Monolithic superaligned carbon nanotube composite with integrated rewriting, actuating and sensing multifunctions

Multifunctionality has become a mainstream trend in the development of smart clothing and flexible wearable devices. Nevertheless, it remains a grand challenge to realize multiple functions, such as sensing, actuating and information displaying, in one single multifunctional material. Here, we present one multifunctional integration strategy by employing monolithic superaligned carbon nanotube (SACNT) composite, which can leverage three different functions through fascinating features of SACNT. Firstly, by using thermochromic dye as a color-memorizing component and SACNT as a photothermal converter, the composite film can be utilized as a flexible rewritable medium. It demonstrates excellent rewriting performances (reversibility > 500 times). Secondly, the composite can be tailored to fabricate an actuator, when its length direction is along the SACNT alignment. The actuator shows a bending-morphing when illuminated by near-infrared light. The morphing is attributed to a large difference in volume change between the SACNT and polymer when the SACNT absorbs the optical energy and heats the composite. Thirdly, owing to the unique anisotropy of SACNT, the composite is easily to be stretched in the direction perpendicular to the SACNT alignment, accompanied by a change in electrical resistance. Therefore, the composite is able to be used as a strain sensor. Finally, we fabricate two smart wearable devices to demonstrate the applications, which realize the functions of human-motion detection (sensing) and rewritable information display (rewriting) simultaneously. This multifunctional SACNT composite is expected to have potential applications in the next-generation wearable devices, smart clothing and so on.