Soft strain sensors that can transduce stretch stimuli into electrical readouts are promising as sustainable wearable electronics. However, most strain sensors cannot achieve highly-sensitive and wide-range detection of ultralow and high strains. Inspired by bamboo structures, anti-freezing microfibers made of conductive poly(vinyl alcohol) hydrogel with poly(3,4-ethylenedioxythiphene)-poly(styrenesulfonate) are developed via continuous microfluidic spinning. The microfibers provide unique bamboo-like structures with enhanced local stress to improve both their length change and resistance change upon stretching for efficient signal conversion. The microfibers allow highly-sensitive (detection limit: 0.05% strain) and wide-range (0%–400% strain) detection of ultralow and high strains, as well as features of good stretchability (485% strain) and anti-freezing property (freezing temperature: −41.1 °C), fast response (200 ms), and good repeatability. The experimental results, together with theoretical foundation analysis and finite element analysis, prove their enhanced length and resistance changes upon stretching for efficient signal conversion. By integrating microfluidic spinning with 3D-printing technique, the textiles of the microfibers can be flexibly constructed. The microfibers and their 3D-printed textiles enable high-performance monitoring of human motions including finger bending and throat vibrating during phonation. This work provides an efficient and general strategy for developing advanced conductive hydrogel microfibers as high-performance wearable strain sensors.
The application of nonlinear conductivity coatings in high-voltage power module is a promising strategy for significantly improving electrical insulation performance. The core of the improvement principle is that the nonlinear conductivity realizes a dynamic optimization of the discharge risk inside the material. The realization of this nonlinear conductivity requires sufficient microscopic arrangement of fillers that align with the macroscopic insulation structure. However, conventional methods fail at precise arrangement control so that typically require high filler concentration, which markedly increases dielectric loss and leakage current. Drawing inspiration from the bamboo structure, metamaterials offer an efficient tuning of nonlinear characteristics with lower filler concentrations through thoughtful design. In this context, we introduce a novel approach to fabricate SiC whisker / silicon elastomer metamaterial coatings leveraging the dielectrophoretic effect. Comprehensive testing of the physical and chemical properties of the composites confirmed the successful preparation of the material. And the metamaterial exhibits excellent nonlinear conductivity and low dielectric loss across various temperatures. Notably, after applying the metamaterial coating, the maximum electric field stress within the power module was reduced by nearly ten times, and the partial discharge inception voltage (PDIV) increased by 58.9 %, 74.7 %, and 32.8 % at 30 °C, 60 °C, and 90 °C, respectively. From solid physical mechanism to exquisite material design and practical device-level implementation, this study offers valuable insights into enhancing the insulation performance of power module and demonstrates substantial potential for further industrial applications.
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