Computational method and parameters analysis of piezoresistive sensing properties of wearable graphene composites
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摘要: 随机堆叠石墨烯制成的石墨烯复合材料(GC)的不均匀性，使得GC的压阻传感性能与其细观单元的尺寸密切相关。根据GC的微观结构特点，发展了一种GC压阻传感性能计算方法，依次计算了GC的电子渗流概率、初始方阻和相对电阻-应变关系。结果表明：GC的电子渗流概率随着石墨烯面分比的增大而增大，大长宽比石墨烯组成的GC的渗流阈值更低，电子迁移网络连通的最小面分比是0.5；GC代表单元的最小边长可由它的初始方阻确定，大面分比GC拥有更小的代表单元，当石墨烯面分比分别为1.2、1.4、1.6、1.8、2.0时，GC代表单元的最小边长与石墨烯边长的比值为35、30、25、20、15。最后，不同石墨烯面分比、长宽比的GC代表单元的计算结果证实，增大石墨烯的面分比与长宽比能够延长GC的线性感知阶段，提高GC的总感知范围。Abstract: Due to the inhomogeneity of graphene composites (GC) made of randomly stacked graphene, the piezoresistive sensing performance of GC is closely related to the size of meso element. According to the microstructure characteristics of GC, a calculation method for piezoresistive sensing performance of GC was developed. The electron percolation probability, initial sheet resistance and relative resistance-strain relationship of GC were calculated in turn. The results show that the electron percolation probability of GC increases with the increase of graphene area fraction. The percolation threshold of GC with large aspect ratio graphene is lower, and the minimum area fraction of graphene to keep the electron transport network connected is 0.5. The minimum side length of GC representative element can be determined by its initial sheet resistance. GC with large area fraction has smaller representative element, and the minimum ratios of the side length of representative element with area fraction of 1.2, 1.4, 1.6, 1.8 and 2.0 to graphene side length are 35, 30, 25, 20 and 15, respectively. Finally, the calculation results of GC representative elements confirm that the linear sensing stage and total sensing range of GC can be enlarged by increasing the area fraction or aspect ratio of graphene.
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Key words:
- graphene /
- composites /
- percolation threshold /
- representative element /
- piezoresistive performance
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图 1 石墨烯复合材料(GC)模型与细观单元的选取示意
Figure 1. Schematics of graphene composites (GC) model and the selected meso element
图 4 细观单元的边长对GC电子渗流概率的影响
Figure 4. Effect of the side length of meso elements on GC electron percolation probability
图 5 石墨烯的长宽比对GC电子渗流概率的影响
Figure 5. Effect of the graphene aspect ratio on GC electron percolation probability
图 6 GC细观单元的初始方阻均值与标准差
Figure 6. Mean value and standard deviation of the initial sheet resistances of GC mesoelements
图 7 GC细观单元的初始方阻相对偏差
Figure 7. Relative deviation of the initial sheet resistances of GC mesoelements
Ei (i=1-8)—ith model
图 8 GC细观单元的相对电阻-应变关系曲线
Figure 8. Relative resistance-strain curves of GC meso elements
图 9 不同面分比的GC相对电阻-应变与灵敏度-应变曲线
Figure 9. Relative resistance-strain and gauge factor-strain curves of GC with different area fractions
图 10 低面分比和高面分比GC局部石墨烯滑移示意图
Figure 10. Graphene slip schematics of the local parts in GC with low and high area fractions
图 11 不同长宽比GC相对电阻-应变与灵敏度-应变曲线
Figure 11. Relative resistance-strain and gauge factor-strain curves of GC with different aspect ratios
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