Studies of Viscophoresis -- Drift in a Viscosity Gradient

粘度电泳研究——粘度梯度漂移

• 批准号: 1904511
• 负责人: Derek Stein
• 金额: $ 42.66万
• 依托单位: Brown University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-07-15 至 2023-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1904511&HistoricalAwards=false
• 关键词: Studies; Viscophoresis; Drift; Viscosity; Gradient

Non-technical Abstract:By applying a difference in pressure, voltage, or temperature to the ends of a tube filled with liquid, we can cause the fluid or small particles within it to move, and the mechanisms underlying the motion are well understood. It was recently discovered that when a small glass tube is filled with liquid and the viscosity is held at different values at either end, an electrical current begins to flow; the origin of that motion of electrical charges is not understood at present. This project is experimentally investigating the origins of that phenomenon by measuring the motion of salt ions and small fluorescent particles inside nanofluidic channels, where the physical dimensions and the properties of the liquid can be carefully controlled. The results shed new light onto the theory of the Brownian motion - the random motion of small particles caused by its collisions with the molecules of a liquid. Remarkably, more than a century after the publication of Einstein's famous theory of Brownian motion, the question of whether a particle drifts in a viscosity gradient, and if so, in which direction, is still debated. The conventional picture of the Brownian motion is a walk with steps taken in random directions and step sizes that are inversely proportional to the viscosity. When the viscosity varies in space, one must choose whether the size of each step in the random walk corresponds to the viscosity at the beginning of the step, the end of the step, or somewhere in between, and this seemingly insignificant choice has measurable consequences. In fact, different choices can be appropriate in different physical situations. Experiments can settle the debate and deepen our understanding of microscopic phenomena that are important in living cells, in industrial applications, and possibly beyond. The team is producing a scientific cartoon to explain the Brownian motion and its fundamental importance to a broad audience of non-specialists. Technical Abstract:This project is exploring the origins of a recently discovered nanofluidic transport phenomenon whereby small particles in solution drift due to a gradient in the viscosity of the solvent. The team has named this transport phenomenon "viscophoresis". Measurements of the transport of ions and fluorescent quantum dots in nanofluidic devices with well-defined dimensions establish the quantitative relationships between the drift velocity, the viscosity gradient, and other experimental parameters. The results of those experiments are needed to shed new light on the longstanding "Ito-Stratonovich" theoretical problem of noise-driven dynamics with multiplicative noise. Viscophoresis is significant because nanofluidic transport processes play a vital role in biology, in geology, and in micro- and nanofluidic technology. This project can lead to new insights or applications in those domains, where large viscosity gradients frequently arise. This project provides an excellent training opportunity for a graduate student, and an educational scientific cartoon is being created to reach a broad audience of non-specialists.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.

非技术摘要：通过对充满液体的管子两端施加压力、电压或温度差，我们可以使管内的流体或小颗粒运动，并且运动背后的机制很好理解。 最近发现，当一根小玻璃管充满液体并且两端的粘度保持在不同值时，电流开始流动；目前尚不清楚电荷运动的起源。该项目正在通过测量纳米流体通道内盐离子和小荧光颗粒的运动来实验性地研究这种现象的起源，其中液体的物理尺寸和特性可以得到仔细控制。这些结果为布朗运动理论提供了新的线索——小颗粒因与液体分子碰撞而引起的随机运动。值得注意的是，在爱因斯坦著名的布朗运动理论发表一个多世纪后，粒子是否在粘度梯度中漂移，如果是，朝哪个方向漂移的问题仍然存在争议。布朗运动的传统图像是在随机方向上采取步长且步长与粘度成反比的行走。 当粘度在空间中变化时，必须选择随机游走中每个步骤的大小是否对应于步骤开始时、步骤结束时或中间某个位置的粘度，而这种看似微不足道的选择却具有可测量的后果。 事实上，不同的选择可以适合不同的身体情况。实验可以解决争论并加深我们对微观现象的理解，这些现象对于活细胞、工业应用甚至其他领域都很重要。该团队正在制作一部科学漫画，向广大非专业观众解释布朗运动及其根本重要性。技术摘要：该项目正在探索最近发现的纳米流体传输现象的起源，即溶液中的小颗粒由于溶剂粘度的梯度而漂移。研究小组将这种运输现象命名为“粘泳”。对具有明确尺寸的纳米流体装置中离子和荧光量子点的传输的测量建立了漂移速度、粘度梯度和其他实验参数之间的定量关系。这些实验的结果需要为长期存在的“伊托-斯特拉托诺维奇”噪声驱动动力学与乘性噪声理论问题提供新的线索。粘滞电泳非常重要，因为纳米流体传输过程在生物学、地质学以及微纳流体技术中发挥着至关重要的作用。该项目可以在那些经常出现大粘度梯度的领域带来新的见解或应用。该项目为研究生提供了绝佳的培训机会，并且正在制作一部教育科学漫画，以吸引广大非专业人士的受众。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Osmotically Driven and Detected DNA Translocations

• DOI: 10.1038/s41598-019-51049-4
• 发表时间: 2019-10
• 期刊: Scientific Reports
• 影响因子: 4.6
• 作者: A. McMullen;George Araujo;M. Winter;D. Stein

Electrokinetic-Noise-Assisted Barrier Crossing in a Nanofluidic Environment

纳米流体环境中的动电噪声辅助穿越障碍

• DOI: 10.1103/physrevapplied.16.024019
• 发表时间: 2021
• 期刊: Physical Review Applied
• 影响因子: 4.6
• 作者: Lameh, Shayan;Zhao, Tim;Stein, Derek
• 通讯作者: Stein, Derek

Ionic current driven by a viscosity gradient

由粘度梯度驱动的离子电流

• DOI: 10.1039/d3fd00053b
• 发表时间: 2023
• 期刊: Faraday Discussions
• 影响因子: 3.4
• 作者: Wiener, Benjamin;Stein, Derek
• 通讯作者: Stein, Derek

Controlled Amplification of DNA Brownian Motion Using Electrokinetic Noise

利用动电噪声控制 DNA 布朗运动的放大

• DOI: 10.1103/physrevapplied.14.054042
• 发表时间: 2020
• 期刊: Physical Review Applied
• 影响因子: 4.6
• 作者: Lameh, Shayan;Ding, Lijie;Stein, Derek
• 通讯作者: Stein, Derek