TY - JOUR A1 - Paust, Tobias A1 - Neckernuss, Tobias A1 - Mertens, Lina Katinka A1 - Martin, Ines A1 - Beil, Michael A1 - Walther, Paul A1 - Schimmel, Thomas A1 - Marti, Othmar T1 - Active multi-point microrheology of cytoskeletal networks JF - Beilstein Journal of Nanotechnology PY - 2016/// VL - 7 SP - 484 EP - 491 SN - 2190-4286 DO - 10.3762/bjnano.7.42 PB - Beilstein-Institut JA - Beilstein J. Nanotechnol. UR - https://doi.org/10.3762/bjnano.7.42 KW - cytoskeleton KW - intermediate filaments KW - lock-in technique KW - microrheology KW - optical tweezers N2 - Active microrheology is a valuable tool to determine viscoelastic properties of polymer networks. Observing the response of the beads to the excitation of a reference leads to dynamic and morphological information of the material. In this work we present an expansion of the well-known active two-point microrheology. By measuring the response of multiple particles in a viscoelastic medium in response to the excitation of a reference particle, we are able to determine the force propagation in the polymer network. For this purpose a lock-in technique is established that allows for extraction of the periodical motion of embedded beads. To exert a sinusoidal motion onto the reference bead an optical tweezers setup in combination with a microscope is used to investigate the motion of the response beads. From the lock-in data the so called transfer tensor can be calculated, which is a direct measure for the ability of the network to transmit mechanical forces. We also take a closer look at the influence of noise on lock-in measurements and state some simple rules for improving the signal-to-noise ratio. ER -