Using a conductive sphere as a probe to characterize the sensitivity of soft piezoresistive films
Using a conductive sphere as a probe to characterize the sensitivity of soft piezoresistive films
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DOI：
10.1002/app.50349
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发表时间：
2020-12
影响因子：
3
通讯作者：
C. Green;J. Rogers;Robert Kovenburg;B. Aksak
中科院分区：
文献类型：
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作者：
C. Green;J. Rogers;Robert Kovenburg;B. Aksak
柔性压阻膜，例如炭黑/聚二甲基硅氧烷（C-PDMS）复合材料，通常用作皮肤模拟物并集成到用于触觉感测的复杂阵列传感器中。传感器特性的均匀性在很大程度上取决于复合材料的均匀性。因此，局部表征将被集成到复杂力传感器中的膜的能力可能是至关重要的。本文提出了一种表征柔性压阻薄膜局部灵敏度的方法。使用导电球，这是选择一个平面探针，以消除错位问题，薄膜复合材料的表面是缩进的平均应变方面的电阻率的变化进行表征。用15和18重量%的不同厚度的炭黑C-PDMS膜进行实验。使用约翰逊-罗伯茨-肯德尔接触理论估计探针与压阻膜的接触半径。发现理论接触面积估计值与通过光学显微镜观察到的使用光学透明PDMS膜进行的接触半径测量一致。结果表明，具有15重量%炭黑的C-PDMS表现出比具有18重量%炭黑的相同厚度的膜更高的电阻率和应变系数变化率。另一方面，较厚的膜对于两种测试的炭黑含量表现出较高的计量因子。在多个位置进行的测试产生了一致的灵敏度值，使这些类型的复合材料适用于阵列型力传感器。
Flexible piezoresistive films, such as, carbon black/polydimethylsiloxane (C‐PDMS) composites, are often used as skin analogs and integrated into complex array sensors for tactile sensing. The uniformity of the sensor characteristics heavily depends on the homogeneity of the composite. Therefore, the ability to locally characterize a film that will be integrated into a complex force sensor could be critical. Here, a method to characterize the local sensitivity of flexible piezoresistive films is presented. Using a conductive sphere, which was chosen over a flat probe to eliminate misalignment issues, the surface of a thin film composite is indented to characterize the change in resistivity in terms of average strain. Experiments were performed with 15 and 18 wt% carbon black C‐PDMS films of varying thickness. The contact radius of the probe with the piezoresistive film was estimated using the Johnson‐Roberts‐Kendall contact theory. Theoretical contact area estimates were found to agree with contact radius measurements carried out using optically transparent PDMS films observed through an optical microscope. Results show that C‐PDMS with 15 wt% carbon black exhibit a higher rate if change of resistivity and gauge factor than films of same thickness with 18 wt% carbon black. On the other hand, thicker films exhibit higher gauge factors for the two tested carbon black contents. Tests carried out at multiple locations yielded consistent sensitivity values, making these types of composites suitable for array type force sensors.