Filtration device for assays

A device for analyzing a biological fluid sample comprising:

• a filter configured to filter the biological fluid sample resulting in a filtrate comprising a target analyte;
• an exposed surface having a sensor area, wherein the sensor area comprises a sensor coated with a chemical specific for the target analyte;
• a sedimentation capillary disposed above the sensor area having an outlet in proximity to the sensor area;
• a dried reagent at the top of the sedimentation capillary, wherein the reagent comprises magnetic particles functionalized to react with the target analyte;
• a delivery capillary having an inlet in proximity to the filter and an outlet fluidically connected to the sedimentation capillary, wherein the delivery capillary is configured to deliver the filtrate to the sensor area before the filtrate flows up the sedimentation capillary to the dried reagent;
• and
• a bulking agent, wherein the bulking agent is configured to dry the magnetic particles, and wherein the bulking agent is configured to solubilize upon contact with the filtrate.