Electrochemical sensors with redox polymers

One area where the relationship between the structure of the polymer matrix and the physical processes of the thin layer has been studied in detail is that of electrodes modified with polymer films. The polymer materials investigated in these studies include both conducting and redox polymers. Such investigations have been driven by the many potential applications for these materials. Conducting polymers have been applied in sensors, electrolytic capacitors, batteries, magnetic storage devices, electrostatic loudspeakers and artificial muscles. On the other hand, the development of electrodes coated with redox polymers have been used extensively to develop electrochemical sensors and biosensors. In this discussion,... 

The electrochemical behavior of redox molecules in polymer films and gels has been investigated [4,7,18,23,61-66], but such behavior has usually been studied by using a modified electrode coated with a polymer film or gel in the presence of an outer electrolyte solution. In a few examples, entirely solid-state voltammetry was also achieved, but by using a microelectrode array [65,66] composed of working, counter, and reference electrodes because of the slow ionic or molecular diffusion in the soHd matrices. The apparent diffusion coefficient (Dapp) of a redox substrate in the films or solids coated on an electrode was very small [4,7,18,23,62-66], usually of the order of less than 10 cm s Another example of solid state votammetry is a report on the electrochemistry of Prussian blue in silica sol-gel electrolytes [67], but only Pt gauze working and counter electrodes for a - 1 mm-thick silica solid were used. Moreover, it is well known that solid electrolytes have been used on various sensors, electro chromic devices, etc. [68,69]. However, in spite... 

The use of conducting polymers in sensor technologies involves employing the conducting polymers as an electrode modification in order to improve sensitivity, to impart selectivity, to suppress interference, and to provide a support matrix for sensor molecules [7,9,16,18,22,25,26,113-216]. All electrochemical transducer principles can also be realized with conducting-polymer-modified electrodes. The role of the conducting polymer may be active (for instance, when used as a catalytic layer, as a redox mediator, as a switch, or as a chemically modulated resistor, a so-called chemiiesistor ) or passive (for instance, when used as a matrix) [7,9,16,22,23,26,122,123,167,168,176,177]. 

So far, it has been reported that redox polymers, such as polysiloxane or polyarrylamide on which ferrocene is introduced as a side chain, are effective mediators [15-25]. Other effective mediators include poly(vinyl pyridine) or poly(vinyl imidazole) on which osmium complex is introduced in the side chain. However, the structure-mediator fimction correlation has been poorly understood. Here, the glucose sensor was used as an example of enzyme sensors, and as shown in Table 1, sensors using enzymes other than glucose oxidase have also been actively studied. It is now possible to detect electrochemically materials in the body using an electrode with an enzyme and a polymer gel. 

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