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HOME > No.20, Feb 2020 > Electronics Integrated to the Muscle via 'Kirigami'

Electronics Integrated to the Muscle via 'Kirigami'

Donut-shaped kirigami device enabling accurate and robust signal acquisition from the muscle By Takeshi Kawano
Takeshi Kawano

A research team lead by Associate Professor Takeshi Kawano from the Department of Electrical and Electronic Information Engineering and the Electronics-Inspired Interdisciplinary Research Institute (EIIRIS) at Toyohashi University of Technology (TUT) has developed a donut-shaped kirigami device for electromyography (EMG) recordings. The proposed device reduces device displacement on a large deformable muscle surface. Accurate and robust EMG recordings offer EMG signal-based human–machine interfaces which allow prosthesis control for amputees. The results of this research were published in an issue of Advanced Healthcare Materials on December 5, 2019. The article also appeared on the inside back cover.

Fig.1 2D donut shape (left: before deformation) and 3D cylindrical shape (right: after deformation).

An accurate and robust EMG signal recording is necessary in EMG signal-based human–machine interfaces to allow prosthesis control for amputees using their residual muscle. In 2017, this research team previously proposed an electrode device using the kirigami structure for the intimate integration of the electronic device and biological tissues. (Y. Morikawa et al., 10.1002/adhm.201701100).

The remarkable potential of the kirigami structure stems from its high stretchability, including its high strain ratio and the small force required for stretching the device. The kirigami structure can be stretched with a low strain force and its mechanical characteristics are similar to soft biological tissues, such as in the brain and muscles. However, it is challenging to obtain an accurate and robust bio-signal recording without displacement of the electrode. Device displacement occurs when the kirigami device is applied to biological tissues, such as the heart and muscles, which undergo large deformation.

A research team lead by Associate Professor Takeshi Kawano from TUT’s Department of Electrical and Electronic Information Engineering and EIIRIS has developed a donut-shaped kirigami device for EMG recordings to solve the issue of device displacement during muscle deformation.

Fig.2 Fabricated donut-shaped kirigami device (inset: embedded electrodes).

The donut-shaped kirigami structure is able to transform from a 2D donut shape to a 3D cylindrical shape. The cylindrical shape is suitable for numerous spherically or columnar-shaped deformable biological tissues (e.g. upper limb, lower limb, finger, abdomen, and heart). The donut-shaped kirigami device carries out the fixation mechanism to the target tissues and reduces the device displacement during tissue deformation with minimized stress to the biological tissue. The recording capability of the proposed device was confirmed through EMG signal recording from the hind limb of a mouse, thus raising the prospect of using the device for an EMG-based human-machine-interface in the future.

"The first demonstration using our conventional sheet-shaped kirigami device could not follow the deformation of a beating heart. We discussed the device structure, which enables the device to follow deformable tissues. In the preliminary experiment, we used a paper, which was patterned into the proposed donut-shape of the kirigami by the box cutter, and we demonstrated its stretchable and deformable capabilities for the muscle. However, it was uncertain whether the micro-scale donut-kirigami device would show these device properties or not. We explored them through fabricating the device by using the microfabrication process and device characterizations, and were able to confirm that the fabricated device exhibited the expected deformation beyond expectations," explains the first author of the article, Ph.D. candidate Yusuke Morikawa.

Fig.3 Schematic image showing the EMG signal recording (left) and photograph showing the donut-shaped kirigami device attached on the muscle surface

The donut-shaped kirigami device still needs further improvements in terms of durability and the dense array of the microelectrodes. Moreover, the influence of the device implantations on the biological tissues when used for a long period still remains to be clarified. However, it is expected that the proposed device will be applicable to an EMG based human-machine-interface and so contribute to the improvement of the quality of life of amputees.

This work was supported by Grants-in-Aid for Scientific Research (B) (No. 17H03250, No. 16H05434), for Young Scientists (A) (No. 26709024), on Innovative Areas (Research in a proposed research area) (15H05917), and Strategic Advancement of Multi-Purpose Ultra-Human Robot and Artificial Intelligence Technologies program from NEDO. Y.M. was supported by the Leading Graduate School Program R03 of MEXT. R.N. was supported by Takeda Science Foundation. K.K. was supported by Toyota Physical & Chemical Research Institute Scholars.


Yusuke Morikawa, Shota Yamagiwa, Hirohito Sawahata, Rika Numano, Kowa Koida, and Takeshi Kawano. (2019). "Donut‐Shaped Stretchable Kirigami: Enabling Electronics to Integrate with the Deformable Muscle." Advanced Healthcare Materials, 10.1002/adhm.201900939.

筋肉に一体化できる 'Kirigami' エレクトロニクス

By 河野 剛士



本研究チームが2017年に開発した切り紙構造を用いた非常に高い伸縮性を持つ神経電極は、マウスの脳や心臓からの信号計測の可能性を示しました(Morikawa et al., 2017 10.1002/adhm.201701100)。この切り紙構造による高い伸縮性は生体組織の持つ柔らかさに近く、一般的に用いられる柔軟性材料やゴムによる柔軟性や伸縮性を持った電極に対して生体へ与える負担を軽減します。しかし、これまでの切り紙構造を用いた電極では、大きな変形を示す生体組織(例えば心臓や筋肉など)に対して、電極の位置ずれやまた電極自身が組織から剥がれる問題がありました。






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Researcher Profile

Takeshi Kawano
Name Takeshi Kawano
Affiliation Department of Electrical and Electronic Information Engineering
Title Associate Professor
Fields of Research Micro/Nano Devices, Neural Interface Devices