Fluorescence Activated Quantum Dot Sorter

VON BILDERLING C.; CALVO J.J.; BRAGAS A.V.; MARTINEZ O. E

San Carlos de Bariloche

Workshop; Pan American Advanced Studies Institute (PASI) on “Bioinspired Nanoscience and Molecular Machines”, NSF 03-506; 2005

National Science Foundation y Department of Energy

In this project we plan to build a device to produce populations of Quantum Dots (QD) with controlled size dispersion, based on the optical detection of the photoluminescence of single QD. The aim is to use this narrowed size distribution of QDs as electric field sensitive devices, specifically for their use as voltage membrane sensors.The peak value of the single particle photoluminescence spectrum is intimately related to the size of the QD and, hence, a spectrum classification is equivalent to a particle size sorting. A droplet generator apparatus generates droplets containing one QD in average, starting from a solution of colloidal CdS and CdSe chemically synthesized QD. A resonant laser excitation and optical detection of the photoluminescence is performed by using a high sensitive CPM (channel photomultiplier) with dark noise lower than 3 cps. In view of performing the sorting of the droplets, a trigger signal will be generated from the intensity changes in the photoluminescence of single particles. This signal will be used for applying a deflecting voltage to electrically charged droplets, in order to form a controlled size dispersion population.