Measuring the non-uniform surface interactions experienced by a Janus particle

Janus粒子是以微米为单位测量的小粒子，具有不均匀的表面化学。它们有可能给许多技术带来革命性的变化，包括国防应用、了解微生物在自然界中的行为，以及通过充当微米级货运载体来改善人类健康。该奖项旨在解决的主要挑战是了解Janus粒子如何与边界相互作用，这与这些应用程序中的每一个都相关。为了实现这一目标，项目团队计划使用一种独特的显微镜来研究这些相互作用。此外，该团队还将研究Janus粒子在接近边界时如何使用化学信号进行导航。此外，他们的目标是标准化和传播基于胶体和界面现象的教育模块，这是在这项工作中探索的一个基本概念。在过去的十年中，Janus粒子已经成为一种很有前途的各向异性粒子类型，在各种技术领域具有潜在的应用。该奖项的主要目标是精确测量边界附近活跃和非活跃Janus粒子的非均匀表面相互作用。为了实现这一目标，拟议的工作将利用最近开发的一种名为散射形态分辨全内反射显微镜(SMR-TIRM)的工具来研究Janus粒子的相互作用和动力学。该方法包括映射Janus粒子在不同方位角的散射，然后使用这些信息来跟踪移动的Janus粒子的位置和方向。尽管最近在理解这些复杂材料方面取得了进展，但关于它们的动力学仍然存在重大问题。该奖项旨在解决其中两个问题，这些问题与Janus粒子在存在和不存在自我推进的情况下经历的非均匀相互作用有关。要回答这些问题，监测Janus粒子动力学并推断粒子所经历的表面力是至关重要的。特别是，项目团队将在化学燃料的存在和不存在的情况下进行这些测量，化学燃料是催化Janus粒子用来产生机械力的。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Janus particles are small particles that are measured in micrometers and have a non-uniform surface chemistry. They have the potential to revolutionize many technologies, including defense applications, understanding microorganisms' behavior in nature, and improving human health by serving as micrometer scale cargo carriers. The primary challenge this award aims to address is understanding how Janus particles interact with boundaries, which is relevant to each of these applications. To achieve this goal, the project team plans to use a unique microscope to study these interactions. Additionally, the team will investigate how Janus particles use chemical signals to navigate when they are near a boundary. Further, they aim to standardize and disseminate educational modules based on colloidal and interfacial phenomena, which is a fundamental concept explored during this work.Over the past decade, Janus particles have emerged as a promising type of anisotropic particle with potential applications in various technological fields. The main goal of this award is to accurately measure the non-uniform surface interactions of both active and non-active Janus particles near a boundary. To achieve this objective, the proposed work will leverage a recently developed tool called Scattering Morphology Resolved Total Internal Reflection Microscopy (SMR-TIRM) to investigate the interactions and dynamics of Janus particles. The approach involves mapping the scattering from Janus particles at different azimuthal angles and then using this information to track the position and orientation of a mobile Janus particle. Despite recent progress in understanding these complex materials, significant questions remain about their dynamics. This award aims to address two of these questions related to the non-uniform interactions experienced by a Janus particle in the presence and absence of self-propulsion. To answer these questions, it is crucial to monitor the Janus particle dynamics and infer the surface forces that the particle experiences. In particular, the project team will conduct these measurements in the presence and absence of chemical fuel, which a catalytic Janus particle uses to generate a mechanical force.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.