Patent ID: 7846132

Claim:
A cannula insertion device comprising: a housing defining an opening for receiving therethrough a cannula and further defining a channel; a cannula forming a lumen, the cannula adapted for sliding movement within the housing from a retracted position to an extended position in which the cannula extends into a body tissue, wherein: when the cannula is in the retracted position, the lumen is located remotely from the channel and the channel is in fluidic communication with the opening; and when the cannula is in the extended position, the lumen is in fluidic communication with the channel to deliver a fluid from the channel through the cannula into the body tissue; a plunger for driving the cannula from the refracted position to the extended position; a needle disposed in the lumen when the cannula is in the retracted position; a ramp body comprising a ramp surface in sliding contact with the plunger; and a drive spring, wherein the drive spring applies a torsion force to the ramp body for driving the cannula from the retracted position to the extended position.