Preparative fractionation of single walled carbon nanotubes in microfluidic channels by means of combined centrifugal and electrical separative forces

通过离心力和电分离力的组合在微流体通道中制备单壁碳纳米管

• 批准号: 382064650
• 负责人: Professor Dr.-Ing. Sören Hirsch
• 金额: --
• 依托单位: Fachbereich Technik
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/382064650?language=en
• 关键词: Preparative; fractionation; single; walled; carbon

Single-walled carbon nanotubes consist of a single graphene sheet rolled up into a seamless cylinder. There are two kinds of single-walled carbon nanotubes to distinguish: metallic and semiconducting. For the realization of nanotube-based electronics, it is necessary to manipulate metallic and semiconducting nanotubes separately. Unfortunately, metallic and semiconducting nanotubes typically grown together and synthesis produce a mix of semiconducting and metallic tubes. In this context, the separation of metallic and semiconducting nanotubes becomes actuality. The most developed separation methods of nanotubes in suspension used the microfluidic and dielectrophoresis techniques. Microfluidics technique is based on a laminar flow in microfluidic channels where due to asymmetric flow conditions occurs the separation. In terms of dielectrophoresis the difference of the relative dielectric constants of metallic and semiconducting tubes with respect to the solvent results in an opposite force acting on metallic and semiconducting tubes along the electric field gradient. Inside an applied electrical field dielectrophoresis enables the deposition of metallic nanotubes at the floating microelectrodes. However, the throughput rate of both microfluidic and dielectrophoresis techniques need to be scaled up for most uses. The aim of the project is increasing the throughput rate by separation of nanotubes. The positive dielectrophoresis force acting between metallic nanotubes and metallic micro particles performs this task. The electrical field applied to cell electrodes induces the inhomogeneous electrical field around metallic micro particles that are free moving in solvent. In this inhomogeneous field, the metallic tubes aligned with metallic micro particles and move together with these carrier particles. Due to sedimentation in centrifugal field the metallic particles achieve the cell region without electrical field, where metallic nanotubes become free from carrier particles. In this way the collection of metallic nanotubes occurs at one side of microfluidic cell. The semiconducting nanotubes remain free in solvent and move to the other side of microfluidic cell due to asymmetric flow conditions. The application of metallic parties as carrier with high sedimentation rate increases the effective volume of microfluidic cell significantly. This performs the enhanced throughput rate of separation. The design of single cell has to be optimized. This needs the selection of optimal process parameters such as flow rate of suspension, concentration of nanotubes, amplitude and frequency of applied electrical field. The results of separation will be tested by means of different spectroscopic techniques. The simulation of processes occurring in microfluidic cells will be carried out. The mesoscopic level can be achieved by means of connection of several individual microfluidic cells in parallel.

单壁碳纳米管由一个石墨烯片卷成一个无缝的圆柱体组成。单壁碳纳米管有两种：金属性和半导体性。为了实现基于纳米管的电子学，有必要分别操纵金属和半导体纳米管。不幸的是，金属和半导体纳米管通常生长在一起，合成产生半导体和金属管的混合物。在这种情况下，金属和半导体纳米管的分离成为现实。目前发展最快的纳米管悬浮液分离方法是微流控和介电泳技术。微流体技术是基于微流体通道中的层流，其中由于不对称流动条件而发生分离。在介电电泳方面，金属和半导体管相对于溶剂的相对介电常数的差异导致沿着电场梯度作用在金属和半导体管上的相反的力。在施加的电场内，介电电泳使得金属纳米管能够沉积在浮动微电极处。然而，微流体和介电电泳技术的吞吐率需要扩大到大多数用途。该项目的目的是通过分离纳米管来提高生产率。作用在金属纳米管和金属微粒之间的正介电泳力执行此任务。施加到池电极的电场在溶剂中自由移动的金属微粒周围诱导不均匀电场。在这种非均匀场中，金属管与金属微粒对齐，并与这些载体颗粒一起运动。由于在离心场中的沉降，金属颗粒在没有电场的情况下达到单元区域，在该区域中金属纳米管变得不含载体颗粒。以这种方式，金属纳米管的收集发生在微流体单元的一侧。半导体纳米管在溶剂中保持自由，并且由于不对称的流动条件而移动到微流体单元的另一侧。采用高沉降率的金属颗粒作为载体，显著提高了微流控池的有效体积。这实现了分离的增强的吞吐率。必须优化单电池的设计。这需要选择最佳的工艺参数，如悬浮液的流速，纳米管的浓度，外加电场的振幅和频率。分离结果将通过不同的光谱技术进行测试。将进行微流体细胞中发生的过程的模拟。介观水平可以通过并联连接几个单独的微流体单元来实现。