Work function characterization of electroactive materials using an E MOSFET

Materials with redox properties have been widely used in sensing applications. Understanding the redox properties of these materials is an important issue. In order to investigate the redox properties, there are several methods, such as using the Kelvin probe and a conductivity sensor, or using other well-known electrochemical techniques. In this paper, we introduce another possibility to characterize redox materials by investigating their work function using an electrolyte metal-oxide semiconductor field effect transistor (/sup E/MOSFET) device, in which the studied redox material is applied as gate electrode. In the /sup E/MOSFET, the conductivity of the channel is modulated by the work function of the studied material. The change in the work function of a redox material due to electrically and chemically induced processes will be shown by an example of the /sup E/MOSFET having a potassium ferric ferrocyanide gate

Catalytic hydrogen peroxide decomposition La_1-xSr_xCoO_3-δ perovskite oxides

Lanthanide perovskite oxides are mentioned as material for hydrogen peroxide sensor because they can catalytically decompose hydrogen peroxide in an aqueous medium. The catalytic properties of these perovskite oxides to hydrogen peroxide are suggested due to their oxygen vacancies influenced by the oxide non-stoichiometry. In this paper, we investigate the catalytic hydrogen peroxide decomposition of a La1-xSrxCoO3-δ thin film with x = 0.7 for sensing application. The oxygen vacancy concentration in the oxide is estimated via the work function measurement using an electrolyte metal oxide semiconductor field effect transistor (EMOSFET) with a platinum remote gate. The experimental results show the catalytic properties of this oxide to hydrogen peroxide increases with increasing its non-stoichiometry, x

Electroactive gate materials for a hydrogen peroxide sensitive E-MOSFET

Describes the detection principle of a hydrogen peroxide sensor based on the electrolyte metal oxide semiconductor field effect transistor (EMOSFET) and possibilities of using different types of redox materials as the gate material for the sensor with respect to the sensitivity and detection limit. After discussing the fundamentals of hydrogen peroxide detection and a short description of the EMOSFET characteristics in terms of its threshold voltage, the basic measuring principle of hydrogen peroxide using the EMOSFET is shown. The EMOSFET with electro-active gate materials such as iridium oxide, potassium ferric ferrocyanide, and Os-polyvinylpyridine containing peroxidase, have been studied. These different materials are compared with each other with respect to their sensitivity, detection limit, and stability. The sensitivity of the sensors is improved by applying an external current between the gate and the solutio

Sensing properties of perovskite oxide La0.5SR0.5Co0-3-d obtained by using pulsed laser deposition

La1−xSrxCoO3−δ belongs to the group of perovskite oxides of the ABO3 structure, with a trivalent rare earth in the A position (La) and a trivalent metal ion in the B position (Co). Doping with divalent Sr-ions at the trivalent La-positions creates oxygen vacancies which give the oxide catalytic properties to H2O2. However, the conventional techniques which are used to prepare this oxide such as chemical methods are not suitable for making a thin film. In this paper, a thin layer of La1−xSrxCoO3−δ (x=0.5) perovskite oxide is deposited on a Pt electrode by using the pulsed laser deposition (PLD) technique. The catalytic properties of this perovskite oxide to hydrogen peroxide due to the presence of the oxygen vacancies will be discussed. The results show the possibility to use this perovskite oxide as a sensing material for potentiometric hydrogen peroxide sensors

Hydrogen peroxide detection with improved selectivity and sensitivity using constant-current potentiometry

In this paper, a potentiometric H2O2 sensor based on a FET structure is presented. The sensor has a redox active gate contact such as Os-polyvinylpyridine (Os-PVP) containing the enzyme horseradish peroxidase (HRP) which has a high sensitivity to H2O2. The basic principle of the sensor is to measure hydrogen peroxide concentration by means of measuring the change in the work function of the electroactive gate of the FET due to its redox reaction with H2O2. A constant current potentiometric mode is used to improve the sensitivity of the sensor. To avoid the influence of ascorbic acid on the sensor, an additional layer of Nafion is mounted on top of the electroactive gate. The influence of the Nafion concentration on the characteristics of the sensor (sensitivity and selectivity) has also been investigated