Froberg James, Jayasooriya Vidura, You Seungyong, Nawarathna Dharmakeerthi, Choi Yongki
Department of Physics, North Dakota State University, Fargo, North Dakota 58108, USA.
Department of Electrical and Computer Engineering, North Dakota State University, Fargo, North Dakota 58108, USA.
Appl Phys Lett. 2017 May 15;110(20):203701. doi: 10.1063/1.4983785. Epub 2017 May 17.
Nanoelectronic devices integrated with dielectrophoresis (DEP) have been promoted as promising platforms for trapping, separating, and concentrating target biomarkers and cancer cells from a complex medium. Here, we visualized DEP and DEP gradients in conventional nanoelectronic devices by using multi-pass atomic force microcopy techniques. Our measurements directly demonstrated a short range DEP only at sharp step edges of electrodes, frequency dependent DEP polarity, and separation distance dependent DEP strength. Additionally, non-uniform DEP along the edges of the electrodes due to a large variation in electric field strength was observed. The strength and apparent working distance of DEP were measured to be an order of a few nN and 80 nm within the limited scale of particles and other parameters such as an ionic strength of the medium. This method provides a powerful tool to quantify the strength and polarity of DEP and allows optimizing and calibrating the device's operating parameters including the driving field strength for the effective control and manipulation of target biomolecules.
集成介电电泳（DEP）的纳米电子器件已被视作从复杂介质中捕获、分离和浓缩目标生物标志物及癌细胞的极具潜力的平台。在此，我们通过多程原子力显微镜技术在传统纳米电子器件中可视化了DEP及DEP梯度。我们的测量直接证明了仅在电极的尖锐台阶边缘处存在短程DEP、DEP极性与频率相关以及DEP强度与分离距离相关。此外，还观察到由于电场强度的大幅变化，电极边缘处的DEP不均匀。在颗粒的有限尺度以及诸如介质离子强度等其他参数范围内，DEP的强度和表观工作距离经测量约为几纳牛和80纳米。该方法为量化DEP的强度和极性提供了一个强大工具，并允许优化和校准器件的操作参数，包括用于有效控制和操纵目标生物分子的驱动场强。
