Flow-through
assay reaction chamber (6) of cassette has back and forth liquid mixing in
narrow gap (G) over array of capture agent (S), with net flow advance to waste confinement (19), produced by reversible pumps (3 or 12), operable with rolling diaphragm action with at least limited elastic
recovery that advance sample or buffer liquids through conditioning paths (4A, 8, 8′, 9, 14, 15, 15′) before reaching the
reaction chamber (6). A single pump produces accurate flow control, liquid conditioning, e.g., liquefying dry
reagent from internal surfaces of flow-dividing material (14a, 15A, 15A′, e.g.
open cell foam or
frit), heating (4A), and
air bubble removal (8, 8′, 9), as well as replenishment of
reagent while accomplishing mixing within the flow-through
reaction chamber (6). Lower
viscosity buffer liquid is arranged to propel higher
viscosity reagent, the flow-dividing
storage material preserving reagent concentration. A
blister pack (11) acts as a reversible pump (12) in producing accurate forward and backward flows with the net flow advance. Cascaded bubble traps (8, 9) on the cassette render the
system tolerant of minor pumping error during cassette priming.