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Home » Why FPCs are replacing microwires in MIS medical devices

By Philip Johnston, CEO, Trackwise

Any kind of surgery is stressful and can be very disruptive to normal life. It is also very time-consuming as, aside from the time taken to have the surgical procedure in a hospital or other healthcare setting, there will be a recovery period when you may not be able to work, exercise or perform normal daily tasks. Today’s surgical techniques are improving patient recovery times as they differ from traditional procedures when the patient would often be left with a large incision following open surgery. These days, whenever possible, surgeons will limit the size and number of incisions they make by using minimally invasive surgery (MIS).

The advantages of MIS

MIS (sometimes called keyhole surgery) is a state-of-the-art procedure when surgeons use endoscopic techniques to address a number of issues. MIS has numerous benefits over traditional open surgery including smaller incisions, less pain and scarring, faster recovery times and shorter hospital stays. MIS offers a higher accuracy rate compared to open surgery as procedures often use a camera which allows surgeons to monitor internal organs more effectively.

Current wiring systems in medical devices

Medical devices used in MIS procedures must be in the most compact of form factors in order to be as ‘non-invasive’ as possible. Any component parts inside the devices must be extremely small in order to save space whilst still allowing the device an elevated level of functionality. The wiring in MIS instruments, like any other components, takes up space too. Conventional electro-surgical instrument designs usually incorporate electrical interconnects that are based on microwire technology. Wires are often combined into bundles of around 600µm in diameter but their rigidity can make them difficult to apply to enclosure formats with unusual shapes.

The benefits to using FPCs in MIS instruments

Flexible printed circuits (FPCs) can replace microwires and have already been used in a variety of wearable and implantable medical devices. As well as supporting high degrees of signal integrity and prolonged operational reliability, FPCs also offer substantial space, weight and cost savings especially when consideration is given to reduced device assembly time and costs. An FPC can be bent or shaped to fit the dimensions of an enclosure and is much thinner than a traditional microwire bundle. The composite structure of FPCs offers considerable mechanical robustness and, by using them in a device, medical designers make considerable cost savings as a single FPC can replace multiple microwire interfaces. FPCs can reduce the complexity of the wiring assembly in the instrument they are designed into with just one FPC replacing up to 12 microwires. Designers can implement conductive traces with a thickness of only 25μm wide by using an FPC.

In order for FPCs to be effective replacements for microwires, it has to be possible to manufacture them to any length. This has been an obstacle until now with most FPC manufacturers only capable of producing lengths of up to 0.6 metres and only a few able to achieve 2 metres long. The catheters used in cardiac procedures should be a minimum length of 1.1m tor clinical staff to be able to use them correctly and 2m wiring lengths are required in instruments used for procedures such as interventional neuroradiology.

Using IHT to manufacture FPCs for medical applications

Trackwise now offers medical sector OEMs ultra-thin multi-layer FPCs of any length achieved through our proprietary Improved Harness Technology™ (IHT) manufacturing techniques. This breakthrough gives a weight- and space-saving, length-unlimited alternative to the current solutions on the market. The fully patented, dynamic manufacturing process used is based on advanced roll-to-roll electro-lamination techniques creating reliable, repeatable FPCs.

For more information on FPCs for medical applications, read our white paper Trackwise’s Improved Harness Technology™ Ready to Enable the Next Generation of MIS Instruments.