Fast and Accurate Photodiode-Based Detection of Multiple Trap Optical Tweezers with Crosstalk-Elimination

Abstract

Multiple trap optical tweezers have proven instrumental for a variety of exciting biophysical discoveries, e.g., from shedding light on molecular motor mechanisms to revealing intricate details of DNA-protein interactions. This ‘second’ generation of optical tweezers allows for advanced trapping geometries beyond single traps, however, these increased manipulation capabilities typically come at the price of more challenging position and force detection. The accuracy of position and force measurements is often compromised by crosstalk between the detected signals, this crosstalk leading to systematic and significant errors on the measured forces and distances. We developed an easy-to-implement simple method that enables simultaneous three-dimensional tracking of several individual objects in dual trap optical tweezers [1] and multi-trap holographic optical tweezers [2,3]. The method is based on spatial filtering and is highly compatible with standard back-focal-plane photodiode-based detection offering unrivaled temporal and spatial resolution with minimal crosstalk. This fast and accurate photodiode-based detection offers distinct advantages over camera-based solutions and opens the possibility for a variety of new biophysical assays. The reported technique significantly improves the accuracy of force-distance measurements, e.g., of single molecules, and hence provides much more scientific value for the experimental efforts.Publications:[1] D. Ott, S.N.S. Reihani, & L.B. Oddershede, “Crosstalk elimination in the detection of dual-beam optical tweezers by spatial filtering,” Review of Scientific Instruments,(2014).[2] D. Ott, S.N.S. Reihani, & L.B. Oddershede, “Simultaneous three-dimensional tracking of individual signals from multi-trap optical tweezers using fast and accurate photodiode detection,” Optics Express (2014).Filed Patent:[3] L.B. Oddershede, D. Ott, S.N.S. Reihani, “A detection system for an optical manipulation system for manipulating micro-particles or nano-particles of a sample by means of at least two optical traps,” PA 2014 70097, Denmark.