Zeinali Soheila, Çetin Barbaros, Oliaei Samad Nadimi Bavil, Karpat Yiğit
Mechanical Engineering Department, Microfluidics and Lab-on-a-chip Research Group, Bilkent University, Ankara, Turkey.
Mechanical Engineering Department, Microsystem Design and Manufacturing Center, Bilkent University, Ankara, Turkey.
Electrophoresis. 2015 Jul;36(13):1432-42. doi: 10.1002/elps.201400486. Epub 2015 May 18.
Microfluidics is the combination of micro/nano fabrication techniques with fluid flow at microscale to pursue powerful techniques in controlling and manipulating chemical and biological processes. Sorting and separation of bio-particles are highly considered in diagnostics and biological analyses. Dielectrophoresis (DEP) has offered unique advantages for microfluidic devices. In DEP devices, asymmetric pair of planar electrodes could be employed to generate non-uniform electric fields. In DEP applications, facing 3D sidewall electrodes is considered to be one of the key solutions to increase device throughput due to the generated homogeneous electric fields along the height of microchannels. Despite the advantages, fabrication of 3D vertical electrodes requires a considerable challenge. In this study, two alternative fabrication techniques have been proposed for the fabrication of a microfluidic device with 3D sidewall electrodes. In the first method, both the mold and the electrodes are fabricated using high precision machining. In the second method, the mold with tilted sidewalls is fabricated using high precision machining and the electrodes are deposited on the sidewall using sputtering together with a shadow mask fabricated by electric discharge machining. Both fabrication processes are assessed as highly repeatable and robust. Moreover, the two methods are found to be complementary with respect to the channel height. Only the manipulation of particles with negative-DEP is demonstrated in the experiments, and the throughput values up to 105 particles / min is reached in a continuous flow. The experimental results are compared with the simulation results and the limitations on the fabrication techniques are also discussed.
微流控技术是将微纳制造技术与微尺度流体流动相结合，以寻求控制和操纵化学及生物过程的强大技术。生物颗粒的分选和分离在诊断和生物分析中备受关注。介电泳（DEP）为微流控设备提供了独特优势。在DEP设备中，可采用不对称的平面电极对来产生非均匀电场。在DEP应用中，面对3D侧壁电极被认为是提高设备通量的关键解决方案之一，因为沿微通道高度会产生均匀电场。尽管有这些优势，但制造3D垂直电极面临相当大的挑战。在本研究中，提出了两种用于制造带有3D侧壁电极的微流控设备的替代制造技术。第一种方法是使用高精度加工同时制造模具和电极。第二种方法是使用高精度加工制造带有倾斜侧壁的模具，并使用溅射法将电极沉积在侧壁上，同时结合通过放电加工制造的荫罩。两种制造工艺都被评估为具有高度可重复性和稳健性。此外，发现这两种方法在通道高度方面具有互补性。实验中仅展示了对具有负介电泳的颗粒的操纵，并且在连续流中达到了高达105个颗粒/分钟的通量值。将实验结果与模拟结果进行了比较，并讨论了制造技术的局限性。
