Refill system for medical device using jet delivery principle

A fluid injection device of the type that injects fluid in a skin of a patient by ejecting a jet stream of fluid, the fluid injection device comprising:

• a housing having an outlet nozzle, the housing defining a fluid collection chamber for collecting fluid to be ejected, the fluid collection chamber being in fluid communication with the outlet nozzle;
• a coupler for coupling the fluid injection device with a fluid container;
• a piston head configured to be received in the housing, the piston head being movable in the housing to increase and decrease a volume of the fluid collection chamber;
• a piston rod, coupled to the piston head and having an internal flow channel,
• wherein the flow channel of the piston rod extends with respect to said piston rod for penetration of the fluid container, so as to provide a flow path from said fluid container to said piston head, and
• wherein the piston head includes a valve that has an open (O) and closed (C) position, the valve being made of an elastically deformable material and comprising a radial flow channel that provides a flow path from the piston head to the fluid collection chamber, the radial flow channel of the valve being open when the piston head and piston rod are moved in a direction that increases the volume of the fluid collection chamber and the radial flow channel of the valve being closed by an elastic deformation of the elastically deformable valve material when the piston head and the piston rod are moved in a direction that decreases the volume of the fluid collection chamber.