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NTU scientists invent editable fabric-like power source for use in wearable electronic devices

NTU scientists invent editable fabric-like power source for use in wearable electronic devices

Scientists at Nanyang Technological University, Singapore
(NTU Singapore) have
created
a customisable, fabric-like power source that can be cut, folded or
stretched without losing its function, and will be of use in wearable
electronic devices.

The team led by Professor Chen Xiaodong, Associate Chair
(Faculty) at the School of Materials Science & Engineering, reported in the
journal Advanced Materials (print edition, January 8) how they have created the
power source, a supercapacitor, which works like a fast-charging battery and
can be recharged many times.

This supercapacitor is customisable or “editable”, meaning that
its structure and shape can be changed after it is manufactured, while
retaining its function as a power source. Existing stretchable supercapacitors
are made into predetermined designs and structures, but the new invention can
be stretched multi-directionally, making it easier to match while combining it
with other electrical components. 

The supercapacitor is made of strengthened manganese dioxide
nanowire composite material, a common material for supercapacitors. However,
the ultralong nanowire structure, strengthened with a network of carbon
nanotubes and nanocellulose fibres, allows the electrodes to withstand the
associated strains during the customisation process. 

When edited into a honeycomb-like structure, the new
supercapacitor has the ability to store an electrical charge four times higher
than most existing stretchable supercapacitors. In addition, when stretched to
four times its original length, it maintains nearly 98 per cent of the initial
ability to store electrical energy, even after 10,000 stretch-and-release
cycles.

Experiments done by Prof. Chen and his team also demonstrated
that when the editable supercapacitor was paired with a sensor and placed on
the human elbow, it performed better than existing stretchable supercapacitors.
The editable supercapacitor was able to provide a stable stream of signals even
when the arm was swinging. These signals are then transmitted wirelessly to
external devices, such as one that captures a patient’s heart rate. 
  

The team has filed a patent for the technology. They believe
that the editable supercapacitor could be easily mass-produced as it would rely
on existing manufacturing technologies. Production cost is estimated to be low at
about SGD$0.13 (USD$0.10) to produce 1 sq cm of the material.

Professor Chen said, “A reliable and editable supercapacitor
is important for development of the wearable electronics industry. It also
opens up all sorts of possibilities in the realm of the ‘Internet-of-Things’
when wearable electronics can reliably power themselves and connect and
communicate with appliances in the home and other environments.”

“My own dream is to one day combine our flexible
supercapacitors with wearable sensors for health and sports performance
diagnostics. With the ability for wearable electronics to power themselves, you
could imagine the day when we create a device that could be used to monitor a
marathon runner during a race with great sensitivity, detecting signals from
both under and over-exertion,” he added.

The NTU team also collaborated with Dr. Loh Xian Jun, Senior
Scientist and Head of the Soft Materials Department at the Institute of
Materials Research and Engineering (IMRE), under the Agency for Science,
Technology and Research (A*STAR).

Dr. Loh commented, “Customisable and versatile, these
interconnected, fabric-like power sources are able to offer a plug-and-play
functionality while maintaining good performance. Being highly stretchable,
these flexible power sources are promising next-generation ‘fabric’ energy
storage devices that could be integrated into wearable electronics.”