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...

Straßenbahnen sind eines der wichtigsten urbanen Verkehrsmittel, um den wachsenden öffentlichen Personennahverkehr (ÖPNV) ökologisch, nachhaltig und emissionsfrei zu transformieren. Doch mit verstärkter Auslastung wächst der Wartungsbedarf und das Verlangen nach einer zustandsabhängigen Instandhaltungsstrategie. Die Schwingungsdiagnose ist eine gängige Methode für die Zustandsüberwachung von Maschinen. In dieser Arbeit wird gezeigt, wie mittels energieeffizienter und smarter Sensorsysteme trotz rauer Betriebsbedingungen eine Zustandsüberwachung der Drehgestelle von Straßenbahnen...

This thesis develops highly sensitive electrochemical sensors for continuous monitoring of nitrogen and phosphorus compounds in water. Overuse of these fertilizers dramatically impacts aquatic ecosystems and poses health risks, necessitating efficient field-deployable sensors.Carbon screen-printed electrodes (CSPE) serve as transducers for all analytes due to their ease of use, high surface area, and minimal sample requirements. Three sensors were developed: (1) Gold nanoparticles (~12 nm) capped with polyethylenimine for nitrite detection, achieving the lowest reported limit of detection...

Rehabilitation therapy often relies on subjective assessments of exertion and fatigue, lacking objective metrics to guide treatment. This thesis explores surface electromyography (sEMG) as a tool for force estimation and fatigue detection in hand rehabilitation. Eight sEMG sensors were placed on key flexor and extensor muscles. Voluntary force was measured using a grip strength dynamometer for maximal force and a numeric dynamometer for continuous estimation, while fatigue was classified from sEMG features. Distinct muscle contributions were observed at different force levels, with clear...

Excessive nitrite in water poses serious health and environmental risks, requiring reliable long-term monitoring. Electrochemical sensors offer advantages due to their sensitivity, low cost, and ease of use; however, they suffer from aging, which affects accuracy over time. This thesis addresses this limitation by developing and optimizing a nitrite sensor based on screen-printed carbon electrodes modified with electrodeposited gold. The sensor achieved promising performance, including a 15-day shelf life. A multidisciplinary study investigated aging mechanisms using electrochemical...