The new
stretchable material, when used in light-emitting capacitor devices, enables
highly visible illumination at much lower operating voltages, and is also
resilient to damage due to its self-healing properties.
This innovation,
called the HELIOS (which stands for Healable, Low-field Illuminating
Optoelectronic Stretchable) device, was achieved by Assistant Professor
Benjamin Tee and his team from the NUS Institute for Health Innovation &
Technology and NUS Materials Science and Engineering. The results of the
research were first reported in prestigious scientific journal Nature Materials
on 16 December 2019.
Durable, low-power
material for next-gen electronic wearables and soft robots
“Conventional stretchable optoelectronic
materials require high voltage and high frequencies to achieve visible
brightness, which limits portability and operating lifetimes. Such materials
are also difficult to apply safely and quietly on human-machine interfaces,â€
explained Asst Prof Tee, who is also from NUS Electrical and Computer
Engineering, N.1 Institute for Health and the Hybrid Integrated Flexible Electronic
Systems programme.
To overcome these
challenges, the team of five NUS researchers began studying and experimenting
with possible solutions in 2018, and eventually developed HELIOS after a year.
In order to lower
the electronic operating conditions of stretchable optoelectronic materials,
the team developed a material which has very high dielectric permittivity and
self-healing properties. The material is a transparent, elastic rubber sheet
made up of a unique blend of fluoroelastomer and surfactant. The high
dielectric permittivity enables it to store more electronic charges at lower
voltages, enabling a higher brightness when used in a light-emitting capacitor
device.
Unlike existing
stretchable light-emitting capacitors, HELIOS enabled devices can turn on at
voltages that are four times lower, and achieve illumination that is more than
20 times brighter. It also achieved an illumination of 1460 cd/m2 at 2.5 V/µm,
the brightest attained by stretchable light-emitting capacitors to date, and is
now comparable to the brightness of mobile phone screens. Due to the low power
consumption, HELIOS can achieve a longer operating lifetime, be utilised safely
in human-machine interfaces, and be powered wirelessly to improve
portability.
HELIOS is also
resistant to tears and punctures. The reversible bonds between the molecules of
the material can be broken and reformed, thereby allowing the material to
self-heal under ambient environmental conditions.
Describing the
potential impact of HELIOS, Asst Prof Tee said, “Light is an essential mode of
communication between humans and machines. As humans become increasingly
dependent on machines and robots, there is huge value in using HELIOS to create
‘invincible’ light-emitting devices or displays that are not only durable but
also energy-efficient. This could generate long-term cost savings for
manufacturers and consumers, reduce electronic waste and energy consumption,
and in turn, enable advanced display technologies to become both wallet and
environmentally friendly.â€
For example,
HELIOS can be used to fabricate long-lasting wireless displays that are
damage-proof. It can also function as an illuminating electronic skin for
autonomous soft robots to be deployed for smart indoor farming, space missions
or disaster zones. Having a low-power, self-repairing illuminating skin will
provide safety lighting for the robot to manoeuvre in the dark while remaining
operational for prolonged periods.
Next steps
The NUS team has filed for a patent for the new material, and is looking to scale up the technology for specialty packaging, safety lights, wearable devices, automotive and robotics applications.