Electrodeposition sensors

Viga A, Radoib A, Mumoz-Berbel X, Gyemantc G, Marty JL (2009) Impedimetric aflatoxin Ml immunosensor based on colloidal gold and silver electrodeposition. Sensor Actuator B 138 214-220... 

Simultaneous and continuous measurements of extracellular pH, potassium K+, and lactate in an ischemic heart were carried out to study lactic acid production, intracellular acidification, and cellular K+ loss and their quantitative relationships [6, 7], The pH sensor was fabricated on a flexible kapton substrate and the pH sensitive iridium oxide layer was electrodeposited on a planar platinum electrode. Antimony-based pH electrodes have also been used for the measurement of myocardial pH in addition to their application in esophageal acid reflux detection. 

S.A. Marzouk, Improved electrodeposited iridium oxide pH sensor fabricated on etched titanium substrates. Anal. Chem. 75, 1258—1266 (2003). 

Favier, F., Walter, E.C., Zach, M.P., Benter, T. and Penner, R.M., Hydrogen sensors and switches from electrodeposited palladium mesowire arrays, Science, 293,2227,2001. 

The third example of new technology with increasing interest is electrodeposition of multilayers. For example, Schlesinger et al. (29) have shown that this technology can be applied to produce systems with nanometer-scale structural and compositional variations. Giant magnetoresistance (GMR) in electrodeposited Ni/Cu and Co/Cu multilayers was reported by Schlesinger et al. (28). Those constructs have a number of immediate applications in the areas of sensors as well as nanometer-scale electronic circuitry. For a more complete reference fist as well as apphcations to date, see the review article by Schwartzacher and Lashmore (30). 

Space available in porous glass [487], ultrafine Nafion [488, 489], and metallic membranes [490, 491] has also been utilized for the development of smal particles. Cylindrical micropores in alumina membranes have been used, for example, as templates for the electrodeposition of parallel arrays of gold particles (0.26 pm in diameter, 0.3 pm to 3 pm in length) which were infrared transparent [491] and could be used as chemical sensors [490],... 

Ir Ir02 electrodes (commercially available from Cypress Systems, Lawrence, KS) can measure pH in harsh environments or microscopic spaces [S. A. M. Marzouk, Improved Electrodeposited Iridium Oxide pH Sensor Fabricated on Etched Titanium Substrates, Anal. Chem. 2003, 75, 1258 A. N. Bezbaruah and T. C. Zhang, Fabrication of Anodically Electrodeposited Iridium Oxide Film pH Microelectrodes for Microenvironmental Studies, Anal. Chem. 2002, 74. 5726 D. O. Wipf. F. Ge, T. W. Spaine, and J. E. Baur, Microscopic Measurement of pH with Ir02 Microelectrodes, Anal. Chem. 2000, 72, 4921]. For pH measurement in nanoscopic spaces, see X. Zhang,... 

Today, a large number of important technologies are based on or related to electrodes reactions. Besides the chlor-alkali and aluminium industries, energy conversion in batteries and fuel cells, electrodeposition, electrorefining, organic electrosynthesis, industrial and biomedical sensors, corrosion and corrosion protection, etc. are amogst those technologies. In many of them, kinetic, catalytic or specificity aspects of electrode processes are of enormous importance. 

The use of piezoelectric mass sensors for solution phase measurements is still under development. Whereas considerable success has been achieved with these devices for detecting the mass of electrodeposited analytes in... 

The acid-base properties of polyaniline can be utilized to produce solid-state pH sensors where polyaniline works both as the pH-sensitive material and as the ion-to-electron transducer. An excellent example is the electrodeposition of polyaniline on an ion-beam etched carbon fiber with a tip diameter of ca. 100-500 nm resulting in a solid-state pH nanoelectrode with a linear response (slope ca. — 60mV/pH unit) in the pH range of 2.0-12.5 and a working lifetime of 3 weeks [104]. The response time vary from ca. 10 s (around pH 7) to ca. 2 min (at pH 12.5). 

A wide variety of methods exist for the immobilisation of enzymes on a sensor surface. Screen-printed carbon electrodes are often the favourite base for these sensors due to their inexpensiveness and ease of mass production. Methods used for the construction of AChE-containing electrodes include simple adsorption from solution [22], entrapment within a photo-crosslinkable polymer [20,23], adsorption from solution onto microporous carbon and incorporation into a hydroxyethyl cellulose membrane [24], binding to a carbon electrode via Concanavalin A affinity [25,26] and entrapment within conducting electrodeposited polymers [27]. 

Other early work in this field included the use of tetrakis(p-aminophenyl)-porphyrin (Fig. 7a), which was electrodeposited onto glassy carbon and showed a near-Nernstian response to iodide [76]. Electrodeposited methylthiophene-methylpyrrole copolymer was deposited and shown to give a near-Nernstian response to bromide [77]. Pyrrole-3-boronate (Fig. 7b) could be deposited to give films with a good response and marked selectivity to fluoride [78]. A cobalt aminophthalocyanine could also be electropolymerised to give a good sensor for nitrite [79] or sulphide ion [80]. 

A PPy/PQQ modified GC electrode was used for amperometric detection of V-type nerve agent decomposition products. The electropolymerization of pyrrole was efficiently used for immobilization of the biocatalyst, PQQ. The introduction of CaCl2 as a supporting electrolyte during electrodeposition significantly improves the response of the sensor to DMAET and DEAET. Amperometric studies targeted to detection of DMAET and DEAET by PPy/PQQ electrode were performed at a constant potential set at 0.25 V, and the electrode characteristics such as sensitivity and the analyte detection limit were determined. 

Spataru, T., Roman, E. and Spataru, N. (2004), Electrodeposition of cobalt oxide on conductive diamond electrodes for catalytic sensor applications. Rev. Roum. Chim., 49(6) 525-530. 

Using a different approach, the research gronps of Fabre and Freund have synthesized boronate-functionalized conjugated polymers, which serve as electrochemical sensors. For example, a conjugated redox-active film of polypyrrole (174) was electrodeposited onto a platinum electrode from acetonitrile solution. Addition of fluoride anions led to a new redox system that showed an anodic shift relative to polypyrrole itself, which was attributed to fluoride binding to the boronate group. A related poly(aniline boronic acid) (175) was also reported and studied for saccharide detection. " ... 

The electrochemical reduction method can produce mesostmctured metals in the form of thin films. By electrodeposition of plating mixtures made from appropriate salts, mesostmctured metal films can be produced on the electrode surface with high surface areas and good mechanical and electrochemical stabihty. The ability to produce ordered mesostmctured metal films may lead to new types of electrode materials for apphcations such as batteries, fuel cells, and sensors. 

The surface-enhanced Raman scattering (SERS)-active substrates were prepared by electrodeposition of Ag nanoparticles in multiwalled carbon nanotubes (MWCNTs)-based nanocomposites for SERS sensor application. 

---