Abstract: This invention relates to microfluidic apparatus for reading, writing and sorting magnetic tags attached to chemical and biological molecules and other entities. We describe apparatus for separating chemical or biological molecules or moieties each individually attached to a MBM tag miniature multi-bit magnetic tag capable of adopting a plurality of remanent magnetic configurations corresponding to binary information, the apparatus comprising: at least one input for said tagged molecules or moieties; at least two outputs for said tagged molecules or moieties; a microfluidic flow channel incorporating: magnetic readers to read said binary information; magnetic writers to write said binary information; and a switch to direct said tagged molecules or moieties to a selected said output responsive to said binary information. The invention also relates to planar multibit magnetic tags suitable for use with such apparatus.

Abstract: This invention relates to microfluidic apparatus for reading, writing and sorting magnetic tags attached to chemical and biological molecules and other entities. We describe apparatus for separating chemical or biological molecules or moieties each individually attached to a MBM tag miniature multi-bit magnetic tag capable of adopting a plurality of remanent magnetic configurations corresponding to binary information, the apparatus comprising: at least one input for said tagged molecules or moieties; at least two outputs for said tagged molecules or moieties; a microfluidic flow channel incorporating: magnetic readers to read said binary information; magnetic writers to write said binary information; and a switch to direct said tagged molecules or moieties to a selected said output responsive to said binary information. The invention also relates to planar multibit magnetic tags suitable for use with such apparatus.

Abstract: A magnetic element comprises a closed loop of ferromagnetic material having an even number of magnetic domains of opposite sense. The magnetisation within the domains is in a circumferential direction, and the domains have leading and trailing walls extending from the inside to the outside of the loop. The magnetic element has a geometry such that there are at least two stable equilibrium domain configurations in which the domain walls are confined in predetermined portions of the loop and wherein the element is switchable between the stable configurations upon the application of a external magnetic field.

Abstract: A magnetic element comprises a closed loop of ferromagnetic material having an even number of magnetic domains of opposite sense. The magnetisation within the domains is in a circumferenial direction, and the domains have leading and trailing walls extending from the inside to the outside of this loop. The magnetic element has a geometry such that there are at least two stable equilibrium domain configurations in which the domain walls are confined in predetermined portions of the loop and wherein the element is switchable between the stable configurations upon the application of a external magnetic field.