Page 10 - Industrial Technology EXTRA 26th October 2020

ELECTRIC MOTORS...

Considerations for miniature

motors in medical pumps

Miniature motors used in medical pumps have very specific requirements, and the
selection of the right product for a given task is far from trivial. Dr Norbert Veignat,

PhD of Portescap looks at the design considerations, and the advantages and
disadvantages of each motor option

he development of small, portable
infusion pumps heralded a new
chapter in medical care. Capable of
Tdelivering carefully metered and
timed doses of medicine, they opened up new
possibilities for delivering continuing care at
the patient’s home. In addition, ambulatory
infusion pumps powered by batteries have
given patients even more freedom, delivering the
likes of insulin, nutritive supplements and anti-
cancer drugs.
The use of such infusion pumps mean patients
can be safely discharged from hospital for extended equipment. So is efficiency, which is especially
periods of time, making life a lot less restrictive and important in battery powered equipment, providing
significantly increasing quality of life. It goes longer time between charging. Further, the patient
without saying, of course, that the highest levels of should not be disturbed by the pump noise, either
reliability are required for these systems, placing at rest or in social surroundings, requiring the use of
stringent requirements on the key components a very quiet motor.
involved. While the primary goals of the motor are clear,
For the design engineer, a key area of focus is the choice of product is often less so. The design
the electric motor which drives the pump. engineer must select from a number of different
Performance (in particular the ability to deliver the technologies, where each might offer decisive
required torques over a speed range), size and advantages in some areas of the performance
lifespan are all prime considerations. specification but imply compromises in others.
Miniaturisation is often crucial to assure The choice of miniature motor for infusion pump
convenience for the user, particularly with portable products comes down to three major technologies:

October 2020 • INDUSTRIAL TECHNOLOGY EXTRA • p10