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Details of Grant 

EPSRC Reference: EP/J011746/1
Title: Optoelectronic Detection of Explosives
Principal Investigator: McHugh, Dr C
Other Investigators:
Researcher Co-Investigators:
Project Partners:
BASF University of Strathclyde
Department: School of Science
Organisation: University of the West of Scotland
Scheme: First Grant - Revised 2009
Starts: 02 April 2012 Ends: 01 April 2014 Value (£): 100,399
EPSRC Research Topic Classifications:
Analytical Science
EPSRC Industrial Sector Classifications:
No relevance to Underpinning Sectors
Related Grants:
Panel History:
Panel DatePanel NameOutcome
01 Dec 2011 EPSRC Physical Sciences Chemistry - December 2011 Announced
Summary on Grant Application Form
Current research in explosives detection focuses across key themes spanning the mode of signal transduction involved, including Optical, Electrical, Gravimetric and Calorimetric based solutions. Significant progress has been made in optical based detection systems and to date the most successful strategies are based upon solid state fluorescent materials and modulation of analyte interactions via electron transfer. With the exception of the conjugated polymers however, few materials have been incorporated or commercialised into device driven architectures. The future for fluorescence based sensors is in exploitable solid state technologies with enhanced sensitivity and selectivity. This proposal aims to combine the advantages of optical and electrical signal transduction to facilitate a synergistic optoelectronic sensor based upon bi-layer thin film photoconductor technology.

Bi-layer heterojunctions play key roles in optoelectronic devices such as photovoltaics, organic light emitting diodes (OLEDS) and photoreceptors. The interface is responsible for creation and dissociation of photogenerated excitons into charge carriers that are transported to the electrodes via applied bias. Compared with chemiresistors and field effect transistors, separation of the processes of charge generation and charge transport into two different films in a heterojunction facilitates a more simplistic optimisation of the physical processes involved. Analyte detection via modulation of current output from lateral bi-layer photoconductors is possible using exciton generating layers whose photoluminescence efficiency is affected by local environment. Many potential organic fluorophores that could fulfil this role are however, poorly emissive in the solid-state from aggregation induced quenching effects and rational control of these unfavourable interactions is crucial for their future realisation in functional applications.

Organic dyes and pigments are ubiquitous materials in photoconductive technologies such as xerography, upon which lateral bi-layer heterojunction sensors are based. They are effective in charge generation through careful manipulation of purity, crystallinity and morphology and as such make extremely attractive materials for the construction of bi-layer sensors. Furthermore, many dyes and pigments are amenable to organic functionalisation and crystal engineering, facilitating introduction of analyte specific recognition sites, tuneable absorption and controlled morphology to provide broadband sensor architecture. Thus, this proposal aims to develop a systematic understanding of the role of molecular design and crystal engineering on the solid state chemistry of photoluminescent dyes and pigments which can be exploited via the bi-layer approach. This aspect of the proposed research addresses several technical challenges in materials science and the fabrication of a device employing organic dyes and pigments, and metal oxides will require an in-depth understanding of their preparation, photochemistry and solid state properties. Devices based upon this structure offer significant advantages in explosives detection, providing an opportunity for high sensitivity, large dynamic range and selective target recognition with built in adaptability to changing threats. Additionally, this type of system would be non-invasive, portable and rugged, with few moving parts and the potential to offer a rapid analyte response mechanism that can be directly modulated into an electrical output.
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