Rheological measurements typically require at least 20–50 mg of sample. We set up a miniaturized sliding-plates shear rheometer (mgRheo) that requires only 2 mg sample or even less. We designed a flexure-based force-sensing device that could measure force ranging from the micronewton to millinewton scale, e.g., 40 μN–400 mN for one particular spring constant. The setup was strain-controlled by a piezostage and could perform standard rheological tests such as small amplitude oscillatory shear, step strain, and stress relaxation. The accuracy and consistencies were evaluated on polydimethylsiloxane viscoelastic standard, entangled poly(hexyl methacrylate), and polystyrene. The obtained phase angles quantitatively agreed with those from commercial rheometers. The exact values of the modulus are prone to the overfilling of the sample. The storage G′ and loss G″ moduli from the mgRheo were systematically higher than those from commercial rheometers (i.e., within 5% with careful trimming or 30% with excessive overfilling). Between 10² and 10⁶ Pa, G′ and G″ were in good agreement with commercial rheometers. Such a setup allowed for general rheometric characterizations, especially obtaining linear viscoelasticity on soft matters that are synthetically difficult to obtain in a large quantity.

中文翻译：

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使用 2 毫克样品执行 SAOS 的微牛顿剪切流变仪

流变测量通常需要至少 20–50 mg 的样品。我们建立了一个小型滑板剪切流变仪 (mgRheo)，它只需要 2 毫克甚至更少的样品。我们设计了一种基于弯曲的力传感装置，可以测量从微牛顿到毫牛顿量级的力，例如，对于一个特定的弹簧常数，40 μN–400 mN。该装置由压电台进行应变控制，可以执行标准流变测试，例如小振幅振荡剪切、阶跃应变和应力松弛。在聚二甲基硅氧烷粘弹性标准、缠结聚（甲基丙烯酸己酯）和聚苯乙烯上评估了准确性和一致性。获得的相位角在数量上与商业流变仪的相位角一致。模量的精确值容易导致样品过度填充。存储mgRheo 的G'和损失G"模量系统地高于商业流变仪的模量（即，仔细修整时误差在 5% 以内，过度填充时误差在 30% 以内）。在 10 ²和 10 ⁶  Pa 之间，G'和G"与商业流变仪非常一致。这种设置允许进行一般的流变表征，特别是在软物质上获得线性粘弹性，而这些软物质在综合上难以大量获得。