Controlled Transport of Micrometre-Sized Cargoes by Hydrogel Actuation

通过水凝胶驱动控制微米级货物的运输

• 批准号: EP/E022561/1
• 负责人: Ullrich Steiner
• 金额: $ 20.58万
• 依托单位: University of Cambridge
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2007
• 资助国家: 英国
• 起止时间: 2007 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FE022561%2F1
• 关键词: Controlled; Transport; Micrometre; Sized; Cargoes

An important issue in nanoscience and engineering is the controlled, directed motion of of small objects or volumes of liquid. A typical example are diagnostic arrays (e.g. DNA or protein chips) that are able to probe a large number of chemical reactions on a small surface area. While typically manufactured by robotic devices that place different reagents at specific lattice positions, it is desirable to develop strategies that provide a more simple and precise control to position chemical substances at microscopically defined positions on a surface. Two strategies to achieve this are micro-electro-mechanical systems (MEMS) or microfluidic devices. Both require a highly localised actuation that either controls the local motion of a mechanical device or the flow of an externally driven liquid. The most common way to design such micro actuators makes use of established lithographic methods to pattern silicon, silicon oxide, or related materials. There is, however, an increasing realisation that the use of soft materials may be beneficial for the design of such systems. Polymeric rubbers and gels have a much lower elastic modulus compared to silicon or ceramic materials, requiring much lower actuation pressures to achieve a large displacement. The potentials that drive these pressures are therefore much smaller compared to conventional actuators.Good candidates for soft actuation are swollen polymer networks (gels). Polymer gels are known to undergo a reversible discontinuous volume phase transition (they swell or deswell by a factor of more then 100) in response to infinitesimal changes in its environment. It is well established that a relatively small change in temperature, pH, or electric field can give rise to a dramatic change in its volume and the related mechanical properties. But despite the early realisation that this phase transition is potentially important for a number of technological applications, the technological implementation of gel actuation has yet to emerge. In this project we plan to make use of swelling-deswelling cycles of thin gel layers to transport micrometre-sized cargoes. The main idea is to induce waves on the surface of the gel, by which cargo particles are moved along. We have identified three physical mechanisms that can be used to propel weakly adsorbed particles across a gel surface. The purpose of this project is to explore the swelling/deswelling kinetics and morphology of thin supported hydrogel layers and their use to transport micrometre-sized cargoes in a well controlled fashion.

纳米科学和工程中的一个重要问题是小物体或大量液体的受控、定向运动。一个典型的例子是能够在小表面积上探测大量化学反应的诊断阵列（例如 DNA 或蛋白质芯片）。虽然通常由将不同试剂放置在特定晶格位置的机器人设备制造，但需要开发提供更简单和精确控制的策略，以将化学物质定位在表面上微观定义的位置。实现这一目标的两种策略是微机电系统 (MEMS) 或微流体设备。两者都需要高度局部化的驱动，以控制机械装置的局部运动或外部驱动液体的流动。设计此类微型执行器的最常见方法是利用现有的光刻方法对硅、氧化硅或相关材料进行图案化。然而，人们越来越认识到软材料的使用可能有利于此类系统的设计。与硅或陶瓷材料相比，聚合橡胶和凝胶的弹性模量要低得多，需要低得多的驱动压力才能实现大位移。因此，与传统执行器相比，驱动这些压力的电势要小得多。软驱动的良好候选者是膨胀的聚合物网络（凝胶）。众所周知，聚合物凝胶会响应其环境的微小变化而经历可逆的不连续体积相变（它们膨胀或消膨胀超过 100 倍）。众所周知，温度、pH 值或电场相对较小的变化会导致其体积和相关机械性能发生巨大变化。但是，尽管人们很早就认识到这种相变对于许多技术应用可能很重要，但凝胶驱动的技术实现尚未出现。在这个项目中，我们计划利用薄凝胶层的膨胀-消膨胀循环来运输微米大小的货物。主要思想是在凝胶表面产生波，从而使货物颗粒沿着波移动。我们已经确定了三种物理机制，可用于推动弱吸附的颗粒穿过凝胶表面。该项目的目的是探索薄支撑水凝胶层的膨胀/消膨胀动力学和形态，以及它们以良好控制的方式运输微米级货物的用途。

项目成果

Aging of thin polymer films cast from a near-theta solvent.

• DOI: 10.1103/physrevlett.105.227801
• 发表时间: 2010-11
• 期刊: Physical review letters
• 影响因子: 8.6
• 作者: A. Raegen;Mithun Chowdhury;C. Calers;A. Schmatulla;U. Steiner;G. Reiter

Metastable Underwater Superhydrophobicity

• DOI: 10.1103/physrevlett.105.166104
• 发表时间: 2010-10-14
• 期刊: PHYSICAL REVIEW LETTERS
• 影响因子: 8.6
• 作者: Poetes, Rosa;Holtzmann, Kathrin;Steiner, Ullrich
• 通讯作者: Steiner, Ullrich