620 Ingenieurwissenschaften und zugeordnete Tätigkeiten
Refine
Document Type
- Article in a Periodical of the TH Wildau (95)
- Article (48)
- Conference Proceeding (48)
- Book (2)
- Doctoral Thesis (2)
- Part of a Book (1)
- Master's Thesis (1)
- Preprint (1)
Year of publication
Institute
Keywords
- Bildverarbeitung (4)
- bioprinting (4)
- band-pass filter (3)
- dye (3)
- nanocomposite (3)
- optical constant (3)
- optical spectra (3)
- silicon photonics (3)
- thermo-optic coefficient (3)
- 3D measurement (2)
A semiconductor based hydrogen sensor system was optimized by various modifications, which allow an improved detection of very low concentrations of hydrogen in air. The foundation for new investigations on the sensor structure are modifications of substrate and gate structures. Establishment of reference structures is a major aim. A possible drift compensation could be the use of aluminum or alloys for sensor system in order to stabilize signal in Metal Oxide Semiconductor (MOS) respectively Metal Electrolyte Insulator Semiconductor (MEIS) structures. Gold is more likely not capable to function for drift compensation as a pure metal. Nafion™ treatment for cover up the palladium gate seems not to be suitable as a reference, besides could be an option to stabilize sensor signal responses and protect sensors from environmental influences.
The advancement of 3-dimensional printing technology over the past ten years has raised interest in and accessibility to these devices. Due to its consistent growth and demand, 3D printing is becoming a consumer-friendly, reasonably priced craft. Due to technological advancements, it is becoming increasingly integrated into broader fields of science and research, as well as the manufacturing sector. The need for customized solutions is constantly growing across several industries. The 3D extrusion of hydrogels is advancing in the field of biomaterials with a broad spectrum of biomedical applications. Hydrogel extrusion prints heads often use stepper motors or pneumatic pressure systems to push the substrate onto a surface. These techniques are well-suited for materials with high viscosity. While these systems are usually bound to the syringe volume, a refillable reservoir enables them to print above the syringe’s limitations. We developed a low-cost standalone heating system for flexible tubes to control the temperature, hence avoiding jellification and clogging of the tubing system leading to the nozzle of the print head. The system connects to an in-house made peristaltic pump, which forces the e.g. gelatin through the nozzle with low pulsation, enabling us to extrude multiple layers of precise tempered gelatin. The heating system is based on easily available materials and electronic components and does not require expensive tools.
This study presents the characterization of 316L stainless steels fabricated by selective laser melting (SLM), focusing on the influence of printing parameters on microstructure and mechanical properties. The choice of process parameters is crucial for achieving desired material properties, as it directly affects the microstructure and mechanical behavior, which is important when optimizing for potential applications in several fields, such as aerospace and automotive. In this study, different scanning speeds were tested to identify optimal settings, followed by the evaluation of the effects of orientation relative to the build plate and hatching strategies to enhance performance. To assess the impact of these factors, tensile tests, microhardness measurements, and X-ray diffraction (XRD) analyses were conducted. Tensile tests revealed that higher laser scanning speed generally reduces ultimate tensile strength and elongation, likely due to an increase in porosity and a less homogeneous fusion of layers. The analysis of samples printed with different orientation relative to the build plate highlighted a strong mechanical anisotropy, with the samples printed vertically exhibiting lower tensile strength and ductility compared to horizontally printed samples. Microhardness testing further confirmed an anisotropy in material properties. XRD analysis reveals a preferential orientation of austenitic grains depending on building direction. This, in turn, influences the anisotropic behavior. These findings highlight the critical role of process parameters in tailoring the microstructure and mechanical performance of SLM-produced parts, thereby providing insights into the optimization of additive manufacturing for specific applications.
Studies of ultrafast dynamics in substrate-free nanoparticles at ELI using Timepix3 optical camera
(2025)
We present a novel application of the Timepix3 optical camera (Tpx3Cam) for investigating ultrafast dynamics in substrate-free nanoparticles at the Extreme Light Infrastructure European Research Infrastructure Consortium (ELI ERIC). The camera, integrated into an ion imaging system based on a micro-channel plate (MCP) and a fast P47 scintillator, enables individual time-stamping of incoming ions with nanosecond timing precision and high spatial resolution. The detector successfully captured laser-induced ion events originating from free nanoparticles disintegrated by intense laser pulses. Owing to the broad size distribution of the nanoparticles (10-500 nm) and the variation in laser intensities within the interaction volume, the detected events range in occupancy from near-zero to extremely high, approaching the readout limits of the detector. By combining time-of-flight and velocity map imaging (VMI) techniques, detailed post-processing and analysis were performed. The results presented here focus on the performance of Tpx3Cam under high-occupancy conditions, which are of particular relevance to this study. These conditions approach the limitations imposed by the camera readout capabilities and challenge the effectiveness of standard post-processing algorithms. We investigated these limitations and associated trade-offs, and we present improved methods and algorithms designed to extract the most informative features from the data.
This publication presents an improved manufacturing method for tetrahedral metal effect pigment particles that demonstrates reduced flowlines in injection-molded polymer components compared with conventional platelet-shaped pigment particles. The previously published cold forming process for tetrahedral particles, made entirely from aluminum, faced manufacturing challenges, resulting in a high reject rate due to particle adhesion to the micro-structured mold roller. In contrast, this study introduces a new manufacturing method for tetrahedral particles, now consisting of metallized UV-cured thermoset polymer. These particles, dispersed in amorphous matrix thermoplastics, have shown to maintain their shape during the injection molding process. The manufacturing technique for these novel particles is based on UV imprint lithography, omitting the reject rates compared with the previously presented cold rolling process of tetrahedral full aluminum particles. Thus, the novel manufacturing technique for tetrahedral pigment particles shows increased potential for automation through roll-to-roll manufacturing in the future.
Reflectometric method for measuring residual oxides in through-silicon vias for 3D chip integration
(2025)
A significant aspect of fabricating 3D chip architectures is ensuring proper contact between the different layers of the chip, which often requires removing the underside of isolation layers before filling vias with conductive material. Currently, scanning electron microscopy is the established method for investigating such structures. In this paper, we propose a rapid, non-destructive optical analysis technique for the simultaneous measurement of through-silicon vias (TSV) depths, silicon wafer thickness, and residual oxide thickness. The proposed method utilizes Fourier peak shift analysis (FPSA) of reflectance measurements in the near-infrared (1200 nm—2200 nm) spectral regions. The application of FPSA to representative samples taken from a commercial TSV integration process for MEMS and CMOS fabrication demonstrated good agreement with reference scanning electron microscopy measurements, confirming the feasibility of the method for in-line and in-situ metrology. The results indicate that FPSA has great potential for real-time process monitoring and control during 3D chip manufacturing.
Pressure sensors based on photonic integrated circuits (PIC) offer the prospect of outstanding sensitivities, extreme miniaturization and have the potential for highly scalable production using CMOS compatible processing. PIC-based pressure sensors detect the change in optical properties, i.e. the intensity or phase of the optical carrier wave inside miniaturized waveguide structures. The detection of ultrasound is achieved by engineering the waveguide architecture such that a pressure causes a high change in the effective refractive index of the waveguide. A range of PIC-based pressure sensors have been reported, but a comparison of the sensitivity of the different approaches is not straightforward, since different pressure sensitive waveguide architectures as well as photonic layouts and measurement setups impact the performance. Additionally, the used sensitivity unit is not uniform throughout the different studies, further complicating a comparison. In this work, a detailed simulation study is carried out by finite element modeling of different pressure sensitive waveguide architectures for a consistent comparison. We analyze three different sensor architectures: (A) a free standing membrane located within a tiny air gap above the waveguide, (B) a waveguide located on top of a deflectable membrane as well as (C) a waveguide embedded inside a pressure-sensitive polymer cladding. The mechanical response of the structures and the resulting changes in mode propagation, i.e. the change of the effective refractive index, are analyzed. The waveguide sensitivities in RIU/MPa for different waveguide types (strip, slot) and polarization states (TE, TM) are compared. The results reveal inherent limitations of the different waveguide designs and create a basis for the selection of suitable designs for further ultrasound sensor development. Possibilities for enhancing waveguide sensitivity are identified and discussed. Additionally, we have shown that the studied approaches are extensible to SiN waveguides.
Interdisciplinary thinking is becoming an increasingly important competence for meeting the challenges of our time, for example in the areas of sustainability or even digitalization. Successful value creation can only be achieved if all subject disciplines work together. Universities, too, must adapt to these needs and anchor the teaching of these competencies in their courses of study. In this context, interdisciplinary cooperation cannot be limited to the curricula, but must also bring together the teachers and the learners in a common context. Traditionally, universities have found it difficult to develop interdisciplinary scenarios. The teaching scenarios themselves must already provide interdisciplinary content and learning objectives. The challenge here is multi-level. First, it is a great challenge to connect the modules of a course of study in a thematically meaningful way. Second, it is the linking with other study programs that brings about the most sustainable interdisciplinary effects. One possible solution, which has been tested for several years, is to set up a fictitious company as a digital learning factory, which serves as a basis and reference for the interlinking of individual modules of the various courses of study. The scenarios that can be depicted here are extremely application-oriented, which means that not only can internal university modules be very easily aligned with them, but external partners, can also get a simple participation. Furthermore, the participating courses of study can continue to maintain their original core competencies while participating in the interdisciplinary scenarios via the modules that are aligned accordingly with the learning factory. A company from the vehicle construction sector was selected as the business model in order to be able to map another focus at the same time, autonomous driving. The individual departments of the company are linked professionally with the contents of the individual courses of study. Study programs, such as industrial engineering, form the design department, whereas technology-oriented study programs, such as business computing, represent technical development, in particular the area of driver assistance system development. In addition, the relevant departments also include economics and so on. The special feature, however, is the fact that real products in the form of vehicles on a scale of 1:14 are also created and continuously developed, which is an important success factor of the learning factory. The following article transfers the experiences made into a scheme of different levels of interdisciplinary forms of teaching within the framework of the learning factory and classifies and explains the existing scenarios accordingly. Furthermore, the teaching formats used, which have proven to be effective in imparting competences, are described.
This publication demonstrates that determining the maximum speed or Ideal Cycle Time (ICT) of machinery or cyber-physical systems is crucial for uncovering the limits of automation in a given system. Possibly increasing Overall Equipment Effectiveness (OEE) and identify opportunities for further digitization, automation, and AI integration. Based on literature review and expert interviews, methods for establishing ICT, mentioned in literature were identified and crosscheck with what practitioners in operation actually use and how they apply them. The identified methods were: Empirical Measurement and Data Analysis, Time Studies, Statistical Process Control (SPC), Benchmarking, Simulation and Modeling, Expert Judgment, and Continuous Improvement Practices we. We contrast these with insights obtained from interviews conducted with experts from companies in the German federal State of Brandenburg, representing diverse industries and sectors. Findings suggest that while companies recognize somewhat their ICT or maximum operational speeds, they often lack a structured method for determining them. They frequently use combinations of established methods inconsistently. We deduce that a formalized approach to defining ICT can better reveal system limitations and potential for expanding them through advanced automation and. We argue that a well-defined ICT is essential for pushing the boundaries of automated systems, contributing to more effective and Humanity–Centered Automation (HCA) solutions.
Im Rahmen des Projekts ESPEK wurden Häufigkeit und Relevanz bestimmter Schäden an verbreiteten Waggontypen analysiert und basierend darauf im Rahmen eines Konzepts „KI-gestützte Inspektion“ praxistaugliche, datenbasierte, durch künstliche Intelligenz unterstützte digitale Lösungen entwickelt, um Schäden an ausgewählten Personenwaggons automatisiert visuell zu erkennen. Ausgehend von den bisher maßgeblich manuellen Inspektionsabläufen und Checklisten können selbige durch die vorgeschlagenen Software- und Hardwareautomatisierungen effizienter gestaltet werden. Übergeordnet werden die Sicherheit der Fahrgäste erhöht, das Problem des Fachkräftemangel bekämpft sowie Ausfall- und Standzeiten reduziert, was letztlich zur besseren Auslastung des Systems Schiene insgesamt beiträgt und Zugfahren preiswerter und pünktlicher machen kann.

