In this paper preparation method of nano-porous alumina based humidity sensors is presented. Investigation of relation between technological process parameters, sensor's porous layer structure and electric parameters is main aim of this study. Surface morphology was investigated by scanning electron microscopy. Impedance spectroscopy was used to identify electrical parameters of the sensor.
Results of impedance measurements of humidity sensors with epoxy resins containig quarternary ammonium salts are presented in this paper. The humidity sensitive membranes were prepared from polyethyleneimine (PEI). PEI was cross-linked using 1,4-butanediol diglycidyl ether (BDDGE) and glycidyl trimethyl ammonium chloride (GTMAC) was added as a humidity sensitive epoxy monomer.
The effect of humidity influence on characteristics of a ceramic sensor with a porous dielectric Al2O3 layer is presented. Influence of chosen electrolytic process parameters on electrical properties of the sensor is shown. The experimental data of two groups of sensors are interpreted using two, known from literature, electric equivalent circuits.
Construction and properties of electrocatalytic gas sensor based on samarium-doped ceria solid electrolyte are described. Electrocatalytic sensors form a new group of gas sensor, which employ kinetics of controlled chemical reaction. Measurements in mixtures of synthetic air and nitrogen dioxide are shown. Current-voltage response has unique shape, which depends on NO2 concentration. Influence of voltage sweep rate and temperature on sensor characteristics is reported. The constructed sensor can be used for nitrogen dioxide monitoring.
In the present paper, results of computer simulation of cyclic voltammetry applied to electrocatalytic solid state sensor are presented. The computer software developed by D.Gosser is based on explicit finite difference method. The software is devoted for the simulation of cyclic voltammetry experiments in liquid electrochemistry. However the software is based on general electrochemical rules and may be used for simulation of experiments in solid state electrochemistry. The electrocatalytic sensor does not have a reference electrode and therefore it is necessary to employ virtual reference electrode into the model of the sensor. Data obtained from simulation are similar to measurement one what confirms correctness of assumed sensing mechanism.
In the paper the amperometric properties of polymer humidity sensor based on polythyleneimine are presented. Usually properties of this sensor are examined by means of impedance spectroscopy. The new approach is proposed. It is shown that the current flow in the investigated sensor is a result of the electrode reaction at the anode. The quasi-static diffusion current is a linear function (in the log-lin scale) of relative humidity, so this sensor can be used as an amperometric. An equivalent circuit, containing the elements representing diffusion effect, has been proposed. The shape of impedance plots show diffusion related process.
The results of impedance measurements of thin film polymer humidity sensors are presented in this paper. The sensors were made of chemically modified polyethyleneimine, spread on alumina substrate with comb type gold electrodes. Electrical properties of the sensors are strongly dependent on relative humidity (RH). The influence of the selected cross-linking agents on the properties, measuring range, and technology of preparation of the sensors is discussed.
In the paper the results of temperature investigations of polymer humidity sensor based on polyethyleneimine is presented. Sensor was prepared by chemical modification of polyethyleneimine and vacuum sputtering of gold electrodes on thick polymer film. The high thickness of the film limit the dynamic properties of the sensor. Electrical properties of the sensor were examined by impedance spectroscopy. The results allow structure optimization and improvement of dynamic properties of the sensor.
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