Micro-glassy carbon inks for thick-film electrodes

Abstract

A description follows concerning the formulation of a model conductive ink system and the physico-chemical characterisation of thick films based on spherical glassy carbon micro-particles with low molecular mass polystyrene binding polymer. The study considers the effects of the carbon and polymer ( C P ) mass ratio from 0.43 to 9.0 on the film surface morphology, electrical resistance and electrochemical properties. The surface structure of micro-glassy carbon films was examined by electron microscopy showing that surfaces have high polystyrene content when the C P ratio falls below 2.3. Electrical resistances corresponding to dielectric materials are found for thick films prepared with inks containing 30% m/m or less carbon in the formulation. It was necessary to introduce the micro-spherical carbon to proportions beyond 60% m/m in order to reduce film resistances to less than 1 kΩ. The electrochemical properties of micro-glassy carbon films correlate with C P ink values, where a transition is observed from insulator characteristics to random array microelectrode and ultimately a micro-porous macroelectrode.