A two-step coating technique was applied to modify a lateral field excitation sensor with complex membranes made up of nanoparticles (NPs) and supermolecules. A comparison was made after each coating step by SEM and an impedance analysis technique. Due to the rigidity of the cast material and the uniformity of the NP films, the NP coating could be used without any attenuation of the acoustic wave or decrease in the quality factor of the sensor. This kind of sensor has been successfully developed into an organic vapour detector with certain levels of selectivity among several analytes, as well as good stability and a fast uptake/release time. Such a composite coating procedure is expected to realize localized deposition of different sensitive materials on a sensor array. The bottom uniformly-arranged NP layer defines the acoustic properties of the whole device and serves as an easy loading platform, while the second layer provides sensitivity and selectivity.
- gas sensor
- lateral field excitation
- piezoelectric crystal
- two-step modification technique