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Download fileFlexible and Transparent Cellulose-Based Ionic Film as a Humidity Sensor
journal contribution
posted on 28.01.2020, 16:43 authored by Yang Wang, Lina Zhang, Jinping Zhou, Ang LuA transparent and
flexible cellulose/KOH composite ionic film (CKF)
is fabricated as a humidity sensor. CKF exhibits high optical transmittance
(87.14% at 550 nm), which has rarely been reported among humidity
sensors as a result of the small pore size of the cellulose matrix
caused by water-evaporation-induced dense packing and uniform distribution
of amorphous KOH via simply soaking–drying. CKF also possesses
flexibility and robust mechanical property. The conductive CKF shows
fast and reversible real-time response to relative humidity (RH) in
the 11.3–97.3% RH range with conductance varying over 200 times,
response/recovery times of 6.0/10.8 s, which are shorter than the
majority of the reported values, as well as a hysteresis error of
0.57%, which is significantly less than that reported in the literature.
Furthermore, CKF is insensitive to both the temperature (10–70
°C) and pressure (0–120 kPa), indicating high selectivity
as humidity sensors. In both the non-contact fingertip moisture detection
and breathing rate detection, the flexible and transparent CKF-based
humidity sensor responds favorably to RH change. Moreover, a flexible
and transparent CKF-based wearable skin moisture detector is assembled
to measure the moisture of human skin in different situations, whose
measurement is very close to the commercial detector. The results
offer real-time moisture information on human skin and demonstrate
the potential of a CKF-based moisture detector as a promising modular
component in integrated intelligent wearable equipment.