Conventional approaches to chemical sensors have
traditionally made use of a “lock-and-key” design,
wherein a specific receptor is synthesized in order to
strongly and highly selectively bind the analyte of
interest.1-6 A related approach involves exploiting a
general physicochemical effect selectively toward a
single analyte, such as the use of the ionic effect in
the construction of a pH electrode. In the first
approach, selectivity is achieved through recognition
of the analyte at the receptor site, and in the second,
selectivity is achieved through the transduction
process in which the method of detection dictates
which species are sensed. Such approaches are appropriate
when a specific target compound is to be
identified in the presence of controlled backgrounds
and interferences. However, this type of approach
requires the synthesis of a separate, highly selective
sensor for each analyte to be detected. In addition,
this type of approach is not particularly useful for
analyzing, classifying, or assigning human value
judgments to the composition of complex vapor
mixtures such as perfumes, beers, foods, mixtures of
solvents, etc.

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Cross-reactive chemical sensor arrays.

Materials and processes for the effective capture and immobilization of radioiodine: A review

A microelectronic programmable structure and methods of forming and programming the structure are disclosed. The programmable structure generally include an ion conductor and a plurality of electrodes. Electrical properties of the structure may be altered by applying a bias across the electrodes, and thus information may be stored using the structure.

Microelectronic programmable device and methods of forming and programming the same

Programmable microelectronic devices and methods of forming and programming same

Review: highlights in recent applications of electronic tongues in food analysis.

Chalcogenide glass chemical sensors: Research and analytical applications

Conductivity and silver diffusion measured using a 110m Ag tracer have been investigated in AgGeS and AgGeSbSe glasses with silver concentration ranging from 0.008 to 25 at.% Ag. It has been found that the room-temperature conductivity in both systems increases by 9.0–9.5 orders of magnitude with increasing silver content, and its activation energy decreases from ∼ 1 to 0.4 eV. Accordingly, the silver tracer diffusion coefficient at 298 K increases by 5.0–5.5 orders of magnitude with similar decrease of the diffusion activation energy. A comparison of the conductivity and silver diffusion results clearly shows that the ionic transport is predominant in the two systems, even at lowest Ag concentrations. The Haven ratio, H R , decreases with increasing silver content: extremely diluted glasses (0.008–0.1 at.% Ag) exhibit H R ≈ 1; Ag-rich vitreous alloys are characterized by H R = 0.2–0.4. The composition dependencies of the ionic conductivity, σ i , and silver tracer diffusion coefficient, D Ag , exhibit two drastically different transport regimes at low (≤ 2–5 at.%) and high (> 10 at.%) silver concentrations. A power-law composition dependence of σ i and D Ag over 2.5 orders of magnitude in the Ag concentration and 3.5–5.0 orders of magnitude in the ionic conductivity (2–3 orders of magnitude in the diffusion coefficient) is observed at low silver concentrations. This transport regime is attributed to percolation in the critical region just above the percolation threshold. Recent theoretical considerations (the dynamic structure model and statistical (occupation) effects on percolative ionic conduction) are also in good agreement with experimental findings. After essential structural transformations of the glass network on the short- and intermediate-range scales at higher silver content (> 10 at.%), the ionic transport is not caused any more by percolation, i.e., it becomes network-dependent with a strongly correlated motion of the Ag + ions.

Percolation transition in Ag-doped germanium chalcogenide-based glasses: conductivity and silver diffusion results

Electrochemical parameters of sensor response of various chalcogenide glass sensor materials have been studied in solutions of heavy metal cations. The principle attention have been paid to non-specific sensor response characteristics including cross-sensitivity. The dependence between the cation sensitivity and selectivity of the sensor material and the nature of glass-former, especially chalcogen, sulphur or selenium, has been observed. The solid-state chalcogenide glass sensors were included, together with some conventional crystalline sensors into an array (a multisensor system). The array was trained in complex composition solutions, containing Cu 2+ , Pb 2+ , Cd 2+ , Zn 2+ , Cl −1 , F − and SO 4 2− in concentration typical for industrial waste. It was found that such an approach allows all the species in the mixed solutions to be to determined in spite of insufficient selectivity of some sensors. Also, it appeared possible to determine zinc and sulphate for which no selective sensors were present in the array.

Cross-sensitivity of chalcogenide glass sensors in solutions of heavy metal ions

COPPER ION-SELECTIVE CHALCOGENIDE GLASS ELECTRODES Analytical Characteristics and Sensing Mechanism

The present paper deals with some aspects of the analytical application of chemical sensors based on chalcogenide glasses, including measurements in natural and waste waters of different factories both in laboratory and in situ modes. Determination of copper(II), iron(III), chromium(VI), lead, cadmium, and mercury starting at microgram concentration level has been carried out. The results of analysis with chalcogenide glass chemical sensors show a good agreement with those of atomic absorption spectroscopy and other common methods.

E.A. Bychkov

Papers

Chalcogenide glass chemical sensors: Research and analytical applications

Percolation transition in Ag-doped germanium chalcogenide-based glasses: conductivity and silver diffusion results

Cross-sensitivity of chalcogenide glass sensors in solutions of heavy metal ions

COPPER ION-SELECTIVE CHALCOGENIDE GLASS ELECTRODES Analytical Characteristics and Sensing Mechanism

Analytical applications of chalcogenide glass chemical sensors in environmental monitoring and process control