High-Performance Strain Sensors Based on Au/Graphene Composite Films with Hierarchical Cracks for Wide Linear-Range Motion Monitoring

Abstract

Stretchable strain sensors based on nanomaterial thin films have aroused extensive interest for the strain perception of smart skins. However, it still remains challenging to have them achieve high sensitivity over wide linear working ranges. Herein, we propose a facile strategy to fabricate stretchable strain sensors based on Au/graphene composite films (AGCFs) with hierarchical cracks and demonstrate their superior sensing performances. The polydimethylsiloxane substrates were covered with self-assembled graphene films (SAGFs) and sputtered with Au, and then prestretching was applied to introduce hierarchical cracks. The AGCF strain sensors exhibited high sensitivity (gauge factor (GF) ≈ 153) and favorable linearity (R 2 ≈ 0.9975) in the wide working range (0–20%) with ultralow overshooting (∼1.7% at 20%), fast response (<42.5 ms), and also excellent cycling stability (1500 cycles). Besides, these patternable sensors could further achieve higher GF (∼320) via pattern designing. The dominant effect of the intermediate wrinkled SAGFs in forming hierarchical cracks was studied, and the linear sensing mechanism of the as-formed fractal microstructures was also revealed in detail. Moreover, the AGCF strain sensors were tested for motion monitoring of the human body and electronic bird. Due to the remarkable versatility, scalable fabrication, and integration capability, these sensors demonstrate great potential to construct smart skins.

Skin-Inspired Patterned Hydrogel with Strain-Stiffening Capability for Strain Sensors

“…Moreover, for resistive-type strain sensors, the variety of resistance mainly comes from the deformation of the conductive matrix. Different from homogeneous conductive hydrogels, the deformation of each conductive domain and increased distance between conductive domains could magnify the output electronic signals. ,, Therefore, it is compared to the PAAc/PAAm hydrogel without pattern (Figure S8), the calculated gauge factor (GF) of the patterned hydrogel-based strain sensor can reach 1.75 at 100%, and the curves show a high linearity ( R 2 = 0.990) (Figure b). As shown in Figure c, the strain sensor also exhibits fast response and recovery times that benefit from the low hysteresis of the hydrogel.…”

High Sensitivity, Wide Linear‐Range Strain Sensor Based on MXene/AgNW Composite Film with Hierarchical Microcrack

“…Figure 6a shows a comparison of our HMC strain sensor and previously reported crack-based sensors in terms of GF and the first linear sensing range, [3,5,7,17,20,28,34,36,37,[52][53][54][55][56][57][58][59][60][61][62] demonstrating that the HMC sensor is superior among the linear strain sensors. The sensor with high GF (>200) and large linear range (up to 60%) is perfectly adequate for the detection of full-range human motion.…”

“…Stretchable strain sensors, as an essential component of wearable electronics, have shown substantial potential applications in motion monitoring, [1][2][3][4][5] human-machine interface, [6][7][8] electronic skin, [9][10][11][12] and medical rehabilitation. [13,14] In general, wearable devices need to not only accommodate large human body movements (>50%) but also have high sensitivity to monitor subtle body motions (<1%).…”

2D Materials in Flexible Electronics: Recent Advances and Future Prospectives

“…Physical sensing is another area where 2D material-based sensors declared their superiority. The mechanical and electrical robustness of 2D materials allows them to be highly responsive to various physical stimuli. ,− Integrated with system-level readout, processing, and transmission capabilities, these devices show great potential for various applications, including motion sensors, e-skins, etc. , Sun et al demonstrated a graphene-based dual-function acoustic transducer with machine learning-assisted human–robot interface (Figure c) . The graphene-based device was able to perform as both a self-powered microphone and speaker via the triboelectric and thermoacoustic effects.…”