Nanoarchitectonics with MWCNT and Ecoflex film for flexible strain sensors: wide linear range for wearable applications and monitoring of pressure distribution

Recently, highly flexible strain sensors have been widely studied based on the conductive polymer composites, due to their potential applications in wearable electronics, soft robots, and human–machine interfaces. Herein, we fabricate the flexible MWCNT line/Ecoflex strain sensors by 3D printing technology to investigate the effects of preparation conditions on the performance of sensors, and find that gage factor (GF) of such sensors is effected by concentration of MWCNT/IPA solution and curing time of Ecoflex pre-polymer film. Among the obtained samples, the sensor prepared by 2 wt% MWCNT/IPA solution with curing time of 12 min has the highest gage factor, about ~ 23.87. The sensors can detect or monitor subtle motions of facial muscle, breath and pulse, and possess wide linear range besides good repeatability and excellent durability. Meanwhile, the prepared sensors were designed into a 4 × 4 array, and the array achieved monitoring of spatial distribution of the applied pressure. Our strategy could be used to fabricate flexible strain sensors with wide linear range, which facilitate further integration to achieve potential applications in detection of human activity, electronic skin, and soft robots.