Note: A portable magnetic field for powering nanomotors, microswimmers, and sensors

Time-varying magnetic fields are the basis of many modern devices and are used to remotely power and steer nanomotors and microswimmers. However, the required magnetic field setups are often prohibitively bulky laboratory setups that require technical expertise to build, modify, or relocate. Here we introduce a programmable magnetic field setup based on consumer electronics that is both portable and easy to use. The complete setup consists of a laptop computer, an audio amplifier, and audio inductors and was used to create complex magnetic fields in 0.5-2000 Hz frequency range with up to 4.7 mT amplitude. The setup was also validated using an example application, namely a rotating magnetic field with a constant amplitude and fixed frequency, which has applications in powering nanosensors and microswimmers. (C) 2013 AIP Publishing LLC.