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Discrete Volume Assembly at Nano-Scale

Final Report Summary - DIVAN (Discrete volume assembly at nanoscale)

The nanoscience domain has produced vast knowledge on phenomena and characteristics of nanoscale objects, including carbon nanotubes (CNTs) and nanowires (NWs). New promising applications, functions and performances have been identified in the fields of smart materials, mechanical and electronic nanoscale devices and nanoelectronics. However, a prerequisite for harvesting the potential is to have methods for creating discrete patterns of nano-scale objects in a potentially high volume / low cost manufacturing approach. Although basic principles for nanoscale patterning have been researched, a breakthrough is still not achieved. The Marie Curie Intra-European Fellowship (IEF) project 'DIscrete volume assembly at nano-scale' (DIVAN) aimed to lay the foundation of a new research programme working on potentially industrially viable methods for nanoscale assembly and patterning. A new concept for nano-scale patterning was defined: nanospray dielectrophoresis.

The concept combines electrospray of particles and subsequent dielectrophoretic trapping. In electrospraying, a high-potential electrical field pulls droplets out of a thin diameter capillary which is supplied with a solution, and creates a jet of particles which bursts into a plume, forming the spray. The dispersed nanoparticles travel with the jet and are thus sprayed onto a receiving substrate. As the spray moves towards the receiving substrate it evaporates, offering the possibility to present particles in varying humidity states. The main scavenging and patterning mechanism exploited was dielectrophoresis, which is in particular useful if the spray is in a relatively dry state. In dielectrophoresis, a non-homogeneous radio-frequency (RF) electrical field creates a dipole in polarisable objects, and attracts them to, or repels them from, maximum field intensity.

The major advantage of the proposed concept is that it provides more mechanisms for control over particle flows and patterning compared to existing, often fluid based or enabled patterning approaches. The concept has been theoretically and experimentally researched. The main achievement of the project is that experimental proof of the proposed concept has been generated for various modes of trapping and patterning nanoparticles from a spray. Continued joint research is planned to further investigate fundamentals of the developed process and to explore the application potential. To bring the proposed process to applications, the functionality of realised patterns will be investigated for applications in smart materials and nano devices. Two specific utilisation possibilities of the project results are identified: creating pre-concentrators e.g. for medical analysis or mass spectrometry systems and a nanoprinter which is able to print two-dimensional (2D) structures of nanoparticles on thin film substrates. The Imperial College spin-out company Microsaic has expressed interest in a pre-concentrator for mass spectrometry.