posted on 2024-03-18, 08:14authored byWei Song, Ru Xiao
With the development of wearable devices, the demand
for pressure
sensing has prompted the development of flexible pressure sensors
with excellent overall performance, especially flexible piezoresistive
sensors with long-term durability. In this study, covalently interconnected
poly(vinyl alcohol-co-ethylene) (EVOH)/MWCNTs composite
nanofibrous aerogels with typical “layer–pillar”
hierarchical porous structure were prepared by hydroxyl aldehyde condensation
to cross-link thermoplastic nanofibers and hydroxylated carbon nanotube.
Benefiting from the porous structure of composite nanofibrous aerogels
and robust bonding between EVOH and MWCNTs, the prepared composite
nanofibrous aerogel exhibited an ultralow density (18.27 mg/cm3), excellent compressibility and restorability (up to 80%
strain), and remarkable fatigue durability exceeding 1000 times. Meanwhile,
the compressive strength of the cross-linked composite aerogel was
increased by a factor of 3.5 compared to the un-cross-linked composite
aerogel (9.70 kPa). The composite nanofibrous aerogel can be assembled
as a piezoresistive sensor, with a sensing capacity up to 80% strain
(corresponding to 33.49 kPa) and detection limit of 80 Pa. Furthermore,
the dynamic strain sensitivity and pressure sensitivity of the piezoresistive
sensor are GF = 1.51 and S = 0.28 kPa–1, respectively. More importantly, the cyclic stability of the pressure
resistance sensor was outstanding; even after 3000 cycles, its curve
remained essentially consistent with the initial 50 cycles. These
successes ensure the excellent performance of EVOH/MWCNTs composite
nanofibrous aerogels for sensitive monitoring of mechanical signals,
such as body posture monitoring, and show the great potential of aerogel
sensors as the next generation of wearable electronics.