UMD   This Site

Benjamin Shapiro
Fischell Department of Bioengineering
Joint appointment with:
Institute for Systems Research
2246 Kim Building
University of Maryland
College Park, MD 20742
Tel: (301) 405-4191
Fax: (301) 405-9953

b. Manipulation of Single Quantum Dots to Nanometer Precision
Collaborators: Edo Waks, Srinivasan Raghavan, John Fourkas
Students: C.Ropp, Roland Probst, Zach Cummins, R.Kumar

Our control method scales favorably for extremely small particles. With laser tweezers it is very hard to trap nanometer size particles because the trapping forces scale with particle volume, for quantum dots the trapping forces are very close to thermal kT forces. Even if a trap is created it is not specific -- it can suck in multiple quantum dots.

By improving our optics, increasing the fluid viscosity, pausing the control when the quantum dot blinks off and then reacquiring it when it blinks back on, and by adding an additional feedback loop to autofocus in the vertical direction, we have been able to control, to steer and trap, a single quantum dot to nanometer precision for over an hour.

external player





Movies are in Windows Media Format, best viewed in IE6 or higher. If you have trouble viewing the embedded files, try to launch the external viewer by clicking on the link below the movie. Windows Media Player is required for viewing externally. You can download a free player HERE. The file sizes are approx. 300KB.

Best viewed in
or higher

Mozilla requires the
latest Windows
Media Player
Plugin for Firefox.





©2013 |

Aerospace Home UM Home Page BIOE Home Clark School Home