pH-sensitive hydrogels are promising materials to be employed in microfluidic devices, especially microvalves. In this paper, a theory of transient swelling of pH-sensitive micro-valve is presented. A transient constitutive model that captures electrical, chemical, and mechanical fields is considered to model the swelling phenomenon. The diffusion of ions into the hydrogel, the electromigration, and convection are described by implementing the Nernst-Planck equation. Assuming Gent model, hydrogel is considered as a compressible hyperelastic material and osmotic pressure is assumed as an external loading. Due to benefits of in-plane valves, a design of the micro-valve is studied. Design simplicity and great sealing are vital factors which can be considered as an advantage of this valve for fabrication. This design and modeling approach has not been used for pH-sensitive hydrogels in earlier works. Thus, we have studied the transient swelling of pH-sensitive hydrogel microvalve, when effects of fluid-structure-interaction are examined on valve performance. It is noted that in most previous studies, equilibrium conditions have been assumed. While considering transient fully-coupled fluid-structure-interaction is necessary to capture a more realistic modeling. The results illustrate that the microvalve blocks the channel much earlier than reaching the equilibrium-state, which implies importance of the transient behavior of hydrogels.

对pH敏感的水凝胶是可用于微流体设备（尤其是微阀）的有前途的材料。本文提出了一种pH敏感微型阀的瞬时膨胀理论。考虑到捕获电场，化学和机械场的瞬态本构模型，可以对溶胀现象进行建模。通过实现能斯特-普朗克方程来描述离子在水凝胶中的扩散，电迁移和对流。假设采用Gent模型，则将水凝胶视为可压缩的超弹性材料，而将渗透压假定为外部载荷。由于平面阀的优点，对微型阀的设计进行了研究。设计的简单性和良好的密封性是至关重要的因素，可以认为这是该阀门制造的优势。这种设计和建模方法在早期工作中尚未用于pH敏感水凝胶。因此，当研究了流体结构相互作用对阀门性能的影响时，我们研究了pH敏感水凝胶微阀的瞬时膨胀。注意，在大多数先前的研究中，已经假设了平衡条件。在考虑瞬态全耦合的流固耦合时，有必要获取更逼真的模型。结果表明，微阀比达到平衡状态更早地阻塞了通道，这暗示了水凝胶的瞬态行为的重要性。注意，在大多数先前的研究中，已经假设了平衡条件。在考虑瞬态全耦合的流固耦合时，有必要获取更逼真的模型。结果表明，微阀比达到平衡状态更早地阻塞了通道，这暗示了水凝胶的瞬态行为的重要性。注意，在大多数先前的研究中，已经假设了平衡条件。在考虑瞬态全耦合的流固耦合时，有必要获取更逼真的模型。结果表明，微阀比达到平衡状态更早地阻塞了通道，这暗示了水凝胶的瞬态行为的重要性。