Thermal modulation of nanomotor movement.

Motion control is essential for various applications of man-made nanomachines. The ability to control and regulate the movement of catalytic nanowire motors is illustrated by applying short heat pulses that allow the motors to be accelerated or slowed down. The accelerated motion observed during the heat pulses is attributed primarily to the thermal activation of the redox reactions of the H(2)O(2) fuel at the Pt and Au segments and to the decreased viscosity of the aqueous medium at elevated temperatures. The thermally modulated motion during repetitive temperature on/off cycles is highly reversible and fast, with speeds of 14 and 45 microm s(-1) at 25 and 65 degrees C, respectively. A wide range of speeds can be generated by tailoring the temperature to yield a linear speed-temperature dependence. Through the use of nickel-containing nanomotors, the ability to combine the thermally regulated motion of catalytic nanomotors with magnetic guidance is also demonstrated. Such on-demand control of the movement of nanowire motors holds great promise for complex operations of future manmade nanomachines and for creating more sophisticated nanomotors.