H2S is a toxic gas released in many industries such as mining, water treatment and paper production. Even at relatively low concentrations it can cause eye and respiratory tract irritation, and at high concentrations it can cause paralysis or even death. As a result the continuous monitoring of H2S is important to minimise occupational health hazards. The development of a compact, mobile and low power consuming H2S sensor with a high sensitivity and low detection limit for personal exposure is therefore highly desirable. Reporting in Nanotechnology, the researchers at UCR may have achieved just that by using viral-templated nanowires as components in their chemiresistive H2S gas sensor.

Viral templates

Chemiresistive gas sensors change in electrical resistance when the target or analyte gas interacts with the device surface. For this reason, continuous, wire-like nanomaterials which support current flow and possess large surface area-to-volume ratios are desirable device components. To form a selective and sensitive H2S sensing element, the UCR team capitalized on the specificity and one-dimensional structure of a genetically-modified, gold-binding M13 filamentous bacteriophage to form gold nanowires. This high-aspect ratio template was used to organize linear arrays of gold nanoparticles which were used as seeds for electroless deposition. Nanowire thickness and density within the sensor were used to modify electrical resistance.

More than geometry

The real-time sensing behavior was measured for a range of analyte concentrations. H2S gas sensors composed of these viral-templated nanowires were found to be very sensitive at room temperature. More sensitive, in fact, and with faster adsorption and desorption kinetics than sensors in which the bacteriophage were removed with oxygen plasma. Chemical moieties within the viral proteins assist in gas sensing; enhancing performance either through direct or indirect interaction. This is the first report of a bio-templated, room temperature H2S gas sensor, in which the template contributes more than simple geometry to the sensing performance. These findings advance a realm of sensitive, chemiresistive gas sensors which pair functional biomolecule building blocks with inorganic nanomaterials for room temperature operation.

More information about the research can be found in the journal Nanotechnology 25 135205.

Further reading

ZnO nanowire nanogenerators inspire self-powered active gas sensor (July 2013)
Nanofibre-based gas sensors aid environmental monitoring (Sept 2012)
Nanoclusters tailor the response of nanowire-based gas sensors (Apr 2012)