2010

Magnetic actuation has emerged as a useful tool for manipulating particles, droplets and biological samples in microfluidics. A plar coil is one of the suitable candidates for magnetic actuation and has the potential to be integrated in digital microfluidic devices. A simple model of microcoils is needed to optimize their use in actuation applications. This paper first develops an alytical model for calculating the magnetic field of a plar microcoil. The model was validated by experimental data from microcoils fabricated on printed circuit boards (PCB). The model was used for calculating the field strength and the force acting on a magnetic object. Filly, the effect of different coil parameters such as the magnitude of the electric current, the gap between the wires and the number of wire segments is discussed. Both alytical and experimental results show that a smaller gap size between wire segments, more wire segments and a higher electric current can increase both the magnitude and the gradient of the magnetic field, and consequently cause a higher actuating force. The plar coil alyzed in the paper is suitable for applications in magnetic droplet-based microfluidics.