posted on 2020-01-29, 14:37authored byJimin Gu, Donguk Kwon, Junseong Ahn, Inkyu Park
A number
of flexible and stretchable strain sensors based on piezoresistive
and capacitive principles have been recently developed. However, piezoresistive
sensors suffer from poor long-term stability and considerable hysteresis
of signals. On the other hand, capacitive sensors exhibit limited
sensitivity and strong electromagnetic interference from the neighboring
environment. In order to resolve these problems, a novel stretchable
strain sensor based on the modulation of optical transmittance of
carbon nanotube (CNT)-embedded Ecoflex is introduced in this paper.
Within the film of multiwalled CNTs embedded in the Ecoflex substrate,
the microcracks are propagated under tensile strain, changing the
optical transmittance of the film. The proposed sensor exhibits good
stretchability (ε ≈ 400%), high linearity (R2 > 0.98) in the strain range of ε = 0–100%,
excellent stability, high sensitivity (gauge factor ≈ 30),
and small hysteresis (∼1.8%). The sensor was utilized to detect
the bending of the finger and wrist for the control of a robot arm.
Furthermore, the applications of this sensor to the real-time posture
monitoring of the neck and to the detection of subtle human motions
were demonstrated.