Rapid magnetic biosensor

A method, comprising:

• providing magnetic particles to a first region of a reaction chamber, the reaction chamber comprising a sensor surface and a second region, the sensor surface having an analyte-specific probe or an analyte-analogue, wherein the first region and the second region are both outside the sensor surface at opposite ends of the reaction chamber and in a plane of the sensor surface, the sensor surface located between the first region and the second region, and wherein a first portion of the magnetic particles comprises an analyte and a second portion of the magnetic particles do not comprise the analyte;
• applying, during a first period of time, a first magnetic field gradient using a first magnet, wherein the first magnet is outside the reaction chamber below the plane of the sensor surface, wherein the first magnetic field gradient has a gradient with a component perpendicular to the sensor surface and directed toward the second region, wherein the first magnetic field gradient removes all the magnetic particles from the first region laterally over the sensor surface above a plane of the sensor surface, wherein some or all of the first portion of the magnetic particles becomes bound to the sensor surface, and wherein the second portion and any remaining magnetic particles of the first portion move to the second region;
• subsequent to the first period of time, applying, during a second period of time, a second magnetic field gradient within the reaction chamber using a second magnet, wherein the second magnet is outside the reaction chamber below the plane of the sensor surface, wherein the second magnetic field gradient has a component essentially parallel to the sensor surface, wherein the second magnetic field gradient removes all the magnetic particles from the second region laterally over the sensor surface above a plane of the sensor surface, wherein some or all of the remaining first portion of the magnetic particles becomes bound to the sensor surface, wherein the second portion and any still remaining first portion of the magnetic particles move to the first region, and wherein the second period of time starts after the first period of time;
• and
• detecting the first portion of magnetic particles bound to the sensor surface, wherein the first and second magnets are confined to the ends of the reaction chamber such that the first and second magnets do not overlap the sensor surface and no magnet is located directly beneath the sensor surface.