Low-cost credit card-based microfluidic devices for magnetic bead immobilisation

We report a simple low-cost magnetic microfluidic device for magnetic bead separation and immobilisation. One dimensional arrays of localised high magnetic field gradients are constructed at the interfaces between regions magnetised with opposing polarities on the magnetic Fe2O3 composite stripes of credit cards. The localised high magnetic field gradients are employed to trap magnetic beads on the surface of the magnetic stripe, without the need for external magnetic components. A magnetic card writer was used to deterministically pattern the magnetic stripes of credit cards to define arrays of magnetic reversals. The fabrication of the device is based on PDMS to credit card bonding of simple flow channels. Experimental results demonstrate that magnetic beads can be captured with efficiencies of 85, 67 and 27 % at flow rates of 25, 50 and 100 mu L min(-1), respectively. The results show that the credit card-based magnetic separator might offer an efficient, simple, low-cost alternative to traditional microfluidic magnetic separators for applications such as immunomagnetic cell separation.