High-Performance Fiber-Film Hybrid-Structured Wearable Strain Sensor from a Highly Robust and Conductive Carbonized Bamboo Aerogel

Abstract

Bamboo, one of the most abundant biomaterials, has been used as a building material since ancient times; however, its application in functional materials has been rarely explored. Herein, a highly robust and conductive carbonized bamboo aerogel (CBA) is obtained from the natural bamboo through a simple three-step process of pulp oxidization, freeze-drying, and carbonization. The CBA obtained shows not only a low density of 0.02 g/cm3 but also a high conductivity of 6.42 S/m and remarkable elasticity with a maximum recoverable compressive strain of 60% due to its unique three-dimensional (3D) network randomly stacked with the hybrid structure of carbonized bamboo fibers and films. After encapsulation with silicone resin, the CBA/silicone composite prepared exhibits excellent flexibility and stretchability with a low Young’s modulus (0.09 MPa) and a large failure strain (275%). Importantly, the CBA/silicone composite also offers remarkable strain-sensing performance with a maximum gauge factor of 30.6, a short responsive time of 50 ms, and a stable response to cyclic loading over 1000 cycles, which is comparable to those of the piezoresistive composites based on expensive nanomaterials. Moreover, the CBA/silicone composite demonstrates the capability as a wearable strain sensor for human motion recognition comprising finger bending, breathing, and throat movement. Considering the green and sustainable nature of bamboo as a raw material, combined with the excellent piezoresistive performance, low production cost, and simple preparation process, the flexible strain sensors with CBA/silicone composite as a sensing element are promising in wearable electronic devices, personalized healthcare, and artificial intelligence systems.

Direct ink writing of a graphene/CNT/silicone composite strain sensor with a near-zero temperature coefficient of resistance

“…A resistance relaxation phenomenon is observed at the holding periods, which is attributed to the internal stress relaxation behavior of the silicone matrix. 44,45 The response time and recovery time of the GCE strain sensor have also been investigated with a stretchingholding-releasing strain of 30% at an abrupt speed of 16.7 mm s À1 , as shown in Fig. 4d.…”

Comprehensive Investigation of the Temperature-Dependent Electromechanical Behaviors of Carbon Nanotube/Polymer Composites

“…Specifically, under compression loading, the conductive networks formed by CNTs would appear with many discontinuities as a result of the detaching and sliding of CNTs, which causes the increase of resistance. 40,41 The results presented above indicate that the CNT/PDMS composite has significant temperature-dependent piezoresistive behaviors. Generally, when the distance of two neighboring CNTs decreases to be less than 1.4 nm (i.e., cutoff distance), a tunneling effect or tunneling current will occur between them.…”

High-Performance Bamboo Steel Derived from Natural Bamboo

“…Similarly, the disappearance of two peaks at 1736 and 1235 cm −1 corresponding to the stretching vibration of carbonyl and C−O reflects the complete removal of hemicellulose in the delignified bamboo. 25,26 In addition, as shown in Figure 3b, three peaks located at 16.5, 22.5, and 34.6°a re observed from the XRD pattern of bulk bamboo, which are attributed to the cellulose's crystalline planes of (101), (002), and (040), respectively. Although the XRD pattern of the bamboo scaffold is similar to that of the bulk bamboo, the peak intensity is obviously weaker than that of the original bulk bamboo, which indicates that the size of the bamboo fiber bundles is reduced after delignification.…”