Flexible
piezoresistive sensors with high sensitivity, low cost,
and wide response ranges are urgently required due to the rapid development
of wearable electronics. Here, carbon nanotubes (CNTs)/graphene/waterborne
polyurethane (WPU)/cellulose nanocrystal (CNC) composite aerogels
(CNTs/graphene/WC) were fabricated by facile solution mixing and freeze-drying
technology for high-performance pressure sensors. WPU and CNC were
constructed as a 3D structure skeleton, and the synergistic effect
of CNTs and graphene was beneficial to enhancing the sensing performance.
The obtained pressure sensor exhibits a highly porous network structure,
remarkable mechanical properties (76.16 kPa), high sensitivity (0.25
kPa–1), an ultralow detection limit (0.112 kPa),
and high stability (>800 cycles). More importantly, the piezoresistive
sensor could be successfully used to detect various human motions
such as finger bending, squatting–rising, walking, and running
and effectively extract real-time information by the electrical signals.
In addition, the CNTs/graphene/WC composite aerogel exhibits excellent
thermal insulation performance, which can withstand 160 °C for
a long time without any damage to the structure. The CNTs/graphene/WC
composite aerogel, because of its thermal insulation property, endows
the sensor with the potential for application in high-temperature
environments. The results indicate that CNTs/graphene/WC composite
aerogels possess high sensing performance and outstanding thermal
insulation, which means that the aerogels could be used as flexible,
wearable electronics.
Zn and Co oxides possess high theoretical capacity; however, their application in the field of lithium-ion batteries (LIBs) is greatly limited because of poor conductivity and large volume fluctuation. Herein, the multi-protuberant nanofiber structure was formed by combining two-dimensional (2D) Ti 3 C 2 nanosheets and zero-dimensional (0D) ZnCo 2 O 4 nanoparticles on the surface and inside one-dimensional (1D) carbon nanofibers (Ti 3 C 2 @ZnCo 2 O 4 @carbon nanofibers) for lithium-ion storage. The Ti 3 C 2 @ZnCo 2 O 4 @carbon nanofiber composite prepared by electrospinning, annealing, and oxidation at low temperature provides abundant active sites and an efficient conductive network to enhance the storage capacity and transfer rate of lithium ions. The Ti 3 C 2 @ZnCo 2 O 4 @carbon nanofiber anode provides high reversible specific capacity (1112.51 mA h g −1 at 0.2 A g −1 ), outstanding cycle stability (603.796 mA h g −1 at 0.5 A g −1 after 300 cycles), and excellent rate performance (455.05 mA h g −1 at 3 A g −1 and maintains 920.17 mA h g −1 when current is restored to 0.1 A g −1 ). The remarkable Li storage originates from the stable multiprotuberant nanofiber structure and fast electrochemical kinetics. The unique structure design of Ti 3 C 2 @ZnCo 2 O 4 @carbon nanofibers also provides an effective strategy for other electrochemical fields.
Pregnant women are often faced with electromagnetic pollution,
edema, joint pain, mobility difficulties, and abnormalities in the
heart rate. Designing targeted multifunctional intelligent wearable
devices to shield against electromagnetic radiation hazards, relieve
edema and joint pain, monitor movement and pulse is urgent. Herein,
an unprecedented strategy is proposed to combine a metal–organic
framework and a fabric substrate for electromagnetic interference
shielding. Co@C@carbon fabric (Co-CCF) derived from ZIF-67@cotton
fabric was prepared by simple in situ growth and annealing. Subsequently,
the Co-PCCF was prepared by encapsulating Co-CCF using polydimethylsiloxane,
which improves corrosion resistance and adhesive strength. Co-PCCF-1000
(annealing at 1000 °C) with a double conductive network structure
shows efficient electromagnetic shielding performance (blocks more
than 99.9% of electromagnetic waves). Co-PCCF with flexibility also
shows fantastic fastness and stability to avoid damages during their
use by pregnant women (still blocks more than 99% of electromagnetic
waves after being repeatedly bent for 500 cycles at 90° and undergoing
the ultrasonic treatment for 1 h and 1 M acid/salt/alkali corrosion
for 12 h, respectively). In addition, Co-PCCF can reach the required
thermal therapy temperature by controlling the voltage (1.5–3
V corresponding to 41.8–84.9 °C) and illumination intensity
(0.2 W/cm2 corresponding to 70.8 °C). Meanwhile, Co-PCCF
can monitor a wide range of human movement in real time, such as pulse,
breath, and joint activities. Multifunctional Co-PCCF designed for
pregnant women can effectively prevent electromagnetic pollution,
relieve joint pain, and detect the human movement and possesses wide
application prospects.
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