Lassila Petri, Zinn Thomas, Hyvönen Jere, Noriega Benitez Enriqueta, Penttilä Paavo, Salmi Ari, Valoppi Fabio
Electronics Research Laboratory, Department of Physics, University of Helsinki, P.O. Box 64 (Gustaf Hällströmin katu 2), FI-00014 Helsinki, Finland.
Diamond Light Source Ltd., Didcot, Oxfordshire OX11 ODE, United Kingdom.
Cryst Growth Des. 2025 Jun 3;25(12):4394-4404. doi: 10.1021/acs.cgd.5c00291. eCollection 2025 Jun 18.
Ultrasound standing waves (USW) produce a force capable of displacing micrometer-sized free-flowing particles in a fluid, wherein this phenomenon is also referred to as acoustophoresis. However, the effect of acoustophoresis on dynamically changing and growing crystal networks is unclear. An example of such a system are monoglyceride (MG)-based oleogels, which are free-flowing lipids (e.g., vegetable oils) structured with a lipid-crystal network. In this work, we use MG oleogels as an example system to investigate the acoustophoretic effect on the structuration of a growing crystal network. For this purpose, multifaceted characterization is conducted utilizing optical and coded excitation scanning acoustic microscopy as well as small-angle X-ray scattering, respectively. The optical microscopy results show that USW produces local density differences of the structuring crystalline material and induces the orientation of the MG platelets. X-ray diffraction measurements confirm these findings and show a 23% average increase in MG platelet correlation length, which can be linked to platelet thickness, as well as an increase in the MG nanoplatelet surface smoothness. These findings produce a foundation for better understanding the effect of acoustophoresis in dynamically developing lipid-based materials and illuminate the mechanical changes that arise because of USW treatment.
超声驻波（USW）产生的力能够使流体中微米级的自由流动颗粒发生位移，这种现象也被称为声泳。然而，声泳对动态变化和生长的晶体网络的影响尚不清楚。基于甘油单酯（MG）的油凝胶就是这样一个系统的例子，它是由脂质晶体网络构建的自由流动脂质（如植物油）。在这项工作中，我们以MG油凝胶为例，研究声泳对生长晶体网络结构化的影响。为此，分别利用光学和编码激发扫描声学显微镜以及小角X射线散射进行了多方面的表征。光学显微镜结果表明，超声驻波产生了结构化晶体材料的局部密度差异，并诱导了MG血小板的取向。X射线衍射测量证实了这些发现，并显示MG血小板相关长度平均增加了23%，这与血小板厚度有关，同时MG纳米血小板表面光滑度也有所增加。这些发现为更好地理解声泳在动态发展的脂质基材料中的作用奠定了基础，并阐明了超声驻波处理引起的机械变化。
