Materials needed:

  • Dynabeads (ThermoFisher) of 2,7 um in diameter (6,8·10^8 particles/ml)
  • Distilled water
  • 3-copper Helmholtz coil system
  • Oscilloscope
  • Optical microscope with a Zeiss 20x magnification
  • Laboratory power supply PS 405D operating at a constant tension of 14.4
  • 2x40 W Stereo Amplifier Kit 6-18 V/DC (Output frequency in the range of 20 Hz – 20 kHz)
  • TeslaMeter 2000
  • SPOT Digital Camera
  • DAQmx card (National Instruments NI USB-6259)
  • Computer equiped with the following software: LabVIEWTM, Micromanager, FiJi.
  • Circular glass slides of 9 mm radius
  • Support for the glass slide
  • Pipettes and tips

Procedure:

  1. Open the LabVIEWTM script and set the input parameters (amplitude, frequency, and phase of the three signals).
  2. Clean a glass slide and mount it to the support for the microscope
  3. Prepare a 1:10 dilution (concentration of 6,8 * 107 ml-1) of the Dynabead® solution.
  4. Drop 50 μl of this solution on the glass slide.
  5. Turn on the amplifiers and the digital-analog converter.
  6. (Optional) Turn on the oscilloscope in order to visualize the physical intensity signal in the coils.
  7. Place the sample on the sample holder inside the 3-coil system.
  8. Make sure that the sample is centered with respect to each of the three pairs of coils.
  9. Run the LabVIEWTM script.
  10. Start the measurement.
  11. Record a video by turning on the camera and setting the recording parameters (contrast, frames per second, ...) in the software Micromanager.
  12. Combine the frames to generate a video using the software FiJi.