Brownian Disks Lab: Simulating time-lapse microscopy experiments for exploring microrheology techniques and colloidal interactions

Brownian Disks Lab (BDL) is a Java-based application for the real-time generation and visualization of the motion of two-dimensional Brownian disks using Brownian Dynamics (BD) simulations. This software is designed to emulate time-lapse microscopy experiments of colloidal fluids in quasi-2D situations, such as sedimented layers of particles, optical trap confinement, or fluid interfaces. Microrheology of bio-inspired fluids through optical-based techniques such as videomicroscopy is a classic tool for obtaining the mechanical properties and molecular behavior of these materials. The results obtained by microrheology notably depend of the time-lapse value of the videomicroscopy setup, therefore, a tool to test the influence of the lack of statistics by simulating Brownian objects in experimental-like situations is needed. We simulate a colloidal fluid by using Brownian Dynamics (BD) simulations, where the particles are subjected to different external applied forces and inter-particle interactions. This software has been tested for the analysis of the microrheological consequences of attractive forces between particles [1], the influence of image analysis on experimental microrheological results [2], and to explore experimental diffusion with optical tweezers [3]. The output results of BDL are directly compatible with the format used by standard microrheological algorithms [4]. In a context of microrheology of complex bio-inspired fluids, we use this tool here to study if the lack of statistics may influence the observed potential of a bead trapped by optical tweezers.布朗圆盘实验室（Brownian Disks Lab, BDL）是一款基于Java的应用程序，可借助布朗动力学（Brownian Dynamics, BD）模拟实现二维布朗圆盘运动的实时生成与可视化。本软件旨在模拟准二维环境下胶体流体的延时显微实验场景，例如颗粒沉积层、光阱（Optical Trap）束缚体系或流体界面。通过视频显微术（Videomicroscopy）等光学技术开展仿生流体的微流变学（Microrheology）分析，是获取这类材料力学特性与分子行为的经典方法。微流变学的实验结果显著依赖于视频显微成像装置的延时设置参数，因此亟需一款能够在类实验环境中模拟布朗物体，用以评估统计量不足所产生影响的工具。我们采用布朗动力学（BD）模拟构建胶体流体体系，其中颗粒会受到不同的外施作用力与粒子间相互作用。本软件已被应用于多项研究：分析粒子间吸引力对微流变学特性的影响[1]、探究图像分析对实验微流变学结果的作用[2]，以及开展光镊（Optical Tweezers）辅助下的粒子扩散实验研究[3]。BDL的输出结果可直接适配标准微流变学算法所用的数据格式[4]。在复杂仿生流体的微流变学研究语境中，我们借助本工具展开相关研究，旨在探明统计量不足是否会对光镊束缚微球的观测势能造成影响。