Dresden 2006 – wissenschaftliches Programm
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AKB: Biologische Physik
AKB 30: Poster Session I
AKB 30.22: Poster
Montag, 27. März 2006, 15:30–18:00, P1
Calibration of optical tweezers using a piezo-electric translation stage — •Simon F. Tolic-Norrelykke1,2, Erik Schaeffer 3, Francesco S. Pavone 2, Jonathon Howard3, Frank Julicher1, and Henrik Flyvbjerg4,5 — 1Max Planck Institute for the Physics of Complex Systems, Nothnitzer Strasse 38, 01187 Dresden, Germany — 2European Laboratory for Non-linear Spectroscopy, via Nello Carrara 1, 50019 Sesto Fiorentino (Fl), Italy — 3Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany — 4Biosystems Department and Danish Polymer Centre, Riso National Laboratory, DK-4000 Roskilde, Denmark — 5Isaac Newton Institute for Mathematical Sciences, Cambridge, U.K.
We use a piezo-electric stage that is commonly found in optical tweezers setups to calibrate the x-y-z position detection system of optical tweezers. By driving the piezo stage harmonically, a known motion is added to a trapped object’s Brownian motion. This motion produces a sharp spike in the power spectrum, and this spike serves as a “scale-bar” and thus enables the calibration of the detection system. It is not necessary to know friction coefficients, hence neither the viscosity, or temperature of the surrounding fluid. Force calibration is possible if the local temperature is known. We test the method experimentally and find it to be accurate to within 0.5% and have a relative precision better that 1% for both the position and force calibration. The main advantages of this method are the low level of instrumentation required, that it can be applied in situ, and that it is both precise (small error-bars) and accurate (returns true value).