Magnetic Avalanche Digital Detector for Biosensor Applications

Here we present a design for a magnetic avalanche digital detector (MADD) based on a ferromagnetic ring geometry. The sensor has several advantages over previous designs [Megens, M., et al., 2005]. Firstly it operates in an entirely digital manner, rather than relying on reversible deformations within a ferromagnetic element as has been proposed for use in other single bead sensors [Miller, M., et al., 2002]. Secondly, the switching of ferromagnetic rings is known to be simple, fast and repeatable, and is therefore ideal for a precision detector. Finally, the switching fields of ring structures are easily manipulated by changing geometric parameters, offering the potential to "tune" a ring sensor to differentiate between different types of tags.