Researchers successfully demonstrated the use of the human body as a medium for transmitting
and harvesting energy to power wearables.
Advancements in wearable technology are reshaping the way we live, work and play, and also how
healthcare is delivered and received.
Wearables that have weaved their way into everyday life include smart watches and wireless
earphones, while in the healthcare setting, common devices include wearable injectors,
electrocardiogram (ECG) monitoring patches, listening aids, and more.
A major pain point facing the use of these wearables is the issue of keeping these devices
properly and conveniently powered.
As the number of wearables one uses increases, the need to charge multiple batteries rises
in tandem, consuming huge amounts of electricity.
Many users find it cumbersome to charge numerous devices every day, and inconvenient service
disruptions occur when batteries run out.
A research team at the National University of Singapore (NUS), has developed a solution
to these problems.
Their technology enables a single device, such as a mobile phone placed in the pocket,
to wirelessly power other wearable devices on a user’s body, using the human body as
a medium for power transmission.
The team’s novel system has an added advantage – it can harvest unused energy from electronics
in a typical home or office environment to power the wearables.
Their achievement was published in the journal Nature Electronics.
It is the first of its kind to be established among existing literature on electronic wearables.
To extend battery life and sustain fully autonomous – yet wireless – operations of wearable
devices, power transmission and energy harvesting approaches are required.
However, conventional approaches for powering up body area wearables are limited by the
distance that power can be transmitted, the “path” the energy can travel without facing
obstacles, and the stability of energy movement.
As such, none of the current methods have been able to provide sustainable power to
wearables placed around the entire human body.
The NUS team decided to turn the tables on these limitations by designing a receiver
and transmitter system that uses the very obstacle in wireless powering – the human
body – as a medium for power transmission and energy harvesting.
Each receiver and transmitter contains a chip that is used as a springboard to extend coverage
over the entire body.
A user just needs to place the transmitter on a single power source, such as the smart
watch on a user’s wrist, while multiple receivers can be placed anywhere on the person’s
body.
The system then harnesses energy from the source to power multiple wearables on the
user’s body via a process termed as body-coupled power transmission.
In this way, the user will only need to charge one device, and the rest of the gadgets that
are worn can simultaneously be powered up from that single source.
The team’s experiments showed that their system allows a single power source that is
fully charged to power up to 10 wearable devices on the body, for a duration of over 10 hours.
As a complementary source of power, the NUS team also looked into harvesting energy from
the environment.
Their research found that typical office and home environments have parasitic electromagnetic
(EM) waves that people are exposed to all the time, for instance, from a running laptop.
The team’s novel receiver scavenges the EM waves from the ambient environment, and
through a process referred to as body-coupled powering, the human body is able to harvest
this energy to power the wearable devices, regardless of their locations around the body.
Batteries are among the most expensive components in wearable devices, and they add bulk to
the design.
The researcher says that their unique system has the potential to omit the need for batteries,
thereby enabling manufacturers to miniaturise the gadgets while reducing production cost
significantly.
More excitingly, without the constraints of batteries, their development can enable the
next generation wearable applications, such as ECG patches, gaming accessories, and remote
diagnostics.
The NUS team will continue to enhance the powering efficiency of their transmitter/receiver
system, with hopes that in future, any given power-transmitting device, be it a user’s
mobile phone or smart watch, can satisfy the network power demands of all other wearables
on the body, thus enabling a longer battery lifetime.