Steep resonance of parametrically excited active MEMS cantilevers for dynamic mode in Atomic Force Microscopy. - In: Proceedings in applied mathematics and mechanics, ISSN 1617-7061, Bd. 22 (2023), 1, e202200230, S. 1-6
Ongoing developments in nanotechnology demand higher spatial resolution and thus, higher amplitude sensitivity in Atomic Force Microscopy (AFM). In this work, active cantilevers with integrated sensor and actuator systems are parametrically excited using a novel, analog feedback circuit. With that it is possible to adapt the strength and sign of a cubic nonlinearity which provides a bound to the amplitudes in resonance operation. The system response shows steeper resonance curves and therefore higher amplitude sensitivities compared to forced excited cantilevers. Theoretical findings are validated experimentally.
https://doi.org/10.1002/pamm.202200230
Photon-induced near-field interaction in ultrafast low energy electron microscopy. - [Washington, D.C., USA] : Optica Publishing Group. - 1 Online-Ressource (Paper Tu3A.5)
We report the first observation of optical near-field coupling to an ultrafast wavepacket of free, low-energy electrons. Transient optical near-fields, highly spatially confined around a nanometer-sized Yagi-Uda-antenna are probed in a point-projection-microscope with 30-fs resolution.
https://doi.org/10.1364/UP.2022.Tu3A.5
Monitoring considerations of second life lithium ion batteries in battery energy storage systems. - In: PCIM Europe 2022, (2022), S. 1905-1914
This paper presents an analytical study of the most important technical aspects that should be considered in the methodologies for monitoring second-life lithium-ion batteries in stationary energy storage systems. The study is based, on one hand, on the specificity of these batteries in terms of changing their response differently in the second-life than in the first to external and operational influences. On the other hand, it is based on the monitoring requirements of storage systems to obtain an improved monitoring system with sufficient accuracy and more efficient performance of batteries in their second-life.
https://doi.org/10.30420/565822263
Incorporating state of charge estimation methods towards more accurate monitoring of second-life lithium-ion batteries. - In: 2022 13th International Renewable Energy Congress (IREC), (2022), insges. 6 S.
Although several methods are developed for estimating the state of charge of lithium-ion batteries, there is still a challenge regarding monitoring the second life of these batteries due to the expected difference in the behavior and operating conditions in their second life. Considering that each method has its advantages and disadvantages according to the application and operating conditions, and monitoring the batteries in their second life is of special importance because it is required to integrate with the battery management system to balance cells, diagnose faults and prevent overheating. Therefore, the estimation method developed in this study, by incorporating artificial neural network method and Kalman filter method with fine-tuning of the filtering process using Coulomb counting, provides a solution for more accurate online monitoring of these batteries. Aiming to get the best possible performance, considering the specificity of the second life of the batteries in terms of operating voltage, low values of expected capacity, discharge ratio and other operational parameters.
https://doi.org/10.1109/IREC56325.2022.10002052
Micro-diffractive optical element arrays for beam shaping. - In: EOS Annual Meeting (EOSAM 2022), Bd. 266 (2022), 13013, S. 1-2
We describe the design of Fourier type array generators and beam shapers as periodic configurations of refractive-diffractive optical elements in microscale to provide specific beam shaping and imaging functionaliies. We investigate how the addition of micro-nanostructures to regular microstructure arrays enables new degrees of freedom for the design of micro-optical systems, in combination with adapted fabrication techniques yields a better optical performance and leads to enhancement of the array concept, uniformity and efficiency.
https://doi.org/10.1051/epjconf/202226613013
Approaches for the RCWA-based non-destructive characterization of subwavelength-structured gratings. - In: EOS Annual Meeting (EOSAM 2022), (2022), 05012, S. 1-2
Nano-structuring enables us to add additional degrees of freedom to the design of optical elements. Especially the possibility of controlling the polarization is of great interest in the field of nano-structured optics. For being able to exploit the whole range of form-birefringent phase shifts, the aspect ratios of the resulting element are typically much higher than the aspect ratios of conventional diffractive optical elements (DOEs), which does not only pose a challenge on fabrication but also on characterization. We evaluate several well-established approaches for the nondestructive characterization, including Müller-Matrix-Ellipsometry, measurement of the diffraction efficiencies, scattering measurements and calibration with rigorous coupled-wave modelling. The goal is to understand the challenges with all these techniques and combine them to a reliable method for structural reconnaisance of high aspect ratio nanostructures.
https://doi.org/10.1051/epjconf/202226605012
Thermal characterization of passive piezoelectric actuators. - In: ACTUATOR 2022: International Conference and Exhibition on New Actuator Systems and Applications, (2022), S. 334-337
In this paper a workflow for thermal characterization and automatic modeling of passive piezoelectric actuators of prismatic shape is presented. Aim of this work is to generate finite element models of the thermal behaviour of piezoelectric actuators without destroying the actuators. For this purpose an experimental setup was developed, as well as a characterization workflow. The advantage of the workflow lies in the speed of characterization through direct comparison of measurement results with a metamodel and automated finite element model generation for many different actuators that vary in size and shape. The method is exemplarily presented on a PZT stack actuator.
https://ieeexplore.ieee.org/document/9899237
Magnetic microspheres for MPI and magnetic actuation. - In: International journal on magnetic particle imaging, ISSN 2365-9033, Bd. 8 (2022), 1, 2203006, S. 1-4
Magnetic particle imaging (MPI) systems do not only allow for the visualization of the distribution of magnetic nanoparticles, but the magnetic fields of an MPI scanner can be also used to apply a magnetic force or a torque. This enables the actuation of magnetic particles. Here, we demonstrate that magnetic microspheres (MMS) are well suitable candidates for the actuation and visualization with MPI. By means of magnetic particle spectrometer (MPS) measurements, a promising imaging performance of the MMS for MPI was confirmed. We show that MMS can be actuated by rotating focus fields of a preclinical MPI scanner. Since the used MMS can carry therapeutics, which can be released by means of hyperthermia, this approach paves the way towards an MPI monitored targeted drug delivery.
https://doi.org/10.18416/IJMPI.2022.2203006
Influence of magnetic nanoparticles interactions on their magnetic particle imaging performance. - In: International journal on magnetic particle imaging, ISSN 2365-9033, Bd. 8 (2022), 1, 2203083, S. 1-3
Abstract: The here presented study investigated the influence of magnetic particle-particle interactions within the MPI tracer MNP on the imaging performance of the tracers. To realize a proper separation and to increase the distances between the individual tracer MNP (which results in reduced particle-particle interactions), the MNP were diluted by non-magnetic SiO2 spacers in the nanometer range. The obtained MNP/SiO2 mixtures were characterized and used to build up measurement phantoms by embedding the mixture into a long-term stable polymer matrix. In MPS and MPI measurements it was found that reduction of the magnetic interactions encompassed by increasing the MNP distances leads for the tested tracer system to a weaker decrease of higher harmonics in the MPS spectra after immobilization of the particles and thereby, a higher spatial MPI resolution can be achieved.
https://doi.org/10.18416/IJMPI.2022.2203083
Innovation processing of circuit boards with FDM printing and selective electrochemical metallization. - In: Meeting abstracts, ISSN 2151-2043, Bd. MA2022-01 (2022), 57, 2369
https://doi.org/10.1149/MA2022-01572369mtgabs