Harvesting waste biomechanical energy has provided a promising approach to improve the power supplement of wearable devices for extending usage life. Surface morphology is a significant factor for enhancing output performance of triboelectric nanogenerator; however, there is a limitation for evaluating the morphology of the surface and its impact on power generation. To evaluate the relationship between the surface morphology and transfer charge, there is a mathematical theory that is the fractal geometry theory that has been proposed to analyze the characteristic of irregular surface morphology. This theory provided a good understanding of the contact area and roughness of the surface. We have designed three categories of knit structures with cord appearance by using a flat knitting machine and analyzed their surface characteristics. Meanwhile, the geometric structures can be demonstrated through the fractal dimension for evaluating the generated output performance during contacting and separation. The present research exhibits that, with the increasing number of knitted units, the triboelectric power-generation performance continued to reduce due to the available contact area decreasing. After calculating the fractal dimension of different knit structures, the m*n rib structures show the high transfer charge when the fractal dimension is close to number one, especially the fractal dimension of the 1*1 rib structure that can reach 0.99. The fractal theory can be further used as an approach to evaluate the influence on the output performance of irregular surface morphology, unrelated to the uniform convex unit distraction. The result of this research also demonstrated the feasibility of a knitted-based triboelectric nanogenerator in scavenging biomechanical energy for powering portable electronics integrated into garments.

收集废弃的生物机械能提供了一种有前途的方法，可以改善可穿戴设备的功率补充以延长使用寿命。表面形态是提高摩擦纳米发电机输出性能的重要因素。但是，评估表面的形态及其对发电的影响存在局限性。为了评估表面形态与转移电荷之间的关系，提出了一种数学理论，即分形几何理论，用于分析不规则表面形态的特征。该理论对表面的接触面积和粗糙度提供了很好的理解。我们使用横机设计了三类具有帘线外观的针织结构，并分析了它们的表面特性。与此同时，几何结构可以通过分形维数来评估，以评估接触和分离过程中产生的输出性能。本研究表明，随着编织单元数量的增加，由于可用接触面积的减少，摩擦发电性能持续降低。计算不同编织结构的分形维数后，当分形维数接近一时，m * n的罗纹结构显示出较高的转移电荷，尤其是1 * 1的罗纹结构的分形维数可达到0.99。分形理论可以进一步用作评估对不规则表面形态的输出性能的影响的方法，与均匀的凸单元分散无关。