Lead-free oxides for gas detection – OSPÉGAZ

LEFOG
LEad-Free Oxides for Gas detection
Developing portable or fixed instrument systems compatible with the RoHS directive (restriction of dangerous substances) to monitor our environment is one objective of OLDHAM SAS. This company, which is a subsidiary of the ISC (Industrial Scientific Corporation) group, is ISO 14001 certified since 2009 and is therefore one of the European leaders in matters of ecology. Nowadays gas detection uses mainly optical sensors, lead-based electrochemical sensors and catalytic sensors based on platinum/palladium. This is a very fast growing (10% / year) and promising market (estimated at 3 billion €). Medium-term tensions on the platinum market, increasing prohibitions of use of lead on account of its toxicity and the need for new systems of instrumentation dedicated to the monitoring of the interior air quality and to the detection of dangerous substances require the study and development of new sensors compatible with the environmental (RoHS, REACH) and economics stakes (low cost materials, reliable and cheap manufacturing techniques, high lifetime).
The OSPÉGAZ project aims at developing innovative integrated systems of instrumentation dedicated to the characterization of the various environmental exposures in link in particular with the actions recommended within the framework of the PNSE2 for the proven medical impacts. This apparatus which will integrate new gas sensors containing lead free oxides will be dedicated to the detection of flammable gases, protection against toxic risks and air quality monitoring.
The preliminary work on lead-free ferroelectric oxides enabled us to optimize the conditions of thin films manufacturing. The properties of these pyroelectric oxides should also permit other applications such as the gas detection with optoelectronics cells. Catalytic demonstrators made from BaxSr1-xTiO3 (BST) films gave some very encouraging results. These lead free oxides will thus enable us to develop a new generation of innovating gas sensors of various technologies (catalytic passive sensors and optoelectronic cells integrating a pyroelectric sensor, optical sensors). These technologies open us vast opportunities of study and research on the same material, including the detection of a larger panel of gases.
For the proposed gas sensors, the multiple requirements related to the characteristics of thin films (adjustable film composition, various substrates, thickness, variable structure and microstructure) and industrial purpose (technology transfer to industry, low-cost) led us to use several techniques of deposit for the realization of thick and thin films.

OSPÉGAZ project aims therefore at:
- replacing the current lead containing gas sensors (for example, OLDHAM uses 1-2 tons of lead per year for its sensors) by lead free oxides sensors
- producing catalytic sensors without platinum (cost reduction and need for developing an alternative technology before the exhaustion of the platinum resources)
- demonstrating that ferroelectric oxides based pyroelectric sensors open new prospects when applied to the gas detection (high sensitivity and wide range of detection)
- developing new sensors in agreement with the PNSE2 health plan which aims at reducing the aqueous and atmospheric emissions of priority substances (benzene, HAP aromatic hydrocarbons polycyclic, chlorinated solvents…).
By controlling the power consumption of the new sensors, we hope to show that it will be then possible to transfer these new technologies of sensors into OLDHAM SAS instruments. We also wish to quantify the effectiveness of these new sensors on an extended list of gas to include the requirements of PNSE2.