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

悬浮纳米和亚微粒的分类与导电性和几何形状在技术上相关的吞吐量仍然是一个未解决的问题。这里的重要挑战是潜在的干扰，通常会干扰分离机制。这是因为小颗粒容易发生扩散和热对流，因此传统的分馏过程往往失去选择性，特别是在粒径小于10 μ m的颗粒中。该项目的目标是根据材料、形状和尺寸实现5微米以下颗粒的多维分离，达到纳米尺度，最好是在一个分离效率超过80%的设备中，技术上相关的吞吐量（500 mL/h）。为此目的，将开发一种无电极介电泳（ELD）过滤系统，其中颗粒分选是通过电可切换来进行的，选择性颗粒保留在交变电场的局部最大值中。该机制是基于粒子和周围介质在宽间距外部电极之间的电绝缘结构产生的不均匀电场中的频率依赖极化。介电（DEP）力作用在颗粒上，这取决于颗粒的大小，形状和介电性质，以及工艺参数，如施加的场强和频率。在第一个资助期，研究表明，在电开关ELD滤波器中，可以选择材料和尺寸分离微粒（<10 μ m），分离效率超过90%。建立了一个模型，描述了微和亚微米粒子在芯片技术制造的ELD滤波器和具有三个数量级高吞吐量的滤波器中的行为。第二个资助期的目的是应用为多维粒子分选确定的设计标准。在高频电场的影响下，5微米以下直至纳米尺度的颗粒应在技术上相关的吞吐量下选择性地分离材料，然后通过改变电场频率或关闭电场来特定地重新固定形状或尺寸。

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.