Copyright © 2017 American Scientific Publishers
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Printed in the United States of America
Article
Journal of
Nanoscience and Nanotechnology
Vol. 17, 1–6, 2017
www.aspbs.com/jnn
Flexible and Compressible Temperature Sensors
Based on Hierarchically Buckled Carbon
Nanotube/Rubber Bi-Sheath-Core Fibers
Kunkun Wu
1 2†
, Zhongsheng Liu
1 2†
,HaibaoLin
1 2†
, Run Wang
1 2
,QuYin
1 2
,WeiLv
1
,
Jian Su
1
, Ningyi Yuan
1
, Jianhua Qiu
1
, Jianning Ding
1 ∗
, Raquel Ovalle-Robles
4
,
Kanzan Inoue
4
, and Zunfeng Liu
1 2 3 ∗
1
Jiangsu Collaborative Innovation Center of Photovoltaic Science and Engineering,
School of Materials Science and Engineering, Changzhou University, Changzhou 213164, China
2
Jiangnan Graphene Research Institute, Changzhou 213149, China
3
State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Functional Polymer Materials,
Ministry of Education, College of Pharmacy, Nankai University, Tianjin, 300071, China
4
Lintec of America, Nano-Science and Technology Center, Richardson, TX 75081, USA
Flexible and compressible temperature sensors are highly desired for artificial skin and epider mal
electronics. Here we demonstrated a flexible and compressible resistive temperature sensor using
hierarchically buckled carbon nanotube/r u bber bi-sheath-core structure (a buckled carbon nano-
tube outer sheath and a buckled rubber inner sheath wrapped around a rubber fiber core). When
heated, lateral contacts of the adjacent buckles increase, resulting in electrical resistance decrease
and ser ving as highly sensitive temperature sensors. This bi-sheath-core fiber temperature sen-
sor showed high linearity, good repeatability, large negative temperature coefficient of resistance
(NTC =−54.7/
C), and insensitivity to compressive deformations (up to −20% strain). The NTC
and temperature dependence of percent resistance change can be easily tuned by modulating the
buckling bi-sheath-core structures such as varying the number of nanotube layers and the rubber
sheath stiffness.
Keywords: Temperature Sensor, Resistance Change, Bi-Sheath-Core, Negative Temperature
Coefficient of Resistance.
1. INTRODUCTION
Many exciting previous advances in flexible and
deformable temperature sensors have been demonstrated
for po tential applications in artificial skin, epidermal elec-
tronics, robotics, and medical diagnostics.
1–5
For example,
conventional approaches include attaching temperature
sensors (such as thermal couples, resistive temperature
detectors (RTDs), and organic diodes) on flexible elas-
tomer substrates.
6–8
Thermal couple generates a very small
voltage change (40 to 70 V/
C), and RTDs based on
metallic materials generate a relatively small resistance
change of 0.4 /
C, which require high-gain amplifiers
∗
Authors to whom correspondence should be addressed.
†
These three authors contributed equally to this work.
and high-precision circuits for data collection and analysis,
which increase the cost and difficulty for fabr ication and
applications.
2
Conductive polymer composites show large resistance
increase with temperature due to thermal expansion o f
the polymer matrix. Such composites show advantages of
excellent f ormability, moldability, light weight, and flexi-
bility. However, the repeatability of the resistance change
is relatively poor because of the structure evolution of
the polymer matrix during melting-freezing process.
6
This
makes it difficult to be used as a temperature sensor.
Furthermore, polymer composites always show resistance
change under compressive deformation, so the polymer
composites are always made by hard plastic material,
which is not ideal for epidermal electronics applications.
J. Nanosci. Nanotechnol. 2017, Vol. 17, No. xx 1533-4880/2017/17/001/006 doi:10.1166/jnn.2017.14386 1