Pulsing amperometric oxygen sensors: earlier techniques evaluated and a technique implemented to cancel capacitive charge

Abstract

The modifications of pulse amperometry whereby the cathode is open-circuited between pulses of applied potential suffers, in common with the well known steady-state polarisation technique, from considerable dependence on the hydrodynamics of aqueous test solutions. The zero-oxygen readings due to the capacitive component of cell current with classical pulse amperometry are high and unstable. This problem may be eliminated by integrating current to cancel capacitive charge; integration commences with the pulse and the integration period must be one or two orders of magnitude greater than the pulse width. High 'IR losses' in potential during most or all of the pulse width. High 'IR losses' in potential during most or all of the pulse largely explain the nonlinearity and instability of calibration usually, encountered with Clark-type sensors. Sensor design in described.