Auxetic Mechanical Metamaterials to Enhance Sensitivity of Stretchable Strain Sensors
Auxetic Mechanical Metamaterials to Enhance Sensitivity of Stretchable Strain Sensors
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DOI：
10.1002/adma.201706589
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发表时间：
2018-03-22
影响因子：
29.4
通讯作者：
Chen, Xiaodong
中科院分区：
文献类型：
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作者：
Jiang, Ying;Liu, Zhiyuan;Chen, Xiaodong
可拉伸应变传感器在可穿戴设备、软机器人和物联网中发挥着关键作用，但这些可行的应用需要在各种应变下进行微妙的应变检测，通常受到低灵敏度的限制。这种不足的灵敏度源于传统应变传感器中的泊松效应，其中拉伸的弹性体基底在纵向方向上膨胀但横向压缩。在可拉伸应变传感器中，膨胀将活性材料分离并有助于灵敏度，而泊松压缩将活性材料挤压在一起，从而本质上限制了灵敏度。或者，拉胀机械超材料由于其负的结构泊松比而在两个方向上经历2D膨胀。在此，它表明，这种拉胀超材料可以被纳入可拉伸应变传感器，以显着提高灵敏度。与传统传感器相比，灵敏度大大提高了24倍。这种灵敏度的提高是由于减少结构泊松比和应变集中的协同效应。此外，微裂纹被拉长作为一个潜在的机制，通过实验和数值模拟验证。这种采用拉胀超材料的策略可以进一步应用于具有不同组成材料的其他可拉伸应变传感器。此外，它为将机械超材料应用于更广泛的可拉伸电子产品库铺平了道路。
Stretchable strain sensors play a pivotal role in wearable devices, soft robotics, and Internet-of-Things, yet these viable applications, which require subtle strain detection under various strain, are often limited by low sensitivity. This inadequate sensitivity stems from the Poisson effect in conventional strain sensors, where stretched elastomer substrates expand in the longitudinal direction but compress transversely. In stretchable strain sensors, expansion separates the active materials and contributes to the sensitivity, while Poisson compression squeezes active materials together, and thus intrinsically limits the sensitivity. Alternatively, auxetic mechanical metamaterials undergo 2D expansion in both directions, due to their negative structural Poisson's ratio. Herein, it is demonstrated that such auxetic metamaterials can be incorporated into stretchable strain sensors to significantly enhance the sensitivity. Compared to conventional sensors, the sensitivity is greatly elevated with a 24-fold improvement. This sensitivity enhancement is due to the synergistic effect of reduced structural Poisson's ratio and strain concentration. Furthermore, microcracks are elongated as an underlying mechanism, verified by both experiments and numerical simulations. This strategy of employing auxetic metamaterials can be further applied to other stretchable strain sensors with different constituent materials. Moreover, it paves the way for utilizing mechanical metamaterials into a broader library of stretchable electronics.