Flexible wearable sensor based on graphene/PEDOT:PSS composite material

Abstract

As a rapidly emerging field for the intelligent terminals, wearable electronic devices have present a huge market prospect. Flexible resistive strain sensor has become one of the most concerned electrical sensors owing to its attractive properties, such as high sensitivity and biocompatibility. In this paper, a novel graphene (GR)/PEDOT:PSS multi-component hybrid ink material was prepared based on solution blending method. A "resistive" flexible strain sensor was fabricated by direct-inkjet printing technology. Polyimide (PI) flexible film, and GR/PEDOT:PSS multi-component mixed ink were used as substrate and conductive material, respectively. The conductive patterns were printed on the flexible substrate by direct-inkjet-printing technology. The scanning electron microscope (SEM) and electrical test platform were used to characterize and analyze the effect of different graphene doping amounts on the performance and printing process of composite ink materials. The experimental results show that the GR material dispersed by ethanol can be effectively distributed in PEDOT:PSS, which improves its dispersibility in conductive polymer. The line width decreases as the print rate increases and the resistance and sensitivity of the flexible sensors are gradually decreased with the increase of GR doping amount. It can be concluded that the ink material with relatively loosened and dispersive property will be more conducive to improve the device sensitivity. The sensitivity of the flexible wearable sensor can be significantly improved with the increasing aspect ratio of the flexible sensor as well. The resistance change rate (R/R0) is up to 3.414 when the bending angle was 80°, which makes the GR/PEDOT:PSS composite material based sensor promising to be applied in the emerging field of flexible wearable devices.