Nanotechnologies / Materials
Healthcare, Electronics

Cellulose nanofiber coatings against water-induced
short-circuit failures
Department of Functionalized Natural Materials, The Institute of Scientific and Industrial Research (SANKEN)
Ph.D Student / Research Fellowship for Young Scientists (DC1) Takaaki Kasuga

Researchmap https://researchmap.jp/tkasuga

Professor Masaya Nogi

Researchmap https://researchmap.jp/read0151141

Nanotechnologies / Materials

Abstract
Water is detrimental to electronic devices because it easily
causes short circuits. Some electronics can be made at least water-resistant by, for example, using hydrophobic polymers to coatthe electronic circuit, however, it is inevitable that water penetrates
the sealing material if it is cracked or delaminated, and the watercan easily cause malfunctions due to dendrite growth. In this study,
we present a cellulose nanofiber coating that can reliably prevent
malfunctions caused, even if the waterproof seals are damaged
and the circuit becomes wet. The cellulose nanofibers accumulate
at the anode due to electrophoresis, thereby forming a cohesive
cellulose nanofiber layer that prevents short circuits between electrodes more than 24 h.

▍ Background & Results
Most electronic devices are not waterproof, and contact with water can easily destroy them. In many cases, sealing with hydrophobic resin is an effective method to prevent water-induced failures.
However, in case of next generation electronic devices such as
flexible devices and degradable sensor devices, more advanced
protections are required. Here, we present a cellulose nanofiber
coating that can prevent water-induced short circuit failures effectively. When uncoated Cu electrodes were submerged under waterand a voltage was applied, short circuits occurred after 5 min due
to the formation of dendrites between the electrodes. On the otherhand, short circuit failure was inhibited for at least 24 h with the cellulose nanofiber coating. Redispersion of the cellulose nanofibers
occurs in the presence of water. The applied electric field promotes
the migration and dispersion of cellulose nanofibers toward the anode, contributing to the formation of a stable protective layer. The
cellulose nanofiber coating can be combined with existing sealing
technologies to dramatically increase the safety of electronic devices, and can also be applied as a biodegradable circuit protection
coating.

▍ Significance of the research and Future perspective
The technology can be easily combined with existing circuit protection technologies and is expected to further improve safety bylayering waterproof coating and the cellulose nanofiber coating.
In addition, it can be used not only for flexible devices but also for
eco-friendly degradable sensor devices which will contribute toreduce environmental pollution and management and decrease
the disposal costs of sensor devices. It is expected to be a novel
technology that is environmentally friendly and enriches our lives.

P a t e n t patent pending
Kasuga, Takaaki; Nogi, Masaya et al. Cellulose Nanofiber Coatings on Cu Electrodes for Cohesive Protection against Water-Induced Short-Circuit Failures.
Tr e a t i s e
ACS Appl. Nano Mater. 2021; 4 (4): 3861–3868. doi: 10.1021/acsanm.1c00267
UR
L https://www.youtube.com/watch?v=6ENGdrD2vWM&t=105s
K e y w o r d cellulose nanofiber, circuit protection, wearable devices, SDGs