This invention relates generally to improvements in liquid infusion devices of the type used for controlled administration of medication to a patient. More specifically this invention relates to an improved medication infusion device having a space-efficient drive system. Specifically, there is disclosed a liquid infusion device, comprising a flexible drive tape having a plurality of holes aligned essentially linearly along the length of the drive tape, the plurality of holes spaced apart at a fixed increment； a drive shaft comprising at least one gear, the gears comprising a plurality of teeth that align and engage the holes in the flexible drive tape, a piezoelectric motor for advancing the flexible drive tape； a plunger attached to or in communication with at least one end of the flexible drive tape, and a cartridge for containing a liquid medication for receiving the plunger and expelling the liquid medication upon movement of the plunger in the cartridge, wherein the piezoelectric motor turns the drive shaft, thereby advancing the flexible drive tape and driving the plunger into the cartridge in an increment correlating to the fixed increment between holes.
