Magnetic immunosensor with trench configuration and method of use

A point-of-care magnetic immunosensing device, comprising:

• a cartridge housing comprising a base;
• a sample chamber comprising a sample inlet for receiving a sample;
• a conduit in fluidic communication with the sample chamber;
• a sensor chip located within the conduit and formed on the base of the cartridge housing, wherein the sensor chip comprises a single sensing electrode comprising:
• a) a silicon wafer, b) a single trench formed in the silicon wafer, wherein the single trench has a length of from 10 to 500 μm, c) an insulating oxide layer formed on the silicon wafer, d) metal layers formed on the insulating oxide layer, e) a photodefinable polyimide formed on the metal layers, and f) electrode openings formed into the photodefinable polyimide exposing portions of the metal layers and forming a two-dimensional array of microfabricated electrodes formed at a bottom of a single trench;
• a dissolvable dry matrix comprising magnetically susceptible beads, wherein the matrix is configured to dissolve in the sample fluid and wherein the dissolvable dry matrix is located in the sample chamber or the conduit;
• and
• a permanent high-field magnet for retaining at least a portion of said beads in said trench, wherein the permanent high-field magnet is formed in the base abutting a bottom of the sensor chip;
• and
• a pump for moving the sample from the sample chamber through the conduit to the sensing electrode,
• wherein the two-dimensional array of microfabricated electrodes comprises a line of microelectrodes in the single trench.