Controllable pump-free electrokinetic-driven microdevice for single-cell electrorotation

Single-cell electrorotation (ROT) has emerged as a fundamental technique for characterizing cellular electrical properties, yet conventional methodologies face significant limitations including laborious cell loading procedures, time-consuming measurements, low throughput, and confined effective operational regions. To address these challenges, we present an innovative pump-free single-cell ROT device that synergistically integrates electroosmotic flow (EOF) with ROT technologies. Our design employs time-division multiplexed electrical signal modulation to achieve real-time regulation of EOF velocity and directionality, effectively resolving cell positioning challenges while eliminating the need for complex pumping system. This approach not only reduces experimental cost but also significantly simplifies operational complexity. Furthermore, the implementation of thick-electrode architecture successfully mitigates electric field spatial attenuation, thereby expanding the effective ROT zone and enhancing measurement stability and precision. The capability of the proposed method was tested by rotating yeast and colon cancer cells. Using this device, we quantified the membrane permittivity and cytoplasmic conductivity of these two cell types, revealing differences in the electrical parameters of different types of cells. We envision that the pump-free single-cell ROT microdevice will provide a new platform for convenient and high-throughput cell electrical characterization.