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...

The choice of suitable materials influences the sensor properties.Carbon materials such as graphene are promising for electrochemical sensors. Laser-induced graphene (LIG) offers a cost-effective alternative to conventional methods.This work investigates the potential of LIG to improve electrochemical sensors by optimizing the synthesis parameters. We develop LIG-based sensors for the measurement of nitrite and 4-aminophenol in water samples.The working electrode of the 4-aminophenol sensor was fabricated from LIG and multi-walled carbon nanotubes with polyaniline (MWCNT-PANI), which improves...

Walzwerke für flache Walzgüter sind mit modernster Mess- und Automatisierungstechnik ausgestattet. Diese können mit modellgestützten Regelungskonzepten den Umformprozess in Echtzeit optimieren und auch die Produktionsschritte optimal aufeinander abstimmen. Aus diesem Grund ist es möglich qualitativ hochwertige Flachprodukte zu produzieren und einen positiven Beitrag zur Dekarbonisierung zu leisten. Hingegen sind Drahtwalzwerke aufgrund der schwierigen Einbausituationen und rauen Umgebungsbedingungen nur mit rudimentärer Mess- und Sensortechnik ausgestattet, wodurch die Implementierung...

Hand sign recognition (HSR) has emerged as a significant field of research and development in the context of wearable systems and human machine interaction. The aim of this research is to investigate the potential of forearm-attached sensors to recognize hand signs and to propose a novel measurement approach for real-time HSR with reduced ambiguities. Three measurement methods are deeply investigated: Force Myography (FMG), Electrical Impedance Tomography (EIT), and surface Electromyography (EMG). The potential of these methods is evaluated in the context of American Sign Language (ASL). For...

Electrochemical impedance spectroscopy requires linearity, causality, and time invariance for reliable measurements, necessitating precise excitation signal design. This thesis presents a methodology for multisine excitation signal optimization through systematic determination of amplitude, frequency distribution, and phase angles. The framework addresses limitations in conventional approaches, particularly for systems undergoing state changes during low-frequency measurements. A novel regularized linear Kramers-Kronig (rLKK) approach evaluates impedance spectra consistency and serves as...

Epileptic seizures result from abnormal brain activity and involve both electrical and biomechanical signals. Accurate seizure classification is essential for clinical decision-making, yet conventional diagnostic methods, including self-reports and video monitoring, are limited in detecting seizure types. To overcome these limitations, this study investigates a multimodal approach combining electroencephalography (EEG), surface electromyography (sEMG), and inertial measurement unit (IMU) sensors. A synchronized compact wireless system was developed to capture the modalities, ensuring precise...

A novel embedded impedance measurement system for counterfeit detection of bimetallic coins is presented. The system integrates Eddy current sensors with inductive spectroscopy, facilitating the detection of hidden inlay security features and the identification of surface minting. A salient feature of the system is the use of a single Eddy current sensor that operates across multiple frequencies. This feature eliminates the need for extensive calibration procedures typically required when multiple sensor coils are used for each excitation signal frequency. The system employs an undersampling...