Interconnection


Selecting connectors for medical applications


Today’s healthcare industry relies heavily on electronics technology to improve the capability and accuracy of medical systems and patient monitoring. Standards exist to ensure that medical systems are safe to operate and present no danger to the connected patient. Here, David Phillips, managing director of binder UK, outlines the most important selection criteria for connectors in medical applications


the space available both inside and outside the product.


David Phillips, managing director, binder UK T


oday’s medical applications are extremely diverse and range from disposable, single use surgical devices, to a variety of hand-held diagnostics and patient monitoring


systems, up to complex CT and MRI scanning systems. When specifying electronic connectors for medical applications, there are many considerations that apply to every application, but there are some that are unique to the medical sector. There are basic choices to be made concerning the electrical and physical properties that are both directly related and fundamental to connector choice. The current, voltage and the number of contacts, together


Voltage and current The connector’s rated voltage and impulse voltage are defined according to IEC60664-1 - a basic safety standard to achieve insulation coordination specifying clearances, creepage distances and solid insulation, taking into account the voltage stress and surge together with the expected degree of pollution. These factors determine the physical dimensions of the connector. The current carrying capacity of a connector denotes the current that can be carried continuously and simultaneously through all of its contacts and is determined by IEC 60512-5-2. The current carrying capacity is not fixed and decreases with increasing ambient temperatures. Certain applications like those relating to MRI equipment call for shielding against electromagnetic interference (EMI) and these demand screened cable systems that require connectors with good shielding characteristics. This can be offered with metal bodied or metalized plastic connectors.


Mating and environmental protection


How many times the connector will be mated and unmated and the environmental protection (IP rating) requirements have a major influence on the type of mating system and the chosen method will necessarily have a big impact on connector cost. The IP rating determines the degree of protection to dust and liquid. Typically, medical connectors are rated IP54 and above, with many being IP67 for temporary immersion in liquid. Screw connectors provide the ultimate protection against accidental un-mating and have excellent IP performance but, on the downside, they are generally the most expensive type of connector, especially in metal versions.


binder snap-in & bayonet medical connectors


with the cable diameter and level of shielding required all have a direct influence on the connector choice as do the physical characteristics relating to how the connector will be terminated, the method of mating and


24 October 2021 Push-pull connectors can be expensive.


However, the trend towards plastic versions has helped to reduce cost and provides a quick mating IP67 connector with some protection against accidental un-mating. Snap-in and bayonet connectors provide quick and simple mating and are generally


Components in Electronics


new binder ELC medical connector


the lowest cost solution. Recent developments mean that these can now be rated up to IP67 thus providing an economic solution with high performance. New mating systems such as binder’s Easy Locking Connector (ELC) provide positive mating and protection against accidental un- mating with an intuitive locking system featuring snap hooks. It is designed for use where the need for constant mating and un- mating is an important consideration. The connector system is capable of more than 5000 mating cycles which is more than enough to satisfy the operating requirements of many medical system applications. The ELC connector features an intuitive locking system that clicks together to ensure positive mating and protection against un-mating. It is also impossible to mis-mate the connector system as the mating position is defined by the profile shape of the mating area.


Sterilisation and toxicity to skin Medical applications are wide ranging with surgical applications requiring connectors resistant to medical sterilisation via steam autoclave, gamma radiation, gas plasma and so on. However, some applications require no sterilisation while others require the use of the type of material we use which has been tested for cytotoxicity (toxicity to skin) and is free of DEHP phthalates.


Connector standards Today, there are a number of standards which


must be considered when specifying connectors and EN 60601 is a family of standards whose scope covers the safety, essential performance and electromagnetic compatibility of Medical Electrical Equipment and Systems. It is technically equivalent to the international standard IEC 60601 and covers aspects such as vibration, shock, rough handling and finger-proofing. ISO 13485 specifies requirements for a quality management system where an organization needs to demonstrate its ability to provide medical devices and related services that consistently meet customer and applicable regulatory requirements. The US Food & Drug Administration (FDA) continues to promote the development of connectors that reduce the risk of device misconnections. These standards promote patient safety by assuring connectors for unrelated systems are incompatible, so the devices cannot be accidentally linked or forced to fit.


Tailormade connectors


Some applications require a hybrid connector to carry a gas in addition to power and signal and in such cases the best solution may be a bespoke connector. This not only provides the optimum solution but also gives the customer protection of its own intellectual property. Naturally, medical connectors tend be expensive – but what price patient safety?


www.binder-connector.co.uk www.cieonline.co.uk


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