Automatic medium exchange for micro‐volume cell samples based on dielectrophoresis

Abstract

Cell medium exchange is a crucial step for life science and medicine. However, conventional cell medium exchange methods, including centrifuging and filtering, show limited ability for micro‐volume cell samples such as circulating tumor cell (CTC) and circulating fetal cell (CFC). In this paper, we proposed an automatic medium exchange method for micro‐volume cell samples based on dielectrophoresis (DEP) in microfluidic chip. Fresh medium and cell suspension were introduced into the microfluidic channel as the laminar flow. Plane stair‐shaped interdigital electrodes were employed to drive the cells from the cell suspension to fresh media directly by DEP force. Additionally, we characterized and optimized the cell medium exchange according to both the theory and experiments. In the end, we achieved a 96.9% harvest rate of medium exchange for 0.3 μL samples containing micro‐volume cells. For implementing an automatic continuous cell medium exchange, the proposed method can be integrated into the automatic cell processing system conveniently. Furthermore, the proposed method is a great candidate in micro‐volume cell analysis and processing, cell electroporation, single cell sequencing, and other scenarios.

On‐chip microfluidic buffer swap of biological samples in‐line with downstream dielectrophoresis

“…Microfluidic media dilution strategies from prior reports [31,32] are likely to also dilute cells in the sample, while inertial strategies to enhance mixing for media dilution [33] would also alter cell streamlines to cause their flow dispersion and reduce sample collection in the exchanged buffer. Other strategies for buffer exchange utilize acoustophoresis [34] or dielectrophoresis [35] for flow focusing of cells in the sample, so that the suspending media can be exchanged by cascaded ion diffusion. However, selectivity of the trapping force cannot be maintained for all cell types in heterogeneous samples, the trapping force magnitude varies as a function of exchanged media properties [36], and the increasing cell-to-cell interactions that occur during focusing of concentrated samples limit their efficacy.…”