly.
OPTICS AND LASER TECHNOLOGY
(2024)
Article
Chemistry, Physical
Stefan Rung, Niklas Haecker, Ralf Hellmann
Summary: In this study, a comprehensive investigation on laser ablation and micromachining of alumina using a high-power ultrashort-pulsed laser was conducted. The optimal process strategy was determined and discussed based on the variation of laser parameters such as power, pulse duration, repetition rate, and spatial pulse overlap. The results showed that the highest ablation efficiency and ablation rate were achieved at high repetition rate and short pulse duration, while the surface roughness was predominantly affected by the applied laser fluence.
Article
Chemistry, Analytical
Lukang Wang, You Zhao, Yu Yang, Manman Zhang, Yulong Zhao
Summary: This study investigates the effects of processing parameters on the results of femtosecond laser ablation of SiC material, providing insights for achieving precise, controllable, and high-quality machining of SiC using infrared femtosecond laser.
Review
Optics
Qiandong Ran, Hao Li, Wonkeun Chang, Qijie Wang
Summary: This paper reviews the latest advances in self-compression techniques without dispersion compensation optics for high-energy few-cycle pulse generation over the past two decades. Various experimental approaches and their potential applications in generating extremely intense optical fields for strong-field physics research are discussed.
LASER & PHOTONICS REVIEWS
(2023)
Article
Optics
Meiling Chen, Baoshan Guo, Lan Jiang, Zhipeng Liu, Qian Qian
Summary: In this paper, the study focuses on the processing threshold fluence of carbon fiber reinforced polymers (CFRP) using a femtosecond laser and its effects on the width of the heat-affected zone (HAZ) at different scanning speeds. Experimental results reveal that the ablation threshold of carbon fiber in CFRP is approximately twice that of resin. The minimum value of HAZ can be achieved when the laser fluence is 50 to 60 times the ablation threshold fluence of carbon fiber. Furthermore, aligning the scanning direction with the polarization angle of the linearly polarized laser can further reduce the width of the HAZ. The obtained minimum HAZ value in the experiment is about 2 μm, significantly smaller than previous literature values.
OPTICS AND LASER TECHNOLOGY
(2023)
Article
Chemistry, Physical
Stefan Kefer, Julian Zettl, Cemal Esen, Ralf Hellmann
Summary: This article introduces two new methods for micromachining rotational-symmetric sapphire workpieces using femtosecond laser. The first method can produce sapphire fibers with a diameter of 50 μm, while the second method can produce sapphire fibers with a diameter of 90 μm and a length of up to 20 cm. These methods provide an innovative all laser-based approach for the fabrication or microstructuring of sapphire optical devices, and offer a promising alternative to chemical processes.
Article
Chemistry, Physical
Georg Schnell, Christian Polley, Robert Thomas, Stephan Bartling, Johannes Wagner, Armin Springer, Hermann Seitz
Summary: In this study, the researchers used a customized instrument to investigate the lateral adhesion forces on femtosecond laser-structured surfaces. They found that the droplet motion was significantly influenced by the chemical and topographical surface features. The droplet mobility was classified into static, transfer, and kinetic regimes, which is crucial for designing surfaces with extreme wetting characteristics.
JOURNAL OF COLLOID AND INTERFACE SCIENCE
(2023)
Article
Engineering, Biomedical
A. Weizel, T. Distler, R. Detsch, A. R. Boccaccini, H. Seitz, S. Budday
Summary: Numerical simulations using appropriate material models and parameters are valuable for understanding the effects of mechanical stimulation on hydrogels for cartilage replacement. In this study, hyperviscoelastic material parameters for human articular cartilage and two replacement materials were identified using COMSOL Multiphysics (R) v. 5.6. The results revealed that ADA-GEL and ChondroFiller(liquid) exhibit faster stress relaxation and lower relaxation time constants compared to cartilage. Additionally, ADA-GEL and ChondroFiller(liquid) have a predominant elastic response, while cartilage has a predominant viscoelastic response.
JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Abdullah Riaz, Christian Polley, Henrik Lund, Armin Springer, Hermann Seitz
Summary: By fabricating a composite scaffold of titanium alloy (Ti6Al4V) and barium titanate (BaTiO3), the biomechanical stability of Ti6Al4V is combined with the electrical activity of BaTiO3, offering potential for the treatment of critical-size bone defects in load-bearing areas.
MATERIALS & DESIGN
(2023)
Article
Pharmacology & Pharmacy
Robert Mau, Hermann Seitz
Summary: Drop-on-demand (DOD) inkjet printing allows precise dispensing and positioning of single droplets. This study investigates the reproducibility of droplet formation for piezoelectric inkjet printed drug solutions with different solvents. The results suggest that highly volatile solvents lead to rapid drug deposits on the nozzle, while low volatile solvents ensure reproducible droplet formation in long-term inkjet printing of highly concentrated drug solutions.
Article
Materials Science, Multidisciplinary
Tim Dreier, Abdullah Riaz, Alexander Ahrend, Christian Polley, Stefanie Bode, Benjamin Milkereit, Hermann Seitz
Summary: Composite Extrusion Modeling (CEM) is a screw-based material extrusion (MEX) additive manufacturing process that can produce plastic, metal and ceramic parts. This study investigates the processing of aluminum oxide feedstock (Al2O3) for the first time using the CEM process. The optimal process parameters for achieving highly dense green parts were determined, and the debound and sintered parts were also evaluated.
MATERIALS & DESIGN
(2023)
Article
Chemistry, Physical
Hafiz Ahmed Waqas, Muhammad Waseem, Abdullah Riaz, Muhammad Ilyas, Muhammad Naveed, Hermann Seitz
Summary: The design and construction of precast reinforced box culverts need to be improved to meet contemporary demands of reliability and affordability. This research aims to develop an effective and affordable design improvement procedure for a precast box culvert using modern numerical tools. The study reveals that adjusting the haunch geometry and adding reinforcement significantly affect the load-carrying capacity of a culvert, with a potential 25% increase achievable.
Article
Pharmacology & Pharmacy
Robert Mau, Thomas Eickner, Gabor Juettner, Ziwen Gao, Chunjiang Wei, Nicklas Fiedler, Volkmar Senz, Thomas Lenarz, Niels Grabow, Verena Scheper, Hermann Seitz
Summary: A study investigates the long-term medical treatment of the inner ear using patient-individualized drug-releasing implants inserted in the middle ear. Guinea pig round window niche implants loaded with dexamethasone were manufactured with high precision using micro injection molding and tested for drug release, biocompatibility, and bioefficacy in vitro.
Article
Pharmacology & Pharmacy
Natalia Rekowska, Katharina Wulf, Daniela Koper, Volkmar Senz, Hermann Seitz, Niels Grabow, Michael Teske
Summary: Novel 3D printing techniques enable the development of medical devices with personalized drug delivery systems. However, retaining the pharmaceutical functions of proteins remains challenging due to possible crosslinking and the choice of photopolymers.
Article
Engineering, Mechanical
Georg Schnell, Hauke Studemund, Robert Thomas, Hermann Seitz
Summary: This study investigates the effect of partial texturing on the tribological performance of journal bearings using the relatively new technique of femtosecond laser texturing. The research findings show that textures in the high-load region of journal bearings provide the highest lubricant film thickness and lowest friction. Moreover, asymmetric texture designs have a detrimental effect on lubrication performance compared to symmetric designs.
TRIBOLOGY INTERNATIONAL
(2023)
Article
Polymer Science
Timo Banko, Stefan Gruenwald, Rainer Kronberger, Hermann Seitz
Summary: This paper presents a novel approach to manufacturing components with integrated conductor paths using fused filament fabrication (FFF) and isotropic conductive adhesive (ICA). The approach involves embedding the ICA into a printed groove and sealing it with a wide extruded plastic strand. Through parameter studies, a consistent cavity for uniform formation of the ICA path was obtained.
Meeting Abstract
Cell & Tissue Engineering
Juliane Meyer, Christoph Drobek, Robert Mau, Anne Wolff, Kirsten Peters, Hermann Seitz
TISSUE ENGINEERING PART A
(2023)
Meeting Abstract
Cell & Tissue Engineering
Kaarthik Sridharan, Tawakalitu Waheed Okikiola, Wolfgang Krueger, Juliane Meyer, Mario Thuerling, Hermann Seitz, Mareike Meister, Kai Masur, Olga Hahn, Kirsten Peters
TISSUE ENGINEERING PART A
(2023)
Correction
Materials Science, Biomaterials
Sonja Vaupel, Robert Mau, Selin Kara, Hermann Seitz, Udo Kragl, Johanna Meyer
JOURNAL OF MATERIALS CHEMISTRY B
(2023)
Article
Multidisciplinary Sciences
Christoph Drobek, Juliane Meyer, Robert Mau, Anne Wolff, Kirsten Peters, Hermann Seitz
Summary: In order to use regeneratively active cells for cell therapeutic applications, we need to isolate these cells from their resident tissues. The process of cell isolation can subject the cells to mechanical strain, which can affect their viability and yield. Therefore, it is important to have knowledge of the cell volumetric mass density to optimize the isolation procedures. Existing methods for measuring cell volumetric mass density are time-consuming or require special setup. Thus, we have developed a user-friendly method based on readily available instrumentation. This method is based on the linear relationship between the volumetric mass density of the cell suspension and the volumetric mass density, number, and diameter of the cells in the suspension. We have used this method to determine the volumetric mass density of mesenchymal stem cells (MSCs) and compared it to results from the established density centrifugation technique.
Article
Materials Science, Biomaterials
Sonja Vaupel, Robert Mau, Selin Kara, Hermann Seitz, Udo Kragl, Johanna Meyer
Summary: Hydrogels are highly absorbent polymeric networks that can absorb more than 90% of water. They have the ability to retain their shape while swelling and possess various interesting properties including biocompatibility and antimicrobial activity. Hydrogels are suitable for medical applications, particularly in drug delivery systems. Polyelectrolyte-based hydrogels have shown promising properties for long-term and stimulus-responsive applications. However, complex structures and shapes are challenging to achieve using conventional polymerization methods, which can be overcome by additive manufacturing. 3D printing technology using photopolymerizing methods allows the fabrication of complex and customizable designs with high resolution and control. In this study, hydrogels composed of AETMA and PEGDA were 3D printed using Digital Light Processing, demonstrating high swelling degree and adjustable mechanical properties. The hydrogels showed stimulus-responsive drug release behavior and could be printed in complex hollow geometry. This work presents a flexible and swellable material that combines the properties of hydrogels with the ability to print complex shapes.
JOURNAL OF MATERIALS CHEMISTRY B
(2023)