Magnetic actuation for microfluidics based on ferrofluid droplets

In this paper, we report the dynamic behavior of a ferro fluid droplet in time-dependent magnetic fields. The magnetic field was generated by an array of planar coils, which were fabricated on a double-sided printed circuit board (PCB). The permanent magnetic moment of the ferro fluid droplet was created using the field of a pair of permanent magnets. The motion of the ferro fluid droplet is further aligned with the permanent magnetic field of a pair of planar coils. Two other in serial connected planar coils on the other side of the PCB displaces the droplet along a line. The direction of the droplet motion can be controlled by switching the electric current passing through them. Different paprameters affecting the motion of the ferro fluid droplet such as the droplet size, the viscosity of the surrounding medium, the electric current, and the switching frequency were investigated.