Brian Jeffrey Seddon

Amperometric Ion Sensors Based on Laser Patterned Composite Polymer Membranes

Abstract A polymer membrane for the selective amperometric transfer and sensing of molecular ions has been designed and characterised. The membrane was formed from two polymer layers, a supporting film of polyethylene terephthalate on which an electrolyte film containing polyvinylchloride is cast. The polyester layer has a laser-etched pattern of circular micro-holes in one region. These hole structures are arranged in a rectangular geometry and measure 22 μm in diameter with separation distances of 105 μm and 120 μm. The polyvinylchloride underlayer is a composite system comprised of a 2-nitrophenyl octyl ether plasticising solution containing an electrolytic salt of tetrabutylammonium tetrakts-(4-chlorophenyl)borate. In this way, an array of micro-interfaces between an analyte solution and a PVC gel electrolyte is formed and used as a liquid|liquid interface for the amperometric monitoring of ion transfer reactions. The membrane was characterised in terms of the voltammetric response to choline transfer. The study includes an examination of the fabrication methodology, materials composition and membrane structure.

Electrochemical extraction of heavy metal ions assisted by cyclic thioether ligands

Abstract The ion transfer characteristics of a series of divalent heavy metal species have been studied at the polarised water|1,2-dichloroethane interface. Both direct and cyclic thioether assisted transfer mechanisms have been investigated by voltammetric measurements. Half-wave potentials and Gibbs energies for direct ion transfer processes follow the order, Pb2+

Excimer laser-induced electrochemical activity in carbon ink films

The effects on the microscopic and electrochemical properties of composite ink films after exposure to UV radiation from a 193 nm excimer laser source were investigated. The work considered two carbon ink types, a commercial screen ink material and a preparation consisting of micro-spherical glassy carbon with polystyrene. A scanning electron microscopy study of these ink film surfaces has concluded that laser treatments selectively etch the organic binding polymer from the composite surface thereby exposing sub-layers of carbon particulates. The photoablative processes by which the UV radiation interacts with materials not only remove the ink polymer, thereby increasing the surface area, but also chemically modify the carbon surface resulting in an increased rate of electron transfer. The cyclic voltammetric characteristics of potassium hexacyanoferrate(III) and ferrocene carboxylic acid at these modified ink films are analysed using the methodology proposed by Amatore et al. (J. Electroanal. Chem, 147 (1983) 39).

Micro-glassy carbon inks for thick-film electrodes

Reference LEPA-ARTICLE-1997-016View record in Web of Science Record created on 2005-11-07, modified on 2017-05-12

Dual-cylinder microelectrodes. Part 1.—Theoretical consideration of the steady-state current

The feedback diffusion current at a dual-cylinder microelectrode was modelled for the case of steady-state response using bilinear transformation of coordinates in the diffusion space. The model outlined assumes that lines of mass flux and concentration are represented by orthogonal circular functions. An expression for the diffusion current is presented which draws attention to the importance of device geometry, anode and cathode radii, and interelectrode distance. The theoretical treatment shows that significant current amplification can only be expected for a dual-cylinder device over a single-cylinder microelectrode when interelectrode gap reduces to the submicrometer dimension. The practical limitations of the diffusion current equation are discussed in the context of general diffusion theory for feedback devices.

Rotograved Carbon Electrodes for Amperometric Cadmium and Lead Determination

Reference LEPA-ARTICLE-1999-023doi:10.1016/S0022-0728(99)00226-0View record in Web of Science Record created on 2005-11-07, modified on 2017-05-12