With ever more excitement around the possibilities in the implantable medical device sector, it’s crucial to bear in mind the technical challenges around powering them. Getting power into your medical implant is key to success and is heavily influenced by, and influences, how the patient will interact with the implant. In this article, I want to set out my thoughts on the challenges and future approaches.
1 Implantable medical devices are getting smaller
Small is definitely beautiful when it comes to tomorrow’s smart implants. Some that we have been talking about recently are the size of a grain of rice. Where once the medical device industry was content with a chunky pacemaker or a cochlear implant prominently placed behind the ear, nowadays many of our clients have exciting plans for devices so small they can be implanted via an injection.
This is great news for patients and clinicians. But for those actually designing the device, it can only mean one thing. A small implant equals either a small battery or none at all. And that – of course – leads to all sorts of issues. Do we change the implant frequently because of its tiny battery size or can we improve longevity by making the device less power hungry? Could it be rechargeable? Could the power source be an external wearable? These are the questions we need to ask at an early stage in the design process.
2 Medical implants are also going deeper
Wireless charging may seem like the obvious solution to powering a smart implant. Indeed, it is used in the medical device industry for many of today’s implants. After all, if you can boost up your electric toothbrush battery by sitting it on a charger or your phone via a simple mat, then why not use this approach for medical devices in the body?
Wireless charging gives the patient freedom from invasive battery-changing surgery and can allow the device to carry a smaller battery. The problem is, when we are looking at new devices that address all sorts of issues beyond established implants, such as continence or fertility, these implants are deep within the body.
This does not lend itself easily to wireless charging as the distance between charger and implant becomes prohibitive. Small and deep is a real technical challenge but it’s one that must be addressed as this is where the market is going. One solution is to connect the deep implant to a battery closer to the surface of the body, but that comes with other issues that need to be addressed. It’s certainly something we are considering for some of our clients.
3 The medical implant field is highly regulated
The regulatory framework around the strength of wireless battery charging within the body is there to prevent damage to the patient’s own tissue. There are, however, some ways of working within the rules that can still allow for wireless charging at a deeper site within the body.
One route we have been exploring is to pulse the charge rather than setting it at a constantly high rate – thus lowering the average charging field to meet the regulation. This is an approach which is well worth considering. We have also developed technology to manage the strength of the electrical field generated by the charger that we demonstrated at the NANS conference in January 2023. This technique allows more power to reach the implant while continuing to meet the regulations.
4 Patients just want their bodies to work
People don’t want to have a lot of complicated maintenance to interfere with their day. Indeed, we find that patients mostly don’t want to know much about their implants at all, other than that it’s working properly. They simply want them to enable their bodies to work.
For this reason, charging needs to be easy and accessible, with the minimum of fuss. We’ve found that overnight charging fits with a lot of patients’ lifestyles and routines, whereas it can cause more frustration to have an implant that needs recharging every three days, rather than nightly. It then becomes difficult to remember and consequently a source of irritation. At CC, we have an in-depth approach to user experience that ensures the devices we design – and the way the user interacts with them – really do fit the patient lifestyles.
5 It may be time to think about energy harvesting
With the pressure on implants to become smaller, deeper and less of a hassle to patients, could it be time to say goodbye to our usual power solutions altogether? CC was the first company to use Bluetooth within the body back in 2013 when we worked with a leading implant manufacturer to develop a Bluetooth enabled spinal cord stimulator.
The device was approved in the US and EU in 2016. So, we are no strangers to thinking a long way outside of the box. With this in mind, we are already considering some adventurous solutions to the smart implant power problem using energy harvesting. Could we one day see devices using body movement, temperature differences or ultrasound to recharge batteries? I would not be at all surprised if one or all of these becomes reality in the next few years.
6 And for something completely different…
Might it be time to consider ways of powering implants that are altogether completely different to anything that’s gone before? What if we could harness the body’s own energy to fuel a smart medical implant? With our long-standing interest in combining biology with engineering, we have been thinking about whether glucose within the body could be harnessed to power a patient’s implant.
This has been, and continues to be, an active area of academic research. Generating the necessary power of a few milliwatts for typical implant devices is beyond the current technology. But a recent press release from MIT shows good progress in increasing power output of glucose fuel cells.
And ETH Zurich have demonstrated using a glucose fuel cell to generate enough power to stimulate artificial beta cells to release insulin. Depending on the specific application and use scenario, combined with developments in designing lower power electronics, it is becoming possible to envisage a future where recharging an implant device may be as simple as drinking a can of soda or eating a chocolate bar.
To sum up…
We are looking at a future in which medical implants will have a far wider application than at present. Devices will be monitoring many more of the body’s functions and reporting back with crucial data. Hard-to-solve problems such as urinary incontinence or continuous monitoring of cardiac function will routinely be addressed by implants.
All this and so much more is on the horizon. But the ways in which these medical implants are powered is key to their success. We advise thinking about the way in which a smart implant is powered early in the design process, alongside how the user will interact with their implant. This will make all the difference to the smooth development of the device. Please do get in touch with me if you think CC could help with your project.