A device for detecting at least one analyte (and in some embodiments two, three, or four or more different analytes) in a liquid sample generally comprises (i) a support having a chamber for receiving a biological fluid therein, wherein said chamber is an elongate chamber having a length axis; (ii) a carrier or agitator in said elongate chamber, said carrier or agitator having opposite end portions and a side portion, the carrier or agitator dimensioned to travel in said chamber along said length axis and/or permit said liquid sample to flow in the chamber therearound, either (or both) thereby agitating the liquid sample; and (iii) at least one anti-analyte antibody coupled to either the carrier and/or the chamber side wall.