New publication of the VDI/VDE guideline 3520 "Surface temperature measurement with contact thermometers" - contents and background of the development. - In: Journal of sensors and sensor systems, ISSN 2194-878X, Bd. 12 (2023), 1, S. 197-204
Temperature measurement at the surface of solids by means of contact thermometers has its own metrological characteristics, which are in contrast to characteristics of the measurement with immersed contact thermometers. They significantly influence the accuracy and the measurement uncertainty of the measured temperature and its deviations. Up to now, no national or international guideline exists which deals with the determination of the static and dynamic measurement deviations. Therefore, the guideline committee “VDI/VDE-GMA FA 4.62 Contact Thermometry” has developed the new VDI (Association of German Engineers) and VDE (Association for Electrical, Electronic and Information Technologies) guideline 3520 “Surface temperature measurement with contact thermometers”. It contains information about the most important properties of contact surface thermometers and error sources, and it presents typical measurement results for various applications. In addition, the parameters influencing the measurement result and test equipment for their determination are described, and concrete examples of thermometer data sheets are given.
https://doi.org/10.5194/jsss-12-197-2023
Dynamische Messung von sicherheitstechnisch relevanten Explosionsdrücken. - Braunschweig : Physikalisch-Technische Bundesanstalt, 2023. - xii, 127 Seiten. - (PTB-Bericht)
Technische Universität Ilmenau, Dissertation 2023
ISBN 978-3-944659-29-9
Literaturverzeichnis: Seite 120-127
Die Zündschutzart „druckfeste Kapselung“ ist ein im Bereich des Explosionsschutzes häufig verwendetes Schutzprinzip, bei dem verhindert werden soll, dass eine eventuell im Inneren eines Gerätes auftretende Explosion nach außen dringt, um eine dort potenziell vorhandene explosionsfähige Atmosphäre zu entzünden. Bei der Konformitätsbewertung solcher Geräte ist die dynamische Messung von Explosionsdrücken eine der wesentlichen Prüfungen und im Einzelnen von sicherheitstechnischer Relevanz. Im Kontext der gegenseitigen Anerkennung von Messergebnissen ist es darüber hinaus von sehr großer Bedeutung, eine vergleichbare Qualität bei der Messung zu gewährleisten. Ringvergleichsprogramme haben gezeigt, dass diese vergleichbare Qualität nicht durchweg gegeben ist. Die Identifizierung der relevanten Einflussgrößen bei der Messung von Explosionsdrücken, die daraus resultierenden Folgen für die Vergleichbarkeit und die Diskussion von Maßnahmen zum Umgang mit diesen Einflussfaktoren sind wesentlicher Gegenstand dieser Arbeit. Dafür wurden einerseits die Messungen und Prüfparameter der am Ringvergleich teilnehmenden Prüflaboratorien analysiert. Andererseits wurden eigene experimentelle Untersuchungen unter Verwendung unterschiedlicher Prüfmuster, Prüfaufbauten und Prüfparameter durchgeführt. Mit dem Einfluss von Anfangsdruck und -temperatur des explosionsfähigen Gemisches, dem Einfluss des Thermoschockes sowie der Beschleunigungsempfindlichkeit der Drucksensoren ergeben sich drei signifikante Einflussgrößen im Zuge dieser Studien. Im Ergebnis resultieren aus den Untersuchungen anwendbaren Korrekturrechnungsverfahren für die Messgröße, geeignete Präparationsmöglichkeiten für die Drucksensoren sowie Filter- und Verrechnungsverfahren für die Messdaten, um die Einflussgrößen zu reduzieren und die Vergleichbarkeit zu erhöhen. Darüber hinaus wird mittels einer Messunsicherheitsbetrachtung aufgezeigt, dass die üblicherweise verwendete Messkette eine hohe Genauigkeit aufweist und damit eine eher untergeordnete Rolle bezüglich einer Einflussgröße auf den Explosionsdruck einnimmt. Diese Arbeit trägt allgemein zum praktischen und metrologischen Verständnis bei der dynamischen Messung sicherheitsrelevanter Explosionsdrücke bei, nicht zuletzt dadurch, dass die resultierenden Erkenntnisse die internationale Normung im Bereich der druckfesten Kapselung aktiv unterstützen.
Evaluation of hysteresis response in achiral edges of graphene nanoribbons on semi-insulating SiC. - In: Materials science forum, ISSN 1662-9752, Bd. 1089 (2023), S. 15-22
Hysteresis response of epitaxially grown graphene nanoribbons devices on semi-insulating 4H-SiC in the armchair and zigzag directions is evaluated and studied. The influence of the orientation of fabrication and dimensions of graphene nanoribbons on the hysteresis effect reveals the metallic and semiconducting nature graphene nanoribbons. The hysteresis response of armchair based graphene nanoribbon side gate and top gated devices implies the influence of gate field electric strength and the contribution of surface traps, adsorbents, and initial defects on graphene as the primary sources of hysteresis. Additionally, passivation with AlOx and top gate modulation decreased the hysteresis and improved the current-voltage characteristics.
https://doi.org/10.4028/p-i2s1cm
Multipurpose active scanning probe cantilevers for near-field spectroscopy, scanning tunnel imaging, and atomic-resolution lithography. - In: Journal of vacuum science & technology, ISSN 2166-2754, Bd. 41 (2023), 4, S. 042601-1-042601-9
In this work, we report progress on developing a multipurpose scanning probe cantilever applying gallium nitride nanowires as the probe tip. Gallium nitride nanowires possess high potential as probes due to their straight profile, tunable electrical and optical properties, high Young’s Modulus, durability, and high-yield fabrication process. Their wide bandgap enables them to be pumped to emit ultraviolet pulses which can be used for optical imaging and spectroscopy. They can be doped during growth to be electrically conductive, and their sharp tips obtained during epitaxial growth enable confinement of a high electric field at tip-sample interface. Their sharp tips are obtained during fabrication by their epitaxial growth which eliminates the need for postprocess sharpening that is typically required for standard STM tips. We present results of using gallium nitride nanowires for scanning tunnel microscopy applications of atomic-resolution imaging and lithography, and atomic force microscopy applications of imaging and lithography in vacuum and atmospheric environments.
https://doi.org/10.1116/6.0002486
SI traceable small force generation and measurements via photon momentum. - In: SMSI 2023 Conference - Sensor and Measurement Science International, (2023), S. 133-134
In this contribution we present the concept of photon momentum enabled SI-traceably made small force generation and measurements below the conventionally accepted limits. The developed instrumentations, the measurement infrastructure and the obtained results demonstrate the advantages of this concept and further are extended to present the means of systematization of the force measurements covering the range below 10 μN to several tens of nN. The prospects to reduce the relative measurement uncertainties of small force and small weight measurements are discussed.
https://dx.doi.org/10.5162/SMSI2023/B7.1
Permanent tracebility of a nanopositioning and nanomeasuring machine. - In: 2023 ASPE Winter Topical Meeting: Precision Optical Metrology Workshop, (2023), S. 82-86
Due to the frequency stabilization of He-Ne-lasers directly to a frequency comb controlled by a GPS atomic clock disciplined oscillator and their direct coupling with a Nanopositioning and Nanomeasuring Machine, directly traceable measurements are demonstrated.
Tip-based nanofabrication below 40 nm combined with a nanopositioning machine with a movement range of Ø100 mm. - In: Micro and nano engineering, ISSN 2590-0072, Bd. 19 (2023), 100201, S. 1-5
In this paper, the combination of an advanced nanopositioning technique and a tip-based system, which can be used as an atomic force microscope (AFM) and especially for field emission scanning probe lithography (FESPL) is presented. This is possible through the use of active microcantilevers that allow easy switching between measurement and write modes. The combination of nanopositioning and nanomeasuring machines and tip-based systems overcomes the usual limitations of AFM technology and makes it possible to perform high-precision surface scanning and nanofabrication on wafer sizes up to 4 in. We specifically discuss the potential of nanofabrication via FESPL in combination with the nanofabrication machine (NFM-100). Results are presented, where nanofabrication is demonstrated in form of a spiral path over a total length of 1 mm and the potential of this technique in terms of accuracy is discussed. Furthermore, ten lines were written with a pitch of 100 nm and a linewidth below 40 nm was achieved, which is in principle possible over the entire range of motion.
https://doi.org/10.1016/j.mne.2023.100201
In situ, back-focal-plane-based determination of the numerical apertures in optical microscopes. - In: Applied optics, ISSN 2155-3165, Bd. 62 (2023), 3, S. 756-763
In this contribution, we present a technique for in situ determination of the numerical apertures (NAs) of optical microscopes using calibrated diffraction gratings. Many commonly practiced procedures use an external setup to determine the objective and condenser NAs. However, these values may become modified in the used microscope systems, e.g., by system intrinsic apertures. Therefore, in our improved technique, determination of the imaging NA is conducted in situ within the corresponding microscope at hand. Furthermore, the method has been extended to yield the microscope’s illumination NA as well. In total, we tested this procedure for determination of the imaging NA for four different microscope objectives with nominal values of 0.55 and 0.9, together with the illumination NAs for four different circular aperture diaphragms with diameters between 10 µm and 500 µm using several gratings of different pitches. All determined NA values agree essentially with their nominal values within their experimental uncertainties, but the uncertainties have been reduced by typically an order of magnitude as compared with the manufacturer’s specifications.
https://doi.org/10.1364/AO.472223
Stiffness considerations for a MEMS-based weighing cell. - In: Sensors, ISSN 1424-8220, Bd. 23 (2023), 6, 3342, S. 1-15
In this paper, a miniaturized weighing cell that is based on a micro-electro-mechanical-system (MEMS) is discussed. The MEMS-based weighing cell is inspired by macroscopic electromagnetic force compensation (EMFC) weighing cells and one of the crucial system parameters, the stiffness, is analyzed. The system stiffness in the direction of motion is first analytically evaluated using a rigid body approach and then also numerically modeled using the finite element method for comparison purposes. First prototypes of MEMS-based weighing cells were successfully microfabricated and the occurring fabrication-based system characteristics were considered in the overall system evaluation. The stiffness of the MEMS-based weighing cells was experimentally determined by using a static approach based on force-displacement measurements. Considering the geometry parameters of the microfabricated weighing cells, the measured stiffness values fit to the calculated stiffness values with a deviation from -6.7 to 3.8% depending on the microsystem under test. Based on our results, we demonstrate that MEMS-based weighing cells can be successfully fabricated with the proposed process and in principle be used for high-precision force measurements in the future. Nevertheless, improved system designs and read-out strategies are still required.
https://doi.org/10.3390/s23063342
Analytical description of transversally symmetrical hinges :
Analytische Beschreibung transversalsymmetrischer Gelenke. - In: Neunte IFToMM D-A-CH Konferenz 2023, (2023), insges. 2 S.
https://doi.org/10.17185/duepublico/77402