In a device for ambulatory wearing by the patient containing a pump for delivery of injection fluid or for removal of analysis fluid, the drive motor for the mechanically driven pump system is a Lavet-type stepper motor of small size designed for having a high mechanical power and low peak current requirement. Using this Lavet-type motor for syringe-type or peristaltic preferably patch-type pumps high infusion rates needed for e.g. bolus insulin injection or the delivery of therapeutic antibodies are achieved, and important safety features can be easily and reliably controlled, manufacturing costs get significantly reduced, and the overall size and weight of the device becomes smaller, for patient convenience.
