Abstracted/indexed

Applications like air quality, fire detection and detection of explosives require selective and quantitative measurements in an ever-changing background of interfering gases. One main issue hindering the successful implementation of gas sensors in real-world applications is the lack of appropriate calibration procedures for advanced gas sensor systems. This article presents a calibration scheme for gas sensors based on gas profiles with unique randomized gas mixtures.

Traceably calibrated scanning Hall microscopy (SHM) is a versatile tool for the quantitative characterization of magnetic microstructures. To enable SHM with a resolution in the micrometer range under ambient conditions, two Hall sensor materials, gold and graphene, were investigated. A SHM setup utilizing a 5 μm gold Hall sensor was calibrated. The field sensitivity and the detailed uncertainty budget are discussed. The presented traceable calibration is validated by comparison to simulations.

The new concept of a unified pH scale can be used to compare acidities of different kinds of solvents and their mixtures. The aim of the work was to investigate the robustness of the measurement method with four commercially available glass electrodes for non-aqueous media in comparison with the rather specific type of cell used so far for this measurement. The measurement results in aqueous mixtures of ethanol show good agreement.

The necessity to measure harmonic emissions between 2 and 150 kHz is outlined by several standard committees and electrical utilities. This paper presents a measurement system and its traceable characterization designed to acquire and analyze voltages up to 230 V and currents up to 100 A with harmonics up to 150 kHz that may occur in smart grids. The uncertainty estimation is carried out and described in detail for both the fundamental and suprahmarmonics components.

In order to further increase the performance of neural networks in the field of optical quality assurance of soldered joints, a hierarchical classifier can be used instead of a single network. The global expansion of the classifier enables the inspection task to be distributed over several subnetworks, which results in higher accuracy. Since the individual sub-models only concentrate on the identification of certain characteristics, categorical problems can be solved more effectively.

A commercial solid electrolyte gas sensor of the type "Pt|YSZ|Pt, air" based on yttria-stabilized zirconia for colorimetric oxygen detection was operated in optimized dynamic electrochemical modes. Cyclic voltammetry and square-wave voltammetry were used for the detection of NO and O₂ in N₂ in the temperature range between 550 and 750 °C. Due to the differences of electrode kinetics of the single components it is possible to detect these redox active gases selectively and quasi-simultaneously.

This paper describes an optical sensor system based on the technique of laser speckle photometry (LSP) for the application of stress characterization and defect detection in ceramics. The purpose of the research is to develop an in-line inspection solution for the industrial field. The preliminary results show that the LSP technique has the potential to fulfill the task.

In this contribution, an inexpensive and robust impedimetric NO_x sensor is presented. The impedance of a functional thick film depends selectively on the NO_x concentration in the exhaust but shows a dependency on the oxygen concentration. Therefore, an additional temperature-independent resistive oxygen sensor structure was integrated on the same sensor platform. It serves not only to determine the oxygen concentration in the exhaust, but also to correct the oxygen dependency of the NO_x sensor.

In this paper, we present a tactile sensor based on the interaction of coils with a magnetic elastomer. The first experimental approach is sampling the sensor with indentations of constant depth at different positions. A mathematical model is used to reproduce the data. Afterwards, this model is applied to random indentations at the same depth. As a result, we provide conceptual proof for position determination in one direction as a basis for a refined sensor design and further model approaches.

A miniaturized, field-applicable sensor system was developed for the measurement of low hydrogen (H₂) concentrations in air. The sensor system is based on the application of a newly developed miniaturized coulometric detector with gas chromatographic (GC) pre-separation after injection. By optimizing all operational parameters, it was possible to conduct reproducible and 100 % selective H₂ measurements with more than 90 % analyte turnover compared to Faraday's law.

Deep learning has become a state-of-the-art method in machine learning, with a broad range of successful applications. Our goal is to explore the benefits of deep learning techniques for computational optical form measurements. The research is based on solving a nonlinear inverse problem aimed at the reconstruction of optical topographies from given processed interferograms. A U-Net network structure is chosen and tested on a simulated database. The obtained results are promising.

Symmetrical Pt | YSZ | Pt–NO gas sensors were produced with frit-containing and fritless Pt electrodes and fired between 950 and 1300 °C. The sensors were operated by pulsed polarization. With fritless pastes, the sensors responded significantly higher. The firing temperature affects the sensitivity only slightly. The low NO sensitivity of the frit-containing electrodes was attributed to a blocking effect at the triple-phase boundaries that inhibits the oxygen transport through the sensor.