Special issue  

This article introduces a new idea for a micro vacuum sensor. The measuring principle of the sensor is to measure the electrical conductivity of the residual gas in a vacuum chamber. The conductivity is measured between two electrodes that are only 300 nm apart. It has been shown that this type of sensor allows vacuum pressure measurement from atmospheric pressure to high vacuum at very low voltages.

This work presents a cost-effective optical-based sensor for pH monitoring of sample volumes less than 150 µL. As part of a bigger project to develop a stand-alone micro bioreactor system, measurements carried out with phenol red and DMEM reported a standard error of calibration in the physiologic pH range (6.5–7.5) of pH ±0.04. Compared to other accessible optical-based sensors this reported system is a good alternative regarding the overall costs of less than EUR 50.

A novel combustion airstream control concept has been developed based on in situ sensors for combustion temperature, residual oxygen concentration and residual un-combusted CO / HC components. The implementation of this control concept allows for a large reduction in toxic gas emissions by up to 80 % compared to hand-operated furnaces. A stable long-term CO / HC sensor for such an application is not available; thus, the long-term sensor signal stability of different CO / HC sensors is studied.

This article describes a chopper amplifier which has been specially developed for piezoelectric pressure sensors. It is shown that the amplifier provides good results for pressure measurement in injection moulds. A special feature of this work is the signal optimisation through the use of a Kalman filter.

This work describes the development of an optical measurement system for accurate quantification of methane (the main component of compressed natural gas) densities in gas flows based on broadband absorption of infrared light. Using various test environments we validate accuracy and precision of the quantification method. We show that our measurement system can serve as a tool for the development of modern, CO₂ saving internal combustion engines reducing environmental impact of transportation.

Because of their direct impact on patients, medical supply lines are under strict regulations and have to be monitored in terms of purity on a regular basis. State-of-the-art measurement solutions do not allow for continuous bedside monitoring. The aim of the presented work is to provide a compact multispecies monitoring system based on the latest quantum cascade laser technologies allowing for the continuous bedside monitoring of medical gases.

For optical measurement systems, camera noise is the dominant uncertainty factor when optically cooperative surfaces are measured in a stable environment. In this work it will be shown that the resulting spatial noise can be estimated by means of a noise model. The capability of this approach will be demonstrated for a fringe projection system. This provides a valuable tool for a statistical comparison of different evaluation strategies, which is shown for two different triangulation procedures.

In this work we present a cost- and energy-efficient measurement system for the spatial detection of gas phases in liquid fluids with a low permittivity value. We showed that we can simulate the system and its environment and use the calculated results to interpret the results originating from measurements of the electrical capacitance between different electrodes. The proposed system can be modified for, e.g., observation of fluid behaviour in cryogenic tanks for reigniteable space propulsion.

The challenges in the analysis of dynamic measurements significantly limit the use of existing calibration facilities and mathematical methodologies. Several international research projects have developed methodologies for the treatment of dynamic measurements at the NMI level. The transfer to industry, though, remains challenging. Therefore, this work provides a link from these activities to industrial end-users by means of the new versatile and comprehensive software package PyDynamic.

Carbon dioxide is a main greenhouse gas and a gas that well-represents air quality. Therefore, it is important to monitor the CO₂ concentration in air. Creating an affordable and reliable CO₂ sensor is the purpose of this paper. Using a mass-sensitive acoustic sensor (FBAR) we can detect increasing CO₂ concentration by a mass increase on the sensor surface. As humidity changes often interfere with these signals the selection of CO₂ over humidity changes is another topic addressed in this paper.

Fibre optic sensors are excellent tools for monitoring (with) high-voltage current collectors. They are easily integrated into the collector strip and specialized for detection of events like hits on the strip. The sensing system can be used in regular trains and make monitoring of the overhead contact line routine, which is done "along the way", helping not only to prevent accidents by small intruders, but also allowing the prediction of wear and is used to optimize service and repair cycles.

A method to generate broadband waveforms with low peak-to-peak amplitude based on distinct frequency domain profiles is presented, which includes random phase variation and numerical optimization. The peak-to-peak amplitude can be reduced by 71 % compared to zero-phase pulses with equal frequency domain characteristics. Used as excitation signals for impedance spectroscopy, the waveforms yield good results at significantly reduced measurement duration compared to established measurement methods.

Completeness checking of constructional steel structures with several hundred weld-on parts still represents a great challenge. By the use of 3-D scanners, it is possible to obtain sufficiently comprehensive information about the actual configuration (as-is state). By using an adapted algorithm for post-processing of the resulting point clouds, difference figures are superimposed over the respective 3-D model as the target state. The difference figures signal the missing parts.

Maritime study sites utilized as a physical experimental test bed for sensor data fusion, communication technology and data stream analysis tools can provide substantial frameworks for design and development of e-navigation technologies. Increasing safety by observation and monitoring of the maritime environment with new technologies meets forward-looking needs to facilitate situational awareness. The study highlights research potentials and foundations achieved by distributed optical sensors.

We have analyzed the requirements of a smart heating system and, in particular, the necessary sensors and their integration in a control system. The system comprises temperature and localization sensors as measuring elements and heating foils as actuators. The system components were studied in a demonstrator room, and the entire heterogeneous system has now been deployed in an apartment for further field studies during the heating season of 2016/2017.

An ultrasound process tomography system has been developed, which enables the imaging of the local filler distribution in plastic melts. The objects investigated were extruded rods made of polypropylene (PP) with radial filler gradients. During extrusion, sound velocity and attenuation of the plastic melt were determined and processed via a modified reconstruction algorithm according to Radon transform into 2-D sectional images.

A new wireless communication system (WCS) for sensor-actuator communication has been developed to facilitate energy and environmental monitoring on the shop floor of industrial production sites. Its wireless technology is presented in detail. The WCS is able to efficiently use the available spectrum together with the other wireless systems around. Measured results for the coexistence capability are shown.

An FEM model is used to improve the sensor design of a Tian–Calvet calorimeter. By modifying the basic part of the sensor (a sensor disc based on low temperature co-fired ceramics), the sensitivity was increased by a factor of 3. The model was validated and the sensors were calibrated. Indium and tin samples were measured. The melting temperatures show a deviation of 0.2 K while the enthalpy was measured with a precision better than 1 %. The values for tin deviate by less than 2 % from literature.

Measurement of electrical current is important for many scientific and industrial applications. Often shunt resistors are used. However, thermal effects due to self-heating and ambient temperature variation limit the achievable accuracy. In this work, a dynamic compensation method is presented which takes static and dynamic temperature drift effects into account. It significantly reduces the remaining measurement errors. The approach can also be used to improve existing measurement systems.