A bubble entrapment device has a cylinder, a plunger, and a centre tube. Threads on the centre tube engage threads of the cylinder and the plunger respectively. The device has a chamber with a tapered end configuration provided by the fact that the cylinder has a funnel-shaped base and the plunger has a corresponding concave shape. Rotation of the tube handle while holding the cylinder causes the chamber to change in volume, but the chamber outlet remains in the centre of volume throughout. During use, the chamber will be retained at or near maximum volume, but near end of dose this may be reduced so that residual liquid is expelled. This is particularly advantageous for applications such as neo natal delivery systems, where dose volumes are small.
