A miniaturized catalytic gas sensor for hydrogen detection based on stabilized nanoparticles as catalytic layer

Micro-technologically based catalytic gas sensors offer great advantages regarding sensitivity, power consumption and response time, especially in connection with a porous catalyst layer, which however often provides no sufficient long-term stability. This paper presents a miniaturized catalytic gas sensor for hydrogen detection based on colloidally prepared platinum nanoparticles as a catalytic layer. Compared to conventional sensors, the sensitivity of the catalytic layer is increased while the amount of catalytic material is decreased, due to the high surface of nanoparticles and the direct contact to the sensor. Because of the susceptibility of the nanoparticles to thermally induced sintering, an approach is adopted where the nanoparticles are embedded in an organic network, consisting of stabilizing surfactants adsorbed on the nanoparticle's surface. Agglomeration is reduced and the adhesion to the substrate is improved so that a highly improved stability compared to sensors fabricated with nanoparticles without surfactants is observed. Additionally, the sensor design allows a precise control of the temperature of the catalyst, which also contributes to the stability by keeping the temperature constant. Thermal loading effects are avoided. A sensitivity of up to 2.5 mV/100 ppm was observed.