Abstract: The present invention provides a method of detecting the presence of at least one target analyte 14 in a fluid sample 9, as well as linear array devices 5 fo use in the method. In the method is provided a linear array device 5 comprising an elongate substrate 6 having a linear array of different spatially addressable probe moieties 7 anchored thereto. The device 5 is contacted with the sample under conditions conducive to selective binding with a probe moiety which is specific therefor. The device 5 is drawn past reading apparatus 3 for providing linear spatial address data for said probe moieties 7 and so as to detect signal indicating the presence of bound analyte 14, and the address data is correlated with bound analyte signal data so as to determine the linear spatial address of any probe moiety having analyte bound thereto, thereby to determine the identity of said probe moiety and thence indicate the presence or absence of target analyte 14.

Abstract: A detector for sensing the presence of a magnetic tag having an axis of easy magnetization, which comprises (1) either (i) a magnet or (ii) a pair of magnets arranged in magnetic opposition, the magnet or magnets being disposed so as to define a spatial region through or across which the magnetic tag is, in use, passed, the disposition of the magnet(s) and the resultant magnetic field pattern being such as to cause a change in polarity of the magnetization of the magnetic tag in the course of its passage through a magnetic null within the spatial region; and (2) a receiver coil or coils positioned above and in proximity to one pole of the magnet (where a single magnet is employed), or positioned between the pair of magnets (where two magnets are employed) and arranged to detect magnetic dipole radiation emitted by a magnetic tag as it passes through the magnetic null with the easy axis of magnetization of the tag oriented in the direction of travel.