Carbon nanotubes/acetylene black/Ecoflex with corrugated microcracks for enhanced sensitivity for stretchable strain sensors

The booming development of wearable devices especially flexible strain sensors has attracted widespread attention in human motion detection. Although many microstructures have been studied for sensing functions, the manufacture of strain sensors with excellent sensitivity and wide detection range remains a challenge. Herein, a corrugated microcrack structure was designed by the simple method of dripping carbon nanotubes (CNTsi)/acetylene black (AB) conductive mixture onto pre-stretched Ecoflex. This corrugated microcracks can effectively improve the sensitivity of the strain sensor. Compared with the CNTs/AB/Ecoflex-based strain sensor without pre-stretching (gauge factor (GF) of 340 within 0-25% strain and 207.58 for a strain of 38,100%), the strain sensor with corrugated microcracks through pre-stretching is significantly improved. GF is up to 1610 at the strain of 50-100% without sacrificing the strain detection range at the prestrains coefficient of 60%. In addition, the strain sensor with the structure of corrugated microcracks also demonstrates excellent performance including high elongation at break (up to 400% strain), great durability, and repeatability (> 1000 cycles). The CNTs/AB/Ecoflex-based strain sensor is successfully assembled on human to monitor the activity of joints, demonstrating its ability to be a promising candidate in wearable electronic devices.