Joint research project

Sensors based on germanium and carbon nanostructures

Project leaders
Claudio Ferrari, Sevda Abdullayeva
AZERBAIJAN - ANAS - Azerbaijan National Academy of Sciences
CNR/ANAS biennio 2018-2019 2018-2019
Engineering, ICT and technologies for energy and transportation
Thematic area
Engineering, ICT and technologies for energy and transportation
Status of the project
Report for renewal

Research proposal

Techniques to detect high-explosive materials, such as TNT (trinitrotoluene), RDX (cyclotrimethylene trinitramine), PETN (pentaerytritol tetranitrate) at traces levels in luggage, vehicles, mail, aircraft and soils are of great interest for security.
Functionalised nanostructure can offer a possible sensing solution to realise detectors offering a high sensitivity and at the same time a very limited weight and electrical powe requirement. The favourable surface/volume ratio typical of nanostructure can be exploited to realise sensitive, selective and small detectors suitable to be carried by unmanned aerial vehicles (UAV).
The project is based on to two types of nanostructures which demonstrated a high sensitivity to traces of explosives molecules in air and already obtained at IMEM Institute in Italy and in Institute of Physics of Academy of Sciences in Azerbaijian:
Semiconducting nanowires can detect TNT down to a detection limit of ~1x10-6 ppt by surface functionalization with an electron-rich amino-silane which binds the electron-deficient explosive molecules of TNT through charge-transfer donor-acceptor interactions thus causing sharp changes in the conductance of the electrical-sensing nanoelements[1].
Functionalized single-walled carbon nanotubes (SWNT) are highly responsive to their physical and chemical environment. SWNT are unique among nanoscale sensor platforms in their ability to detect the adsorption of as few as a single molecule of an analyte [L. Cognet et al. 2]. Single-walled carbon nanotubes (SWNT) may be covalently functionalized with urea, thiourea, and squaramide. Carbon nanotube (CNT) based chemiresistors display promising performance in explosive sensing [Schnorr et al 3]. CNT chemiresistors can be deposited between electrodes by evaporation or dispersions, or can be effectively drawn from compressed CNT solids.

Both these systems demonstrated a very high sensitivity in detecting explosives, in particular of molecules of trinitrotoluene (TNT), which is a common explosive used in improvised explosive devices (IED).
Sensors based on functionalised nanostructures, and in particular those based on the effect on the conductivity changes of nanowire and nanotubes are
- very sensitive, with detection limit up to a few molecules per cm3
- selectivity can be achieved by combining nanostructures with different functionalization
- the conductance signal can be easily detected with simple instrumentation (a signal amplifier) and does not need complex environment, such as a laser beam (LIBS, Raman), an UV (fluorescence) or a IR beam (IR), high voltage (MS), special gas fluxes (GC) meaning a very limited need of electrical power
The aim of the present project is preparation of explosive sensors based on semiconductor nanowires or carbon nanotubes, which appear now as the most interesting type of nanostructures for producing gas sensors. Devices prepared on nanostructures are characterised by a very limited mass, electrica power requirement and dimensions, and are suitable to be mounted on small drones for the exploration of dangerous environment or buildings.

[1] A. Lichtenstein, E. Havivi, R. Shacham, E. Hahamy, R. Leibovich, A. Pevzner, V. Krivitsky, G. Davivi, I. Presman, R. Elnathan, Y. Engel, E. Flaxer and F. Patolsky, Nature Comm., 5 (2014) 4195.
[2] L. Cognet, D. A. Tsyboulski, J. D. R. Rocha, C. D. Doyle, J. M. Tour, R. B. Weisman. Science 316 (2007) 1465-1468.
[3] Schnorr, Jan M.; van der Zwaag, Daan; Walish, Joseph J.; et al. ADVANCED FUNCTIONAL MATERIALS Volume: 23 Issue: 42 Pages: 5285-5291 Published: NOV 13 2013Sensory Arrays of Covalently

Research goals

Functionalised Doped Germanium nanowires for the preparation of field effect transistors (FET) for ultra-high sensitive explosive detectors using gold as catalyst and doped by fluxing the nanowire under metal-organic non toxic precursor in a MOCVD chamber. Attempts to prepare a nanowire based FET transistor will be made by contacting single nanowires between metal contacts that will provide the source and the drain of a FET device.

Functionalised Carbon nanotubes (CNT) will be grown by the Aerosol CVD technique (ACVD) to obtain single walled and monodispersed nanotubes to be used as explosive detector device after proper functionalization.
Attempts to prepare a nanotube based sensor will be made by contacting a drop deposited network of functionalized carbon nanotubes.

Last update: 27/11/2021