A Wide‐Range Linear and Stable Piezoresistive Sensor Based on Methylcellulose‐Reinforced, Lamellar, and Wrinkled Graphene Aerogels

Abstract

such as graphene-based materials, boron nitride, and transition metal dichalcogenides, which have been predicted to show piezoelectric properties by density functional theory analysis. [3] Aerogels are porous materials with low density, high porosity, and high specific area. [4] Graphene aerogels (GAs), also known as 3D graphene, are macroscopic architectures assembled from graphene nanosheets. [5] GAs have high surface utilization and are suitable for surface functionalization. [6] The preparation methods of GAs are relatively simple, including self-assembly, [7] sacrificial template, [8] and 3D printing methods. [9] GAs have been widely investigated for the photothermal conversion, [10] electromagnetic shielding, [11] gas sensing, [12] surface catalysis, [13] and wearable devices. [14] GAs are assembled from the graphene sheets via van de Waals forces during the synthesis processes, where the physical connection between the graphene sheets provides macroscopic electrical conductivity. [15] In general, deformation occurs when an external pressure is applied to the GAs, which increases the area of contact between the graphene sheets, and increases the electrical conductivity. [16] It is this mechanism that makes GAs be suitable for piezoresistive sensors. The high sensitivity, wide linear range, good stability, low detection limit, and short response time are all critical features required for a piezoresistive sensor. [17] Although GAs meet most of these requirements due to their 3D interconnected architectures, the disordered microstructure of most isotropic GAs leads to a poor stability and a limited linearity, which severely limits their practical applications. [18] Innovative attempts to control the architectures with the introduction of orientation, reinforcing, wrinkling, and hierarchical pores can help to overcome these limitations. GAs with ordered microstructures can be prepared via air foaming, [19] 3D printing, and freeze-drying. [20] In the case of freeze-drying, the ice crystals act as a solid template, and the graphene sheets can aggregate along the ice crystals. [21] Parallel stacked lamellar architectures with a periodic arrangement could be produced via freeze-drying. [22] The unique architecture could result in Graphene-based aerogels (GAs) have been extensively studied for pressure sensing applications due to their high compressibility and conductivity. But the usually-adopted high-temperature treatment generally damages the flexibility and stability. It is still challenging to prepare piezoresistive sensors with a wide linear range, and reliable cyclic performance. Herein, we demonstrate an excellent wide-range piezoresistive sensor based on an aerogel of methylcellulose reinforced reduced graphene oxide (MC/GA). A steaming reduction at 120 °C is proposed to properly control the intermolecular forces and the chemical bonding between MC and GA. The finite element analysis indicates that wrinkled lamellae with hierarchical pores are beneficial to minimize the stress concentrations. As a result ...

Ultra-Broad Linear Range and Sensitive Flexible Piezoresistive Sensor Using Reversed Lattice Structure for Wearable Electronics

“…In addition, a comparison of the sensing performance in terms of linearity, sensitivity, and linear range between the RLS sensor and other previously reported highly linear pressure sensors was conducted, as shown in Figure S23 and Table S1. Our sensor has achieved outstanding performance in ultra-broad linear pressure sensing, which, to the best of our knowledge, has not been previously reported and has been challenged. ,,,,,− Furthermore, a comparison with other 3D printed flexible porous sensors was conducted and listed in Table S2, demonstrating its distinguishable characters with broad linear range, compact size, and without 3D model design. − ,− …”

Strain and Pressure Sensors Based on MWCNT/PDMS for Human Motion/Perception Detection

“…Among them, flexible piezoresistive sensors can be manufactured in various modes through different combinations of elastic substrate materials and micro-nano conductive media, which have the advantages of a simple structure, easy manufacturing process, low cost, high sensitivity and a wide response range. The resistive sensors with flexible substrates such as silicone, PDMS, and gel are closer to the mechanical properties of human skin by virtue of their flexibility and high ductility [ 9 , 10 , 11 ].…”

Graphene-based Two-Stage Enhancement Pressure Sensor for Subtle Mechanical Force Monitoring

“…Li et al utilized methylcellulose-reinforced, lamellar, and wrinkled graphene aerogels to prepare a sensor with high linearity over a wide range. 37 Jia et al employed an rGO film with a wrinkled structure as a sensitive layer for subtle mechanical sensing. 38 Hu et al developed a graphene-based e-textile to realize the perception of physiological signals.…”

“…Currently, various mechanical sensors are being explored for subtle mechanical force monitoring. Li et al utilized methylcellulose-reinforced, lamellar, and wrinkled graphene aerogels to prepare a sensor with high linearity over a wide range . Jia et al employed an rGO film with a wrinkled structure as a sensitive layer for subtle mechanical sensing .…”