Fig. 4 | Nature Communications

Fig. 4

From: Real-time magnetic actuation of DNA nanodevices via modular integration with stiff micro-levers

Fig. 4

Actuation of micro-lever. a Images of the micro-lever rotated over 360 degrees at 1 Hz shown rotating 90° every fourth of a second corresponding to 0, 0.25, 0.5, 0.75, and 1 s. Scale bar is 1 μm. b Levers were actuated at four frequencies 0.1, 0.5, 1, and 2 Hz (black, blue, green and red) with rotation traces overlaid for 17 different beads. Inset: Representative tracking of one micro-bead attached to the micro-lever. c External in-plane magnetic fields were applied in four orthogonal directions to reorient the lever. d Representative tracking of bead fluctuations in an in-plane external magnetic field oriented in the +y direction with strengths 10, 20, 30, 40, 50 and 100 Oe (black, blue, green, red, yellow, and cyan). The asterisk indicates the origin. The standard deviation of the e in-plane and f out-of-plane fluctuations of 13 lever arms, each tested at four orthogonal orientations at every field strength (each color indicates a different lever arm-bead construct, and error bars indicate s.d. over four orientations). Insets show the average and standard deviation of the e in-plane and f out-of-plane angular fluctuations across all 13 micro-levers (black trace), and the red traces represent the average of the four longest micro-levers. g The in-plane angular distribution of the bead shown in purple in e and f shows greater confinement at 100 Oe (cyan in d) compared to 10 Oe (black in d). h The free energy landscape assuming Boltzmann weighting was calculated from the probability distributions for the same bead at 10 Oe and 100 Oe. i The torque on the same magnetic bead was also calculated at 10 Oe (purple circles) and 100 Oe (purple diamonds) by differentiating the free energy landscapes

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