Highly permeable, electrically switchable filter for multi-dimensional sorting of suspended submicron particles

悬浮态纳米和亚微米颗粒在技术上相关的吞吐量下的导电性和几何形状的分类仍然是一个悬而未决的问题。这里的重要挑战是通常干扰分离机制的潜在干扰。这是因为小颗粒容易扩散和热对流，因此传统的分馏过程往往失去选择性，特别是当颗粒直径低于10微米时。该项目的目标是实现按材料、形状和大小对小于5微米的颗粒进行多维分离，最好是在一个分离效率高于80%、具有技术相关产量(500毫升/小时)的设备中。为此，将开发一种无电极介质电泳(ELD)过滤系统，在该系统中，通过在交变电场的局部极大值中保持可电切换的、选择性的颗粒来执行颗粒分选。其机理是基于粒子和周围介质在不均匀电场中的频率相关极化，该电场是由分布广泛的外部电极之间的电绝缘结构产生的。介电泳力作用在微粒上，这取决于微粒的大小、形状和介电性质，以及工艺参数，如外加磁场强度和频率。在第一个资助期，研究表明，在电开关ELD滤光器中，有材料和尺寸选择性地分离微粒(&lt；10微米)是可能的，分离效率超过90%。建立了一个模型，描述了微米和亚微米粒子在芯片技术制造的ELD过滤器中的行为，以及在吞吐量高三个数量级的过滤器中的行为。第二个资助期的目的是应用为多维颗粒分类确定的设计标准。在高频电场的影响下，5微米以下至纳米级的颗粒应该在技术上相关的吞吐量上选择性地进行材料分离，然后通过改变电场频率或关闭电场来具体地重新动员形状-或尺寸。

The sorting of suspended nano- and submicroparticles with respect to conductivity and geometry at technically relevant throughputs is still an unresolved problem. Important challenges here are potential disturbances that typically interfere with the separation mechanism. This is, because small particles are prone to diffusion and thermal convection, whereby conventional fractionation processes often lose their selectivity, especially at particle diameter below 10 µm. The aim of this project is to achieve multidimensional separations of particles below 5 µm down to the nanometer scale by material, shape and size, preferably in one device with separation efficiencies above 80 % and technically relevant throughputs (500 mL/h). For this purpose, an electrodeless dielectrophoretic (ELD) filtration system will be developed, in which particle sorting is carried out by an electrically switchable, selective particle retention in local maxima of alternating electric fields. The mechanism is based on the frequency-dependent polarization of particles and the surrounding medium in an inhomogeneous electric field generated by electrically insulating structures between widely spaced external electrodes. A dielectrophoretic (DEP) force acts on the particle, which depends on the particle size, shape and its dielectric properties as well as on process parameters such as the applied field strength and frequency.In the first funding period it was shown that a material- and size-selective separation of microparticles (<10 µm) is possible in electrically switchable ELD filters with separation efficiencies above 90 %. A model was developed that describes the behavior of micro- and submicron particles both in ELD filters manufactured in chip technology and in filters with three orders of magnitude higher throughput. The aim of the second funding period is to apply the design criteria determined for multidimensional particle sorting. Under the influence of a high-frequency electric field, particles below 5 µm down to the nanometer scale should be material-selectively separated at technically relevant throughputs and then shape- or size-specifically remobilised by means of a changed field frequency or by turning the electric field off.