Device with a Lavet-type motor

A device for ambulatory wearing by a patient, comprising:

• a pump for delivery of injection fluid including a pump system with a fluid reservoirs;
• and
• a Lavet-type stepper motor to drive the pump system, the stepper motor including a rotor with a magnet made of high energy density magnetic material which is a magnetic alloy including a rare earth element,
• wherein when the stepper motor successfully performs a step, there is an induced current of opposite polarity with respect to applied voltage pulse, and when the stepper motor does not successfully perform the step, there is an induced current that is of a same polarity with respect to the applied voltage pulse,
• wherein a maximum speed of the stepper motor is restricted by a design of the stepper motor,
• wherein a maximum torque of the stepper motor is restricted by a design of the stepper motor,
• wherein the injection fluid includes therapeutic proteins like insulin or antibodies.