The flexible pressure sensor based on a porous structure has excellent sensing performance. It is critical to develop a large-scale and lowcost manufacturing method for realizing high-performance flexible sensors with porous structures. Herein, a porous polydimethylsiloxane (PDMS) was prepared by a modified microwave irradiation process, and an ultrahigh sensitive flexible piezoresistive sensor with wide sensing range was obtained by coating carbon nanotubes (CNTs)/graphene on the porous PDMS surface. Due to the uniform macroporous structure in PDMS and the synergistic conductive effect of graphene and CNTs, the sensitivity of the flexible sensor is up to 300.31 kPa −1 in 0−50 kPa and 52.51 kPa −1 in 50−200 kPa. Moreover, the flexible device has good reversibility, rapid response speed, good stability, and a certain anti-electromagnetic interference ability. The application in the monitoring of physiological signals demonstrates that the porous PDMS-based sensor prepared by the convenient and environmental microwave irradiation process has remarkable ability in monitoring human health. In addition, the modified microwave irradiation method also provides a way for the preparation of porous materials for other applications such as electromagnetic shielding materials.
Microstructures can effectively improve the sensing performance
of flexible piezocapacitive sensors. Simple, low-cost fabrication
methods for microstructures are key to facilitating the practical
application of piezocapacitive sensors. Herein, based on the laser
thermal effect and the thermal decomposition of glucose, a rapid,
simple, and low-cost laser direct-printing process is proposed for
the preparation of a polydimethylsiloxane (PDMS)-based electrode with
a hybrid microstructure. Combining the PDMS-based electrode with an
ionic gel film, highly sensitive piezocapacitive sensors with different
hybrid microstructures are realized. Due to the good mechanical properties
brought about by the hybrid microstructure and the double electric
layer induced by the ionic gel film, the sensor with a porous X-type
microstructure exhibits an ultrahigh sensitivity of 92.87 kPa–1 in the pressure range of 0–1000 Pa, a wide
measurement range of 100 kPa, excellent stability (>3000 cycles),
fast response time (100 ms) and recovery time (101 ms), and good reversibility.
Furthermore, the sensor is used to monitor human physiological signals
such as throat vibration, pulse, and facial muscle movement, demonstrating
the application potential of the sensor in human health monitoring.
Most importantly, the laser direct-printing process provides a new
strategy for the one-step preparation of hybrid microstructures on
thermal curing polymers.
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