Gradient-induced droplet motion over soft solids
Gradient-induced droplet motion over soft solids
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DOI：
10.1093/imamat/hxaa015
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发表时间：
2020-06-01
影响因子：
1.2
通讯作者：
Shearer, Michael
中科院分区：
文献类型：
--
作者：
Bardall, Aaron;Chen, Shih-Yuan;Shearer, Michael
在外力或身体力的作用下，可以诱导液滴在刚性或柔性表面上移动。我们将柔性基板材料特性变化的影响描述为运动机制。在本文中，我们考虑将液滴放置在具有刚度或表面能梯度的基底上，并考虑其通过与基底的弹性变形耦合而运动的潜力。为了阐明接触角的作用并获得易于处理的模型，我们考虑二维液滴。基底材料特性的梯度引起不对称的固体变形和不相等的接触角，从而在液滴上产生力。然后，我们使用动态粘弹性模型来预测液滴的动力学结果。量化梯度效应的数值结果表明，利用表面能梯度诱导液滴运动更为可行。结果表明，诱导液滴运动所需的弹性模量梯度的大小超出了软固体生产中实验上可行的极限，因此不太可能作为细胞运动的被动机制。在表面能或弹性模量的两种情况下，启动运动的阈值都是在材料特性的较低平均值下实现的。
Fluid droplets can be induced to move over rigid or flexible surfaces under external or body forces. We describe the effect of variations in material properties of a flexible substrate as a mechanism for motion. In this paper, we consider a droplet placed on a substrate with either a stiffness or surface energy gradient and consider its potential for motion via coupling to elastic deformations of the substrate. In order to clarify the role of contact angles and to obtain a tractable model, we consider a 2D droplet. The gradients in substrate material properties give rise to asymmetric solid deformation and to unequal contact angles, thereby producing a force on the droplet. We then use a dynamic viscoelastic model to predict the resulting dynamics of droplets. Numerical results quantifying the effect of the gradients establish that it is more feasible to induce droplet motion with a gradient in surface energy. The results show that the magnitude of elastic modulus gradient needed to induce droplet motion exceeds experimentally feasible limits in the production of soft solids and is therefore unlikely as a passive mechanism for cell motion. In both cases, of surface energy or elastic modulus, the threshold to initiate motion is achieved at lower mean values of the material properties.