THEORETICAL AND EXPERIMENTAL-DETERMINATION OF CELL CONSTANTS OF PLANAR-INTERDIGITATED ELECTROLYTE CONDUCTIVITY SENSORS

In this paper, an analytical expression is presented for the cell constant of planar-interdigitated electrodes used as electrolyte conductivity sensors. The result of this expression is compared with results of measurement carried out with several differently shaped planar probes provided with a thin Ta2O5 insulating film, showing good agreement. More than 10 different devices have been fabricated with predicted cell constants ranging from 0.14 to 4.44 cm(-1). The measured cell constants are typically 10-20% smaller, possibly due to fringing effects.