Real-time monitoring of infinitesimal deformations on complex morphologies is essential for precision biomechanical engineering. While flexible strain sensors facilitate real-time monitoring with shape-adaptive properties, their sensitivity is generally lower than spectroscopic imaging methods. Crack-based strain sensors achieve enhanced sensitivity with gauge factors (GFs) exceeding 30,000; however, such GFs are only attainable at large strains exceeding several percent and decline below 10 for strains under 10 −3 , rendering them inadequate for minute deformations. Here, we introduce hypersensitive and flexible “meta-crack” sensors detecting infinitesimal strains through previously undiscovered crack-opening mechanisms. These sensors achieve remarkable GFs surpassing 1000 at strains of 10 −4 on substrates with a Poisson’s ratio of −0.9. The crack orientation–independent gap-widening behavior elucidates the origin of hypersensitivity, corroborated by simplified models and finite element analysis. Additionally, parallel mechanical circuits of meta-cracks effectively address the trade-off between resolution and maximum sensing threshold. In vivo real-time monitoring of cerebrovascular dynamics with a strain resolution of 10 −5 underscores the hypersensitivity and conformal adaptability of sensors.

中文翻译：

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用于实时生物医学监测的高灵敏度超裂纹应变传感器


实时监测复杂形态上的无限小变形对于精密生物力学工程至关重要。虽然灵活的应变传感器具有形状自适应特性，有助于实时监测，但它们的灵敏度通常低于光谱成像方法。基于裂纹的应变传感器在标量系数 （GF） 超过 30,000 时实现更高的灵敏度;然而，这种 GF 只能在超过 0% 的大应变下获得，而对于低于 10 −3 的应变，这种 GF 下降到 10 以下，这使得它们不足以应对微小的变形。在这里，我们介绍了超灵敏和灵活的“元裂纹”传感器，它们通过以前未被发现的裂纹打开机制来检测极小的应变。这些传感器在泊松比为 -0.9 的衬底上实现了超过 1000 的 GF，在 10 −4 的应变下。与裂纹方向无关的间隙扩大行为阐明了超敏反应的起源，简化模型和有限元分析证实了这一点。此外，元裂纹的并联机械电路有效地解决了分辨率和最大传感阈值之间的权衡。以 10 −5 的应变分辨率对脑血管动力学进行体内实时监测强调了传感器的超敏反应和适形适应性。