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We pursue a promising novel self-adaptive spiking neural analog-to-digital data conversion (SN-ADC) design that uses spike time to carry information. Thus, SN-ADC can be effectively translated to aggressive new technologies to implement reliable advanced sensory electronic systems. The SN-ADC supports self-x (self-calibration, self-optimization, and self-healing) and machine learning required for the internet of things and Industry 4.0 and is based on a self-adaptive CMOS memristor.

Digitalization is gaining momentum. Therefore sensory functions have to be integrated into rotating systems and harsh environments, requiring a reliable energy supply. To support product designers an estimation model for an autonomous sensor node is derived from basic electrical relations and simplified to make it usable for designers. Subsequently the model is used to define operation strategies influencing the energy consumption, which are tested in different ambient conditions.

We motivate how integrated waveguides (WGs) can be part of an on-chip non-dispersive infrared sensor system for environmental sensing. We report the hurdles in maintaining WG quality when integrating emitter and detector structures on the same chip. Thus, we introduce the concept of how to determine the intrinsic loss and a process scheme to protect WG structures from damage caused during fabrication. This could pave the way to systems for environmental sensing with a minimal footprint.

Imaging of greenhouse gases is of great interest due to global warming. A spectroscopic method, using an active illumination of the scene, is presented. It allows for imaging and concentration measurements of much smaller gas plumes and leaks than current state-of-the-art gas cameras (optical gas imaging cameras). A real-time camera is realized and validated using known methane concentrations.

Tracking individual parts in manufacturing processes helps to lower production cost by assigning a full record of production steps to each part, and therefore enabling targeted quality control. A novel approach is presented, which shows that the printing quality can be monitored using images of the printed result only. Analysing data from long-term tests shows which characteristics of the part marking are suitable to be used as indicators for maintenance needs.

We describe the development and characterization of a three-dimensional (3D) magnetic coil system that is able to produce magnetic flux densities of up to 2 mT in an arbitrary field direction. The coil system can be used to calibrate 3D magnetometers efficiently, and the measurements are traceable to national SI units.

This work deals with process monitoring. In particular, the process of used-sand regeneration is monitored with the aid of impedance spectroscopy and can be controlled in the future with the measurement data obtained in this way. This results in the following aspects: a consistently high quality of the process material is realized by a controlled process. At the same time, energy consumption is minimized. The result is a process that is both more resource-efficient and more economical.

High-temperature stable piezoelectric resonators are coated with oxide electrodes. The impact of the oxide electrode conductivity on the mass sensitivity and on the resonance frequency of the device is described by electrical and mechanical models, which are used to analyse the experimental data. Furthermore, the impact of an increasing oxide electrode conductivity is discussed with respect to the application of oxide electrodes and for gas sensing.

Modern production concepts generate a demand for reliable, energy-efficient, fast, and secure wireless communication solutions. Therefore, the current consumption should not increase substantially due to additional security operations. This paper shows a principle current measurement method that is exemplary of a transceiver for IO-Link Wireless protocol. The results show that the current consumption only increases slightly with acceptable measurement uncertainty.

In this paper, a near-infrared LED system is proposed for autonomous vehicles to distinguish between weather-induced road surface conditions (dry, wet, snow, ice, water). For the LED spectra, the influence of the LED bandwidth is investigated. To assess the performance of the system for a long detection range, experiments with large incident angles are conducted. The feasibility of this system is proved via a laboratory experiment with three near-infrared LEDs and a camera.

Gas analysis by absorption spectroscopy helps to optimize combustion processes in engines. Optical distance sensors are non-contact and offer high accuracy and precision. Both sensor applications benefit from light sources with a rapidly swept wavelength to monitor dynamic processes. In our paper, we precisely characterize the dynamic wavelength sweep of a rapidly pulsed VCSEL (vertical cavity surface emitting laser), a tiny semiconductor laser well suited for optical sensing.

A fundamental problem of machine learning (ML) is measurement uncertainty and the influence on ML results. Measurement uncertainty, which is critical in hazardous gas detection, is directly addressed in this paper. A previously published toolbox is extended for regression. One of the benefits of this approach is obtaining a better understanding of where the overall system should be improved. This can be achieved by either improving the trained ML model or using a sensor with higher precision.

Acceptance and reverification testing for industrial CT systems is described in different standards. The characterisation and testing of CT system performance are often achieved with test artefacts containing spheres. This simulative study characterises the influence of different geometrical error sources – or geometrical misalignments – on these sphere measurements.

The measurement principle shows how to measure calibration torque moment shunts in a 5 MN m torque standard machine using an interferometer and hinge flexure stiffness. The analysis of the measurement uncertainty influences shows that the measurement uncertainty of transversal force measurement ranges from 0.61 % to 3.04 % and stays constant at 1.7 % for torque measurement. A FE validation was performed. The measurement uncertainty of the calibration torque moment sank from 0.106 % to 0.100 %.

We present a photoacoustic sensor enabling fast, inexpensive, and highly sensitive methane detection in environmental monitoring applications. Six different T-cell designs were both theoretically and experimentally investigated. The aim was to understand the photoacoustic signal generation and resonances in relation to the different cell geometries, and determine the long-term stability and the detection limits for methane. These were below the methane background concentration in air of 1.8 ppm.

Industrial X-ray computed tomography is a holistic measurement technique for dimensional metrology. However, the relatively long measurement time is a hindrance to its application. A possibility to reduce measurement times, the continuous scan mode, is characterized in this work. The question is how much the time reduction impacts the accuracy of the dimensional measurements. The core result of the paper is an estimate of the effect along with experimental proof that this estimate is reasonable.

Diabetes Mellitus (DM) is one of the very common diseases with no viable cure. However, it can be controlled by regulating the daily sugar intake. Diabetic patients need to prick their fingers a few times a day for monitoring sugar levels. To find an alternative, researchers have been working for decades on the development of a true non-invasive technique. In this effort, we developed a cost-effective non-invasive technique for measuring blood sugar levels using capacitance spectroscopy.

The paper describes a novel energy-harvesting system based on the Wiegand effect. The energy provided by this harvester is analysed and correlated to the required energy to start a microcontroller and perform some wireless data transfer. The energy consumption is analysed in detail down to component level. A demonstrator including an additional sensor and wireless transmitter was built, proving that sufficient energy is provided by the harvester for the wireless transfer of the sensor data.

A high-temperature gauge to simultaneously determine electrical conductivity, the Hall constant, and the Seebeck coefficient was developed. Screen-printed heating structures on a ceramic sample holder generate temperatures up to 800 °C. Heating structures were designed using FEM simulations. The temperature distribution was validated by thermal imaging. Measurements on constantan (reference material) and boron-doped silicon wafer confirm the functionality of the gauge up to 800 °C.

The paper presents a specimen and evaluation method for interface structural resolution testing of X-ray computed tomography systems based on CT simulations. The geometry is oriented to the norms of image quality investigation. The evaluation is based on profile lines of the cross-sectional images that pass through the boreholes. All statements on resolution refer to the entire measurement chain and, thus, in addition to the reconstruction algorithm also to the surface determination method used.

Differential scanning calorimetry (DSC) is a widely used tool to analyze thermal material properties. This study focuses on the advancement of a miniaturized DSC chip as an alternative to conventional devices. The first development steps for the integration of a weighing system are shown, starting with model considerations and simulation-based optimization to initial measurements. Three different measurement methods are investigated and show promising results.

In this work, we have developed and validated a semi-automatic approach that greatly reduces the amount of interaction and effort needed for analyzing samples via gas chromatography–mass spectrometry. Further, unlike many other approaches, our developed tool is accessible to the novice and does not require any programming experience. Using whisky as an example substance, we show how the analysis method compares to conventional software, and we validate our approach against that.

Mathematical models are often required to process sensor data in a digital twin platform. The translation of models to an updateable format enables predicting hidden states of the physical object, which are not directly measurable. The linking of different models is demonstrated by data from field tests on fruit transportation in refrigerated containers. We programmed a streaming platform that enables easy integration of such updatable models with only a few milliseconds of processing overhead.

In this work, a novel approach to deduce the release of the natural radioactive noble gas ²²²Rn from solid sources containing the isotope ²²⁶Ra is presented. Therein, supporting radioactivity measurements of the source are used in conjunction with a theoretical description of the dynamics. For radiation protection and environmental research, reliable and comparable ²²²Rn measurements, and therefore reference atmospheres of ²²²Rn, are needed. This work improves their realization.

Infrared spectroscopy is great for determining the composition of liquids. Combined with attenuated total reflection (ATR), one can just put the sample on the sensitive surface. We made a compact device with a diamond-coated silicon ATR crystal to protect the surface against aggressive fluids. Silicon crystal, light source and detector are hermetically sealed in a housing. Our tests show that the diamond coating enhanced the sensitivity compared to uncoated ATR elements as predicted by theory.

In this work, we investigated whether artificial feedback in the form of vibration has an effect on the accuracy and precision of eye tracking glasses. The results enabled the development of design proposals for vibrotactile feedback in gaze-based control systems for robotic arms.

In order to save time and avoid overheating of food during unfreezing, the study of ice content can be very useful. The aim of the research is to design an ultrasound-based sensor system that is able to comment on the content of ice in the sample food product. Some sample food products are tested, and the observations and challenges concerning the same are mentioned in the research paper.

We have managed to reduce the measuring time of previously common hydrogel-based sensors from a few minutes to a few seconds. For this, the arrangement of the hydrogel in the sensor was changed so that the volume of the hydrogel could be reduced. The biggest challenge, apart from generating a very thin pattern, was to firmly bond the hydrogel to a silicon surface. This was to ensure that the resulting forces of the bimorph effect can be absorbed.