Enrico Tosoratti

Last Name

Tosoratti

First Name

Enrico

ORCID

0000-0002-7152-9361

Organisational unit

09706 - Bambach, Markus / Bambach, Markus

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Publications1 - 10 of 13

3D-Printed Reinforcement Scaffolds with Targeted Biodegradation Properties for the Tissue Engineering of Articular Cartilage
Tosoratti, Enrico; Fisch, Philipp; Taylor, Scott; et al. (2021)
Advanced Healthcare Materials
Achieving regeneration of articular cartilage is challenging due to the low healing capacity of the tissue. Appropriate selection of cell source, hydrogel, and scaffold materials are critical to obtain good integration and long-term stability of implants in native tissues. Specifically, biomechanical stability and in vivo integration can be improved if the rate of degradation of the scaffold material matches the stiffening of the sample by extracellular matrix secretion of the encapsulated cells. To this end, a novel 3D-printed lactide copolymer is presented as a reinforcement scaffold for an enzymatically crosslinked hyaluronic acid hydrogel. In this system, the biodegradable properties of the reinforced scaffold are matched to the matrix deposition of articular chondrocytes embedded in the hydrogel. The lactide reinforcement provides stability to the soft hydrogel in the early stages, allowing the composite to be directly implanted in vivo with no need for a preculture period. Compared to pure cellular hydrogels, maturation and matrix secretion remain unaffected by the reinforced scaffold. Furthermore, excellent biocompatibility and production of glycosaminoglycans and collagens are observed at all timepoints. Finally, in vivo subcutaneous implantation in nude mice shows cartilage-like tissue maturation, indicating the possibility for the use of these composite materials in one-step surgical procedures.
Functional graded NiTi manufactured with powder bed fusion
Weber, Rico; Tosoratti, Enrico; Spierings, Adriaan B.; et al. (2024)
Progress in Additive Manufacturing
Nickel–titanium (NiTi) is a versatile material with unique inherent properties, such as shape recovery, superelasticity, and biocompatibility, that makes it suitable for various engineering applications. While NiTi can be additively manufactured using powder bed fusion for metals (PBF-LB/M), challenges arise due to the material sensitivity to process parameters and the challenge of achieving desired mechanical and functional properties. Mechanical and functional properties of NiTi are highly infuenced by the alloy composition which in turn is afected by the process parameters. This study aims to investigate the feasibility of tailoring the properties of NiTi to manufacture functionally graded structures. Promising shape recovery strains of 4.16% and superelastic strains of 7% under compression are achieved with cycling stability outperforming the conventional manufactured NiTi. By varying the process parameters, the austenite fnish temperature could be shifted between 29 ± 5 °C and 72 ± 5 °C, while achieving a maximum relative material density of 99.4%. Finally, the study demonstrates the potential of powder bed fusion to manufacture complex and functional graded structures, enabling spatial control. This potential is showcased through the sequential actuation of a demonstrator structure. The fndings of this research highlight the promising capabilities of powder bed fusion in producing functional graded NiTi structures, with potential applications in robotics, aerospace, and biomedical felds.
A training-free machine learning approach for 3D powder bed reconstruction and defect detection in PBF-LB/M
Tosoratti, Enrico; Potthoff, Ugne; Bennewitz, Christopher; et al. (2025)
Progress in Additive Manufacturing
We introduce a novel in situ quality monitoring approach for the Laser Powder Bed Fusion (PBF-LB/M) process that operates independently of prior experimental data and can be integrated into existing systems. We employ a cost-effective, high-resolution CMOS camera coupled with a bright and darkfield lighting arrangement to acquire data layer-by-layer. Using computer vision techniques, specifically the GrabCut algorithm, we automate the inspection and the virtual reconstruction of fused part geometries. Our results, compared with nominal slice data and computed tomography scan data, indicate a robust accuracy in quantifying geometric deviations (mean deviation of 15.60 μm and 15.20 μm respectively, Jaccard scores of 0.99). The proposed training-free framework, unlike traditional machine learning methods, requires no labeled datasets or prior training, offering a cost-effective and adaptable solution. This eliminates the dependency on material, scan strategy, or part geometry, which typically hinders the scalability of conventional approaches. Additionally, our method facilitates automatic defect detection such as recoater strikes, recoater hopping, and powder shortages, with balanced accuracy scores of up to 0.87. These advantages highlight the framework’s potential as a practical tool for in situ process monitoring and quality assurance in PBF-LB/M systems.
Effect of powder properties, process parameters, and recoating speed on powder layer properties measured by in-situ laser profilometry and part properties in laser powder bed fusion
Spurek, Marvin A.; Sillani, Francesco; Haferkamp, Lukas; et al. (2024)
Additive Manufacturing
In laser-based powder bed fusion of metals (PBF-LB/M), the powder layer is the link between the powder properties and the resulting part quality. Powder layer quality is a key metric related to powder spreadability and ultimately part quality, yet it is still unclear how it can be quantified. This is due to the difficulty of studying powder layer properties during the process. This study investigates the influence of powder properties, process parameters, and recoating speed on the surface roughness of the powder layer and the part, as well as on the effective thickness of the powder layer and solidified layer, and the resulting relative part density. Utilizing in-situ laser profilometry, high-resolution topographical data of the powder layer and the part surface were acquired, with minimal interference to the PBF-LB/M process. Six AlSi10Mg powders with varying particle size distribution, morphology, and flowability were processed using a wide range of recoating speeds and scan speeds to create powder layers with a wide range of properties. The results reveal a strong correlation between energy input and the effective powder layer thickness where lower scan speed results in an increased effective powder layer thickness due to material losses. Additionally, faster recoating decreases the powder layer density, which is moderated by the median particle size where the effect is strongest for fine powders. The surface roughness of the powder layer and top part surface are influenced by the recoating speed, energy input, and particle size, and they are strongly linked to each other. This highlights the importance of considering realistic substrate surface roughnesses in both powder spreading experiments and simulations. Finally, layer properties affect the process stability, resulting in small differences in relative part density.
Additively Manufactured Semi-Flexible Titanium Lattices as Hydrogel Reinforcement for Biomedical Implants
Tosoratti, Enrico; Incaviglia, Ilaria; Liashenko, Oleksii; et al. (2021)
Advanced NanoBiomed Research
Hydrogels are one of the most widespread biomaterials used in tissue engi- neering. However, they possess weak mechanical properties and are often unstable in load-bearing applications in vivo. A novel class of exible Ti–6Al–4V titanium alloy lattices manufactured using laser powder bed fusion (L-PBF) serves as a tunable reinforcement for hydrogels, providing them with additional mechanical stability and exibility, while ensuring biocompatibility. A study on the design parameters of the structural elements of the lattices is performed to evaluate their inuence on the mechanical properties of the structure. Mechanical testing of Ti–6Al–4V lattices shows a compressive modulus ranging from 38.9 to 895.5 kPa in the exible direction. In the other two directions, the lattices are designed to have minimal exibility. Lattices embedded in a 1% agarose hydrogel show a strain-rate-dependent, viscoelastic behavior given by the hydrogel component with the additional stiffness of the titanium lattice. Stress distribution upon lo ading is simulated using nite element analysis (FEA) and compared to experimental data using multiple regression statistical analysis. As a proof of concept, an intervertebral spinal disc implant is designed with mechanical properties matching the compressive moduli of the nucleus pulposus and anulus brosus reported in the literature.
Tailoring the Sensitivity of Microcantilevers To Monitor the Mass of Single Adherent Living Cells
Incaviglia, Ilaria; Herzog, Sophie; Fläschner, Gotthold Viktor; et al. (2023)
Nano Letters
Microcantilevers are widely employed as mass sensors for biological samples, from single molecules to single cells. However, the accurate mass quantification of living adherent cells is impaired by the microcantilever’s mass sensitivity and cell migration, both of which can lead to detect masses mismatching by ≫50%. Here, we design photothermally actuated microcantilevers to optimize the accuracy of cell mass measurements. By reducing the inertial mass of the microcantilever using a focused ion beam, we considerably increase its mass sensitivity, which is validated by finite element analysis and experimentally by gelatin microbeads. The improved microcantilevers allow us to instantly monitor at much improved accuracy the mass of both living HeLa cells and mouse fibroblasts adhering to different substrates. Finally, we show that the improved cantilever design favorably restricts cell migration and thus reduces the large measurement errors associated with this effect.
Advanced Biofabrication Strategies for Personalised Reconstructive Medicine
Tosoratti, Enrico (2022)
The capability to fabricate biomimetic scaffolds that closely resemble a host's tissue environment is critical for the success of tissue engineering. In order to recapitulate the complexity of native tissues, the chemical, mechanical, and biological characteristics of the scaffold must be considered. Indeed, it appears that providing suitable mechanical and biological signals to the cells is key to promoting tissue regeneration. Furthermore, due to the complex hierarchical organization and length scales of human tissues, the choice of biofabrication technique, or set of techniques, is critical for the formation of functional tissues. With the advancement in additive manufacturing technologies, novel techniques and materials are rapidly emerging to produce highly biocompatible and biomimetic 3D scaffolds. Additive manufacturing techniques have given birth to a new branch of personalized medical care, where starting from CT scans, it is now possible to manufacture patient-specific implants with high resolution and better host integration. In the future, these implants will contain living cells which will contribute to tissue regeneration. This thesis focuses on the development of advanced additive manufacturing strategies for the fabrication of patient-specific implants. For this purpose, four main topics have been studied. In the first study, we focused on the development of flexible metallic reinforcement strategies to support hydrogel constructs. This was achieved by creating a library of semi-flexible titanium lattices which could be used to reinforce soft, cell-laden hydrogels. In this study, titanium lattices provided additional mechanical stability to the embedded viscoelastic agarose hydrogels. As a proof of concept, an intervertebral spinal disc implant was designed which had compressive moduli in the range of native human nucleus pulposus and anulus fibrosus. In the second study, we aimed at developing a personalized and flexible wireframe to improve upon the current clinical procedures used in ear reconstruction. Firstly, a statistical shape model (SSM) of the ear was developed using head CT images from 100 subjects. This SSM allowed the calculation of both a statistically ‘average’ human ear as well as captured variation modes encompassing the entire range of human ear anatomical variation. Using data from literature, the SSM was further developed to estimate the shape and thickness of the underlying cartilaginous structure. Finally, a wireframe was designed to capture the external anatomy of a subject’s ear when placed under his or her skin. The flexible Ti-6Al-4V wireframe implants were 3D printed and implanted subcutaneously in nude rats. The implanted wireframe allowed for excellent aesthetic reconstruction of the human auricular shape, which was retained over the time of implantation in vivo. In the third study, we studied the use of a biodegradable polymer in providing mechanical support to soft, cell-laden hydrogel constructs. The polymer was 3D printed using fused deposition modelling and embedded in an enzymatically-crosslinked hyaluronan hydrogel, together with human epiphyseal chondroprogenitors. The degradation of the lactide copolymer was compensated for by the stiffening of the hydrogel component, as the cells secreted increasing amounts of extracellular matrix. The maturation of the reinforced construct was evaluated over the course of 63 days, showing excellent cell viability and glycosaminoglycan and collagen II deposition. In the final study, we explored new techniques to improve shape retention of soft and mechanically unstable hydrogels. A novel biofabrication technique termed ‘alginate shells’ is presented for the casting of soft hydrogels. Cell-laden materials were enclosed within a thin, semi-permeable hydrogel shell that retains the desired shape while still allowing for the diffusion of nutrients and gasses needed for optimal cell proliferation. The thickness of the alginate shells was tuned by controlling the length of exposure to an ion-eluting mold. The semi-permeable alginate shell allowed the development and maturation of cell-laden soft hydrogels in complex and biologically relevant shapes without need for additional components or support materials. Overall, this thesis makes important steps towards bridging the gap between established clinical techniques for the treatment of craniofacial and skeletal deformities and the state-of-the-art tissue engineering techniques developed in academic settings. The feasibility of different biofabrication approaches for the regeneration of auricular and articular cartilage are described, as well as the realization of flexible patient specific implants which can serve as a true alternative to conventional ear reconstruction surgery.
The beneficial effect of Fe addition on the hot cracking susceptibility and mechanical properties of eutectic AlMgSc alloy processed by powder bed fusion
Turani, Matteo; Monti, Chiara; Spierings, Adriaan B.; et al. (2025)
Journal of Alloys and Compounds
This paper presents findings on the positive impact of adding 1.8 wt% of iron to an eutectic AlMgSc alloy processed by laser powder bed fusion. Examination of process parameters reveals that the addition of Fe enhances material processability, reducing susceptibility to hot cracking and enabling the fabrication of crack-free samples with an optical density exceeding 99.8 % on a centimeter scale. From an early stage of solidification (fs ≈ 0.01), intergranular nano-sized Al6(Fe,Mn) particles precipitate alongside the α-Al matrix, their capability in pinning the grain boundaries produces zones characterized by fine grains that hinder the epitaxial growth of large and columnar grains. The refined microstructure can better accommodate thermally induced strains and facilitate liquid backfilling at the terminal stage of solidification, thus limiting hot cracking susceptibility. Moreover, the formation of interdendritic network of Al6(Fe,Mn) particles during the solidification of the central part of the melt pool provides early coalescence of Al dendrites, reducing the time the material spends in a cracking-sensitive state and limiting its tendency to form hot cracks. The formation of the metastable Al6(Fe,Mn) phase, as opposed to the stable Al13Fe4 phase, enhances material strength while preserving ductility. Notably, samples tested perpendicular to the build direction in their as-built conditions achieved a yield strength of 248 ± 2 MPa, an ultimate tensile strength of 406 ± 2 MPa, and an elongation at fracture of 19.6 ± 0.4 %.
Modeling of 3D-printed shape memory alloys
Afrasiabi, Mamzi; Hosseinzadeh, Hamed; Tosoratti, Enrico; et al. (2025)
Additive Manufacturing of Shape Memory Materials - Techniques, Characterization, Modeling, and Applications
This chapter provides a comprehensive exploration of modeling techniques applied in the domain of 3D-printed shape memory alloys (SMAs). The initial sections introduce the fundamentals of metal additive manufacturing (MAM) processes and describe their numerical modeling frameworks, with a specific focus on challenges related to 3D-printed SMAs. We then examine the details of physics-based modeling procedures necessary to understand various aspects of 3D-printed SMA simulations across different time- and length scales. The fourth section of the chapter is dedicated to data-driven modeling, analyzing the current state of research and machine learning (ML) applications at different stages of the fabrication process. This will enable us to assess the benefits and limitations of ML models in SMA 3D printing developments. We conclude this chapter by outlining future research directions and emerging trends, including method optimization, multiscale modeling, computational alloy development, and the implementation of closed-loop control mechanisms. The modeling aspects of 3D-printed SMAs discussed here are hoped to serve as a valuable resource for researchers and practitioners seeking to enhance the processability, reliability, and performance of these exotic materials through computational approaches.
Investigating the Influence of Iron Content on the Microstructure and Mechanical Properties of a High Strength Al-Alloy for Additive Manufacturing
Turani, Matteo; Jannic, Walter; Esteves, Paulo Davi Borges; et al. (2024)
The Minerals, Metals & Materials Series ~ Light Metals 2024 (TMS 2024)
Scalmalloy (R), a 5xxx series aluminum alloy modified with Sc and Zr to suit additive manufacturing needs, displays significant potential for automotive and aerospace applications due to its exceptional strength, low density, and resistance to corrosion. This study investigates the impact of iron, a prevalent impurity in secondary aluminum, on the microstructure and mechanical properties of Scalmalloy (R) produced via laser powder bed fusion (PBF-LB). Three Scalmalloy (R) variations were examined: the original composition and two modified versions with a total Fe content of 1.8 and 3.5 wt.%. Microstructural analysis through electron microscopy and X-ray diffraction unveiled the existence of metastable Fe-rich precipitates at mid-low Fe concentrations, while stable Al-Fe intermetallics were observed in the variant with high Fe content. The influence of these distinct microstructures was assessed using hardness and compressive tests. These assessments demonstrated augmented material strength at room temperature when increasing the Fe content in the composition for both as-built and peak-aged conditions. However, this enhancement diminished when the alloy containing 3.5wt% Fe was subjected to compression at 300.C, resulting in outcomes comparable to the alloy with a Fe content of 1.8 wt.%. These findings contribute to an enhanced comprehension of the properties of commercial aluminum alloys containing trapped impurities, which hold the potential to expand the utilization of secondary aluminum alloys within the additive manufacturing industry.

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Enrico Tosoratti

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