Up in the air31 October 2017
The final frontier of the wireless revolution is power – but when will we see it for real? Eleanor Wilson explores what wireless charging could do for healthcare and the steps it must take to succeed, with Integer’s Beth Meyers, Sanjay Gupta of WiTricity and Bill von Novak at Qualcomm.
The question has hung in the air since the advent of Wi-Fi: if we don’t need internet cables, can we get rid of power cords, too? And yet, implant recipients still live with permanent openings in their bodies for charging leads, and undergo surgery every few years to change batteries.
In the operating room, flat batteries in surgical tools delay procedures and put patients at risk, while cables trailing along surgery floors are trip hazards that are impossible to sterilise. The demand is clear. But wireless charging has yet to hit the healthcare market and news is scarce. What’s the hold-up? There is, in fact, more than one kind of wireless power transfer in development. Static wireless charging, or magnetic induction, has been used for several years now in consumer devices such as electric toothbrushes, which are held in place in a dock to charge through a contact strip. For this kind of wireless power transfer to work, the transmitter and receiver need to be in constant contact and held in exactly the right position. This isn’t practical for implants, and using a dock system for surgical tools still requires the docking unit to be plugged into a power outlet with a standard cord.
Wireless charging mats are just beginning to hit the consumer market, but they have run into similar problems. Dell recently launched a laptop with an accompanying wireless charging mat that charges at the same rate as a power cord. That’s progress, but it still requires laptop and mat to be in contact, and for the mat to be plugged into a power socket. For wireless power to make an real difference to healthcare, a different solution is needed.
Through the air
The company behind the Dell laptop is WiTricity, headquartered in Massachusetts in the US. Its founders were physicists at the Massachusetts Institute of Technology. They first published their work on a new kind of wireless power transfer, called magnetic resonance, in 2007. This method uses oscillation and magnetism to send energy wirelessly from one resonator to another through the air – or through 1in or so of non-metallic material, such as a table or human tissue.
“Every human being is different; they don’t come out of the same mould, so that inductive solution was never going to be practical for medical applications,” says Sanjay Gupta, WiTricity’s vice-president of product management. “One of the things that the spatial freedom [of magnetic resonance] allows you to do is, for the first time, use the wireless charging technology in medical applications.” For patients with implants, that could mean a completely sealed device with no cable that doesn’t need regular replacements.
In 2011, WiTricity announced a project with Thoratec to develop a completely wireless, fully implantable left-ventricular assist device. Besides the infection risk of a permanent cable opening, and the financial and physical cost of surgical battery replacements, Gupta says wired power is also a limiting factor on the design evolution of implanted devices.
“The size of the devices is really limited by the size of the battery that you can put in there,” he says. “Now, the size of the battery of those neurostimulators or pacemakers or defibrillators can go down significantly because you can charge them every day, if you so desired it. The batteries can get smaller, the devices themselves can get smaller, you don’t have to [perform] surgery to take them out.”
WiTricity licensed its magnetic resonance technology in 2012 to medical device manufacturer and outsourcer Greatbatch, which later merged with Lake Region Medical to form Integer. The exact nature and status of the Integer project is still tightly under wraps, but Beth Meyer, director of strategic marketing in the advanced surgical and orthopaedics division, reveals it is looking into the benefits of wireless power transfer for tools, implants and hospital equipment.
“You could have a battery-powered item that’s being charged while in use and the power’s being sent through part of the operating room, or perhaps an implantable that recharges while [patients are] sleeping instead of being strapped to a recharger,” she says.
Meyer and her team toured hospitals, and spoke to nurses and surgeons to get a sense of their biggest gripes when it came to corded devices. “We’ve done surveys with healthcare professionals, and nine out of ten see low and dead batteries as a significant issue in the OR,” she says. “Cord reliability – four out of five see that as a challenge. I’ve spent time in the operating rooms, and had a nurse point to the tangled cords and say, ‘If there’s a purgatory, this must be it’.”
As well as being safer in a multitude of ways, wireless power transfer could save significant time and stress when a room needs to be reconfigured. For hospital staff, it could mean the ability to power tools and machines simply by parking them on a charging mat or placing them near a transmitter. Currently, the workaround for batteries going flat in the middle of surgery is to stock extra batteries in the OR. “Anything that gets pulled through the operating room has to be processed again, so every time it gets processed that’s additional cost, but it also hurts the life cycle of the product,” Meyer says.
However, the wireless power revolution is a gradual one. “One thing that I have learned in wireless technology is to be patient, because you have to create both sides: the transmit and the receive side,” says Gupta. The existing technology can power a smartphone at 2.5W or a laptop at 30W so it can easily handle the power requirements of wearables and implants, which are usually less than 1W. A transmitter should also be able to power multiple devices at once and send power to a receiver several feet away. The components don’t require unique equipment or processes to manufacture. But one major reason for the slow pace of development is that the industry still has yet to decide on a standard. The tension between the two technologies can discourage companies from investing in one at the potential expense of the other.
The battle is playing out in the consumer space where the Qi standard, overseen by the Wireless Power Consortium, is competing with Rezence, backed by the AirFuel Alliance. Qi uses magnetic induction technology and has a larger share of the consumer market; it can be found in phone cases, IKEA furniture and wireless charging points in Starbucks tables. Its backer, the Wireless Power Consortium, has 240 member companies to the AirFuel Alliance’s 105. But Rezence represents the technology the healthcare industry is hoping for – the magnetic resonance technology pioneered by WiTricity.
“Qualcomm’s been working with wireless power for about ten years now, and our initial forays into it involved wide-area charging, or charging everything in a room. We eventually settled on pursuing what became the AirFuel Alliance, which is magnetic resonance charging,” says Bill von Novak, a principal engineer and wirelesspower team leader at Qualcomm. The firm is one of the most active members of the AirFuel Alliance – Qualcomm’s then-vicepresident of engineering, Kamil Grajski, founded one of the two groups that joined forces to create it.
Novak expects the first medical devices to adopt wireless charging will not be entirely new creations, but rather improved versions of existing products. Pacemakers, defibrillators and neurostimulators will definitely be on the agenda, but there are other devices with small batteries that could benefit from a sealed wireless design.
“One of the challenges with hearing aids is making them last a long time, because moisture and earwax gets into them and that’s why most of them fail,” he says. “So if you can seal a device like that, with the battery inside but no penetrations to the outside world, you can potentially get a much longer-lived hearing aid.”
Meyer says the time will come for implants, but they may not be the first to hit the market. “As a general rule, a surgical tool may take less time than an implantable device, regardless of the foundational technology,” she says.
Most of the work done by Qualcomm and WiTricity has been in the consumer field. In the US, where the major players in the wireless power game are operating, consumer device manufacturers answer to the Federal Communications Commission. To bring the technology to healthcare, manufacturers must get to grips with a whole new set of regulations from FDA.
To make sure it meets FDA standards, Qualcomm is starting from scratch in its designs rather than trying to adapt consumer technology. “There are temperature rise standards: the device can’t raise the temperature more than a few degrees to be safe inside your body. And that impacts us in terms of what efficiency we have to target, how much power we can dissipate and what the overall efficiency of the wireless power link has to be,” says Novak.
While industry groups struggle for dominance, keen scientists are already demonstrating what we might see ten years from now. A group at Stanford University recently found a way to transmit wireless power to a moving target, which could give implant recipients even more freedom. Novak’s team at Qualcomm is looking into ways to charge devices implanted as deep as 20cm into the body.
“If you can charge at that distance, you can charge anywhere in the body,” Novak says. “That’s required us looking at new frequencies, different power levels, different designs for receiver and transmitters.”
There are also potential applications of wireless power as a non-invasive therapy that stimulates nerves and triggers the body’s parasympathetic responses to treat conditions like high blood pressure. “These therapies can’t be used in outpatient contexts, because the power requirement is too high and some of this stuff hasn’t been invented [yet], but it can be very pinpointed and targeted,” says Gupta.
The reality is that a completely cordless operating room is unlikely to appear for at least another decade. How much wireless power can contribute to the medical industry will depend on whether the technology that makes it to market can be used by the healthcare industry, and whether implanted devices can be charged without compromising patient safety. The saving grace may be that even though the industry has been waiting for its advent for years, wireless power is still the kind of futuristic tech that fires imaginations.