With the rapid development of the smart industry, wearable sensor devices continue to appear in all aspects of people’s lives, including bionic limbs, health exercise monitoring equipment, medical equipment, etc., most of which enable people to form a convenient, energy-saving, and intelligent health lifestyle. At the same time, high-performance pressure sensors play a vital role in wearable sensor devices. However, how to achieve an ideal pressure sensor with high sensing sensitivity, ultra-low detection limit and fast response is still the main problem restricting its further application. Therefore, finding an efficient and reliable wearable pressure sensor is imperative and challenging at the same time. Classified according to different working mechanisms, pressure sensors have many types such as piezoresistive, piezoelectric, friction and capacitive. For piezoresistive sensors, its internal structure is controllable, and the resistance can also be changed under different working conditions. At the same time, piezoresistive sensors have been widely used in various application fields due to their fast response speed and flexible deformation. It is worth noting that aerogels have excellent properties of high porosity, low density and controllable three-dimensional (3D) porous structure, and have shown vigorous development in the fields of environmental treatment, catalytic carriers, thermal insulation compounds, electromagnetic shielding, and energy storage devices. Huge application potential. Research has shown that aerogel has good electrical properties in the field of pressure sensors. Conductive aerogel has realized its practical value in pressure sensors with its portability, real-time monitoring and reliable recyclability.

  Recently, Professor Zhang Meiyun and Engineer Yang Bin of Shaanxi University of Science and Technology published an article titled: Highly Compressible, Thermally Stable, Light-Weight, and Robust Aramid Nanofibers/Ti3AlC2 MXene Composite Aerogel for Sensitive Sensor in the internationally renowned academic journal ACS Nano The paper, in this work, reported and demonstrated a promising MXene/ANFs aerogel for piezoresistive sensors, which has 3D layering, mortar brick porous structure and ultra-low 25 mg/cm3 density. In this study, ANFs and entangled ANF networks with excellent mechanical properties were selected as the framework material and anti-oxidation protective layer to compensate for the unsatisfactory brittleness, poor compression resilience and oxidation tendency of MXene. Accordingly, MXene provides unique conductivity for this functional aerogel. The microstructure of MXene/ANFs aerogels, the adjustment mechanism of porous structure, electrical properties and the perception of different pressures were studied. This paper also monitors the real-time perception of different human motion behaviors by aerogel. As a multifunctional piezoresistive sensor, MXene/ANFs aerogel sensor has good mechanical properties, heat insulation properties and sensitive sensing performance. It has shown great applications in the field of human motion monitoring and even extreme conditions. potential.

Figure 1. MXene/ANFs aerogel sensor preparation process diagram.

Figure 2. The internal combination of MXene and ANFs results in the final resistance of the MXene/ANFs aerogel.

Figure 3. SEM images of MXene/ANFs composite aerogels with different mass ratios at different magnifications.

Figure 4. Schematic diagram of the porous structure and regulation mechanism of ANFs/MXene composite aerogel.

Figure 5. Mechanical properties of MXene/ANFs aerogel.

Figure 6. MXene/ANFs aerogel has excellent thermal insulation properties.

Figure 7. Piezoresistive properties of MXene/ANFs aerogel.

Figure 8. 30 wt% MXene/ANFs aerogel sensors are used to monitor the behavior of the human body when attached to the heel and elbow.

    In short, MXene/ ANFs aerogels with high compressibility, excellent thermal insulation performance and sensitive measurement performance have been successfully manufactured through feasible processes such as controllable vacuum filtration and freeze-drying, which provides a way for the realization of scalable production. possibility. With the increase of the amount of MXene, the aerogel resistance will be greatly reduced until it reaches 30 wt%. This has a preferred uniform and laminated porous 3D structure composed of directional ice crystal growth, which can achieve high compression up to 1000 times. Resilience, and the tight connection between ANF and MXene provides strong mechanical strength to withstand external pressure. The sensor can maintain super high heat preservation performance for a long time at a high temperature of 200°C without any damage. As we all know, composite sensors have obvious sensing characteristics. In this regard, 30 wt% MXene/ANFs aerogel exhibits highly sensitive sensing characteristics (128 kPa) to different compressions of various frequencies (0.2-0.8 Hz) and different detection ranges (compression strains of 2.0-80.0%). -1), ultra-low detection limit (100 Pa), fast response time (320 ms), and no hysteresis during pressure removal (recovery time is 98 ms). Surprisingly, the aerogel maintains sensitive sensing properties, can detect normal human skipping, walking and even running movements after being stepped on, the electrical signal is stable, and real-time feedback is provided. MXene/ANFs aerogel has excellent comprehensive properties, especially high-sensitivity sensing performance and excellent thermal stability, and has huge application potential in human behavior monitoring sensors and sensing under extreme conditions.

Literature link:

https://dx.doi.org/10.1021/acsnano.0c04888.

Information source: MXene Frontie

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