The temperature dependence of the resonance frequency of quartz resonators can be used for thermal infrared sensors. The quartz chips must be very thin to obtain a good sensor signal. This work describes how to manufacture and package sensors with 5 µm thin chips. Different sensor layouts are ion beam etched; they influence the vibration of the resonators, which is shown by impedance measurements. The temperature coefficient of the resonance frequency is determined to be around 90 ppm K^-1.

This article describes a small prototype sensor designed to sense carbon dioxide (CO₂) levels for indoor air quality monitoring. The device uses a photoacoustic detector fabricated using a wafer-bonding process. This allows for high-volume production of the sensors. The prototype presented is small in size and can detect CO₂ levels as low as 81 ppm with a response time of 53 s. Our results show suitability for application in indoor air quality control systems.

An airborne measurement system with an onboard computer for data processing and recording that does not require constant radio communication for inspection and maintenance is presented. It detects, locates, and quantifies methane leaks using a gimbal-mounted sensor. A model that correlates wind speed with drone attitude is presented and compared to measurements made with an anemometer. The quantification of methane emissions was evaluated in a laboratory setup and at an open-area test site.

A human activity recognition (HAR) system carried by masseurs for controlling a therapy table via different movements of legs or hip was studied. This work starts with a survey on HAR systems using the sensor position "trouser pockets". Afterwards, in the experiments, the impacts of different parameters and configurations on the classification accuracy is examined to get a thorough understanding of the classification process.

The purpose of our study is to demonstrate the detection of hydrogen in a mixture with natural gas by means of ultrasound measurements. In the coming years, hydrogen will be mixed with natural gas and distributed in the available gas pipeline network; therefore, monitoring the hydrogen content in real time becomes a necessity. We show the implementation of miniature ultrasound transducers (CMUTs) for this purpose by measuring the speed of sound of the mixture.

A very small, anharmonic but periodic signal is separated from a noise background that is orders of magnitude larger than the pure signal. The approach consists of a sequence of filters and transformations and is demonstrated on an interferometric measurement of the high-temperature chemical expansion of a thin film, containing heat haze, thermal length drift, and parasitic vibrations. The displacement is 38 % larger and the uncertainty 35 % lower than when evaluated with previous approaches.

The paper presents a concept for fabricating a biosensor with enhanced long-term stability and offers new options for designing photonics-based microsystems aimed at analysing biosamples. In order to couple the light used to probe samples, a grating is illuminated from the back side, thus realizing an inverted grating configuration. This offers the possibility of designing microsystems that can be operated more conveniently and with a much extended lifetime.

This study introduces four sensors utilizing multiple fiber Bragg grating constellations embedded in a silicon dioxide single-mode fiber for simultaneous pressure, temperature, and bending curvature measurement. By varying grating constellation, dimensions, and materials, researchers optimized sensor performance. Results indicate that the optimal configuration involves a high cladding-to-coating ratio, less-stiff coating, and the combination of two gratings to form a Fabry–Pérot interferometer.

High levels of nitrate can cause negative effects on aquatic plants, fishes and human health. A simple, reusable and sensitive electrochemical sensor based on silver nanoparticles with a modified gold screen-printed electrode has been developed for the detection of nitrate in water.  The sensor exhibited good performances such as high sensitivity, reproducibility, repeatability and selectivity. The proposed approach was successfully used to determine nitrate in freshwater.

3D thermograms are a good alternative when a single traditional 2D thermal image does not reveal enough information to analyze a complex object. However, the 3D thermography field is still under exploration. This paper shows a comparison of a thermography system operated with two different 3D sensors. The results indicate that the depth sensor with more accurate measurements captures the object geometry better, and therefore the interpretation of the 3D thermograms is improved.