Schnelle T, Müller T, Gradl G, Shirley S G, Fuhr G
EVOTEC BioSysteme AG, Hamburg, Germany.
Electrophoresis. 2000 Jan;21(1):66-73. doi: 10.1002/(SICI)1522-2683(20000101)21:1<66::AID-ELPS66>3.0.CO;2-A.
Planar and three-dimensiònal multi-electrode systems with dimensions of 2 - 40 microm were fabricated by IC technology and used for trapping and aggregation of microparticles. To achieve negative dielectrophoresis (repelling forces) in aqueous solution, radiofrequency (RF) electric fields were used. Experimentally, particles down to 100 nm in diameter were enriched and trapped as aggregates in field cages and dielectrophoretic microfilters and observed using confocal fluorimetry. Theoretically, single particles with an effective diameter down to about 35 nm should be trappable in micron field cages. Due to the unavoidable Ohmic heating, RF electric fields can induce liquid streaming in extremely small channels (12 microm in height). This can be used for pumping and particle enrichment but it enhances Brownian motion and counteracts dielectrophoretic trapping. Combining Brownian motion with ratchet-like dielectrophoretic forces enables the creation of Brownian pumps that could be used as sensitive separation devices for submicron particles if liquid pumping is avoided in smaller structures.
采用集成电路技术制造了尺寸为2至40微米的平面和三维多电极系统，并将其用于微粒的捕获和聚集。为了在水溶液中实现负介电泳（排斥力），使用了射频（RF）电场。实验上，直径小至100纳米的颗粒在电场笼和介电泳微滤器中富集并作为聚集体捕获，并使用共聚焦荧光法进行观察。理论上，有效直径小至约35纳米的单个颗粒应该可以捕获在微米级电场笼中。由于不可避免的欧姆加热，射频电场会在极小的通道（高度为12微米）中引起液体流动。这可用于泵送和颗粒富集，但会增强布朗运动并抵消介电泳捕获。将布朗运动与棘轮状介电泳力相结合，能够创建布朗泵，如果在较小结构中避免液体泵送，布朗泵可用作亚微米颗粒的灵敏分离装置。
