| Summary: | <p>Explosives detection plays an important role in both military and civilian applications. However, the detection of explosive vapours remains challenging because of the low vapour pressures of explosive materials. The aim of this project is to develop a system for the ultra-sensitive molecular detection of explosives. The sensor is based on a percolation network of conductive polymers, supported on a scaffold of gold nanoparticles. By operating the sensor at the percolation threshold a higher sensitivity can be achieved compared to more traditional polymer thin film based sensors.</p> <p>The first component of the sensor, the gold nanoparticle scaffold, was created by dewetting a gold thin film. The nanoparticle size and separation were controlled by controlling the initial gold thin film thickness and the annealing time and temperature. Furthermore, stepwise resistance changes were observed during gold deposition and annealing. Next, conductive polymers were deposited on the gold nanoparticle scaffolds, creating polymer networks ranging from thin films to networks close to the percolation threshold. Additionally, simulations were used to confirm that a sensor based on a percolation network has a higher sensitivity than a thin film based sensor. Finally, initial testing of sensors with various polymer coverages in the presence of ammonia has provided a proof of concept of a sensor based on a percolation network of conductive polymers.</p>
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