Overmoulded cable assemblies for medical devices -- COMPAMED Trade Fair


Axon Cable SAS

Overmoulded cable assemblies for medical devices

Overmoulded cable assembly

Limiting the propagation of bacteria and other microbes in hospitals is essential for patient wellbeing. The manufacturers of medical devices must design their systems so as to be perfectly sterilizable. Right from the initial design of interconnect links for medical applications, Axon’ Cable takes into account this requirement not only in the choice of materials but also in the techniques of moulding and overmoulding. This is the key issue: the overmoulding must perfectly adhere to both cable and connector in order to limit the proliferation of bacteria in the areas which are not accessible for the cleaning or sterilization of the assembly.

Limit contamination

The expertise of Axon’ in these techniques allows the company to offer cable assemblies perfectly sealed to contaminations, not only in the connecting area but also in the branch area. This is the case when a cable assembly is made with several branches. The harness must be protected by a Y-shaped overmoulding. Axon’ has a wealth of expertise and knowledge in this type of complex overmoulding in both low pressure and high pressure. Low pressure overmoulding is made, for example, with silicone for cable assemblies which have to be autoclaved. High pressure moulding is used with thermoplastic materials including polyurethane or santoprene for cable assemblies which have to be disinfected or sterilized with ethylenoxyde (ETO) or others.

In addition to avoiding the spread of bacteria, a perfect adherence between the overmoulding and the cable mechanically protects the assembly and guarantees the cable life. The cable assembly must withstand handling from both medical staff and patients.

Make the cleaning easier

Axon’ medical cable assemblies are insulated and overmoulded with thermoplastic polymers (such as PVC, TPU, TPE) and other plastic materials. These have been chosen for the method of sterilization (disinfecting, plasma sterilization, ethylenoxyde, gamma sterilization) and for the level of biocompatibility required by the customer (FDA, USP class VI, ISO 10993). The overmoulding shapes are also designed to make the cleaning easier.

Axon’ also uses silicone or thermoplastics (FEP, TPE, etc) to manufacture assemblies designed for autoclave sterilization at 121°C or 134 °C. Both low pressure and high pressure overmoulding techniques are well known by Axon’. The company can offer an overmoulding with a different material to the one used for the cable – for example, a silicone overmoulding (low pressure) on a TPU insulated cable – whilst guaranteeing the adherence of the materials between one another. Axon’ Cable designs and manufactures the moulds with a dedicated team, which allows the company to be more reactive and rapidly meet customer’s requirements.

A reinforced anti-microbial protection

Nosocomial infection, which affects in-patients, can come from contamination via surgical or medical instruments. Microbes can also build-up on cables or assemblies of medical devices including echography, shavers and laparoscopes. In order to combat bacteria, virus and fungi, Axon’ has patented a process which consists of integrating silver ion micro-flux into the jacket, moulding and overmoulding of the assemblies.

The presence of silver ion at the surface disturbs or stops the process of growth and multiplication of bacterial cells. Noso-free® polymers are efficient against a large variety of virus’ and bacteria including bacteria which resist antibiotics.

Other advantages: any polymer can be modified with antibacterial agents. The manufacturing process does not affect either the properties, or the colour or the biocompatibility of the materials. The antibacterial activity is efficient during the whole lifetime of the cable or the assembly.

From prototyping to one-stop shop cable assembly

Axon’ Cable, which has been ISO 13485 approved since January 2011, is particularly aware of the rules regulating medical devices. From the design, engineers take into account standards about electrical safety of equipment (EN 60601) or other standards depending on the application of the medical device. A study of the life cycle of the product is carried out with the customer. Potential risks linked to the use and handling of the cable assembly from the patient or the medical staff is identified from the product design. During the study phase, Axon’ Cable can rapidly provide prototypes of moulds or connectors manufactured by its fast prototyping workshop which is equipped with 3D printers.

Once the design has been fixed, in accordance with ISO 13485 procedures, no change of the process or the product can be made without the customer’s authorization. Equipped with an ISO 7 clean room, Axon’ Cable can produce interconnect solutions in a very clean environment. Operators equipped with overalls, face masks, gloves, head caps and suitable footwear terminate, overmould, test and pack cable assemblies.

Measurements of temperature, hydration, air pressure, concentration of airborne particles as well as microbiological analysis (concentration of bacteria) are taken regularly. If necessary, it’s possible to achieve an even higher standard by using 2 laminar flow systems for the workstations, which would then be classified ISO class 5.