Multi-Arch-Structured All-Carbon Aerogels with Superelasticity and High Fatigue Resistance as Wearable Sensors

Abstract

Compressible and ultralight all-carbon materials are promising candidates for piezoresistive pressure sensors. Although several fabrication methods have been developed, the required elasticity and fatigue resistance of all-carbon materials are yet to be satisfied as a result of energy loss and structure-derived fatigue failure. Herein, we present a two-stage solvothermal freeze-casting approach to fabricate all-carbon aerogel [modified graphene aerogel (MGA)] with a multi-arched structure, which is enabled by the in-depth solvothermal reduction of graphene oxide and unidirectional ice-crystal growth. MGA exhibits supercompressibility and superelasticity, which can resist an extreme compressive strain of 99% and maintain 93.4% height retention after 100 000 cycles at the strain of 80%. Rebound experiments reveal that MGA can rebound the ball (367 times heavier than the aerogel) in 0.02 s with a very fast recovery speed (∼615 mm s–1). Even if the mass ratio between the ball and aerogel is increased to 1306, the ball can be rebound in a relatively short time (0.04 s) with a fast recovery speed (∼535 mm s–1). As a result of its excellent mechanical robustness and electrical conductivity, MGA presents a stable stress–current response (10 000 cycles), tunable linear sensitivity (9.13–7.29 kPa–1), and low power consumption (4 mW). The MGA-based wearable pressure sensor can monitor human physiological signals, such as pulses, sound vibrations, and muscular movements, demonstrating its potential practicability as a wearable device.

Ultralight and Hyperelastic Nanofiber‐Reinforced MXene–Graphene Aerogel for High‐Performance Piezoresistive Sensor

“…To the best of our knowledge, the sensitivity of this present sensor is better than most previously reported graphene-based aerogel piezoresistive sensors under pressure less than 500 Pa (Figure 4f). [36][37][38][39][40][41] For piezoresistive sensors, durability is another essential feature to assess the device's performance. In order to evaluate the stability and durability of aPANFs/MX-rGA as a piezoresistive sensor, 17 000 cycles of compression experiments were performed under a pressure of 125 Pa. As presented in Figure 5a, the sensor could maintain a high signal strength after 17 000 compression cycles, powerfully demonstrating its excellent structural stability and durability.…”

Printed aerogels: chemistry, processing, and applications

“…Graphene 104,311,312 or fibrous carbon-based 313 aerogels are highly flexible, and can endure high strain through expansion and compression processes, resulting in a large change in the contact area between the nanosheets or fibres, and consequently, the overall electrical resistance. 311 The application of printing technology can further increase the deformation range of the flexible aerogels. For example, 3D printed porous GO-CNT aerogel mesh can reach 200% elongation, whereas traditional aerogels break at 25%.…”

Fatigue Resistant Aerogel/Hydrogel Nanostructured Hybrid for Highly Sensitive and Ultrabroad Pressure Sensing

“…[7,8] In addition, conventional piezoresistive pressure sensors often employ semiconducting active layers that are low fatigueresistant and incompressible, resulting in unsustainable durability and narrow sensing ranges. [9][10][11] Engineering semiconducting elastic aerogels as the active layer has proven to be an effective technique to improve mechanical flexibility and responsive range. [12][13][14] These aerogels are fabricated by a wide variety of building blocks such as carbon nanotubes, [15] reduced graphene sheets, [16] and conducting polymers.…”

“…Employing elastic substrates such as polydimethylsiloxane (PDMS) and polyimide could improve mechanical flexibility and sensing range of the aerogel-based sensor. [5,9,25] However, these substrate materials always exhibit limited conductance and nonhealable behavior, impeding their contribution to electrical sensitivity and decreasing resistance to incidental mechanical damage. [26,27] Polymeric hydrogels are promising candidates as flexible substrates.…”