In recent years, highly sensitive pressure sensors that are flexible, biocompatible, and stretchable have attracted significant research attention in the fields of wearable electronics and smart skin. However, there has been a considerable challenge to simultaneously achieve highly sensitive, low-cost sensors coupled with optimum mechanical stability and an ultralow detection limit for subtle physiological signal monitoring devices. Targeting aforementioned issues, herein, we report the facile fabrication of a highly sensitive and reliable capacitive pressure sensor for ultralow-pressure measurement by sandwiching MXene (Ti 3 C 2 T x )/poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) composite nanofibrous scaffolds as a dielectric layer between biocompatible poly-(3,4-ethylenedioxythiophene) polystyrene sulfonate /polydimethylsiloxane electrodes. The fabricated sensor exhibits a high sensitivity of 0.51 kPa −1 and a minimum detection limit of 1.5 Pa. In addition, it also enables linear sensing over a broad pressure range (0−400 kPa) and high reliability over 10,000 cycles even at extremely high pressure (>167 kPa). The sensitivity of the nanofiber-based sensor is enhanced by MXene loading, thereby increasing the dielectric constant up to 40 and reducing the compression modulus to 58% compared with pristine PVDF-TrFE nanofiber scaffolds. The proposed sensor can be used to determine the health condition of patients by monitoring physiological signals (pulse rate, respiration, muscle movements, and eye twitching) and also represents a good candidate for a next generation human−machine interfacing device.
Recently, flexible capacitive pressure
sensors have received significant
attention in the field of wearable electronics. The high sensitivity
over a wide linear range combined with long-term durability is a critical
requirement for the fabrication of reliable pressure sensors for versatile
applications. Herein, we propose a special approach to enhance the
sensitivity and linearity range of a capacitive pressure sensor by
fabricating a hybrid ionic nanofibrous membrane as a sensing layer
composed of Ti3C2T
x
MXene and an ionic salt of lithium sulfonamides in a poly(vinyl
alcohol) elastomer matrix. The reversible ion pumping triggered by
a hydrogen bond in the hybrid sensing layer leads to high sensitivities
of 5.5 and 1.5 kPa–1 in the wide linear ranges of
0–30 and 30–250 kPa, respectively, and a fast response
time of 70.4 ms. In addition, the fabricated sensor exhibits a minimum
detection limit of 2 Pa and high durability over 20 000 continuous
cycles even under a high pressure of 45 kPa. These results indicate
that the proposed sensor can be potentially used in mobile medical
monitoring devices and next-generation artificial e-skin.
Understanding of the triboelectric charge accumulation from the view of microcapacitor formation plays a critical role in boosting the output performance of the triboelectric nanogenerator (TENG). Here, an electrospun nanofiber-based TENG (EN-TENG) using a poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE)/MXene nanocomposite material with superior dielectric constant and high surface charge density is reported. The influence of dielectric properties on the output performance of the EN-TENG is investigated theoretically and experimentally. The fabricated EN-TENG exhibited a maximum power density of 4.02 W/m 2 at a matching external load resistance of 4 MΩ. The PVDF-TrFE/MXene nanocomposite improved the output performance of the EN-TENG fourfold. The EN-TENG successfully powered an electronic stopwatch and thermohygrometer by harvesting energy from human finger tapping. Moreover, it was utilized in smart home applications as a selfpowered switch for controlling electrical home appliances, including fire alarms, fans, and smart doors. This work presents an effective and innovative approach toward self-powered systems, human-machine interfaces, and smart home applications.
Advancement
of sensing systems, soft robotics, and point-of-care
testing requires the development of highly efficient, scalable, and
cost-effective physical sensors with competitive and attractive features
such as high sensitivity, reliability, and preferably reversible sensing
behaviors. This study reports a highly sensitive and reliable piezoresistive
strain sensor fabricated by one-step carbonization of the MoS2-coated polyimide film to obtain MoS2-decorated
laser-induced graphene. The resulting three-dimensional porous graphene
nanoflakes decorated with MoS2 exhibit stable electrical
properties yielding a reliable output for longer strain/release cycles.
The sensor demonstrates high sensitivity (i.e., gauge factor, GF ≈1242),
is hysteresis-free (∼2.75%), and has a wide working range (up
to 37.5%), ultralow detection limit (0.025%), fast relaxation time
(∼0.17 s), and a highly stable and reproducible response over
multiple test cycles (>12 000) with excellent switching
response.
Owing to the outstanding performances of the sensor, it is possible
to successfully detect various subtle movements ranging from phonation,
eye-blinking, and wrist pulse to large human-motion-induced deformations.
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