Biological microparticles detection based on differential capacitive sensing and dielectrophoresis manipulation

The manipulation and detection of living cells are essential requirements for many applications in biology, biotecnology and medicine. In this study, we propose a microfluidic device, which facilitated of a differential capacitively coupled contactless conductively detection (DC⁴D) coplanar capacitor structure and a dielectrophoresis (DEP) concentrator based on circular electrodes for detecting of living cells. With the proposed device, first, the target and non-target cells are guided toward the center of the working chamber due to the dielectrophoresis forces. Then the target cells are captured by the electrode covered with aptamers, which possess a high affinity to the target cells. After being flushed to wash away the non-target cells in the working chamber, the differential capacitance is read to identify the presence of target cells. Numerical simulations of the DEP manipulation and DC⁴D were performed to proof the concept of the proposed design. A prototype of the proposed device was fabricated using micromachining technology. Manipulation and sensing performances of the device were investigated. The evaluation results show that the capacitance output changes up to 3fF corresponding to the presence of about twenty-five cells captured at the electrode.