Jarmoshti Javad, Siddique Abdullah-Bin, Rane Aditya, Hyler Alexandra R, Adair Sara, Bauer Todd W, Swami Nathan S
Electrical and Computer Engineering, University of Virginia, Charlottesville, Virginia 22904, United States.
Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States.
ACS Sens. 2025 Jun 27;10(6):4116-4126. doi: 10.1021/acssensors.5c00192. Epub 2025 Jun 6.
Microfluidic cell separation by dielectrophoresis, based on biophysical and electrical physiology metrics, is often optimized using on-chip fluorescence microscopy or off-chip flow cytometry of the separated fractions. However, these techniques require fluorescent reporters or stained samples that operate as end point assays, preventing the separated cell fractions from being utilized for longitudinal or transplantation studies. Single-cell impedance cytometry has a small footprint for facile integration toward label-free quantification of the separated fractions based on cell size, viability, and biophysical metrics. However, this is limited by low impedance signal-to-noise ratios in the low-conductivity media optimal for dielectrophoretic separation and by irreversible dielectrophoretic cell capture on impedance acquisition electrodes, while its single-cell resolution ability is limited by the high channel depths used to enhance sample throughput. Herein, using viscoelastic flows for elasto-inertial cell focusing over the channel depth, the throughput of dielectrophoretic separation is maintained, and bubble formation is avoided, while the downstream voltage for impedance cytometry can be maximized without irreversible cell capture to enhance impedance sensitivity in the dielectrophoretic separation media. This multichannel cytometry capability is integrated for automated optimization of the dielectrophoretic enrichment of live circulating tumor cells released into the suspension of pancreatic cancer cell cultures, using impedance metrics to monitor the separated fractions for feedback toward the selection of live cells within specific size ranges and with minimized transmembrane voltage-induced cell damage.
基于生物物理和电生理指标，通过介电泳进行微流控细胞分离时，通常会使用芯片上的荧光显微镜或分离组分的芯片外流式细胞术进行优化。然而，这些技术需要荧光报告分子或染色样本作为终点检测方法，这使得分离出的细胞组分无法用于纵向研究或移植研究。单细胞阻抗细胞术占用空间小，便于集成，可基于细胞大小、活力和生物物理指标对分离组分进行无标记定量。然而，这受到介电泳分离最佳低电导率介质中低阻抗信噪比的限制，以及阻抗采集电极上不可逆的介电泳细胞捕获的限制，同时其单细胞分辨率能力受到用于提高样本通量的高通道深度的限制。在此，利用粘弹性流在通道深度上进行弹性惯性细胞聚焦，可保持介电泳分离的通量，避免气泡形成，同时在不进行不可逆细胞捕获的情况下，可将阻抗细胞术的下游电压最大化，以提高介电泳分离介质中的阻抗灵敏度。这种多通道细胞术能力被集成用于自动优化释放到胰腺癌细胞培养悬浮液中的活循环肿瘤细胞的介电泳富集，使用阻抗指标监测分离组分，以反馈选择特定大小范围内且跨膜电压诱导的细胞损伤最小化的活细胞。
