Making a healthy connection

Technology advances in electronic consumer devices and the telecommunications industry are converging at a rapid rate with medical device technology. For example, the medical industry now embraces membrane switches from the appliance industry and relies on mobile phone interconnects within portable medical monitoring devices. In addition, super-precise surgical tools have been further improved by combining advanced fibre optic and interconnect design technologies.

Converged technologies like these have not only greatly enhanced the ability of healthcare professionals to provide direct patient care in clinics and hospital settings, but have also helped monitor patient conditions remotely. In today’s interconnected world, it is not unusual for healthcare professionals to consult with another healthcare professional in another city or around the globe. Increasingly, mobile communications are being used to monitor and coach patients with chronic conditions like diabetes.

Healthcare reform has also stimulated integrated approaches for patient diagnostics and real-time patient monitoring. Today’s telecommunications systems provide the super highway for managing digital information as illustrated by Picture Archival and Communications Systems (PACS). PACS enables images such as x-rays and scans to be stored electronically and viewed on screens, creating a near film-less process and improved diagnosis methods. Doctors and other health professionals can access and compare images at the touch of a button.

But as medical device manufacturers further improve existing products and bring new products to market that take advantage of the latest technologies, engineers face conditions unique to the medical industry that make designing and manufacturing more challenging. This is particularly true in the current economic climate, where the pressure is on to deliver healthcare more cost-effectively. Whereas medical interconnects have traditionally been supported by specialty manufacturers, industry trends are increasingly leaning towards standards from other industries, such as consumer electronics and telecommunications.

The Molex Circular MT Expanded Beam Interconnect solution is one example of how advanced electronics are driving medical device innovations.

Making it better
When developing medical devices, manufacturers must consider durability and reliability to a greater degree compared to the consumer and telecommunications market. That’s because medical devices are expected to last for many years, and in cases where devices are invasive to the human body, they must perform consistently in relatively harsh environments. This is a real challenge as it relates to the use of industry-standard interconnects in the medical environment, where the form factor may be correct, but the materials and lifecycle may not match.

The need for ‘modified-off-the-shelf’ (MOTS) interconnects is a compromise of taking existing technology like a micro HDMI connector used in home audio/visual devices and perhaps ruggedising it with different plating or retention features for use in medical devices. MOTS is where there is significant value for both the device designers and the interconnect providers - using prior art at an 80 percent level, for example, can replace the need for a custom interconnect. When considering MOTS, it is beneficial to work with the company’s application engineers to identify the risks and benefits of a particular interconnect solution.

The caveat is that many healthcare devices are attached on or into patients. In these cases, many medical device designers also face the extra challenge of providing functionality within small spaces with biocompatibility. In most cases the medical device manufacturer will already have a pre-defined list of biocompatible materials that can be used. A part of this material definition is determined through regulatory bodies, though since the responsibility of material choice relies on the device manufacturer there can be some high-spec materials included.

The human body itself is a pretty stable environment but once non-organic materials enter it the saline, blood and high humidity levels can cause serious corrosion. These biocompatible materials must also not react or be rejected by the body; a material that has nickel in it, for example, must be avoided as a relatively high proportion of the population is allergic to it.

Metal alloys are predominantly used by medical device manufacturers including cobalt chromium, titanium, NP35N and stainless steel. Titanium, a very light-weight, strong and corrosion-resistant material, is commonly used in orthopaedic medicine for hip replacements, though is very expensive. NP35N is a conductive metal alloy that is highly resistant to the corrosive elements found in the body and is widely used for invasive cardiac applications. Medical-grade silicones have also become generally accepted for applications including defibrillator pads.

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Specification-driven
Micro engineering must conform to the need for devices, such as pace makers and hearing aids, to fit as comfortably as possible within the human body. Again, the form factor could be in the correct scale, but biocompatibility and handling ease become the principle drivers. Due to the unique needs of the medical device market, there will always be a level of customisation that requires a detailed specification. Specification-driven applications can benefit from previous designs from other industries, with adjustments to the medical application requirements.

Thus, a key consideration for device manufactures is the choice of interconnects that make it possible to reliably transmit data, signals, images and power. The effectiveness of healthcare devices relies heavily on the underlying electronic interconnects with robust design and engineering that enable devices to perform as expected.

For medical devices, the interconnects must have secure contacts with high mating cycles, long lifetimes and durable materials to survive the rigours of everyday use in environments that can include a variety of fluids. Devices must also take into account possible accidental physical interference, such as hospital carts running over cables. In addition, interconnects must meet many other challenges and requirements, including tight signal integrity tolerances; a high number of mating and actuation cycles; and reduced losses due to resistance, stringent electromagnetic interference, radio frequency and crosstalk characteristics.

When choosing interconnects for medical devices, it helps to work with a manufacturer that has proven expertise in developing connectors that perform in harsh environments from other industries such as chemical, solar, manufacturing, pharmaceutical, military and telecom. These industries require some of the same rigorous attributes that the medical device industry requires, such as reliability, durability, flexibility, high speed copper or fibre-optic and small size, and manufacturers with experience in developing interconnects for such conditions typically offer a range of connector platings that ensure durability.

Working with medical device interconnects that feature all of these attributes is now more important than ever because of the critical nature of medical device performance. As electronics advance and merge, it is critical that the risks and benefits of interconnects be assessed with the device designer. Failure of a heart monitor, for example, carries much greater risk than failure of a smart phone or a router handling consumer phone calls.

And with the rising cost of healthcare significantly changing how patients receive treatment, and with in-home care becoming more common, the demand for smaller and portable medical equipment is likely to increase sharply in the coming years. Medical design firms will need to choose their interconnects wisely in order to meet this need effectively.

Molex has been delivering proven solutions to medical device manufacturers since 2005, and recently formed the Medical Connector and Cable Assembly Business Unit to directly address the increasing demand for advanced interconnect products in this market. A diverse range of products and solutions are available through the company’s MediSpec portfolio.

The MediSpec Hybrid Circular MT Cable and Receptacle System combines both optical ferrules and electrical contacts in one interface. The multifunctional connector uses Molex’s circular MT optical connector and receptacle technology, providing three configurable MT ferrule compatible ports for a combination of copper or fibre media carrying electrical power, low speed copper signalling, optical data or video signals. A more streamlined approach to medical system design, it is ideal for a variety of applications including robotic surgery, neurosurgery, orthopaedic surgery, diagnostic imaging, optical coherence tomography, guidance/illumination/navigation, interventional energy lasers and Picture Archival Communications (PACS).

The acquisition of Temp-Flex, a manufacturer of micro-miniature wire, cable and continuous coils using biomedical coating and medical grade base metals and several new ground-breaking products introduced under its MediSpec portfolio, help realise the company’s goal of developing technologies that provide medical device manufacturers with the maximum in product efficiency, reliability and flexibility for the ultimate in patient care.


About the Author
Anthony J. Kalaijakis is Strategic Medical Marketing Manager for Molex Incorporated, a global leader in the design and manufacture of electronic, electrical and fibre optic interconnect systems.