Die stark zunehmende Verbreitung leistungsfähiger Akkumulatoren im Rahmen der Energiewende erfordert elektrische Diagnoseverfahren für Batterien wie die Impedanzspektroskopie. Sie ermöglicht durch die Messung des elektrischen Verhaltens einen Einblick ins Innere einer Batterie. Die Auswertung der gemessenen Impedanzspektren stellt eine große Hürde dar. Einen Ausweg bieten Zeitkonstantendichtespektren (DRT), die sich aus Impedanzdaten berechnen lassen. Sie ermöglichen eine schnelle Identifikation der Anzahl der wirkenden Mechanismen zusammen mit deren Stärken und Zeitkonstanten und...

Surface electromyography (sEMG), force myography (FMG) and surface electrical impedance myography (sEIM) are investigated for perspective wearable embedded systems. A database has been collected from more than 100 healthy subject performing American sign language (ASL). Classification methods have been proposed based on Extreme Learning Machine (ELM) supported by a grasshopper optimization algorithm (GOA) as a core weight pruning process. To ensure the GOA population diversity a K-tournament selection strategy is included. The K-Tournament Grasshopper Optimization Algorithm (KTGOA) has been...

Inductive power transfer (IPT) systems intolerance to misalignment limits their ability to transfer energy to objects with flexible or dynamic position. In this thesis, a novel misalignment tolerant multi-coil design is proposed for supplying stationary and dynamic battery-free wireless devices. A compact architecture composed of individually switchable 3 layers of printed coils arranged with overlap for excellent surface coverage. A hybrid architecture based on three compact AC supply modules reduces the supply circuit complexity on the sending side. The sending side activation procedure is...

Die transurethrale Resektion der Prostata (TURP) ist eine elektrochirurgische Behandlung der gutartigen Vergrößerung der Prostata. Hierbei treten sehr selten gebrochene Resektionsschlingen auf, deren Ursachen in der Literatur unzureichend dokumentiert sind. In dieser Arbeit erfolgt die Untersuchung der Eignung von Methoden zur Schlingenverschleißanalyse bei der TURP. Es gilt die aktuell offenen Fragen zu klären, wie sich zum Beispiel der Schlingenverschleiß äußert, ob dieser Ursache für gebrochene Schlingen während einer Operation ist und ob er Einfluss auf den Leistungseintrag ins...

Sensors in two-dimensional matrices can be addressed one by one using multiplexers. However, without special precautions, the measurement signal may flow through other sensors and leads to significant measurement deviations. To reduce this so-called cross-talk effect in two-dimensional matrices, a multi-row excitation strategy using AC signals having different frequencies is proposed in this thesis, which avoids DC deviations of electronic components and enables a multiplexer-free simultaneous measurement of resistive targets. This method is named the AC - Zero Potential Circuit (AC-ZPC Type...

Various applications of Wireless Sensor Networks (WSNs) require accurate localization of sensor nodes. The quantity and locations of anchor nodes, which serve as reference points for distance estimates, as well as the localization process itself, affect the localization accuracy. Furthermore, because numerous communications are sent between nodes for localization, energy consumption must be considered. This work presents an energy-aware and accurate localization method. It is based on a combined anchor deployment and energy-aware localization. The proper number and distribution of anchors...

High levels of nitrates and nitrites harm human health and aquatic ecosystems, and their concentration varies dynamically, necessitating their simultaneous detection. Among electrodes for electrochemical sensors, Laser-induced graphene (LIG) offers a flexible, one-step alternative, yet CO2 laser interactions with Kapton remain underexplored. Optimization studies are not performed over entire range and defects on the surface are overlooked which are crucial for high electrochemical activity. This thesis develops LIG-based electrochemical sensors modified with nanomaterials for simultaneous...

Vibration converters based on piezoelectric materials are currently becoming increasingly important for powering low-power wireless sensor nodes and wearable electronic devices. Piezoelectric materials generate variable electrical charges under mechanical stress, requiring an energy management interface to meet load requirements. Resonant interfaces like Parallel Synchronized Switch Harvesting on Inductor (P-SSHI) are highly efficient and robust to energy sources and loads variations. Nevertheless, SSHI circuits require synchronous switch control for efficient energy transfer. At irregular...

This thesis addresses the identification of defects in transmission lines, emphasizing the importance of cable network reliability in critical industries like telecommunications, automotive, and aerospace. Cable faults are classified into hard and soft faults, both of which can lead to significant safety risks and financial losses. Effective fault prediction and localization are essential.We explore methods like time-domain reflectometry (TDR) and frequency-domain reflectometry (FDR) for fault location, noting their limitations in networks with parallel branches and unknown topology,...

Bioimpedance spectroscopy is a non-invasive measurement technique in medical applications. It requires low amplitude current excitation to maintain safety. Designing a current source for this purpose is a challenge as it needs to maintain a stable and safe excitation current, below 0.5 mA, independent of the impedance and frequency.Various topologies of voltage controlled current sources exist in the literature, where the Enhanced Howland Current Source (EHCS) and the Dual HCS (DHCS) show advantages concerning low output current deviation and high output impedance.They are composed of...