US 5,232,664 A · Liquid dispenser

Abstract

A dispenser 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 linked to a dispense chamber via a check valve, the two chambers preferably being in the form of syringes. An outlet line leading from the dispense chamber to a nozzle includes a delay check valve (preferably a ball inside a cylindrical chamber) 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 from the reservoir chamber creates reverse flow in the nozzle and causes a hanging drop of liquid at the tip of the nozzle to be withdrawn.

Claims30

Dependent claims

A liquid dispenser comprising:

a reservoir chamber;
a dispense chamber;
a supply channel connecting the reservoir chamber and the dispense chamber, the supply channel containing a means for providing a resistance to flow between the reservoir chamber and the dispense chamber;
a dispense channel extending from the dispense chamber and terminating at an orifice for delivering a fluid from the liquid dispenser, the dispense channel containing a delay check valve means, the delay check valve means operative to allow a continuous flow of liquid from the dispense chamber and out through the orifice and to allow a predetermined volume of liquid to flow from the orifice and into the dispense chamber, shutting off flow of liquid towards the dispense chamber after the predetermined volume of liquid has entered the dispense chamber;
and
means to expel liquid from the dispense chamber through the dispense channel.

3 more elements

Dependencies are inferred from the claim text.

Liquid dispenser

Life of this patent

Liquid dispenser

Life of this patent

Abstract

Claims30