posted on 2019-02-11, 00:00authored byMinglu Zhu, Qiongfeng Shi, Tianyiyi He, Zhiran Yi, Yiming Ma, Bin Yang, Tao Chen, Chengkuo Lee
Wearable
devices rely on hybrid mechanisms that possess the advantages
of establishing a smarter system for healthcare, sports monitoring,
and smart home applications. Socks with sensing capabilities can reveal
more direct sensory information on the body for longer duration in
daily life. However, the limitation of suitable materials for smart
textile makes the development of multifunctional socks a major challenge.
In this paper, we have developed a self-powered and self-functional
sock (S2-sock) to realize diversified functions including
energy harvesting and sensing various physiological signals, i.e., gait, contact force, sweat level, etc., by hybrid integrating poly(3,4-ethylenedioxythiophene) polystyrenesulfonate
(PEDOT:PSS)-coated fabric triboelectric nanogenerator (TENG) and lead
zirconate titanate (PZT) piezoelectric chips. An output power of 1.71
mW is collected from a PEDOT:PSS-coated sock with mild jumping at
2 Hz and load resistance of 59.7 MΩ. The study shows that cotton
socks worn daily can potentially be a power source for enabling self-sustained
socks comprising wireless transmission modules and integrated circuits
in the future. We also investigate the influences of environmental
humidity, temperature, and weight variations and verify that our S2-sock can successfully achieve walking pattern recognition
and motion tracking for smart home applications. On the basis of the
sensor fusion concept, the outputs from TENG and PZT sensors under
exercise activities are effectively merged together for quick detection
of the sweat level. By leveraging the hybrid S2-sock, we
can achieve more functionality in the applications of foot-based energy
harvesting and monitoring the diversified physiological signals for
healthcare, smart homes, etc.