Stretchable hydrogel-based strain sensors suffer from limited sensitivity, which urgently requires further breakthroughs for precise and stable human-computer interaction. Here, an efficient microstructural engineering strategy is proposed to significantly enhance the sensitivity of hydrogel-based strain sensors by sandwiching an emulsion-polymerized polyacrylamide organohydrogel microsphere membrane between two Ecoflex films, which are accompanied by crack generation and propagation effects upon stretching. Consequently, the as-developed strain sensor exhibits ultrahigh sensitivity (gauge factor (GF) of 1275), wide detection range (100% strain), low hysteresis, ultralow detection limit (0.05% strain), good fatigue resistance, and low fabrication cost. In addition, the sensor features good water, dehydration, and frost resistance, enabling real-time strain monitoring in various complex conditions due to the encapsulation of Ecoflex film and the addition of glycerol and KCl. Through further structural manipulation, the device achieves superior response to tiny strains, with a GF value of 98.3 in the strain range of less than 1.5%. Owing to the high strain sensing performance, the sensor is able to detect various human activities from swallowing to finger bending even under water. On this basis, a wireless sensing system with apnea warning and single-channel gesture recognition capabilities is successfully demonstrated, demonstrating its great promise as wearable electronics.
Flunarizine, topiramate, and the combination of flunarizine with topiramate are all effective and have good tolerability in migraine prophylaxis. Adding topiramate to flunarizine may reduce the latter's impact on body weight.
Compared
with two-dimensional (2D) graphene sheets, recently, three-dimensional
(3D) structured and porous graphene has attracted much attention in
gas and humidity sensing owing to its increased specific surface area,
abundant reaction sites, and superior sensing performance. This review
begins with the introduction of the device configurations and working
mechanisms of 3D graphene-based gas sensors, followed by the elaboration
of various synthesis strategies of 3D graphene. In addition to the
gas-transducing properties of 3D and suspended graphene, the modification
effect of metal oxides, small molecules, conductive polymers, noble
metal nanoparticles, 2D materials, etc. on the gas-sensing performance
of 3D graphene is also systematically discussed. 3D structured graphene
not only performs as excellent gas-sensing material but also shows
great advantages in humidity sensing due to its porous structure and
a large number of adsorption sites for moisture. The humidity-sensing
mechanism is elucidated to reveal the reactions between graphene and
water molecules, followed by the introduction of devices. Finally,
the existing key challenges that hinder the further development and
practical application of 3D graphene-based gas/humidity sensors are
presented, followed by proposing the future perspectives.
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