Highly stretchable and conformal electromagnetic interference shielding armor with strain sensing ability

Abstract

Lightweight and stretchable electromagnetic interference (EMI) shielding materials are desirable for wearable electronics. Herein, a graphene armor composed of laminated graphene film (LGF) and hierarchical porous graphene foam (HGF) with film/foam/film sandwich architecture is reported for human EMI shielding and motion monitoring. The LGF with micron-level interlayer spacing (∼2 μm) is fabricated by laser induction in a single step under an ambient atmosphere. Attributed to abundant interfaces and excellent electrical conductivity of 1670 S/m, the LGF exhibits an EMI shielding effectiveness (SE) up to 36.3 dB at a thickness of 19.4 μm. Due to the three-dimensional porous foam structure with the tunability of graphene content, the EMI SE of the HGF can range from 10 to 80 dB. Based on HGF with a graphene content of 27 wt%, the sandwich graphene armor with a thickness of about 2 mm exhibits an EMI SE up to 69.8 dB at an ultralow density of 0.228 g/cm3. Furthermore, the graphene armor possesses excellent mechanical properties as strain sensors that the gauge factor can reach 258 at the strain range up to 100%, thus the graphene armor can be used for motion monitoring while protecting the joints of the human body. The results demonstrate that sandwich architecture can not only enhance the EMI shielding performance of foam materials but also be an effective approach to improving the sensitivity of strain sensors. Therefore, the highly stretchable, conformal, and lightweight sandwich graphene armor is promising for multifunctional applications of EMI shielding and strain sensing.