Compressible, Elastic, and Pressure-Sensitive Carbon Aerogels Derived from 2D Titanium Carbide Nanosheets and Bacterial Cellulose for Wearable Sensors

Abstract

Compressible and elastic carbon aerogels (CECAs) hold great promise for applications in wearable electronics and electronic skins. MXenes, as new two-dimensional materials with extraordinary properties, are promising materials for piezoresistive sensors. However, the lack of sufficient interaction among MXene nanosheets makes it difficult to employ them to fabricate CECAs. Herein, a lightweight CECA is fabricated by using bacterial cellulose fiber as a nanobinder to connect MXene (Ti3C2) nanosheets into continuous and wave-shaped lamellae. The lamellae are highly flexible and elastic, and the oriented alignment of these lamellae results in a CECA with super compressibility and elasticity. Its ultrahigh structural stability can withstand an extremely high strain of 99% for more than 100 cycles and long-term compression at 50% strain for at least 100 000 cycles. Furthermore, it has a high sensitivity that demonstrates not only an ultrahigh linearity but also a broad working pressure range (0–10 kPa). In particular, the CECA has a high linear sensitivity in almost the entire workable strain range (0–95%). In addition, it has very low detection limits for tiny strain and pressure. These features enable the CECA-based sensor to be a flexible wearable device to monitor both subtle and large biosignals of the human body.

Wood‐Derived Lightweight and Elastic Carbon Aerogel for Pressure Sensing and Energy Storage

“…It can even withstand long‐term compression for 30 000 cycles, with a high stress retention of 79.1% and height reduction of only 11.4% (Figure 4d,e). The fatigue resistance of C‐AL/CNF‐5 is superior to those of graphene‐derived aerogels,33–37 GO/CNT composite aerogel,38 carbonaceous nanofibrous aerogel,39 MXene‐derived aerogels,40,41 and so on42,43 (Figure 4f and Table S3, Supporting Information). Generally, energy loss coefficient as a result of sliding friction among carbon unites is an important parameter to evaluate the structural stability of carbon materials.…”

MXene hydrogels: fundamentals and applications

“…Such overwhelming merits make them promising candidates for microwave absorption, electromagnetic interference shielding, flexible electronics, and solar energy conversion. Thus far, there are several methods for preparing MXene aerogels including (1) direct freeze-drying of MXene NC dispersions, 16,25,35,36 (2) calcination after freeze-drying of MXene NC dispersions, [37][38][39][40][41] and (3) freeze-drying of MXene hydrogels. 5,6,12,28,[42][43][44][45][46][47] In all these methods, the sublimation of ice crystals from frozen dispersions or hydrogels was necessary for obtaining MXene aerogels.…”

MXenes and Their Applications in Wearable Sensors

“…Zhuo et al (2019) utilized cellulose nanocrystals (CNCs) as a nano-support to connect MXenes nanosheets into a lamellar carbon aerogel with not only super mechanical performances but also ultrahigh linear sensitivity (Figure 4C). Chen et al (2019) used bacterial cellulose fiber as a nanobinder to connect MXenes (Ti 3 C 2 ) nanosheets into continuous and wave-shaped lamellae to fabricated a kind of compressible and elastic carbon aerogels. Therefore, it is an effective way to prepare high-performance wearable MXenes-based piezoresistive sensors by compounding MXenes with mechanical strength materials and in situ growing into aerogels with high elasticity and high conductivity.…”