Agitation of magnetic beads by multi-layered flat coils

The beads were magnetically agitated inside a droplet by changing the external magnetic-field distribution. We used both the multi-layered flat coils and the permanent magnet for keeping enough magnetic force for driving the beads and for forming a non-uniform magnetic-field. The temperature in the well solution was kept below 35 °C at the appropriate agitation drive currents by adding a heat-sink foil between the flat coils. The agitation performance was evaluated by using an enzymatic reaction. The reaction efficiency increased linearly with increasing reaction time and was more than four times higher with agitation than without agitation.