Berlin 2012 – wissenschaftliches Programm
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SYSD: Symposium SKM Dissertationspreis
SYSD 1: SKM Dissertation Prize
SYSD 1.1: Hauptvortrag
Montag, 26. März 2012, 12:00–12:20, EW 201
Allan variance analysis and fast camera detection schemes for optical tweezers — •Fabian Czerwinski1, 2 and Lene Oddershede1 — 1Niels Bohr Institute, University of Copenhagen, Denmark — 2Lewis-Sigler Institute, Princeton University, USA
In soft-matter and biological physics, optical tweezers are among the most versatile force-microscopy techniques. Optical tweezers allow for non-invasive and localized sample control under physiological conditions. Within a tightly focused laser beam, an optical handle fluctuates. Its positions can be thought of as a thermal, stochastic sampling that is elegantly used to calibrate the trap. Previous protocols emphasize only the high-frequency spectrum (>400Hz), handling unavoidable low-frequency effects with unsatisfying arguments.
To rigorously quantify these low-frequency effects, we pioneered the usage of Allan variance analysis in addtion to existing calibration protocols. It measures an experimental accuracy map and is essentially assumption-free. It allows one to quantify the optimal calibration interval and determine the force sensitivity. It became one of the keystones to calibrate new tweezers setups. At the same time, Allan variance analysis was implemented for other biophysical techniques, including FRET, magnetic tweezers, and ionic currents through nanopores.
In a second project, we built a camera detection scheme to directly visualize fast biological processes. It acquired and stored optical tweezers data up to 40kHz. The scientific community and nanotech companies have been utilizing our hardware and open-source software solutions.