I’m part of a team of experts at CC that specialises in medical implant development. Our work at the frontier of smart active implants includes delivering cutting-edge wireless power transfer (WPT) solutions. Experience tells us that however smart the implant is, the critical factor of power must be considered right from the start. We emphasise to clients that success will be far swifter and simpler to achieve if the issue is confronted as early as possible.

The traditional battery solution has worked perfectly well over the years for familiar and well-established devices such as pacemakers and implantable pulse generators (IPGs). But extraordinary advances in miniaturisation and wireless technologies mean implantable medical devices will address an increasing number of health issues – if the power conundrum can be cracked during development.

As well as their bulk, batteries come with a number of shortcomings. They have a finite lifespan, for example, and replacing them is necessarily invasive. Worries about battery depletion and the looming prospect of replacement surgery can create significant anxiety for patients.

The use of a battery also restricts the design process because it has a direct impact on the overall size of the device, and therefore the comfort of the patient. The problem of battery size can also act as a brake on innovation – advanced features on a device might need so much additional power that the lifespan of the battery, and therefore the implant, will be restricted.

Then there is the impact on clinicians and the health system generally – the time and money involved in monitoring battery levels and scheduling replacement procedures creates an additional layer of complexity for healthcare providers.

Medical implant development

So, does wireless charging represent the best way forward? My colleagues and I certainly think so, but we’re under no illusions about the significant hurdles that need to be overcome during medical implant development. There are no straightforward answers because – as you can imagine – there are multiple technologies that can be employed to transfer power using different segments of the electromagnetic spectrum.

The most-used method today is inductive coupling technology, which underpins wireless phone charging. A transmitter pad generates an alternating magnetic field, and when an implanted receiver coil within the device comes close to it, an electric current is induced in the coil – thereby powering the implant. By eliminating the need for physical wires or charging points this approach is helping to propel the new era of medical devices, as well as offering patients a truly elegant and user-friendly way to charge their implants.

As I said at the outset, the team here has plenty of experience in designing and optimising WPT systems. We’ve already achieved superior performance for clients in a range of applications, including neuroprosthetics, neuromodulation pain management devices, sleep apnoea, incontinence, and more.

Exciting as all these developments are, there’s no doubt that some very real hurdles still need to be overcome before wireless power transfer takes its place as the undisputed go-to power source for implantable medical devices.

Wireless charging systems need many disciplines

For a start, developing a WPT system in a medical device demands expertise in multiple disciplines such as electromagnetics, electronics, software and mechanics. Then there’s the fact that the human body presents numerous challenges that will impact the performance of such a system. Inductive coupling, used at the lower MHz frequencies, is significantly less impacted by the body tissue absorption seen at higher frequencies, and results in lower tissue heating which provides a higher degree of safety for patients.

As is well known, the size and depth of the implanted receiver coil significantly influences transfer efficiency. And with smaller implants necessitating smaller coils, achieving the required efficiency becomes a critical challenge that cannot be overlooked. At CC, we use advanced technologies to tackle these challenges considering everything from the coils to the transmitter power amplifier, rectification at the receiver end, and rest of the electronics.

As the real challenge lies in the intricate details, we consider a vast number of parameters, use cases, and safety regulations throughout the process. From concept generation to detail design, testing, and manufacturing, we work hard to integrate our solutions with the specific needs of our client.

Furthermore, it’s important to acknowledge that the human body is not a static environment in which to place a medical device. This is particularly important for a WPT system, as misalignments between transmit and receive coils can be problematic.

Movement, respiration and changes in posture can alter the position and orientation of the implant relative to the transmitter. We have found that this is a critical challenge to overcome if the system is to maintain optimal efficiency and energy transfer in a wide variety of use cases. Our medical implants team is able to replicate the expected clinical setting for WPT optimisation and used advanced strategies such as multi-coil designs and adaptive power transmission systems to address this issue.

Safety regulations also need to guide the level of energy transfer through body tissues. Managing the heat that this creates within the body is critical to prevent tissue damage or discomfort for patients. Strategies we’ve been exploring include optimising coil design for efficient energy transfer, as well as implementing real-time closed loop power/temperature monitoring within the implant. Developing safe and reliable power regulation circuits within the implant is vital to prevent overcharging or damage to the device.

A revolution in implantable medical devices

In my opinion, it is no exaggeration to say that we are on the brink of a revolution in the field of implantable medical devices – thanks to the potential of wireless power transfer. As I’ve said, technical hurdles and regulatory considerations remain. But the potential benefits for patients and the healthcare system are undeniable.

Just imagine a future in which patients experience a whole new level of freedom and wellbeing. This new era of patient care is within our grasp, characterised by improved comfort, greater functionality, and a brighter outlook for those who rely on these life-changing devices. Wireless power isn’t just about charging implants, it is about empowering patients and unlocking the true potential of medical technology to enhance lives. Reach out to me if you’d like to continue the conversation, I’d love to hear from you.