At the heart of many innovative medical devices are new designs of electric motor and motion-control systems. In pushing forward their design parameters, technology companies are constantly seeking higher efficiency, more speed and increased power from smaller, more robust and quieter equipment. Whether it is for brushless DC (BLDC) electric motors or actuators that can be positioned more accurately or for other essential components, significant investment in R&D is a consistent feature of their work.

The systems under development may not be specifically intended for the medical device sector from the outset, but work to create better technology across a range of verticals often brings many benefits to the med-tech sector. Sensors for motion systems, for example, may have applications in the automotive or energy sectors, but may also find their way into novel medical devices at some stage in the future.

There are many examples of how this process of innovation has enhanced the capabilities of medical devices, as René Erdmann, product manager for drylin E drive technology at igus, explains.

"The development of new electronic semiconductors allows new, smaller, cheaper designs of motion-control boards," he says. "For example, it is easier to let a stepper motor run in a closed-loop control as current control mode means more motor power can be created and there is less heating of the motors.

"It is also easier to connect small devices to the internet or industrial networks for data exchange."

Over the last 50 years, igus has grown from a garage in Cologne, Germany, to become a company with over 2,000 employees and 26 subsidiary companies. It began as a supplier of complex technical polymer components and is now known for its reinforced plastic Energy Chain Systems and injection-moulded polymer bearings.

"We are listening carefully to what customers are asking us and we are looking for trends; beyond that, we try to keep it as simple as possible," says Erdmann. "Maintenance-free is the keyword for us at igus. For instance, we are using sliding plastic bearings instead of ball bearings because they are cheaper, maintenance-free, lighter and quieter.

"Customers are using our smallest linear-table SLN or SLT drives with stepper motors including encoders to improve their devices," continues Erdmann. "With these small, maintenance-free linear tables, the customer can design their devices to be much smaller. The stepper motor with encoder gives them the additional benefit of lower energy consumption with a closed-loop control."

Another company pushing the boundaries is Sonceboz (SBZ), a producer of innovative electric motors and mechatronic drive solutions, which are known for their use of contact-free technology to produce linear or rotary motion. Stepper or BLDC motors, sensors, gear trains and electronic controls are among the key elements of the tailored mechatronic systems it provides to its customers.

Its efforts to improve motion-control technology are made on two fronts. Solutions specifically for the med-tech sector are developed by SBZ, while its subsidiary Moving Magnet Technologies (MMT) works on new designs for electromagnetic motors, actuators and sensors.

"SBZ has recently developed a motion-control technology called LoadSense, in which a brushless permanent-magnet motor is controlled by a system of electronics that allows the measurement of the load angle of the motor," says Herbert Trummer, director of the mechatronic division at Sonceboz. "With this information, we are able to define not only the position, but also the load of the motor at any time. This allows better control of the motor with less power consumption. Due to the fact that we are using a high number of pairs of poles, we get a motor with high torque at rather low speed – in fact, a real direct drive.

"The industry wants maintenance-free products with lower energy consumption, smaller design size, faster delivery and lower cost."

"The measuring of the load angle can either be done sensorless or with a magnetic, high-resolution sensor, which has been especially developed for this application in order to avoid very expensive optical encoders," he adds.

At MMT, key developments include a variety of different motor technologies, of which, two seem to be of special interest for medical device applications. Firstly, the company’s direct-drive actuators are gearless applications, including BLDCs, with high numbers of pairs of poles and drives for X-ray imaging that have hollow shafts for the cabling. Secondly, the firm has developed BLDC and stepper motors that have very low detent torque – the minimal torque present in an unenergised motor – for smooth and noiseless operation and a slim form factor for compact design.

Such developments have already had a big impact on specific medical devices. "Let me take the example of the LoadSense technology," says Trummer. "We applied it in a direct-drive motion-control system for a blood pump in a dialysis machine. Using different motor sizes, we were able to cover a torque range from 0.2Nm to 9Nm directly on the motor shaft, without a gearbox. So we can fulfil the requirements of different pump sizes.

"The result of a drive system without a gearbox and with a motor running at low speed is a very long lifetime," he adds. "Combined with the LoadSense electronics, which are integrated into the motor, we can reach very low noise levels, since we avoid noises and vibrations that would come from the gearbox and a motor running in high speed. A third improvement was the low heating of the system, as a result of the high efficiency we can reach thanks to LoadSense."

Better, faster, stronger

Although the design of new motor and motion-control devices is not always tailored to the medical device industry from the outset, designers understand that this is a key vertical for their products and that they must understand its specific needs. Fortunately, its needs overlap with those of other industries, though the application of the technologies may differ greatly.

Says Erdmann: "The industry wants maintenance-free products with lower energy consumption, smaller design size, faster delivery and, of course, lower cost. The functionality of smaller devices is increasing. We also want to look at noiseless devices for use near ill or injured people.

"We are offering maintenance-free linear bearings for movement in medical devices. We have also developed small, cheap stepper motors for closed-loop control with less energy consumption," he adds.

Part of the challenge for designers of new equipment is to understand the complexity of the medical device market, which has a wide variety of potential applications for electric motors and motion-control devices. "The field of med-tech applications for motion-control systems is very large," says Trummer. "Let me therefore talk about only one aspect, which can probably be an example for others. We believe that, beside other important evolutions, the health sector will be confronted with more and more scarcity of human resources, and higher demand for safety of the medical treatment and cost pressure at the same time. One contribution to a solution of these problems could be a higher degree of automation of the medical processes.

"This means that many operations that today are done manually by the nurse or physician will be done by automated devices and machines. Let’s take one example, which is the reconstitution of bicomponent medicine. Today, the nurse or the patient has to deal with the vials containing the components of the medicine, a syringe and perhaps some plastic parts that allow for appropriate shaking and so forth. This is complicated and time-consuming for the nurse, and a potential source of failure. In addition to that, if the mixing isn’t done correctly, it is a waste of sometimes very expensive medicine," he adds.

Trummer sees an opportunity to use motion-control systems to help automate these types of devices and procedures: "Generally speaking, we think that the challenge for this type of automated system lies in three different elements. Firstly, miniaturisation means that devices will be more and more portable and handheld. So, small size and optimal integration into the device matters.

Secondly, handheld devices are mostly battery-driven. Motors must be as efficient as possible in order to increase battery lifetime. Lastly, the safety factor is of paramount importance. In the automotive industry, we are talking about 0ppm – zero defect!"

"The future belongs to solutions that are able to fulfil not only the functional requirements, but can also give an answer to cost and quality questions," he adds.

Staying close to customers

Each design company has its own areas of expertise and directs its research and development programmes towards specific characteristics of motors and motion-control devices. At igus, the focus is firmly on creating noiseless and maintenance-free components; for Sonceboz and MMT, on making higher-quality devices that are increasingly versatile and cost-effective – characteristics that are both top of the list of priorities for the medical device industry.

"There are two main elements to our work," says Trummer. "I mentioned our subsidiary MMT, which does advanced research. These guys are constantly seeking new, innovative solutions in motors, actuators and sensors. This is one element. Within Sonceboz, we are producing many, many millions of motors for the car industry. As already mentioned, top quality is the keyword for these applications. Sonceboz Medtech has the possibility to realise solutions for our medical customers based on motor technologies produced in high volumes at top-quality level.

"Staying close to customers to understand their needs is an essential element in defining the direction of R&D projects."

"Combining this with the integration of motor, mechanics and electronics into mechatronic drive systems for medical devices, we are able to partner with our customers, and meet the technical, economical and quality challenges they face," he adds. The need to consider the medical device sector while developing innovative technologies for other sectors such as the automotive industry is central to the thinking of companies like Sonceboz and MMT. Staying close to customers to understand their needs is an essential element in defining the direction of R&D projects.

"Our strategy is to realise mechatronic drive systems for medical devices with high customer values," says Trummer. "Our main concern is how we can solve our customers’ drive problems with innovative solutions using the existing technology modules in motors, sensors, electronics and mechanics. The direction of the R&D process is, therefore, very much influenced by motion-control issues in specific application fields today and in the future.

"This is the market-oriented approach we are following within our business unit Sonceboz Medtech. Besides that, with MMT, we continue to develop new motion-control technologies based on the outcome of our market intelligence activities also in the field of med-tech applications.

This is the approach of technological innovation in the field of electromagnetism, allowing us to be ready when the demand for an application for the future arrives."