Ultra-sensitive flexible strain sensors based on hybrid conductive networks for monitoring human activities

Abstract

Flexible strain sensors have aroused great interest because of their prospective applications in motion detection, healthcare, and wearable electronics. However, the construction of strain sensing materials with both ultra-high sensitivity and excellent stretchability via a facile and scalable strategy remains a challenge. Here, an ultra-sensitive and highly stretchable strain sensor with a unique hybrid conductive network was fabricated based on reduced graphene oxide (RGO)/multi-walled carbon nanotubes (MWCNT) hybrid fillers, carbonized woven fabric, and natural rubber (NR). The RGO/MWCNT/carbonized woven fabric (GMWF) composite was obtained by fast reduction of graphene oxide (GO)/acid-treated MWCNT (MWCNT-COOH) hybrid fillers and pyrolysis of woven fabric in an alcohol flame synchronously. The resulting GMWF/NR strain sensor exhibited a laudable trade-off between sensitivity and detection range (gauge factor of 1451, 3587, and 8225 within 0 ~ 32%, 32 ~ 49%, and 49 ~ 67% strain, respectively), fast response (200 ms), low detection limit (0.5%), and outstanding durability (1000 cycles). It could detect full-range (vigorous and subtle) human activities in real time. This integration of synergistic conductive fillers and facile template method to construct the hybrid conductive network demonstrates an effective strategy for fabricating high-performance strain sensors for wearable electronic devices.