Biocompatible Electrodes Research Articles

Culture of mammalian cells on polypyrrole-coated ITO as a biocompatible electrode

Primary culture of the chromaffin cells on polypyrrole-coated indium-tin oxide was performed and the influence of polypyrroles having some kinds of dopants on cell function was investigated. While the cells cultured on indium-tin oxide showed decrease of catecholamine release, those on polypyrrole-coated indium-tin oxide maintained the cell function of release of catecholamines. Furthermore, no influence of various dopants on the secretory function from the cultured cells was observed. To prepare polypyrrole on electrode as a cell-culture substrate was considered to be available for supporting the cell function.

Stimulation, Recording Potential and Antimicrobial Medical Catheter Coatings

Biocompatibility of electrodes for stimulation are difficult to maintain homeostasis. Noble metal stimulating electrodes which are normally biocompatible on keratinized tissue become very non-biocompatible when they are interfaced with nonkeratinized tissue in an area such as the oral cavity. Composite electrodes have been made biocompatible in the oral cavity even at current densities larger than 1 μA/mm2. Electrodes used in potential readings require that the anodic and cathodic polarization remain minimal. Silver-silver chloride electrodes are minimal. Silver-silver chloride electrodes are not always reversible. The range of pH, voltages and current densities when silver-silver chloride are not reversible are presented. Recently at Drexel University reliable silver coatings inside and outside of medical catheters have been fabricated to act as antimicrobial to a variety of bacteria. Noble and nonnoble metals have been combined in coatings with silver to enhance the antimicrobial action.

Biocompatibility considerations at stimulating electrode interfaces.

The choice of biocompatible stimulating electrodes for various biomedical applications varies with the type of electrode-tissue interface, biomolecules present, electrolyte background, preparation of electrode, interfacial potential, current density, electrode material, porosity, geometry, and inflammatory response. Illustrative examples are given to demonstrate the importance of these parameters. Topics discussed are: A) DC electrodes applied to partially keratinized epithelial membranes; B) Variation of the electrical impedance and biocompatibility of stimulating electrodes with electrode potential and surrounding pH; C) Influence of electrode geometry, porosity and pore size on biocompatibility; D) Body defense mechanisms at the sites of implantable stimulating electrodes; E) Thrombus formation at stimulating electrode interfaces and F) Sterilization of electrodes to ensure biocompatibility.

A biocompatible enzyme electrode for continuous in vivo glucose monitoring in whole blood

Electrode fouling and biocompatibility problems remain the greatest obstacles to developing a stable glucose sensor for continuous in vivo monitoring in whole blood. Nafion encapsulation successfully prevents electrode fouling, and substantially inproves the stability and performance of whole blood and plasma glucose sensors in vitro. Results are presented which indicate that Nafion also provides a biocompatible interface with the body, and hence offers the potential for use with implantable sensors. A biocompatible enzyme electrode system is proposed, based on Nafion polymer encapsulation, which has a suitable size and geometry to be tested as an implantable sensor for long-term use. A custom-designed CMOS integrated potentiost was used to evaluate the electrode response in whole blood.