Adaptive Microfluidic Networks for Optimal Transport

从动物的脉管系统到真菌的菌丝网络，再到构成电池的随机多孔介质，复杂网络中的流体输送在生物学和工程学中是丰富的。长期以来，人们一直认为生物网络的形态是优化的，以尽量减少与分支中粘性流动耗散相关的能量成本。然而，最近提出的另一种可能性是，这些网络是质量交换或灌注的最佳选择。然后，我们不仅需要一个有效覆盖空间的网络，而且还需要其形态能使化学物质（催化剂、营养物、氧气等）在所有管道中均匀流动，这样网络的所有部分都能接收到相同数量的化学物质。生命系统不断调整其网络形态以响应刺激；局部反馈与全局流的存在相耦合，导致自组织结构最适合灌注。相比之下，在随机介质的工程网络中，流体速度因管而异，并且总体上遵循指数分布。通过这些多孔介质的运输是低效的，被限制在几个快速通道。目前优化多孔介质流动的策略是逐个分支地构建优化的网络形态。我们项目的目的是结合理论，模拟和实验来产生自适应的微流控网络，其形态自组织响应信号，导致网络形态最适合灌注。除了其根本利益之外，该项目的成果具有广泛的应用，从高效电池的设计和冷却，到具有高传输效率和大反应面的增强型化学反应器的生产，有助于获得更清洁，更实惠的能源。

Flow transport in complex networks is abundant in biology and engineering, from the vasculature of animals, to the hyphal networks of fungi, to the random porous media making up batteries. It has long been thought that biological network morphologies were optimised to minimise the energetic cost associated to viscous flow dissipation in their branches. However, another possibility, raised recently is for these networks to be optimal for mass exchange, or perfusion. We then need not only to have a network that covers space efficiently, but also whose morphology leads to an even flow of chemicals (catalysts, nutrients, oxygen,...) throughout all its tubes, so that all parts of the network receive the same amount of chemical. Living systems continuously adapt their network morphology in response to stimuli; local feedback coupled to the presence of global flows leads to self-organised structures optimal for perfusion. In contrast, fluid velocities in engineered networks of random media differ from tube to tube, and follow an overall exponential distribution. Transport through these porous media is inefficient, being limited to a few fast lanes. The current strategy to optimize flow in porous media is to build, branch by branch, an optimized network morphology. The aim of our project is to combine theory, simulations and experiments to generate adaptive microfluidic networks whose morphology self-organises in response to signals, leading to network morphologies optimal for perfusion. In addition to its fundamental interest, the outcome of this project has a wide range of applications, from the design and cooling of efficient batteries, to the production of enhanced chemical reactors having high transport efficiency and a large reaction surface, contributing to having a cleaner, more affordable energy.