Modeling of subcutaneous injections in soft adipose tissue – a common way to administer pharmaceutical medication – is a challenging multiphysics problem which has recently attracted the attention of the engineering community, as it could help optimize medical devices and treatments. The underlying continuum mechanics of this process is complex and involves finite strain poro-mechanics – where a viscous fluid, containing different charged species, is injected into a porous viscoelastic matrix and absorbed by blood and lymph vessels – as well as electrochemistry, that generates osmotic pressure due to electrical charges attached to the tissue. In this paper, we present a chemo-mechanical model of subcutaneous injections that accounts for the diffusion of electrically charged chemical species – contained in the interstitial fluid – into the tissue, blood and lymph vessels. This work provides the methodology to derive a general theory accounting for the electro-chemo-poro-mechanical couplings in a thermodynamically consistent framework, avoiding phenomenological biases or inconsistencies likely to arise in the derivation of nonlinear theories with many couplings. To motivate its use for the modeling of subcutaneous injections, it is complemented by a simplified, linearized boundary value problem that illustrates the importance of considering these couplings for the prediction of subcutaneous injections key performance indicators.

中文翻译：

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完整的化学-多孔-机械耦合对于皮下注射建模的重要性


软脂肪组织皮下注射的建模是一种具有挑战性的多物理场问题，最近引起了工程界的关注，因为它可以帮助优化医疗设备和治疗。该过程的基本连续介质力学很复杂，涉及有限应变孔隙力学（将含有不同带电物质的粘性流体注入多孔粘弹性基质并被血管和淋巴管吸收）以及电化学，从而产生渗透压由于附着在组织上的电荷而产生的压力。在本文中，我们提出了皮下注射的化学机械模型，该模型解释了间质液中包含的带电化学物质扩散到组织、血管和淋巴管中的情况。这项工作提供了一种方法，可以在热力学一致的框架中推导解释电化学-孔隙-机械耦合的一般理论，避免在推导具有许多耦合的非线性理论时可能出现的现象学偏差或不一致。为了激励其用于皮下注射建模，它由一个简化的线性边界值问题补充，该问题说明了考虑这些耦合对于预测皮下注射关键性能指标的重要性。