Sturdy fabric-based piezoelectric energy harvester takes us one step
closer to wearable electronics

Date:
September 17, 2020
Source:
The Korea Advanced Institute of Science and Technology (KAIST)
Summary:
Researchers presented a highly flexible but sturdy wearable
piezoelectric harvester using the simple and easy fabrication
process of hot pressing and tape casting. This energy harvester,
which has record high interfacial adhesion strength, will take
us one step closer to being able to manufacture embedded wearable
electronics.



FULL STORY ========================================================================== KAIST researchers presented a highly flexible but sturdy wearable
piezoelectric harvester using the simple and easy fabrication process of
hot pressing and tape casting. This energy harvester, which has record
high interfacial adhesion strength, will take us one step closer to being
able to manufacture embedded wearable electronics. A research team led
by Professor Seungbum Hong said that the novelty of this result lies in
its simplicity, applicability, durability, and its new characterization
of wearable electronic devices.


========================================================================== Wearable devices are increasingly being used in a wide array of
applications from small electronics to embedded devices such as sensors, actuators, displays, and energy harvesters.

Despite their many advantages, high costs and complex fabrication
processes remained challenges for reaching commercialization. In addition, their durability was frequently questioned. To address these issues,
Professor Hong's team developed a new fabrication process and analysis technology for testing the mechanical properties of affordable wearable devices.

For this process, the research team used a hot pressing and tape casting procedure to connect the fabric structures of polyester and a polymer
film. Hot pressing has usually been used when making batteries and fuel
cells due to its high adhesiveness. Above all, the process takes only
two to three minutes.

The newly developed fabrication process will enable the direct application
of a device into general garments using hot pressing just as graphic
patches can be attached to garments using a heat press.

In particular, when the polymer film is hot pressed onto a fabric
below its crystallization temperature, it transforms into an amorphous
state. In this state, it compactly attaches to the concave surface of
the fabric and infiltrates the gaps between the transverse wefts and longitudinal warps. These features result in high interfacial adhesion strength. For this reason, hot pressing has the potential to reduce
the cost of fabrication through the direct application of fabric-based
wearable devices to common garments.

In addition to the conventional durability test of bending cycles, the
newly introduced surface and interfacial cutting analysis system proved
the high mechanical durability of the fabric-based wearable device by
measuring the high interfacial adhesion strength between the fabric and
the polymer film.

Professor Hong said the study lays a new foundation for the manufacturing process and analysis of wearable devices using fabrics and polymers.

He added that his team first used the surface and interfacial cutting
analysis system (SAICAS) in the field of wearable electronics to test
the mechanical properties of polymer-based wearable devices. Their
surface and interfacial cutting analysis system is more precise than conventional methods (peel test, tape test, and microstretch test) because
it qualitatively and quantitatively measures the adhesion strength.

Professor Hong explained, "This study could enable the commercialization
of highly durable wearable devices based on the analysis of their
interfacial adhesion strength. Our study lays a new foundation for the manufacturing process and analysis of other devices using fabrics and
polymers. We look forward to fabric-based wearable electronics hitting
the market very soon." The results of this study were registered as a
domestic patent in Korea last year, and published in Nano Energy this
month. This study has been conducted through collaboration with Professor
Yong Min Lee in the Department of Energy Science and Engineering at
DGIST, Professor Kwangsoo No in the Department of Materials Science and Engineering at KAIST, and Professor Seunghwa Ryu in the Department of Mechanical Engineering at KAIST.


========================================================================== Story Source: Materials provided by The_Korea_Advanced_Institute_of_Science_and_Technology_ (KAIST). Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Jaegyu Kim, Seoungwoo Byun, Sangryun Lee, Jeongjae Ryu, Seongwoo
Cho,
Chungik Oh, Hongjun Kim, Kwangsoo No, Seunghwa Ryu, Yong Min Lee,
Seungbum Hong. Cost-effective and strongly integrated fabric-based
wearable piezoelectric energy harvester. Nano Energy, 2020; 75:
104992 DOI: 10.1016/j.nanoen.2020.104992 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/09/200917105401.htm

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