An electroactive microfluidic platform integrated with AM-pDEP focusing and side-counter design for selective cell sorting and single-cell quantification

Rapid isolation and precise quantification of target cancer cells are crucial for precision medicine applications. Conventional fluorescence-based methods require bulky optical instrumentation and specialized expertise. Recent advances in label-free microfluidic techniques have attempted to overcome these limitations but often suffer from reduced reliability and throughput when integrating multiple functions. Here, we demonstrate an electroactive microfluidic platform that integrates functions of selective concentration, particle focusing, and single-cell level quantification without introducing additional complex physical microstructures. Our device employs the dielectrophoresis (DEP) effect combined with an interdigitated cell sorter to achieve selective cell concentration. For quantification and characterization, the device leverages the impedimetric Coulter principle to achieve precise particle counting and characterization at single-cell resolution. To address the inherent tradeoff between sensitivity and throughput in the traditional Coulter counter, we utilize the tilted interdigitated electrode configuration excited by an amplitude-modulated (AM) Positive DEP (pDEP) signal instead of the commonly employed narrow channel or sheath flow to realize the effective focusing and alignment of the cell stream. The focusing module is combined with our side-counter design to detect cells. The performance of our device and its embedded modules has been verified with mixed breast cancer and blood model cell lines, where high consistency between optical and electrical detection has been demonstrated. We expect the integration of the proposed AM-pDEP focusing approach and the corresponding microfluidic design for cell sorter and on-chip flow cytometry would offer an alternative engineering solution to the stream-based on-chip single-cell analysis where reliable cell focusing and single-cell sensing are required.