When considering new sensory technologies one should look to nature for guidance. Indeed, living organisms have developed the ultimate chemical sensors. Many insects can detect chemical signals with perfect specificity and incredible sensitivity. Mammalian olfaction is based on an array of less discriminating sensors and a memorized response pattern to identify a unique odor. It is important to recognize that the extraordinary sensory performance of biological systems does not originate from a single element. In actuality, their performance is derived from a completely interactive system wherein the receptor is served by analyte delivery and removal mechanisms, selectivity is derived from receptors, and sensitivity is the result of analyte-triggered biochemical cascades. Clearly, optimal artificial sensory sys-

Conjugated polymer-based chemical sensors.

An analyte monitor includes a sensor, a sensor control unit, and a display unit. The sensor has, for example, a substrate, a recessed channel formed in the substrate, and conductive material disposed in the recessed channel to form a working electrode. The sensor control unit typically has a housing adapted for placement on skin and is adapted to receive a portion of an electrochemical sensor. The sensor control unit also includes two or more conductive contacts disposed on the housing and configured for coupling to two or more contact pads on the sensor. A transmitter is disposed in the housing and coupled to the plurality of conductive contacts for transmitting data obtained using the sensor. The display unit has a receiver for receiving data transmitted by the transmitter of the sensor control unit and a display coupled to the receiver for displaying an indication of a level of an analyte. The analyte monitor may also be part of a drug delivery system to alter the level of the analyte based on the data obtained using the sensor.

Analyte Monitoring Device And Methods Of Use

Carbon dioxide reduction is an essential component of many prospective technologies for the renewable synthesis of carbon-containing fuels. Known catalysts for this reaction generally suffer from low energetic efficiency, poor product selectivity, and rapid deactivation. We show that the reduction of thick Au oxide films results in the formation of Au nanoparticles (“oxide-derived Au”) that exhibit highly selective CO2 reduction to CO in water at overpotentials as low as 140 mV and retain their activity for at least 8 h. Under identical conditions, polycrystalline Au electrodes and several other nanostructured Au electrodes prepared via alternative methods require at least 200 mV of additional overpotential to attain comparable CO2 reduction activity and rapidly lose their activity. Electrokinetic studies indicate that the improved catalysis is linked to dramatically increased stabilization of the CO2•– intermediate on the surfaces of the oxide-derived Au electrodes.

Aqueous CO2 reduction at very low overpotential on oxide-derived Au nanoparticles.

Introduction. Principles. Theoretical Aspects of FIA Techniques. Components of An FIA Apparatus. Experimental Techniques and FIA Exercises. Review of the Flow--Injection Literature. Flow Injection Analysis Now and in the Future. List of FIA References. Appendix. Index.

Flow Injection Analysis

The gas sensors fabricated by using conducting polymers such as polyaniline (PAni), polypyrrole (PPy) and poly (3,4-ethylenedioxythiophene) (PEDOT) as the active layers have been reviewed. This review discusses the sensing mechanism and configurations of the sensors. The factors that affect the performances of the gas sensors are also addressed. The disadvantages of the sensors and a brief prospect in this research field are discussed at the end of the review.

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Gas Sensors Based on Conducting Polymers

Electrochemical study of gold electrodes with anodic oxide films—I. Formation and reduction behaviour of anodic oxides on gold

A detailed investigation of the acid doping behavior of polyaniline has led to a robust and reproducible procedure for controlled adjustment of the redox state of dry polyaniline films. The initial...

Acid Doping of Polyaniline: Spectroscopic and Electrochemical Studies

Solid state chemical sensors

Nanostructured composite materials of polyaniline (PANI) with gold clusters of different sizes and amounts have been produced. PANI films of the same thickness were grown electrochemically on platinum substrates. Then nucleation of gold clusters in the PANI film was initiated by chemical reduction of tetrabromoaurate ion in acidic solution. The spontaneous process of gold cluster formation was evaluated using UV-vis spectroscopy, scanning electron microscopy, and the Kelvin probe. It was found that the amount and size distribution of gold clusters vary with immersion time. The measured work function of the PANI/Au composite changes its magnitude according to the changes in composition of the materials. Despite the fact that the preparation method makes the gold cluster growth difficult to control in size and in distribution, it is of interest to applications for solid-state potentiometric sensors, batteries, supercapacitors, or catalysis since it modifies the electron affinity of the synthesized conducting polymer/gold composite.

Polyaniline-Gold Nanocomposite System

The reduction of chloroaurate and the incorporation of Au clusters in polyaniline, PANI, films have been investigated. The chloroaurate complex is generated at the electrode surface during Cl- doping of Au/PANI. FTIR and UV/vis data indicate that chloroaurate interacts with PANI and that its reduction to metallic Au occurs preferentially at the nitrogen linkages. The voltammetric and XPS results show that the uptake of both protons and anions is suppressed by the formation of Au clusters due to this interaction. The ability to reduce chloroaurate in PANI films is also demonstrated for Pt electrodes coated with PANI in solutions containing KAuCl4. The preliminary results indicate that Au cluster size distribution remains fairly constant regardless of the method used.

Jiří Janata

Papers

Electrochemical study of gold electrodes with anodic oxide films—I. Formation and reduction behaviour of anodic oxides on gold

Acid Doping of Polyaniline: Spectroscopic and Electrochemical Studies

Solid state chemical sensors

Polyaniline-Gold Nanocomposite System

Electrochemical Formation of Au Clusters in Polyaniline