Optical chemical hydrazine sensor from hybrid organic-inorganic materials

Original hybrid organic-inorganic materials have been synthesised, characte rised and used as optical chemical hydrazine sensors. Because of its optica l and chemical properties, 4-(dimethyl)aminobenzaldehyde (DMAB) was chosen as indicator. DMAB has been immobilised by physical entrapment in a micropo rous silica network or by a chemical bonding on a colloidal silica network. The response time of the sensor was essentially governed by the diffusion of hydrazine in the host matrix whereas its life time was dependent on the retention of DMAB. These two features were controlled by the nature and the quantity of the network agent and the catalyst, by the ageing time of the sol, and the drying and thermal treatment of the films.