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 create single‐scale and multi‐scale surface textures. On these textures, the cell behavior, morphology, metabolic activity and osteogenic differentiation potential of human bone marrow stromal cells are assessed using fluorescence microscopy and MTS assays. Moreover, tissue non‐specific alkaline phosphatase activity served as an early osteoblast production marker. Compared to untextured specimens, both types of textures exhibited higher metabolic activity and cell proliferation. Single‐scale ns‐DLIP textures encouraged cell extensions anchored in groove regions, while ps‐DLIP textures with hierarchical structures promoted cell extensions attaching to nanostructures on sidewalls. The groove width and nanotopographies in groove areas facilitated cell spreading. Surface topography, roughness, and surface chemistry (surface energy, wettability) influenced cell adhesion, proliferation, and differentiation. A comprehensive evaluation of DLIP‐generated surface textures, including their topography and chemical states, complements the factors affecting in vitro cell behavior. Overall, this research demonstrates the potential of surface‐functionalized 3Dprinted titanium for a novel generation of biocompatible implants.

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 capabilities for automated and batch analysis, making it hard to integrate into other applications. Secondly, they are often proprietary and therefore restrict access to some potential users. Lastly, they lack some capabilities when it comes to the analysis of periodic microtextured surfaces. Namely, common parameters such as the peak-to-valley depth, spatial period and homogeneity cannot be calculated automatically. This work aims to address these challenges by introducing a novel Python library, Surfalize, which intends to fill in the gaps regarding this functionality. The functionality is described and the algorithms are validated against established software packages or manual measurements.

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 Direct Laser Interference Patterning (DLIP) on stainless steel plates with a nanosecond-pulsed infrared laser and are characterized by their developed interfacial area ratio. The optimal structuring parameters for increasing the surface area were investigated, reaching peak-to-valley depths up to 12.8 µm and increasing surface area by up to 394%. Heat dissipation in a natural convection environment was estimated by measuring the output voltage of a Peltier element mounted between a hot plate and a textured sample. The resulting increase in output voltage compared to an unstructured sample was correlated to the structure depth and developed interfacial area ratio, finding a maximum increase of 51.4%. Moreover, it was shown that the output voltage correlated well with the structure depth and surface area.

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 coating can greatly improve the friction properties of piston rings. This work expands on these results by fabricating laser‐interference‐induced microchannels on the coating perpendicular to the direction of movement with a mean depth of 0.97 and 3.13 μm spatial period to further optimize the tribology. Fired single‐cylinder engine measurements of the microtextured rings show a significant reduction in mean piston assembly friction of 5% for operation points that are relevant for urban transportation and up to 10% for specific operation points. Subsequent multibody elastohydrodynamic simulations prove that measured friction changes result from the compression ring microtexture. In particular, the microtexture increases the hydrodynamic pressure, reduces hydrodynamic losses, and leads to 20% lowered compression ring losses for an entire combustion cycle of the investigated operation point. In the future, such tribological concepts can be deployed in internal combustion engines that are powered by sustainable hydrogen or methanol.