Chen Xi, Xu Yankai, Zhou Chao, Lou Kai, Peng Yixin, Zhang H P, Wang Wei
Sauvage Laboratory for Smart Materials, School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China.
School of Physics and Astronomy and Institute of Natural Sciences, Shanghai Jiao Tong University, Shanghai 200240, China.
Sci Adv. 2022 May 27;8(21):eabn9130. doi: 10.1126/sciadv.abn9130. Epub 2022 May 25.
Traveling waves are common in biological and synthetic systems, including the recent discovery that silver (Ag) colloids form traveling motion waves in HO and under light. Here, we show that this colloidal motion wave is a heterogeneous excitable system. The Ag colloids generate traveling chemical waves via reaction-diffusion, and either self-propel through self-diffusiophoresis ("ballistic waves") or are advected by diffusio-osmotic flows from gradients of neutral molecules ("swarming waves"). Key results include the experimental observation of traveling waves of OH with pH-sensitive fluorescent dyes and a Rogers-McCulloch model that qualitatively and quantitatively reproduces the key features of colloidal waves. These results are a step forward in elucidating the Ag-HO-light oscillatory system at individual and collective levels. In addition, they pave the way for using colloidal waves either as a platform for studying nonlinear phenomena, or as a tool for colloidal transport and for information transmission in microrobot ensembles.
行波在生物和合成系统中很常见，包括最近发现银（Ag）胶体在水中和光照下形成行波运动。在这里，我们表明这种胶体运动波是一种非均匀可激发系统。银胶体通过反应扩散产生行波化学波，并且要么通过自扩散电泳自行推进（“弹道波”），要么被来自中性分子梯度的扩散渗透流平流（“群体波”）。关键结果包括用对pH敏感的荧光染料对OH行波进行实验观察，以及一个定性和定量再现胶体波关键特征的罗杰斯 - 麦卡洛克模型。这些结果在个体和集体层面上阐明银 - 水 - 光振荡系统方面向前迈进了一步。此外，它们为将胶体波用作研究非线性现象的平台，或用作胶体传输以及微型机器人集合体中信息传输的工具铺平了道路。
