Patent ID: 7963939

Claim:
An injection device comprising: a barrel disposed to contain a liquid solvent and a solid solute, comprising a lateral wall having an interior surface, a plunger end, an opposed delivery end, and a chamber defined within the interior surface between the plunger end and the delivery end; a hollow needle coupled to the barrel at the delivery end of the barrel, having a pointed discharge end, an opposed entry end, and a bore extending from the entry end to the pointed discharge end; a plunger which is slidably engaged with the interior surface of the barrel at the plunger end of the barrel; a barrier disposed within the chamber of the barrel, which is disposed to separate the liquid solvent and the solid solute; means for opening the barrier so as to enable fluid communication between the liquid solvent and the solid solute; and a flow path member disposed between, on one hand, the liquid solvent and the solid solute, and on the other hand, the hollow needle, which flow path member establishes a flow path along which a solution generated by blending of the liquid solvent and the solid solute may flow responsively to urging of the plunger towards the hollow needle, wherein the flow path member comprises an axially expansible, flexible member having a helical configuration including a forward axial surface having a groove tracking the helical configuration, a rear axial surface, a first helical turn, and a last helical turn; and the flow path member is compressible to form a cylindrical member having a continuous cylindrical outer surface, a top surface formed by the forward axial surface of the first helical turn, and a bottom surface formed by the rear axial surface of the last helical turn; and the flow path passes through the cylindrical member and is defined by the intersection of the groove and the rear axial surface and when passing through the cylindrical member, the flow path is exposed to the exterior of the cylindrical member only at the top surface and the bottom surface.