Micro dosing device and method of assembly of the micro dosing device

A micro dosing device for delivering a metered dose of a therapeutic fluid, the micro dosing device comprising:

• a dosing unit comprising a dosing chamber;
• a distal connector unit at a distal end for fluidly connecting a medicament container to the dosing chamber;
• a proximal connector unit at a proximal end for fluidly connecting the dosing chamber to a medicament delivery member;
• and
• an activation mechanism,
• wherein the dosing chamber is configured to receive a therapeutic fluid,
• wherein the micro dosing device comprises a first dosing mechanism, the dosing mechanism providing an exactly metered dose of fluid to be expelled by the medicament delivery member when triggered by the activation mechanism,
• wherein the activation mechanism comprises a piston rod liquid tightly slidably fitted in a piston guide wherein the piston rod has a predefined rod volume, so that when actuated, the piston rod moves into the dosing chamber, wherein the displacement volume of the piston rod defines the metered dose volume to be expelled upon actuation and displacement of the piston rod into the dosing chamber, and
• wherein the activation mechanism comprises one or more lateral arms extending respectively along a lateral side of the activation button, wherein the lateral arms each comprise a ledge at their terminal portion, the ledge being configured to engage with a respective recess of a corresponding lateral side of the dosing unit.