Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
Department of Materials, Science and Engineering, University of California at Berkeley, Berkeley, CA, 94720, USA.
Nat Commun. 2018 Mar 20;9(1):1155. doi: 10.1038/s41467-018-03396-5.
Nanoscale stress sensing is of crucial importance to biomechanics and other fields. An ideal stress sensor would have a large dynamic range to function in a variety of materials spanning orders of magnitude of local stresses. Here we show that tetrapod quantum dots (tQDs) exhibit excellent sensing versatility with stress-correlated signatures in a multitude of polymers. We further show that tQDs exhibit pressure coefficients, which increase with decreasing polymer stiffness, and vary >3 orders of magnitude. This high dynamic range allows tQDs to sense in matrices spanning >4 orders of magnitude in Young's modulus, ranging from compliant biological levels (100 kPa) to stiffer structural polymers (5 GPa). We use ligand exchange to tune filler-matrix interfaces, revealing that inverse sensor response scaling is maintained upon significant changes to polymer-tQD interface chemistry. We quantify and explore mechanisms of polymer-tQD strain transfer. An analytical model based on Mori-Tanaka theory presents agreement with observed trends.
纳米级应力传感对于生物力学和其他领域至关重要。理想的应力传感器应具有较大的动态范围，以适应跨越数量级的局部应力的各种材料。在这里，我们展示了四足量子点（tQDs）在多种聚合物中具有与应力相关的特征，表现出出色的传感多功能性。我们进一步表明，tQDs 表现出压力系数，其随着聚合物刚度的降低而增加，并且变化幅度超过 3 个数量级。这种高动态范围使 tQDs 能够在杨氏模量跨越 4 个数量级的基质中进行传感，范围从顺应性生物水平（100 kPa）到更硬的结构聚合物（5 GPa）。我们使用配体交换来调整填充剂-基质界面，结果表明，即使聚合物-tQD 界面化学发生重大变化，传感器的响应也能保持反向比例。我们量化并探讨了聚合物-tQD 应变传递的机制。基于 Mori-Tanaka 理论的分析模型与观察到的趋势一致。
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