Every medical device starts off as a great idea, whether a flash of inspiration or simply a niggle at the back of the mind that says "this could be done in a better way". Yet for every medical device that becomes a mainstream and invaluable part of a healthcare professional's working day, there will be many more that never make it beyond being a sketch on the back of an envelope, let alone survive the transition from preclinical trial to mass production.
What's more, against a backdrop of growing miniaturisation, advances in nanotechnology and the emerging field of nanopiezotronics, where implantable devices are powered by a patient's natural bio-mechanical and bio-chemical energy (such as a heartbeat, blood-flow or even breathing), medical devices are becoming ever more complex, making them challenging and expensive to produce on any sort of commercial scale.
"For start-ups, innovators and medical device manufacturers, it is imperative to factor into the design process from an early a stage as possible the precision manufacturing techniques required to bring a device to market once it has cleared all its regulatory hurdles," says Professor Svetan Ratchev, director of Nottingham University's Precision Manufacturing Centre, UK.
"In the future we will see many more 'smart' devices coming through that have medical applications. They will be devices that are much more closely integrated to the needs of the patient and, from the manufacturing perspective, are likely to be more compact and have greater functionality. Devices are going to become more intuitive and more integrated with the human function."
Linking manufacturing with manufacturability
One of the more common challenges for device manufacturers is how to bridge the gap between taking a device through preclinical trials and then developing it into a process of volume manufacture, and doing so in a cost-effective way.
"There can be an issue of how you go about detaching the design of medical devices from the actual manufacturing processes," Ratchev explains. "You need to be linking manufacture and manufacturability much earlier in the device development process."
In a climate where devices are becoming smaller and require improved functionality and reliability, manual assembly may become commercially unfeasible simply because of the size of the device.
This can, in turn, mean designers and manufacturers need to think carefully about the underlying technologies and system engineering approaches they will require if they are to develop a robust and viable commercial infrastructure for their device. Often, this process will require them to move to a micro-manufacture approach.
"Precision manufacturing techniques can be appropriate for a range of devices, including implantable devices, devices using mechanical control elements or devices that require an autonomous energy source, such as bio-mechanical devices, and which therefore require a different approach to batteries," says Ratchev.
Yet devices are often designed by people who have come from a strong medical background, which means they may perhaps be less likely to consider the implications and challenges of creating a high-volume, automated manufacturing process.
"It is one thing to get validation from the regulatory process at the clinical stage, but when it moves to full production you may find that you radically need to change your processes," he says. "There needs to be a much earlier engagement with these sorts of issues within the design process."
Within micro-assembly, typical part dimensions can range from tenths of a millimetre up to a few millimetres and sometimes incorporate elements within the micrometre range. Challenges can include the handling, feeding and joining of micro-products, with manufacturers sometimes required to develop bespoke micro-grippers and feeders as a result.
There will also, almost inevitably, be a need to look at how to best automate the assembly processes. Process automation is a key requirement within micro-assembly because of the small size of the parts used and the associated difficulties with manual manipulation and processing.
What has been seen in recent years is an increased focus on the development of a new generation of high-precision micro-actuation, micro-gripping and micro-feeding devices. These, Ratchev explains, have enabled the development of micro-assembly machines with positioning accuracy of up to ten nanometres.
"The evolution of ever more micro-processes also needs to be put in the context of regulatory requirements," he says. The technology, of course, also needs to be adapted to the specific medical or healthcare industry requirements.
"Because medical devices are normally high-value products, created within a heavily regulated industry and with a high level of intellectual input, they can be more suitable for automated, precision-based processes, though there will also be issues around variability and customisation of a product as well as ongoing cost imperatives," he adds.
Another key factor, particularly in the arena of implantable devices, is that the slightest miscalculation within the manufacturing process could result in a medical emergency or a device failing; not necessarily at the time the device is being implanted, but perhaps years later.
Longer term, the industry will increasingly see micro-products being developed and manufactured through 'zero assembly' where there is limited or no assembly required. The key message for device manufacturers is simply that they need to think much earlier about how they intend to bring a product to market if they want to avoid running into process challenges and hurdles later on, stresses Ratchev.
Help at hand
Using the expertise of university-based centres such as the Precision Manufacturing Centre, which straddle the research / academic world and the commercial world, can often be helpful in these circumstances.
At the moment, the centre is working with the Winnipeg Regional Health Authority in Canada on prototyping an implantable ear device and developing a prototype drug-delivery patch for firm based in Loughborough, UK.
"The sort of support we can offer is around helping to moderate designs to make them, more manufacturable and helping firms better understand the implications of micro-processing and precision manufacture," says Ratchev. "Of course, any design process needs to be about developing prototypes and thinking about on-off development, but manufacturers also need to be thinking about the next stage: what is going to be the right process to scale up this device or product?"
Often, understanding how to scale up can be difficult, and there may well be constraints on how to manufacture the device. The superficial view can often be to simply scale up the same process that is already being used, but that is more often than not incorrect.
"It can be a steep learning curve for many device manufacturers, particularly those that are relatively small start-ups or, perhaps, working out of a university medical department," says Ratchev. "There is often a lack of understanding about what is required and also the level of cost that is likely to be required."
Between 60-80% of a device's cost will be in the early design stage. After that it can become expensive to make changes to the design, especially when moving into a more manufacture-friendly stage of design, so it is critical that the right decisions are made as early as possible.