This paper aims to unveil the fundamental response mechanism of photo-sensitive hydrogels subject to light-thermo-pH-salt coupled stimuli, for their potential biomedical uses such as cell scaffolds and extracellular matrices, where biological activity largely depends on internal electrochemical changes. To mimic the microenvironment of biomolecules or cells, we focus on a spirobenzopyran-modified N-isopropylacrylamide hydrogel incorporating acrylic acid as a proton generator and develop a multiphysics model to characterize its behaviour within aqueous solution in response to light intensity, temperature, buffer pH, and salt concentration. The model allows for concurrent chemical reactions, ionic diffusion, electrostatic effects and large mechanical deformation, as well as interaction with the solution domain. Validation was performed by comparison with the published experimental results and showed good agreement. It is demonstrated by the simulation results that the photo-sensitive hydrogel exhibits a varied sensitivity to the external stimuli if incorporated with different molar ratios of acrylic acid. The electrical and pH response characteristics of the hydrogel, especially those in neutral solution, may inspire some potential biomedical applications, such as photo-controlled drug release and cell growth.

本文旨在揭示受光-热-pH-盐耦合刺激作用的光敏水凝胶的基本反应机理，其潜在的生物医学用途如细胞支架和细胞外基质，其中生物活性主要取决于内部电化学变化。为了模拟生物分子或细胞的微环境，我们重点研究了螺苯并吡喃修饰的N-异丙基丙烯酰胺水凝胶，其中掺入丙烯酸作为质子发生器，并开发了一个多物理场模型来表征其在水溶液中响应光强度，温度，缓冲液pH和盐浓度的行为。该模型允许同时发生的化学反应，离子扩散，静电效应和较大的机械变形，以及与溶液域的相互作用。通过与已发布的实验结果进行比较进行验证，并显示出良好的一致性。仿真结果表明，如果掺入不同摩尔比的丙烯酸，光敏水凝胶对外部刺激表现出不同的敏感性。水凝胶的电和pH响应特性，尤其是在中性溶液中，