Novel trithiol-capped gold nanoparticles (~3 nm diameter) are synthesized by wet chemistry and ink-jet deposited onto a prefabricated MEMS device. The change in electrical resistance is recorded as a modality for the chemical detection of reversibly adsorbed vapours on the surface of the nanoparticle film.

The trithiol-capped gold nanoparticles are found to be more stable and sensitive towards the detection of vapours compared with the monothiol-capped gold nanoparticles reported previously. The significantly improved long-term stability of the new sensors is attributed to the much stronger binding of trithiol to the gold nanoparticle surface. The trithiol linkages prevent ligand loss and inhibit thiol oxidation by oxygen in the air. As a result, this new type of nanosensor is particularly robust. This work has solved the major long-term stability issue of gold nanoparticle-based sensors.

The new study, recently published in the journal Nanotechnology, shows the great potential of this type of robust nanosensor for real world applications in detecting toxic chemical vapours for the purpose of environmental monitoring, personal health care and homeland security. Research is in progress to further exploit nanoparticle materials for sensing and other related applications.