S3

"Surface ionization and novel concepts in nano-MOX gas sensors with increased Selectivity, Sensitivity and Stability for detection of low concentrations of toxic and explosive agents."

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 Obiettivo del progetto (Objective)

'The objective of S3 is developing breakthrough technologies in gas sensing that will provide higher sensitivity and selectivity at reduced cost. This objective will be pursued by bringing together excellence and complementary skills of ropean Union and Russian groups. Enhanced sensitivity and selectivity will enable toxic and explosive gases to be detected against a background of air constituents and ubiquitous air contaminants. This task will be pursued by studying sensors and sensing principles based on semiconductor nanowires (NWs) molecularly engineered, in terms of doping level, the used additives and /or functionalization processes and heterostructures and deposited onto SiO2/Si and/or alumina MEMS heater platforms. These platforms will be configured in innovative ways to obtain multiple signals from one and the same sensitive layer. Signals recovered will include resistive, field-effect, ion emission and catalytic/thermal conductivity response of the NW materials. Low power operation and additional enhancements in selectivity will be obtained through pulsed-temperature operation and combined self-heated operation mode using dynamic and steady state responses and modulated optical excitation. Furthermore, the increased stability of NW-based sensing materials will positively affect the reliability of the developed sensors. In order to meet application demands, S3 will further explore novel concepts of sampling, filtering and preconcentration of target substances based on nanostructured filter and enrichment materials. The development and the modelling of this new generation of nanostructured gas-sensing and ion emitting materials will be supported by a wide range of morphological and physico-chemical characterisation techniques. The cooperation between EU Union and Russian groups will be improved and strengthened by short and long term exchanges of researchers, the organization of common workshops and tutorials and the establishment of joint doctoral degrees'

Introduzione (Teaser)

EU-funded scientists are developing novel miniaturised sensing devices to detect toxic or explosive substances. Enhanced performance with minimal power consumption should provide the energy autonomy currently lacking.

Descrizione progetto (Article)

The ability to detect trace amounts of toxic or explosive gases in the air is of vital importance, not only to workplace safety but to homeland security in the face of possible terrorist actions. Metal oxide (MOX) semiconductor gas sensors have received widespread attention due to their stability and sensitivity. They work via a gas-sensitive MOX film whose electrical properties change in the presence of certain molecules.

When the sensing is accomplished by nano-structured materials such as semiconductor MOX-based nanowires (NWs), tremendous decreases in size and power consumption can be achieved. Scientists initiated the EU-funded project S3 to develop a new generation of cost-effective MOX gas nanosensors. These will be used for detecting toxic and explosive gases with superior selectivity, sensitivity and stability (the three S's) combined with miniaturisation and power autonomy.

Investigators are targeting nitrogen dioxide (NO2) and trinitrotoluene (TNT) for explosives applications, and ammonia (NH3) and hydrogen sulphide (H2S) for toxicity monitoring in the environment and workplace. Innovative design is enabling the acquisition of multiple signals consisting of resistive response (RES), surface ionisation (SI) and catalytic heat conductivity (CH) from a single sensing layer. To reduce size and heating power consumption, scientists are studying thin ceramic film heater substrates, the use of single NW gas sensors for microwatt power consumption and a new type of microelectromechanical system (MEMS) based on thin alumina film (TAF).

Novel nano-sensing materials and systems developed for the project are exhibiting clear RES and SI responses. The development of nanometrology tools and theoretical simulations are helping to screen materials and optimise sensing behaviour. Scientists have also built a unit for vaporisation of targets not in gaseous form, such as explosive particle residue and illegal drugs.

S3 is developing multifunctional chemical sensors to detect toxic, explosive or illicit substances. Miniaturised devices based on novel nano-scale structures are facilitating a significant decrease in power consumption, to date the limiting factor to autonomous sensor networks functioning over extended time frames. Devices with decreased size and power consumption together with increased selectivity, sensitivity and stability will no doubt quickly find a niche in the global sensing market.