LIQUID DISPENSER

摘要

2116101 9306449 PCTABS00021 A dispenser (10) which can deliver precise small amounts of a liquid is disclosed. The dispenser is particularly suited to applying reagents in a biological test such as an immunoassay. It includes a reservoir chamber (12) linked to a dispense chamber (11) via a check valve, the two chambers preferably being in the form of syringes (110, 120). An outlet line leading from the dispense chamber (11) to a nozzle (14) includes a delay check valve (preferably a ball inside a cylindrical chamber (135)) which allows continuous outward flow, but shuts off flow in the reverse direction after allowing a predetermined volume to pass. The process of refilling the dispense chamber (11) from the reservoir chamber (12) creates reverse flow in the nozzle (14) and causes a hanging drop of liquid at the tip of the nozzle (14) to be withdrawn.