Michael Kroupa

Sensorial characteristics of conductive polymers

This paper deals with the investigation of intrinsic conductive polymer PEDOT-PSS and development of vapour sensors. These sensors are based on the specific vapours influence on the electrical parameters. The designed sensors consist of glazed ceramic substrate with gold interdigital electrodes covered by a thin layer of conductive polymer. The insulation gap between electrodes was investigated in the range of 50 – 200 µm in order to achieve the maximal sensitivity. Temperature and humidity dependences of PEDOT-PSS layers were measured in the climatic chamber, influence of particular vapours on electrical parameters were measured in the special gas chamber. Except for temperature, humidity and vapour sensitivity, long term stability was also studied.

Potentiostat solution for electrochemical amperometric gas sensor

This study deals with intrinsic parameters of electrochemical amperometric gas sensors with a solid-state polymeric electrolyte. An experimental electrochemical NO2 sensor based on organic ionic liquid was developed. Subsequently, electrical and mechanical parameters of the sensor were studied and an appropriate potentiostat circuit was designed for the evaluation of a sensor response to the particular gas. The description of the sensor, measurement procedures and results of experiments will be presented in more detail.

Organic humidity sensors - improvement of climatic resistance

This paper deals with research and development of humidity sensors based on organic sensitive materials. Organic sensors consist of the substrate with the electrode system covered by the thin sensitive organic layer. The base substrate consists of 99 % alumina. Golden electrodes have the interdigital form with the isolation gap 25 µm wide and finger 25 µm wide. Organic material is applied on the substrate by the spin coating. The main work was focused on the enviromental stabilization of organic sensor layers.

Stabilization of organic materials for sensors

This paper deals with research and development of organic humidity sensors. These sensors are based on organic sensitive layer which is applied on the substrate with interdigital electrodes. The main work is focused on the stabilization of organic sensor layers. The stabilisation of mechanical and electrical parameters is based on passive polymer matrix where the active organic sensitive material is fixed. The sensor sensitivity, impedance-humidity characteristics and long term stability of electrical parameters were measured and discussed in detail.

Design of a singlet oxygen generator based on LED emitters

This article deals with the research of singlet oxygen generation using phthalocyanine photosensitizer. Singlet oxygen is extraordinary reactive and can be used in many applications such as photodynamic therapy, disinfection or chemical synthesis. For singlet oxygen generation, the photosensitized method in a new developed generator based on LED emitters was used. The amount of singlet oxygen generated by LED emitters was compared with laser excitation. The principle of measurement, design of a singlet oxygen generator and control unit are discussed in more detail.

Sensors elements for micro-calorimetric measurements

This study deals with the research of new platinum resistance thermometers for micro-calorimetric measurements. The aim of this study is to design a suitable topology of platinum thermometers for a potential micro-calorimetric sensor based on organic materials. The suitable topology of a pair of thermometers was designed for the future micro-calorimetric sensors. Further, various evaluation methods were examined for reading the signal data from the appropriate arrangement of the pair of platinum thermometers. A thorough description of platinum thermometers, measuring procedures, evaluation methods and results of experiments will be presented.

Electrical characterization of PEDOT:PSS

The purpose of this paper is to summarize the results of electrical measurements carried out on different types of metal-semiconductor heterojunctions based on PEDOT:PSS in order to examine the possibilities of either ohmic contacts or rectifying Schottky junctions formation. The character of created junctions was evaluated according to their I–V characteristics. Unusual electrical behaviour was observed in the case of heterojunctions formed on gold, platinum and carbon with a region of negative differential resistance. The phenomenon supposed to be partly responsible for such nonlinearity is existence of thin barrier layer on the surface of dried PEDOT:PSS, through which charge carriers could pass by tunneling. However, deeper investigation will be necessary to enlighten all the circumstances leading to origin of this behaviour.

Electrical properties of PEDOT

This article deals with electric properties of metal-organic semiconductor junction. Different types of substrates were used for measurement of electrical parameters of poly(3,4-ethylenedioxythiophene) (PEDOT). On these substrates, the thick layer of PEDOT was created. Current-voltage characteristics were measured to find-out if Schottky barrier on the metal-emiconductor junction is created. Then frequency characteristics were measured to obtain an equivalent circuit of this system.

Carbon Nanotube dispersion preparation and deposition of thin layers for gas sensors

This article deals with preparation of carbon nanotubes thin layers which are used as an active element in gas sensors. These layers are made by additive deposition techniques. The homogenous and stable dispersion of Carbon Nanotubes (CNT) is a base for thin layers creation. The principle preparation of the dispersion is described in this article as well. The final liquid material is deposited by several different deposition techniques on alumina substrate with golden interdigital electrodes. The layers were compared to each other and evaluated by measuring electric properties. The substrate with a CNT active layer is prepared for subsequent hazardous gases testing.

Identification of fast-moving objects in frequency band 2.45 GHz

This paper describes system design for the identification of the fast-moving objects based on RFID frequency band 2,45 GHz. Reasons for using this frequency band 2,45 GHz are here summarized. Literature survey of available systems using this frequency band was done. Active tag and reader for identification fast-moving objects have been designed. The antenna and power supply design for active tags are involved. Experience finding can be utilized in the field of transportation for identification of vehicles, goods and other objects.