Patent ID: 8419691

Claim:
A method for a time controlled micro-dosing of a liquid from a liquid reservoir, the method comprising: receiving the liquid reservoir with a structure wherein the structure is portable; securing the liquid reservoir to the structure; providing a drive unit with a first end and a second end, and having a drive motor, wherein the drive unit comprises an anti-rotation element that extends radially outward from the periphery of the drive unit through a longitudinal slot formed through the structure and through a sleeve coupled to the structure; connecting the second end of the drive unit to a displacement piston disposed within the liquid reservoir; activating the drive motor; displacing the drive unit and drive motor with respect to the structure towards the displacement piston in an axial direction; moving the displacement piston axially within the liquid reservoir; and micro-dosing the liquid from the liquid reservoir, wherein displacement in the axial direction of the drive unit and drive motor is effected by rotating with the drive unit a rotatable member coupled to the first end of the drive unit, the rotatable member having an outer thread which engage an inner thread disposed on the sleeve, and arranged between the drive unit and the second member is the anti-rotation element preventing rotation of the drive unit relative to the sleeve and permitting axial displacement of the drive unit relative to the sleeve.