Development of a gas sensor by thick film technology for automotive applications: Choice of materials - Realization of a prototype

As a part of our research on new gas sensors, an original potentiometric gas sensor was developed. The gas sensor consists of a solid electrolyte associated with two different electrodes located in the same gas mixture. Owing to the interesting behavior of this sensor to the action of CO and NOx, it was decided to develop this device within the framework of a European contract and to produce it industrially by screen-printing. The sensor is designed for use in automotive applications. We propose to expose the problems encountered during the development phase as well as the chosen solutions. We first discuss the selection of the materials used in the preparation of the ink required for the screen-printing phase of the sensitive element in terms of ratio between the mineral binder and the functional phase. Then, we compared the responses of the sensors made with electrodes deposited by sputtering or by screen-printing. This enabled us to propose a sensor which can easily be produced in large quantities and whose performances remain close or even better than those obtained with the prototype.