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Miniature Motors for Medical Devices and Dispensing Systems

January 11, 2016

Health care safety is now a top priority and concern among health care practitioners and consumers. In today’s medical devices marketplace, the demand for reliable and safe medical devices and equipment comes not only from the clinical end user, but also from informed patient consumers.

For those involved in the development and manufacture of medical devices and equipment, the demand for safety and quality brings with it new and exciting challenges. How does one build equipment and devices that meet the hundreds of stringent needs of the clinical end user and health care consumer? How does one decide with whom to partner in this far-reaching world of device and equipment manufacturing?

Care givers constantly need products that assist them in achieving the best possible clinical outcomes for their patients. Where do we get motion control solutions, i.e. motors for medical OEMs capable of navigating the demands of the health care industry?

Motors for Medical OEMs:- Medication Delivery

Thanks to a growing body of research, the treatment for many diseases has evolved with time. Today, the key to sustaining and prolonging life also lies in medications used to treat illness and injury. In many cases, pharmaceutical advances have made medication administration the primary means of treatment.

Medications can be delivered by a host of routes and today, the medications a patient receives are largely administered by a registered nurse. Administrating medications is a skill that is taught based on five principles: the right drug, to the right patient, at the right time, via the right route and in the right amount. Simply put, some medications are most effective when given in timed, sequential and exact doses. These are the medications that need to be infused via some type of infusion pump. Due to the intricacies of delivering precise amounts of medication over a particular period of time, infusion pump manufacturers have been facing increased scrutiny. From assuring free flow protection to keeping pace with software enhancements, the infusion pump market seems to present a new set of challenges daily.

Recently, Portescap worked with manufacturers of a general infusion system to supply a 16 mm/dia. DC coreless motor with an integrated magneto resistive encoder, a reduction gearhead with spur gears (ratio 27:1) and a rotor inertia 1.60 kgm2*10-7. This motor for infusion pump was chosen not for its response time but for its low current draw, which would extend the device’s battery life. This presented the advantage of having an extremely quiet motor with a winding / gear reduction ratio that allowed the motor to work close to its peak efficiency point under the most common of the customer’s application conditions. Portescap was involved right from the design initiation and quickly provided sample motors to assist in fluid management with extreme precision that minimized air bubbles during diaphragm operation. This infusion system manufacturer remains extremely satisfied thanks in large part to Portescap’s quality control process and ability to fulfill long-term motor needs as the demand increases.

Portescap's 16mm Brushless DC Motor


Motors for Medical OEMs:- Bi-PAP

Many people suffer from a chronic habit of snoring that torments what should otherwise be a normal restful night. Worse, it also affects others from getting a sound and restful sleep. Thanks to advances in modern medicine, we now know that patients suffering from sleep apnea are at an increased risk for co-morbidities such as high blood pressure, heart attack and stroke. This increased risk is derived from the fact that patients suffering from OSAS actually stop breathing several times during the night. This cessation of breathing denies the body’s internal organs of the fresh oxygen they need to remain healthy. Thus, not only are physicians better at diagnosing OSAS; they also are way better at treating it.

The most common treatment for OSAS is positive airway pressure, or BiPAP. During BiPAP, airway pressure is utilized to “prop open” airway passages. This positive airway pressure is delivered via a device called a BiPAP machine. The machine pumps room air or oxygen through a hose to a mask on the patient’s mouth, nose or both, that the patient wears while sleeping. This allows the influx of fresh air that eliminates the cessation of breathing by patients suffering from OSAS. The key to success and patient compliance with any BiPAP machine is the ability of machine to react to a patient’s breathing pattern. Simply put, for maximum patient comfort, the device must be capable of quickly adjusting airflow pressure so as to avoid issuing a powerful breath while the patient is attempting to exhale. 

A U.S.-based BiPAP manufacturer was developing a new family of BiPAP devices, and approached Portescap for a custom miniature motor for BiPAP machine that would attend to stringent application requirements. The OEM specification required the motor to adjust air-flow pressure in time intervals of 150 to 200ms. For this application, a 22mm brushless DC motor was recommended. Because brushless slotless motors have an extremely low inertia characteristic, once the BiPAP device senses the patient’s breathing pattern, the motor is capable of adjusting airflow pressure in 150-200 ms. This remarkable air-flow adjustment time is achieved thanks to inertia of 3.9 x10-7 kgm2 and a mechanical time constant of 4.2 ms. The motor offers a significant competitive clinical advantage by allowing the bi-pap device to make exceptionally quick airflow adjustments that truly enhance patient comfort, thereby directly improving patient compliance and outcomes.

The ability to react quickly and capably to changing drive needs is not where the capabilities of the brushless motor stop.This BiPAP manufacturer also added one more request to the motor. Most patients require the use of BiPAP therapy while they sleep. Therefore, the motor must be capable of operating in near silence so as to allow the patient the maximum opportunity to rest. The brushless motor is not only packed with tremendous power, but has an extremely low operating noise of less than 30db. In today’s growing BiPAP market the brushless motor provides the drive manufacturer’s need to build the superior solution to patients suffering with obstructive sleep apnea.

Brushless DC Motors at a Glance

The Right Component Provider with which to Engineer a Relationship

As with all medical device projects, it is vital that the component provider be involved early in the design phase. Early involvement allows the solution provider to work with device manufacturers to modify or customize motion control, to suit the specific application needs of the device.