NEEDLE RETRACTION MECHANISM WITH CONTROLLED RETRACTION SPEED

摘要

A needle retraction mechanism includes a hollow handle defining a cavity, a needle hub assembly movably disposed in the handle, a biasing mechanism to move the needle hub assembly from an extended position to a retracted position and a latch to hold needle hub assembly in the extended position against the bias of the biasing mechanism. The needle hub assembly includes a flexible stopper at its proximal end that creates an air tight seal with the inner wall of the handle. This allows a vacuum to be created between the proximal end of the handle and the flexible stopper when the needle hub is moved from the retracted position to the extended position. The configuration of the flexible stopper allows it to change the amount of frictional force created between the inner wall of the handle and the flexible stopper when the device is at different elevations. At high elevations less frictional force exists between the inner wall of the handle and the flexible stopper while at low elevations greater frictional force exists between the inner wall of the handle and the flexible stopper.