We present the development of a simple and fast method for restoring exhaust graphene-based chemi-resistors used for NO2 detection. Exposing the devices repeatedly to gases or to air for more than two days, an overall worsening of the sensing signal is observed. Starting from this hypothesis and from the observation that nitrogen dioxide is soluble in water, we performed a recovery method consisting in the dipping of exhaust devices into ultrapure water at 100°C for 60 sec.

Electrochemically synthesized colloidal Au NPs with controlled dimension and composition were successfully deposited electrophoretically on CNT networked films. Au NP/CNT films were tested as active layers in resistive NO2 sensors, exhibiting a p-type response and a sensitivity depending on Au loading. The impact of the Au loading on gas sensing performance was investigated as a function of the working temperature, gas concentration and interfering gases.

An approach for detecting hazardous volatile organic compounds (VOCs) in ppb and sub-ppb concentrations is presented. Using metal oxide semiconductor (MOS) gas sensors in temperature cycled operation, VOCs in trace concentrations are successfully identified against a varying ethanol background of up to 2 ppm. For signal processing, linear discriminant analysis is applied to single sensor data and sensor fusion data. Integrated gas sensor systems using the same MOS sensors were characterized.

In this article, we propose detecting hydrogen (H2) traces at room temperature with nanostructured PdPt/Al2O3 catalysts. We measure the temperature rise during the exothermic oxidation of H2 by the catalyst. An appropriate formulation of about 1 mg of PdPt/Al2O3 leads to reversible thermal responses of 3°C in only 5 s. We show that this active material is a promising candidate for autonomous and reversible passive transducers for H2 sensors working at room temperature in explosive atmospheres.

Deflectometric measurements of specular surfaces when performed with two reference planes lead to both data for surface points and surface normals. The deviations in the surface points are usually several orders of magnitude larger than those for the surface normals. In this paper we propose a method to fuse these data to increase the accuracy of the surface points. The results show that the accuracy can be increased by more than an order of magnitude.

A time-monitoring oxygen sensor based on a diffusion-controlled oxygen reaction of the indicator system methylene blue (MB)/leuco methylene blue (LMB) and riboflavin was embedded in a water-loaded poly(vinyl alcohol) (PVA) matrix. It can be used in packaging, sensors, and biotechnology applications. Since the oxygen diffusion coefficient in the PVA matrix strongly depends on temperature and humidity, two different approaches were developed within this work to compensate for these two effects.