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    Near-field Acoustical Holography - a new sensor concept for methods of active noise reduction
    The research hypothesis of the project comprises the development process of a sensor principle based on near-field acoustical holography for active noise reduction systems with structural actuators. The main objective is to extend sensor principles from the field of active noise and vibration control by inverse methods for sound field reconstruction. In particular, the influence of the inverse projection of sound field quantities on the stability of adaptive signal processing will be investigated. Compared to already existing approaches, an extension of the scientific knowledge is expected. The reason for this is that the use of acoustic sensors in conjunction with modern inverse acoustics methods enables non-contact observability of the sound field quantities proportional to the sound power in the near-field of arbitrarily shaped structures. Consequently, problems are avoided which arise because structural sensors such as accelerometers cannot be fixed as required. With near-field acoustical holography, a method is chosen which avoids costly measurements of transfer functions between sensor groups. For this purpose, only acoustic models are used, which results in lower uncertainties with respect to the model quality compared to the use of vibroacoustic models. Experiments are carried out in a transmission test facility, first on structural components that can be described analytically and then on complex structural components in the frequency range up to 1 kHz. This frequency range is typical for active noise reduction methods as a complement to passive measures, which are more effective at higher frequencies. Under free-field conditions, the Fourier transform-based near-field acoustical holography serves in the first step as a sensing principle for active noise reduction on a simply supported plate. With the relationship between the Fourier transform of the particle velocity on the plate surface and the directivity pattern of the radiated sound pressure into the far-field, the minimization of the radiated sound power is achieved. With the knowledge gained about the fundamental effects of inverse sound field reconstruction methods as a sensor principle on methods of active sound reduction, the experimental extension of the method to components with more complicated geometries will be carried out. The basic principles for the application of the investigated concept to cavities such as car or aircraft cabins are also to be developed. Therefore, in the last project phase the extension of the near-field acoustical holography-based sensor principle to sound fields in rooms is carried out by introducing reflection surfaces. Finally, comparisons will be made with conventional sensor principles for active sound reduction.
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    3D-printed multi-material polymer microarchitectures for normal and inverse Salvinia surfaces
    Bio-inspired surfaces that either retain stable air layers under water or actively repel gas bubbles offer significant opportunities for process and reactor engineering, for example in drag reduction, wetting control, and improved gas–liquid management. Prominent natural examples are the leaves of the aquatic fern Salvinia and the surfaces of backswimmer insects, which rely on hierarchical hair-like micro- and nanostructures to stabilize air. Despite extensive research, robust design rules linking surface micro-architecture, material combinations, and mechanical properties to interfacial performance are still lacking. The aim of this project is to establish such structure–function relationships in a systematic and quantitative manner. To this end, a combinatorial laser-based printing platform (cLIFT – combinatorial Laser-Induced Forward Transfer) will be used to fabricate elastic, multi-material polymer micro- and nanostructures with precisely controlled geometry, chemical polarity, and stiffness on technology-relevant substrates. The focus lies on hair-like architectures featuring defined anchoring regions, hydrophobic–hydrophilic junctions, and simplified undercut or tip geometries. The project addresses four key challenges: (i) reproducible fabrication of anchored yet liftable polymer hairs on metals, glasses, and polymers; (ii) mechanically robust integration of hydrophobic and hydrophilic materials within individual microstructures; (iii) controlled formation of undercut-like tip geometries that stabilize or repel gas–liquid interfaces; and (iv) quantitative correlations between geometry, elasticity, spatial arrangement, and static as well as dynamic wetting behavior. By creating systematic libraries of surface architectures and applying standardized wetting and bubble-dynamics assays, the project will derive general design principles for Salvinia-inspired and inverse-Salvinia surfaces. The results will provide a foundation for the rational design of functional polymer coatings for reactors, separation technologies, and other multiphase systems.
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    Mechanisch adaptive nanoporöse Metalle durch reversible Metallelektroabscheidung
    Nanoporous metals have attracted significant attention due to their nanostructure-enabled mechanical, optical, and electrochemical properties. Of particular interest are materials with reversibly tunable macroscopic mechanical behaviors, which are essential for adaptive systems capable of responding dynamically to external stimuli. Controlled, reversible modulation of properties such as stiffness, strength, and shape is highly desirable for next-generation smart and multifunctional devices, including soft robotics and artificial muscles. In the past two decades, advances in nanoscale architecture have enabled unprecedented control over mechanical properties through surface and interface effects, facilitated by the high surface-to-volume ratios inherent in these materials. While reversible tuning of strain, namely actuation, in nanoporous metals is well established, reversible tuning of other mechanical properties remains relatively underexplored, especially beyond noble-metal systems. Prior studies have largely focused on electrochemical surface charging and hydroxide adsorption as mechanisms for tunability. This project introduces an alternative and broadly applicable approach: reversible metal electrodeposition (RME). RME offers expanded tunability and compatibility with earth-abundant, cost-effective metals. This project will employ in situ mechanical testing to demonstrate significant, reversible modulation of stiffness and strength in nanoporous metals during RME. The work will also extend to hierarchical nanoporous architectures with dual-scale porosity to optimize the interplay between surface area, mass transport, mechanical performance, and structural integrity. To uncover the underlying mechanisms, we will combine in situ mechanical testing with microstructural characterization such as scanning electron microscopy, transmission electron microscopy and ultra-/small angle X-ray scattering methods. We will elucidate critical structure–property–function relationships by examining how features such as ligament size, coating thickness, hierarchical porosity, and interface characteristics influence the tunable mechanical response. Ultimately, this research aims to establish a hybrid metal–electrolyte nanomaterial system capable of rapid, large-amplitude mechanical switching that could enable a new class of adaptive structural materials and smart devices. Furthermore, we will explore electrodeposition as a fabrication pathway for core–shell nanoporous metal/metal nanocomposites, targeting the rare and valuable combination of high strength and tensile ductility.
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    Nanoconfined Low-Temperature Supercritical Water for Thermal Energy Storage
    This project, SuperLow, aims to elucidate the fundamental behavior of nanoconfined supercritical water (cSCWs), with a particular focus on investigating whether pseudo-boiling and pseudo-condensation phenomena can manifest under extreme nanoconfinement conditions. Such insights have the potential to unlock novel pathways for thermal energy storage (TES) technologies. Distinctively, SuperLow employs a pioneering approach that leverages highly non-wetting water–nanoporous material pairs during intrusion–extrusion processes, in contrast to the conventional use of wetting pairs in adsorption–desorption studies. Recent work by the principal investigators demonstrated that this methodology can induce an unprecedented reduction in the critical temperature of water by approximately 275 K, achieving supercritical behavior at near 100 °C—far below the bulk critical point. Despite considerable scientific interest, many fundamental properties of nanoconfined water remain poorly understood. In particular, the influence of nanopore size, topology, and surface hydrophobicity on phase behavior, critical temperature and pressure shifts, and the potential existence of the Widom line require systematic exploration. This project addresses these critical knowledge gaps by integrating high-pressure intrusion–extrusion calorimetry with operando structural characterization techniques and atomistic simulations. Confirming or refuting the presence of the Widom line and associated pseudo-phase transitions in cSCWs not only advances fundamental thermodynamics but also establishes a strong technological foundation for developing thermal energy storage materials optimized for low- to medium-temperature applications—an area currently lacking viable solutions. In the longer term, this innovative approach offers a promising route to enhancing energy efficiency by enabling the recovery of up to 468 TWh/year of waste heat dissipated below 100 °C in Europe alone. The use of inexpensive, abundant, and well-characterized nanoporous materials, e.g. silica, underscores the practical viability of this concept. The overarching goal of SuperLow is to stimulate a paradigm shift in supercritical water applications through the strategic lowering of critical temperatures via nanoconfinement. By intruding water in its liquid state under megapascals of pressure—rather than relying on vapor phase condensation at sub-saturation pressures—this work pioneers a novel experimental framework with broad implications for both fundamental science and sustainable energy technologies.
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    Experimental investigation of capillary collapse of partially saturated granular soils during saturation (2)
    The objective of the second project phase is to formulate a constitutive model for the capillary collapse of granular soils with bimodal porosity within a continuum mechanics framework. Capillary collapse is defined as an irreversible volumetric deformation triggered by an increase in the degree of saturation of unsaturated soils. This phenomenon is governed by several interacting factors, including irrigation conditions, the applied stress state, and the porosity of the soil. The ongoing first project phase has already provided an extensive experimental basis, ranging from macroscopic tests to particle-scale investigations. These studies have demonstrated that capillary collapse is strongly linked to soil water retention behaviour and to the imposed boundary conditions. In particular, the presence of porous lignite particles has been shown to influence the collapse mechanism. Therefore, evaluating soils with varying lignite contents is essential to capture the true extent of this effect. The main challenge now lies in developing a mathematical expression that integrates the governing factors and accurately predicts the magnitude of collapse. Achieving this will provide the foundation for predictive constitutive modelling. Using the comprehensive experimental dataset already available, the proposed work aims to derive, formulate, and validate a constitutive model that links bimodal porosity, water retention behaviour, and collapse mechanisms. This model will establish the basis for future computational applications and the extension of predictive tools in unsaturated soil mechanics.
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    Classification of laryngeal lesions using advanced endoscopic imaging and real-time evaluation by AI
    Tumors of the upper aerodigestive tract (UADT) are the sixth most common tumor entity in humans, with laryngeal cancer accounting for 30-40%. Thereby, an earlier diagnosis goes along with a better prognosis for the patients concerned. As a visual endoscopic assessment is currently not able to replace histopathological examinations, current standard of care in newly detected laryngeal lesions comprises a so-called microlaryngoscopy under general anesthesia combined with invasive tissue sampling, which is costly as well as time consuming and prone to sampling errors. An optical method enabling an on-site distinction between healthy tissue, dysplastic tissue and cancerous tissue in an outpatient setting would therefore have the potential to revolutionize early laryngeal cancer detection. Various optical techniques providing different information on the tissues investigated have been tested for classification of mucosal lesions of the larynx in (pre-) clinical studies and shown promising results, but they do have their individual limitations as standalone procedures. Therefore, multimodal imaging using a combination of techniques has been suggested and trialed, but – mostly owing to its complexity in data acquisition and interpretation – has not yet progressed into clinically meaningful applications. In a new and promising attempt, we aim to combine optical coherence tomography (OCT) and narrow band imaging (NBI) using a flexible endoscope and thus combining depth and spatial information of the suspicious tissue. To overcome the current limitations of multimodal image interpretation, we aim to study different artificial intelligence (AI) methods to fuse information and assist with image analysis following a spatially and temporally correct registration of the multimodal imaging data. Our first goal in this project is the development of a single outpatient endoscopic procedure that allows for an onsite tissue classification in the larynx (“optical biopsy”). As a second goal, the performance of this automated multimodal endoscopic imaging will be evaluated against the current standard-of-care. To achieve these goals, we will design and manufacture biocompatible OCT fiber probes. The probes will fit into the working channel of a flexible NBI-ready nasopharyngolaryngoscope. To evaluate the multimodal imaging, we will perform a study on 60 awake patients with flat mucosal lesions of the endolarynx and 60 healthy volunteers. State-of-the-art deep learning methods will be applied for an automated tissue classification based on both individual imaging modalities and the multimodal data set. This will make our system for computer-assisted diagnosis (CAD) independent of the experience of the physician, reducing the problem of interrater variability.
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    FOR 5177 SP6: Decoding Spinal Dysfunction: Causal Mechanisms of Muscle and Compensatory Adaptations through Functional Animal and Musculoskeletal Modeling
    The aim of the first funding period of FOR 5177 was to systematically investigate the mechanical influences on tissue adaptation and degeneration following surgical interventions to the spine, using a large animal model combined with numerical simulations. Contrary to the widely accepted assumptions from in vitro studies, neither compensatory hypermobility in adjacent segments after fusion nor persistent hypermobility of the operated segment after nucleotomy could be confirmed in vivo. Instead, movement restrictions were observed, indicating spinal stabilization and suggesting effective neuromuscular adaptations. Complementary finite element analyses demonstrated that local changes in mechanical loading can induce targeted osseous adaptations, and that dynamic loading scenarios promote the restoration of segmental stability. Furthermore, activity level was shown to have a significant impact on the dynamic movement patterns of the spine. Using specially developed AI-supported video analysis methods for large animals, we revealed functional relationships between limb function and spinal motion, thus demonstrating the integrative neuromuscular control underlying spinal movement. Building on these insights, the second funding period focuses on the role of muscle function as a central driver of spinal adaptation processes. The core objective is to analyze causal mechanisms by which muscle dysfunction induces functional alterations in spinal mechanics. For this purpose, we employ a functional large animal model that mimics muscular changes observed in chronic low back pain by inducing selective muscle inactivity through targeted neurotomy. An integrative methodological approach combines functional in vivo assessments (including EMG, kinematics, and behavioral analyses), ex vivo structural evaluations, and in silico simulations to investigate the interplay between muscle (in)activity, mechanical loading, structural changes, and pain mechanisms. The central hypothesis posits a self-reinforcing vicious cycle: muscle dysfunction leads to mechanical overload, which triggers a neuroinflammatory response that promotes pain chronification - thereby further exacerbating muscle dysfunction. This project makes a crucial contribution to the overall initiative by systematically elucidating neuromuscular mechanisms in chronic low back pain and establishing a methodological foundation for improved diagnostics.
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    Establishing a new platform for H2-driven asymmetric catalysis by design of a fusion-enzyme
    Das Ziel dieses Forschungsprojekts ist die Schaffung einer neuen Plattform für die H2-betriebene asymmetrische Katalyse, die bei der Synthese von Feinchemikalien eingesetzt werden kann. Um dies zu erreichen, wird ein bisher einzigartiges Fusionsprotein zwischen der löslichen [NiFe]-Hydrogenase (SH) aus Cupriavidus necator und der Old Yellow Enzyme (OYE)-En-Reduktase aus Thermus scotoductus entwickelt. In früheren Studien zeigte das OYE-Enzym einen Enantiomerenüberschuss ee > 99 % für die asymmetrische Reduktion von 2-Methylmaleimid zu (R)-2-Methylsuccinimid, das als Vorläufer für antimikrobielle Substanzen dienen könnte. Das konstruierte Fusionsenzym wird eine Biokatalyse mit hoher Atomeffizienz unter Verwendung von H2 ermöglichen, um sowohl Elektronen als auch Protonen für die asymmetrische Reduktion zu liefern. Die Untersuchung des Elektronentransfers im Fusionsprotein ist ein Hauptziel dieses Forschungsprojekts. Daher werden verschiedene Protein-Linker mit variablen Eigenschaften eingesetzt, um die Fähigkeit eines direkten Elektronentransfers zu testen. Letzteres würde die Notwendigkeit einer teuren Cofaktor-Regeneration bei Biotransformationen umgehen. Im Vergleich zum direkten Elektronentransfer werden natürliche und künstliche Elektronenträger untersucht. Die Charakterisierung kinetischer und thermodynamischer Parameter sowie die Optimierung der Betriebsbedingungen werden teilweise mithilfe einer automatisierten Reaktionsplattform durchgeführt. Die Inline-Fourier-Transformations-Infrarotspektroskopie (FTIR) ermöglicht eine quantitative Substrat-Produkt-Analyse ohne Probenahme, und die chirale Gaschromatographie (GC) validiert die Stereochemie. Auf der Grundlage der Inline-Analytik wird eine automatisierte Reaktionsplattform entwickelt, die in ein umfassendes Forschungsdatenmanagementsystem (RDM) integriert ist und Datenaustauschstandards wie EnzymeML und Beiträge zu Datenbanken wie BRENDA umfasst, um die Einhaltung der FAIR-Prinzipien zu gewährleisten.
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