Self-assembling nanoparticles in devices
Nanoparticles are changing the face of fields ranging from materials science to biomedicine to energy. A consortium developed novel applications using self-assembled charged nanoparticle systems within the scope of the project 'Metallic and semiconducting nanoparticle source for electronic and optoelectronic applications' (NANOSOURCE) . The team perfected a vacuum-based technique developed by a project partner to generate and deposit charged nanoparticles on substrates. Partners fabricated nanoparticles in the range of two to 10 nanometres with unprecedented surface densities of non-touching particles up to approximately three particles per square centimetre. They were able to further increase density to produce a continuous monolayer of touching nanoparticles or multiple nanoparticle layers. Exploiting the charged nature of the nanoparticles produced with this technique, researchers explored electrostatic self-assembly. They produced one-dimensional arrays in lines defined by conventional lithography. Using the charged particles’ preferential deposition on sharp edges, scientists formed nanowire arrays made of closely packed nanoparticles of width less than 30 nanometres. With surface-enhanced Raman spectroscopy, a technique for single-molecule detection, they demonstrated increased sensitivity compared to that of isolated nanoparticles on a flat substrate. Scientists also investigated applications of two-dimensional nanoparticle structures with impressive results. Both strain and chemical sensors were developed. The sensors exploited changes in resistance correlated with changes in interparticle distance either due to load or binding of an analyte, respectively. The chemical sensing devices successfully identified volatile organic compounds and detected humidity. Researchers have also demonstrated memory devices including flash-like memories storing charge in metallic nanoparticles and a memristor (memory resistor) with enhanced properties and simplified processing. These novel configurations of charged nanoparticles with controlled size and density has pushed sensors and memory devices beyond the current state - of - the - art. The successful collaboration between research and industry promises rapid commercialisation of results for major impact.
Keywords
Nanoparticles, self-assembled, charged, density, sensors, memory devices
