You Jun Fan,Xin Li,Shuang Yang Kuang,Lei Zhang,Yang Hui Chen,Lu Liu,Ke Zhang,Si Wei Ma,Fei Liang,Tao Wu,Zhong Lin Wang,Guang Zhu
Recently emerged electronic skins with applications in on-body sensing and human–machine interfaces call for the development of high-performance skin-like electrodes. In this work, we report a highly robust, transparent, and breathable epidermal electrode composed of a scaffold-reinforced conductive nanonetwork (SRCN). Solution-dispersed Ag nanowires, through facile vacuum filtration, are embedded into a scaffold made of polyamide nanofibers. Optical transmittance of 84.9% at 550 nm wavelength is achieved at a significantly low sheet resistance of 8.2 Ω sq–1. The resistance of the SRCN only slightly increases by less than 0.1% after being bent for 3000 cycles at the maximum curvature of 300 m–1 and by less than 1.5% after being dipped in saline solution for 2500 cycles. The excellent robustness is attributed to the reinforcement from the nanofiber-based scaffold as a backbone that maintains the connections among the Ag nanowires by undertaking most of the loaded stress. The SRCN not only forms tight and conformal bonding with the target surface but also allows the evaporation of perspiration, making it suitable as an epidermal electrode for long-time use. Furthermore, fine and clean-cut circuit patterns with a line width on the micrometer scale can be readily prepared, paving the way for fabricating sophisticated functional electronic skins.
Graphene, a carbon material with high carrier mobility and low current density, is a promising candidate for the fabrication of flexible sensors. However, its production using traditional methods is complex and expensive, whereas the synthesis of laser-induced graphene (LIG) is eco-friendly and inexpensive under ambient conditions. LIG features a 3D porous structure with localized defects, which is influenced by substrate properties, laser parameters, and processing steps. Herein, the influence of the twist angle between two laser irradiation steps on the porous structure and conductive characteristics of LIG is explored. The results show that the optimal twist angle is 4°, at which the square resistance of LIG is as low as 12.0 Ω sq−1. The change in the conductivity of LIG occurs because the optimal twist angle between the two graphene layers opens the band gap. LIG with a twist angle of 4° is selected to prepare a biosensor and a Hall sensor. It is found that the LIG-based biosensor exhibits a lower detection limit of 8.62 μM when detecting uric acid (UA). Furthermore, the Hall sensitivity of the cross and circular Hall sensors is ∼0.59 and ∼0.64 V (A−1 T−1), respectively. This study supports the application of LIG in flexible sensors and provides some guidelines for further exploration of the 3D structure of LIG.
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