iDEP-based single-cell isolation in a two-dimensional array of chambers addressed by easy-to-align wireless electrodes†

Platforms capable of selective single-cell capture and enclosure in a fluidically isolated volume for subsequent analysis are crucial for unmasking cellular heterogeneity. Our research group has previously reported an approach that employs wireless bipolar electrodes (BPEs) to facilitate individual isolation of cells in large arrays of pico- to nanoliter scale chambers by dielectrophoresis (DEP). This device was leveraged for a single-cell enzymatic assay and the isolation of circulating tumor cells (CTCs) from patient-derived blood samples, which takes advantage of the selectivity of DEP. However, alignment of BPEs to the microchamber openings is nontrivial, and augmentation of the array dimensions accumulates alignment error, thereby disrupting the uniformity of cell capture across the device. Thus, tolerance-forgiving designs that are simultaneously expandable are in demand. To address this demand, we present an approach that combines BPEs with insulator DEP (iDEP) to drastically expand alignment tolerance. This iDEP-BPE device offers a vertical tolerance (the distance the BPE is recessed within each microchamber) of 80 μm while the horizontal tolerance is nearly infinite. Further, the iDEP-BPE device decreases the exposure of cells to electrode surfaces and reactive oxygen species, thereby preserving their viability. Finally, this iDEP approach can be carried out with BPEs that are easy to fabricate, lacking features that require high-resolution lithography. These advancements potentiate the broad adoption of the iDEP-BPE approach for selective single-cell capture and on-chip analysis and potentiate its commercialization upon deployment of appropriate thermoplastic materials.