An infusion system comprises a disposable wearable infusion device having a body arranged to be adhered to a patients skin and a reservoir for holding a liquid medicament to be infused into the patient through a cannula extending from the device body to beneath the patients skin. The system further includes a cannula driver arranged to be detachably joined with the infusion device and including the cannula. The cannula driver is arranged to drive the cannula into a deployed position extending from the device body to beneath the patients skin. The cannula driver includes a release mechanism that separates the cannula driver from the infusion device after the cannula is in the deployed position.
