Abstract

pH-sensitive hydrogels are classified as soft materials that can be employed for future imaginative applications due to their interesting characteristics. Smart hydrogels undergo large deformation under exterior stimuli. However, the swelling behaviors of hydrogels that can be harnessed for microfluidic applications are not well perceived. In this paper, the functionality of an assortment of micro-valves which are composed of pH-sensitive cylindrical hydrogel jackets coated on rigid pillars is inspected considering fully coupled fluid–solid interaction analysis. Therefore, in order to introduce the theory of transient swelling of a pH-sensitive micro-check valve, a transient constitutive model capturing electrical, chemical, and mechanical fields for the hydrogel domain is utilized with fluid fields passing around the micro-valve. In this regard, the Nernst–Planck equation is employed to describe the ions’ diffusion, and Gent hyperelastic model is used to account for the large deformation of the hydrogel. Implementing this nonlinear finite element framework, we examine the performance of one cylindrical jacket and also three patterns of multiple cylindrical valves considering transient 3D FSI behavior of the hydrogel micro-valve. The foremost emphasized novelty of this paper is considering three-dimensional geometry, new designs of micro-valves, and time-dependent swelling of hydrogels by coupling ions diffusion and their large deformation.

Article Highlights

• Three-dimensional single and multiple pH-sensitive hydrogel micro-valves

• Electro-chemo-mechanical theory for pH-sensitive hydrogels to predict their transient swelling

• Fluid–solid interaction of Newtonian fluid and hydrogel which can undergo large reversible deformation

中文翻译：

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在单个和多个 pH 敏感水凝胶微阀上：3D 瞬态全耦合流体-固体相互作用研究

摘要

pH 敏感水凝胶被归类为软材料，由于其有趣的特性，可用于未来富有想象力的应用。智能水凝胶在外部刺激下会发生大变形。然而，可用于微流体应用的水凝胶的溶胀行为并未得到很好的理解。在本文中，考虑完全耦合的流体-固体相互作用分析，检查了由涂覆在刚性柱上的 pH 敏感圆柱形水凝胶夹套组成的各种微型阀的功能。因此，为了介绍 pH 敏感微型止回阀的瞬态膨胀理论，利用瞬态本构模型捕获水凝胶域的电、化学和机械场，流体场通过微阀。在这方面，使用能斯特-普朗克方程来描述离子的扩散，使用根特超弹性模型来解释水凝胶的大变形。实施这种非线性有限元框架，我们考虑了水凝胶微阀的瞬态 3D FSI 行为，检查了一个圆柱形夹套的性能以及多个圆柱形阀的三种模式。本文最重要的新颖之处在于考虑了三维几何形状、微型阀门的新设计以及通过耦合离子扩散及其大变形对水凝胶的时间依赖性膨胀。考虑到水凝胶微型阀的瞬态 3D FSI 行为，我们检查了一个圆柱形夹套的性能以及多个圆柱形阀的三种模式。本文最重要的新颖之处在于考虑了三维几何形状、微型阀门的新设计以及通过耦合离子扩散及其大变形对水凝胶的时间依赖性膨胀。考虑到水凝胶微型阀的瞬态 3D FSI 行为，我们检查了一个圆柱形夹套的性能以及多个圆柱形阀的三种模式。本文最重要的新颖之处在于考虑了三维几何形状、微型阀门的新设计以及通过耦合离子扩散及其大变形对水凝胶的时间依赖性膨胀。

文章亮点

• 三维单个和多个 pH 敏感水凝胶微型阀

• pH敏感水凝胶的电化学机械理论预测其瞬时膨胀

• 牛顿流体和水凝胶的流体-固体相互作用可以发生大的可逆变形