Single molecules detection system of optical tweezers

Using optical tweezers we have developed a biomechanical detection system for single molecules detection. This system can control the sample bead which is used as the handle of single molecules with nanometer precision, it also can make quantitative measurements of displacement with nanometer resolution, and measure the Pico-Newton force involved in the dynamical process of the movement of a single biomolecule. We combined two Donut-Mode optical traps with two high-precision observation setups in this system. Experiments described in this paper demonstrate the performance of the system. In our experiments, we monitored the Brownian motion of polystyrene beads, as a result we can calculate the optical-trap stiffness. In summary, the system can be used in the research of the dynamical motion of a single biomolecule.