Assistant Professor Jeremy Gummeson of the Electrical and Computer Engineering Department was a guest on BYURadio’s “Top of Mind” program exploring the concept of the human wrist serving as the charging dock for wireless wearable devices. Gummeson is part of a UMass Amherst team that has designed a prototype system called “Shazam,” which uses skin to charge smartwatches and other wearable devices such as health and fitness trackers.
Gummeson and his Ph.D. student Noor Mohammed are members of the team that has designed Shazam along with Sunghoon Ivan Lee, assistant professor in the UMass Amherst College of Information and Computer Sciences and director of the Advanced Human Health Analytics Laboratory.
This UMass team recently received a $598,720 National Science Foundation grant, shared in collaboration with researchers from Northwestern University, to continue to develop the system’s hardware and software.
As BYU Radio host Julie Rose introduced the segment, “Here’s a wild idea: Human skin conducts electricity, so what if your wrist could serve as a charging dock for your smartwatch? Then you’d never have to take it off. Could this actually work?”
Rose went on to say that “I’m talking with Jeremy Gummeson, he’s a professor of electrical and computer engineering at the University of Massachusetts Amherst working on a concept he and his team call “Shazam,” which is this idea that a device you are wearing could be charged while it’s on you with your body or hand or skin as the wire that conducts the electricity from whatever the power source is.”
Here’s the background for developing Shazam. As smart watches and wearable health-tracking devices are increasingly able to monitor the vital signs of health, including what’s going on when we sleep, a problem has emerged. These wearable, wireless devices are often disconnected overnight while being recharged. In such cases, vital data about medical issues that never show up during visits to doctors, such as certain heart conditions, are lost forever.
In addition, the inconvenience of frequent charging is one of the main reasons users stop using wearable devices such as fitness- and health-tracking devices.
Enter Shazam! “The key concept that we exploit in our Shazam system is using human tissue as a transfer medium for power,” as Gummeson explained.
“So the idea here,” said Gummeson on BYU Radio, “is that [Shazam] was inspired by some experiments where they were putting chargers in the tables at Starbucks locations, or IKEA integrating wireless charging pads for phones into the armrests of your couch.”
Rose intervened to ask, “Where you just have to put the phone on the charging table and you don’t have to plug it into anything?”
“That’s right,” said Gummeson. “So we thought about taking this idea to the logical extreme. You can integrate an electrode into an object that you’re interacting with on a day-to-day basis. This could potentially be a palm rest by your computer keyboard or even an automobile steering wheel. We thought we could use these opportunities to couple a signal through an electrode onto the surface of your skin and then use that to power a wearable device.”
Gummeson then explained that “Our device uses a method called ‘capacitive coupling,’ in which there’s an electric field that couples between the electrode on the steering wheel and the electrode on the watch…We’ve designed all the circuitry such that we can very quickly detect that the user is touching the steering wheel so that the user is in proximity to this charger and then slowly ‘trickle charge’ the battery of the watch or wearable device.”
Trickle charging with a tiny amount of electricity over a period of time is one key to the safety of the device. That way its transmitted power always stays below the upper limit set by the Federal Communications Commission on the amount of power that you can legally subject the human body to over a particular surface area.
“So, in our research,” concluded Gummeson, “we make sure we don’t exceed this threshold by placing a hard limit on the power that we can output and make the electrode on the devices that are in contact with your skin such that we’re not sending too much power [over a small] area.”
When Rose asked Gummeson if the electricity involved could be dangerous to the human user, he replied, “That’s a great question. So, we’re not talking about lots of power…We’re talking about something that might be on the order of a milliwatt of power total. So, to put this into perspective, you could think of this as the amount of power you have in a body composition scale [that’s already on the market].”
“So what would I feel?” asked Rose. “Is it a tickle, a zap? What do I feel.”
“You feel nothing,” said Gummeson.
In a paper published in the Proceedings of the ACM on Interactive Mobile, Wearable, and Ubiquitous Technologies, Gummeson, Lee, and lead author Mohammed described the technical groundwork for Shazam and showcased its feasibility. (August 2021)