Page 22 - IOE_Winter 24

SALINE-CHARGED BATTERY
FOR SMART CONTACT LENSES
Scientists at the Nanyang Technological
University in Singapore have created a flexible
battery as thin as the human cornea that has
been hailed as a breakthrough with enormous
potential to energise smart contact lenses.
Smart contact lenses, equipped to display
information directly onto the cornea, offer
capabilities for access to augmented reality,
health monitoring and even to the recording and
transmission of visual and auditory data to cloud
storage. This development, a battery that is free
from wires and toxic metals, and is produced
entirely from biocompatible materials, overcomes
the problems caused by traditional rechargeable
batteries, the components of which are unsuitable
for eyewear.
The new battery incorporates a glucose-based
coating that reacts with sodium and chloride ions
in a saline solution which then acts as a conductor
for the generation of electricity. Tests conducted
with a simulated human tear solution, which
contains sodium and potassium ions, revealed
that the battery life could be extended by an hour
for every twelve hours of use, in addition to being
conventionally charged from an external power
source.
Under test the battery was able to generate a
current of 45 microamperes and a power output
of 201 microwatts, which is sufficient to power
a smart lens. Its longevity of up to 200 charge-
discharge cycles was found to be comparable to
that of a lithium-ion battery.
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The team has filed for a patent through NTUitive,
NTU’s innovation and enterprise company.
Associate Professor Lee Seok Woo of Nantang
Technological University’s School of Electrical and
Electronic Engineering, comments:
“ Our approach can charge both electrodes
of a battery through a unique combination
of enzymatic reaction and self-reduction
reaction”.
Research Fellow and Co-first Author Dr. Yun
Jeonghun, adds:
“ The most common battery charging system
for smart contact lenses requires metal
electrodes in the lens. Our tear-based battery
eliminates the two potential concerns that
these two methods pose, while also freeing up
space for further innovation in the development
of smart contact lenses.”
Co-first Author Miss Li Zongkang, a PhD student
in NTU’s School of Electrical and Electronic
Engineering, further explains:
“ By combining the battery and biofuel cell into
a single component, the battery can charge
itself without the need for additional space for
wired or wireless components.”
[ Reference: Miles, S., Electronic Specifier, 9th.
November 2023 ]