This study aims at the development of high-performance and cost-efficient gas sensors for sensitive detection of three specific hazardous gases, i.e., formaldehyde, naphthalene, and benzene, commonly present in indoor environments in concentrations of health concern. We used silicon carbide field effect transistors to investigate the sensor performance and characteristics under different levels of relative humidity up to 60%, demonstrating excellent detection limits in the sub-ppb range.

Microcrystalline cellulose, microcrystalline nitrite powders of common formulae MNO2, (M = Na, K) and two-component materials (cellulose + nitrite) have been prepared and characterized by means of optical microscopy and luminescence spectroscopy.The method of determining the nitrite compound traces via their sorption by cellulose using luminescent properties of the NO2- molecular ion has been developed and the low limit of NaNO2 determination in water solution was evaluated as 0.035 mg/l.

A new packaging method to mount a membrane-based thermal flow sensor, flush with the surface, is presented. Therefore, a specific design for the housing is shown that is also adaptable to other conditions. It has been experimentally shown that it is important to mount the sensor flush with the surface. If not, vortices can occur (depending on velocity and the fluid properties) or the reduction of the channel cross section plus a decrease in sensitivity have to be taken into account.

All-solid-state reference electrodes were developed based on particles of graphite/silver/silver chloride synthesized by electroless deposition of metallic silver and silver chloride on graphite powder. These electrodes were not sensitive to abrasion, redox species, pH and high-pressure saturated steam, and were applied successfully in potentiometric cells to measure pH and potassium ions in a complex matrix by direct potentiometry and L-ascorbic acid by potentiometric titration.

A research activity in the context of ambient assisted-living and Internet of Things applications is presented. A new assistance system with an integrated, multi-sensor, low-cost, autonomous, smart spoon device, denoted as Lab-on-Spoon, has been conceived. The goal is to provide assistance for unskilled or challenged consumers by sensory context in ingredients and cooking results. Successful liquid ingredient recognition and quality assessment, i.e., rotting and contamination, was achieved.

The current contribution reports on the substrate influence in multilayer metal-oxide chemical sensors. Measurements of the impedance are used to discuss the sensor performance with quartz substrates, (laboratory) glass substrates and substrates covered by silicon-dioxide insulating layers. Numerical experiments based on previous measurement results show that inexpensive glass substrates contribute up to 97% to the overall sensor responses.

In this paper we present a systematic method to determine sets of close-to-optimal sensor calibration points for a polynomial approximation.For each set of calibration points a polynomial is used to fit the nonlinear sensor response to the calibration reference. The polynomial parameters are calculated using ordinary least square fit. In an experiment, barometric MEMS pressure sensors are calibrated using the proposed calibration method at several temperatures and pressures.

We tested two types of home-made sensing elements – four coupled silicon micro-levers and a multilayer graphene membrane – which have the potential to further enhance the sensitivity of laser photoacoustic spectroscopy. Graphene sheets possess outstanding electromechanical properties and demonstrate impressive sensitivity as mass detectors. Their mechanical properties make them suitable for use as micro-/nano-levers or membranes, which could function as extremely sensitive pressure sensors.

The performance of a low-cost partially integrated cantilever-based airborne nanoparticle (NP) detector (CANTOR-1) is evaluated in terms of its real-time measurement and robustness. The device is used for direct reading of exposure to airborne carbon engineered nanoparticles (ENPs) in indoor workplaces.

We report on the high-temperature piezoresistivity of carbon-containing silicon oxycarbide nanocomposites (C/SiOC). The piezoresistive behavior of the C/SiOC nanocomposites relies on the presence of dispersed nanocrystalline graphite and non-crystalline carbon domains. In comparison to highly ordered carbon, C/SiOC exhibits strongly enhanced sensitivities, even at high temperatures. Thus, k values of ca. 80 at the highest temperature reading, 1200°C, reveal that C/SiOC is a primary candidate.

This paper represents a theoretical modelling of the dynamics of surface acoustic waves with horizontal polarization propagating in the layered system of viscoelastic film covered with a bulk liquid. Theoretically predicted "missing mass" effect is important for the correct interpretation of the experimental data. The results of the theory may be used for the quantitative analysis of SAW-based sensors operated in liquid environments and biosensors.

A concept to measure in situ sulfidation of silica pellet catalysts loaded with nickel is evaluated. During sulfidation between 100 and 400°C nickel sulfides form. The electrical impedance of the pellets was recorded in situ. At first, the particles are highly insulating but during sulfidation their conductivity increases by decades. Since nickel sulfides are less conductive than nickel, the strong conductivity increase may be due to conducting percolation paths that form during sulfidation.

Measurement tasks of modern micro- and nanometrology with decreasing structure sizes and rising aspect ratios require nanometre-resolving 3-D capable sensors. A 3-D probing system based on electrical interaction is presented which is operated on a nanopositioning system NMM-1. New 3-D measurement procedures for the probing system as well as for micrometrology measurement tasks in general are shown.

In this paper we show that for radially symmetric piezoceramic disks non-zero sensitivity of the electrical impedance to the whole material parameter set can be computed using a system of 3-ring electrodes and non-uniform electrical excitation. We formulate an optimisation problem for increasing this sensitivity. However, the system displays multiple optimal configurations for the radii of said ring electrodes and we have shown some results from optimising such configurations using simulations.

A novel sensor principle for determining binary fluid mixtures of known components is presented. A bluff body is placed in the fluid channel, causing the formation of a stationary pair of vortices behind the body. The length of the vortex pair depends on the mixture’s viscosity and thus its composition. It is measured by placing a microheater in the vortex area and making use of forced convection which changes with the size of the vortices.