Recent years have seen incredible advances in implant technology. The most cutting-edge pacemakers today are leadless and the size of a vitamin capsule. Meanwhile, through its radical ‘electroceuticals’ initiative, GSK hopes to make grain-ofrice- sized bioelectronic devices, which can attach to nerves and alter the signals sent between the brain and other organs, a reality in the not-too-distant future.
But though developments in technologies that can be implanted – and, increasingly, injected – into the body are going full steam ahead, the wireless charging systems that keep them functioning remain relatively inefficient and cumbersome.
Typically around the size of a hockey puck and worn in a gun-holster-type belt, they have to line up exactly with where the implant is inside the body. This means that the patient either needs to sit still for the two hours or more it takes their implant to fully charge, or wear it for longer than is comfortable as they move around and the device charges at suboptimal efficiency.
When worn for too long, the power being transferred from the charger through the skin can even result in thermal wounds.
The mother of invention
Following discussions with the companies involved in the business of manufacturing implantable neurostimulators – such as pacemakers – and the doctors dealing with the patients being treated with these devices, product design and development firm Cambridge Consultants decided to develop a solution.
A breakthrough in through-body wireless power transfer technology targeted at the manufacturers of today’s tiniest and most advanced implantable devices, the MagLense system enables flexible, efficient and safe wireless power transfer to devices inside the body, without needing precise alignment with the implant, and regardless of the size and body shape of the patient. This is down to two new ‘novelties’.
The first is the company’s use of multiple uniquely shaped flexible coils, which can bend and flex without any impact on performance.
“There are patients with different body types, and different implants go in different parts of the body, so we needed to come up with a technology that was agnostic to all of that,” says Dr Arun Venkatasubramanian, the head of implanted connectivity at Cambridge Consultants, and one of the two-person team behind the invention of MagLense. “If we had just come up with a technology that was flexible, there would be nothing new about that – it would be the same as existing phone-charging pads. But with MagLense, it still maintains its performance when you bend it. Also, it’s not wasting energy in the form of heat on the skin.”
The second “clever bit of technology”, as Venkatasubramanian puts it, is the fact that MagLense is uncaring as to the orientation of the implant. Newer pacemakers, which are implanted directly into the patient’s heart through minimally invasive surgery, are not only much smaller than their conventional counterparts, they can also move around within the body.
MagLense’s software is self-calibrating so that it can deliver the optimum power for different implant locations, orientations, sizes and shapes. In addition, it intelligently targets only the intended implant – avoiding any heat damage to surrounding tissue or other implants. According to its inventor, MagLense could open up almost the whole body to the possibility of medical implants, heralding a new era of treatment for people with chronic and episodic conditions, such as epilepsy, diabetes, obesity and depression. It could also enable more widespread use of microimplants for targeted nerve stimulation, the sort of innovation GSK’s ‘electroceutical’ approach is designed to eventually bring to market.
“There are several new applications, and we’re talking to multiple companies about how MagLense could be used to power their next generation of bioelectronic medicines or their next generation of traditional implants,” Venkatasubramanian says. As Cambridge Consultants is a design and development company (the team doesn’t build and sell commercial products), the hope is that some of these conversations will lead to actual product development. The challenge is figuring out where the technology can deliver the greatest value.
“We have created the IP, we have created the novelty aspects and we’ve shown it works,” Venkatasubramanian says. “Now we’re talking to these companies about where the biggest bang for the buck is – where the technology is absolutely needed or the system won’t work, rather than being a ‘cute addition’.”
The biggest driver behind MagLense’s development was feedback from doctors about the negative impact of existing wireless charging systems on quality of life. In this regard, Venkatasubramanian is confident the new system will make a difference.
“Because of the clever algorithms and coil designs that went into MagLense, and the fact that it is agnostic to implant orientation and position in the body, and automatically calibrates itself when movement occurs, patients are not restricted in their quality of life,” he says. “They don’t have to minimise movement – they can go for a jog and do all sorts of things while wearing the belt and it will still charge. That’s the whole purpose of why we started this.”
Life-saving performance
While there is certainly scope for the technology to be used for consumer devices too, Venkatasubramanian doesn’t believe this is where its greatest potential lies.
“In the consumer world, the emphasis is on usability, whereas in the medical world, it’s on performance,” he says. “If you have a patient with a pacemaker who has to wear a charger so it continues to work, that’s life critical; whereas if you have a body patch that is recording your sweat or hydration levels and you have to wear a shirt with this technology in it to charge it up, it’s a different story.
“The criticality of those two scenarios and the level of performance needed for them are different. So while MagLense’s technology could be used for either industry, its greater value is with the medical industry.”
Turn the radio up
Researchers from the Massachusetts Institute of Technology (MIT) have collaborated with local Brigham and Women’s Hospital to create a new system that can wirelessly power and communicate with medical devices inside the body.
The new in-vivo networking system employs radio waves to power implanted devices. This is expected to eliminate the need for a battery, in turn reducing device sizes.
For their study, the team used a prototype similar in size to a rice grain but are hopeful that its size could be further decreased.
To address the weak nature of radio waves inside the body, the researchers used an array of antennas that can emit these waves at marginally different frequencies.
These radio waves overlap and integrate during their travel, and the overlapping of high points generates the energy required to power an implant.
MIT Media Lab assistant professor Fadel Adib explains, “Even though these tiny implantable devices have no batteries, we can now communicate with them from a distance outside the body. This opens up entirely new types of medical applications.”
The researchers expect the system to facilitate the development of devices for drug delivery, and monitoring and treatment of a variety of diseases.
One of the applications includes wireless brain implants for deep brain stimulation in order to treat neurological disorders, like Parkinson’s disease and epilepsy.
In tests in pigs, the researchers showed they could send power from up to 1m outside the body to a sensor that was 10cm deep in the body. If the sensors are located close to the skin’s surface, they can be powered from up to 38m away.
“There’s currently a trade-off between how deep you can go and how far you can go outside the body,” Adib says.
The researchers are now working on making the power delivery more efficient and transferring it over greater distances. This technology also has the potential to improve radio-frequency identification applications in other areas, such as inventory control, retail analytics and smart environments, allowing longer-distance object tracking and communication, the researchers say.
