Diffusion limited current characteristics of Zirconia amperometric Oxygen sensor

Abstract The geometry of the diffusion barrier defines the characteristics of a diffusion limited Zirconia amperometric Oxygen sensor. The fabrication details and characteristics of a miniature Zirconia amperometric Oxygen sensor are reported in this paper, where; (i)the diffusion barrier is an Alumina disc with a micro-hole in its middle created using a microneedle during its green stage and (ii)a glass ring is used to ensure a predetermined separation between the diffusion barrier and the Oxygen pump. While the microneedle based micro-hole creation provides a low cost sensor fabrication process, the use of glass-ring separator provides consistent sensor geometry and sensor characteristics. The fabrication process was optimized to obtain diffusion limited current characteristics, falling within the bulk diffusion regime. Also reported are few anomalous observations in the I-V characteristics noticed during the initial stages of sensor development. The observed pressure/altitude dependence of the limiting current of the sensor is ascribed to mixed gas diffusion containing both bulk and Knudsen diffusion paths in the sensor.