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Thursday, November 5, 2009
3pm (2:45pm refreshments)
RLE Conference Room, 36-428
Microfluidic Systems for Nanostructure Synthesis
Prof. Klavs Jensen, MIT
ABSTRACT
Chemically synthesized nano materials such as nanocrystalline quantum dots are being considered as the active element in many applications, including photovoltaics, displays, and bio-chem sensing. Current nanoparticle synthesis in a batch mode suffers from several deficiencies. There is irreproducibility of size, size distribution, and quality of the nano-material from batch to batch. There is inherent difficulty in scaling up to quantities more reasonable for device development and optimization. Studies of the reaction kinetics of the nucleation and growth process are severely limited by batch to batch variations. Continuous flow reactors based on microfluidics (microreactors) integrated with heaters and fluid control elements offer a solution to these problems as well as additional advantages. Microreactors allow for a degree of control and inline feedback that is impossible with a batch process, e.g., on-line measurement and optimization. Moreover, microreactor offers the opportunity to synthesized nanocrystalline materials under conditions difficult to achieve in conventional batch processes. The devices can be operated safely at elevated temperatures and pressures (including supercritical conditions) potentially allowing synthesis of new nanostructure systems and reduction of crystalline defects. We illustrate the application of these microfluidic systems to the synthesis of nanomaterials, including metal particles, core shell oxide particles, and compound semiconductor quantum dots at conditions up to 400ºC and 200 bar.
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