A device for detecting the presence of an antigen including (1) a cell
having antibodies which are expressed on the surface of the cell and are
specific for the antigen to be detected, where binding of the antigen to
the antibodies results in an increase in calcium concentration in the
cytosol of the cell, the cell further having a emitter molecule which, in
response to the increased calcium concentration in the cytosol, emits a
photon; (2) a liquid medium for receiving the antigen and in which the
cell is immersed; and (3) an optical detector arranged for receiving the
photon emitted from the cell.
