Fluid delivery device and method

A fluid delivery injector comprising:

• a syringe having:
• a barrel with a peripheral wall having a longitudinal axis and a distal end wall;
• a plunger movable with the barrel parallel to the longitudinal axis towards and away from the end wall;
• at least one hollow needle anchored at its proximal end to the plunger and extending parallel to the axis towards the end wall with the needle contained within the barrel;
• a fluid retention reservoir defined in at least the barrel;
• the fluid retention reservoir in fluid communication with inlet port of the needle when a volume confining pressure is applied to the fluid;
• an energy storage device is provided for retaining the plunger in a default position spaced from the end wall with the at least one hollow needle contained within the barrel and for returning the needle to the default position once the pressure is released from the plunger;
• whereby the needle is projected beyond the end wall of the barrel only when pressure is applied to the plunger in the direction of the distal end wall;
• wherein the plunger includes a closed cavity with an elastomeric membrane forming an expandable chamber in communication with the hollow needle and the fluid retention reservoir is formed within the barrel between the plunger and the end wall and is in communication with the expandable chamber through conduits defined in the plunger.