Dipl.-Phys.

König, Niels

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  • Publication
    A concept for a large-scale non-contact strain measurement system using nanostructures
    ( 2024-06-24)
    Ulm, Andreas
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    König, Niels orcid-logo
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    Schmitt, Robert
    The monitoring of mechanical strain is essential in developing new materials, designing mechanical components and structural health monitoring. In applications where contactless measurement is required, a novel method is needed to allow for absolute and long-term measurements. We discuss a measuring principle based on diffractive nanostructures featuring these advantages. For the measurement, periodic nanostructures are applied to a component, illuminated with a defined light source and the resulting color impression is monitored. The relationship between the stretched geometry of the nanostructure and diffraction spectra allows to quantify the component’s strain. We present a guide-line for the design of industrial applicable and sensitivity-optimized nanostructures and discuss the advantages in different application scenarios.
  • Publication
    5G in Production - from Use Case to Business Case
    ( 2024-04-26)
    König, Niels orcid-logo
    The widespread rollout of 5G in the manufacturing industry depends heavily on its contribution to improving the economic performance of manufacturing companies. The presentation introduces a methodology for calculating the techno-economical potential of 5G use cases. A specific manufacturing use case is presented as a case study, showing the technical and business KPIs and potential economic benefits.
  • Publication
    Young’s Modulus-Independent Determination of Fibre Parameters for Rayleigh-Based Optical Frequency Domain Reflectometry from Cryogenic Temperatures up to 353 K
    ( 2023-05-09)
    Girmen, Caroline
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    Dittmar, Clemens
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    Siedenburg, Thorsten
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    Gastens, Markus
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    Wlochal, Michael
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    König, Niels orcid-logo
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    Schröder, Kai-Uwe
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    Schael, Stefan
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    Schmitt, Robert H.
    The magnetic spectrometer AMS-100, which includes a superconducting coil, is designed to measure cosmic rays and detect cosmic antimatter in space. This extreme environment requires a suitable sensing solution to monitor critical changes in the structure such as the beginning of a quench in the superconducting coil. Rayleigh-scattering-based distributed optical fibre sensors (DOFS) fulfil the high requirements for these extreme conditions but require precise calibration of the temperature and strain coefficients of the optical fibre. Therefore, the fibre-dependent strain and temperature coefficients 𝐾T and 𝐾𝜖 for the temperature range from 77 K to 353 K were investigated in this study. The fibre was integrated into an aluminium tensile test sample with well-calibrated strain gauges to determine the fibre’s 𝐾𝜖 independently of its Young’s modulus. Simulations were used to validate that the strain caused by changes in temperature or mechanical conditions was the same in the optical fibre as in the aluminium test sample. The results indicated a linear temperature dependence of 𝐾𝜖 and a non-linear temperature dependence of 𝐾T. With the parameters presented in this work, it was possible to accurately determine the strain or temperature of an aluminium structure over the entire temperature range from 77 K to 353 K using the DOFS.
  • Publication
    Towards automated CAR-T Cell Manufacturing. Keeping up with Technological Advancement
    ( 2023-05-04)
    Herbst, Laura
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    Erkens, Frederik
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    Hort, Simon orcid-logo
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    Bäckel, Niklas
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    Nießing, Bastian
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    Popp, Georg
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    Franz, Paul
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    König, Niels orcid-logo
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    Hudecek, Michael
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    Rafiq, Qasim
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    Goldrick, Stephen
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    Papantoniou, Ioannis
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    Schmitt, Robert H.
    The AIDPATH project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement no 101016909. The material presented and views expressed here are the responsibility of the author(s) only. The EU Commission takes no responsibility for any use made of the information set out.
  • Publication
    Adaptive phase contrast microscopy to compensate for the meniscus effect
    ( 2023-04-08)
    Nienhaus, Florian orcid-logo
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    Piotrowski, Tobias
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    Nießing, Bastian
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    König, Niels orcid-logo
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    Schmitt, Robert H.
    Phase contrast is one of the most important microscopic methods for making visible transparent, unstained cells. Cell cultures are often cultivated in microtiter plates, consisting of several cylindrical wells. The surface tension of the culture medium forms a liquid lens within the well, causing phase contrast conditions to fail in the more curved edge areas, preventing cell observation. Adaptive phase contrast microscopy is a method to strongly increase the observable area by optically compensating for the meniscus effect. The microscope’s condenser annulus is replaced by a transmissive LCD to allow dynamic changes. A deformable, liquid-filled prism is placed in the illumination path. The prism’s surface angle is adaptively inclined to refract transmitted light so that the tangential angle of the liquid lens can be compensated. Besides the observation of the phase contrast image, a beam splitter allows to simultaneously view condenser annulus and phase ring displacement. Algorithms analyze the displacement to dynamically adjust the LCD and prism to guarantee phase contrast conditions. Experiments show a significant increase in observable area, especially for small well sizes. For 96-well-plates, more than twelve times the area can be examined under phase contrast conditions instead of standard phase contrast microscopy.
  • Publication
    Optical coherence tomography and convolutional neural networks can differentiate colorectal liver metastases from liver parenchyma ex vivo
    ( 2023)
    Amygdalos, Iakovos
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    Hachgenei, Enno
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    Burkl, Luisa
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    Vargas, David
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    Goßmann, Paul
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    Wolff, Laura I.
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    Druzenko, Mariia
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    Frye, Maik
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    König, Niels orcid-logo
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    Schmitt, Robert
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    Chrysos, Alexandros
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    Jöchle, Katharina
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    Ulmer, Florian
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    Lambertz, Andreas
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    Knüchel-Clarke, Ruth
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    Neumann, Ulf Peter
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    Lang, Sven A.
    Purpose: Optical coherence tomography (OCT) is an imaging technology based on low-coherence interferometry, which provides non-invasive, high-resolution cross-sectional images of biological tissues. A potential clinical application is the intraoperative examination of resection margins, as a real-time adjunct to histological examination. In this ex vivo study, we investigated the ability of OCT to differentiate colorectal liver metastases (CRLM) from healthy liver parenchyma, when combined with convolutional neural networks (CNN). Methods: Between June and August 2020, consecutive adult patients undergoing elective liver resections for CRLM were included in this study. Fresh resection specimens were scanned ex vivo, before fixation in formalin, using a table-top OCT device at 1310 nm wavelength. Scanned areas were marked and histologically examined. A pre-trained CNN (Xception) was used to match OCT scans to their corresponding histological diagnoses. To validate the results, a stratified k-fold cross-validation (CV) was carried out. Results: A total of 26 scans (containing approx. 26,500 images in total) were obtained from 15 patients. Of these, 13 were of normal liver parenchyma and 13 of CRLM. The CNN distinguished CRLM from healthy liver parenchyma with an F1-score of 0.93 (0.03), and a sensitivity and specificity of 0.94 (0.04) and 0.93 (0.04), respectively. Conclusion: Optical coherence tomography combined with CNN can distinguish between healthy liver and CRLM with great accuracy ex vivo. Further studies are needed to improve upon these results and develop in vivo diagnostic technologies, such as intraoperative scanning of resection margins.
  • Publication
    High-Speed-Microscopy for Scalable Quality Control in Automated Production of Stem Cell Spheroids for Tissue Engineering
    ( 2023)
    Krieger, Judith
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    Nießing, Bastian
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    König, Niels orcid-logo
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    Schmitt, Robert
    The EU Horizon 2020 project »JointPromise« implies the conception and implementation of an end-to-end automated production platform for three-dimensional joint implants, paving the way for tissue-engineered implants able to regenerate deep osteochondral defects. Spheroid-based implants provide a novel approach in tissue engineering by aggregating progenitor cells into potent microtissues. After the differentiation of cartilaginous microtissues, functional joint implants are assembled via 3D bioprinting to match the complex structural organization of native cartilage tissue. As the automation approach of the project aims to overcome bottlenecks in manual production such as product variability, lack of scalability and high personnel costs, a high-throughput quality control system is crucial for the production of reliable Advanced Therapy Medicinal Products (ATMPs). By establishing not only a technical solution for the full digitization of the cell culture plates but also an intelligent image processing algorithm for the detection of the cell spheroids, relevant process parameters like size distribution and growth curves can be detected. Critical thresholds in spheroid growth are evaluated to minimize risks of carcinogenic tissue formation in vivo as well as to define harvest criteria to prevent inhomogeneous bioprinting results. In order to calculate the required throughput and elaborate optimization potentials of the automated spheroid production, voids in the cultivation vessel or disrupted aggregates due to media changes or transportation are detected. Ultimately, the high-speed-microscopy complies with the requirements of a high-throughput automated cell production platform to meet the rising demand for alternative therapeutic approaches in regenerative medicine.
  • Publication
    Optische Kohärenz Tomografie (OCT) zur intraoperativen Untersuchung von Gewebeproben
    ( 2018-04-18)
    Beck, Rafael
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    Riediger, Max
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    Dietz, Andreas
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    Pallasch, David
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    König, Niels orcid-logo
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    Witte, Michael
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    Schmitt, Robert
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    Chalopin, Claire
    Bei Tumorresektionen im Kopf-Hals-Bereich ist es geboten, eine R0-Resektion mittels Schnellschnitten zu sichern. Die optische Kohärenz-Tomografie (OCT) ist ein Bildgebungsverfahren, das intraoperative, nicht invasive und kontaktlose Untersuchungen von Gewebe mit einer hohen Auflösung ermöglichen könnte. Im Rahmen einer Anwendungs- und Machbarkeitsstudie wurde untersucht, ob die OCT geeignet ist, Tumorgewebe von tumorfreiem Gewebe zu unterscheiden.