SnO2-based chemoresistive sensors integrated in complementary metal-oxide-semiconductor technology were functionalized with ultrasmall Pt nanoparticles, resulting in carbon monoxide sensing properties with minimized humidity interference.

CuO nanowire arrays, synthesized on chip, were evaluated for their gas sensing capabilities. The gas sensors were fabricated on test structures containing gold electrodes for conductometric measurement, a resistive heater and a thermocouple for proper temperature control. The initial metal structure was fabricated by electron beam lithography, thermal evaporation and lift-off process. In a consecutive step the metal structure is thermally oxidized at a temperature of 400°C. As a result of the temperature treatment nanowire growth is promoted during the thermal oxidation process. A CuO nanowire array is formed. This nanowire array is evaluated for carbon monoxide, - and a hydrocarbon-mixture (acetylene, ethane, ethene, and propene) for VOC testing at three relative humidity levels.

We present the integration of thin film SnO2 gas sensor on CMOS microchips. A spray pyrolysis process was used to deposit the gas sensitive film, with a thickness of 50 nm, on CMOS microhotplates. The exposure of the CMOS integrated gas sensor to carbon monoxide at different operating temperatures and humidity levels lead to a significant decrease in the sensor resistance. At an operating temperature of 375 °C a sensor response of almost 50% was achieved. The integration of the sensing material on CMOS microhotplates makes it possible to reduce the size and power consumption of metal oxide gas sensors.

Metal oxide nanostructures like tungsten oxide nanowires are intensively studied materials for sensor applications. In this work we report on tungsten oxide gas sensors integrated on a CMOS fabricated microhotplate chip. Tungsten oxide gas sensors were prepared by drop coating of a nanowire network suspension onto interdigitated electrodes prefabricated on the CMOS microhotplate chip. The tungsten oxide nanowire network was characterised by TEM and Raman spectroscopy, confirming their non-stoichiometric state. Using tungsten oxide nanowire networks as gas sensing material we observed high sensitivity to hydrogen sulphide: concentrations of 1 ppm have been detected with a sensor response up to 55%.

In this work, we present the integration of functionalized tin dioxide gas sensors on CMOS fabricated microhotplate chips. Spray pyrolysis was used to deposit the gas sensitive films, with a thickness of 50 nm, on CMOS microhotplates. The SnO2 thin films were functionalized with noble bimetallic nanoparticles - PdAu - by inkjet printing and the influence of the nanoparticles on the sensor performance was evaluated. The functionalization of the CMOS integrated SnO2 sensors with PdAu nanoparticles lead to an almost three times higher sensor response towards carbon monoxide compared to the bare SnO2 thin film. The CMOS microhotplate chips are also applicable for 3D-integration of different gas sensing systems based on through-silicon-via technology. Building devices for daily life applications is possible with such 3D-integrated nanosensors.