A multifunctional sensor that combines force/strain and temperature sensing functions into a single element is much more advantageous in saving space and avoiding technical complexity than integrating multiple sensing elements together. In this work, we realized force/strain and temperature sensing with a lightweight aerogel composite of silver nanowires and poly(dimethylsiloxane) (AgNWs/ PDMS). The AgNWs/PDMS aerogel composite was prepared using a sugar cube as a sacrificial template, and the AgNWs were uniformly distributed on the inner surface of the porous structure. Multifunctional sensors made of the AgNWs/PDMS aerogel composite show sensitive responses to various stimuli in resistivity. When serving as a force/strain sensor, it exhibits an excellent sensitivity (gauge factor ∼32) in the strain range of 60−90%. While working as a temperature sensor, the multifunctional sensor presents a temperature sensitivity of 0.33%/°C. Moreover, the porous aerogel structures can also be used to absorb pollutants such as oil and organic solvents, which will make them revive once their sensing function degrades. The proposed composite shows great potential in multifunctional wearable devices, sensor arrays for the Internet of things, and pollutant cleaning.
Piezoresistive composite is one of the promising candidates for wearable and flexible force sensors due to its simple and low‐cost preparation and conformability to various surfaces. However, it is challenging to achieve a wide sensing range and a high sensitivity simultaneously. Herein, it is proposed to use multilevel porous structure to address the conflict between sensing range and pressure sensitivity. The multilevel porous structure consists of alternately stacked polyacrylonitrile nanofibers and silver nanowires. The nanostructure presents a multilevel deformation when increasing the applied pressure. The sensor has a broad sensing range while maintaining its sensitivity. These results show that the pressure sensor has a superior sensitivity (defined by the resistance change ratio per unit pressure) of 0.437 kPa–1 and a wide stress range of 0–48.4 kPa. The unique multilevel porous structure makes the sensor stable, repeatable, and durable even after a test of 8000 cycles. Moreover, the sensor also shows small size and lightweight which can be used to detect the movement of various body motions, including facial muscle movements, vocalization, and joint motions. This work provides an effective strategy to achieve high sensitivity and a broad range of piezoresistive sensor through rationally building a multilevel porous structure.
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