Numerical calculation and analysis of a novel complex impedance sensing approach for in-flow droplet detection utilizing the C 4 D technique

This study proposed a C 4 D sensor structure with a novel approach utilizing the complex impedance analysis method, which includes both resistance and reactance analysis. The complex impedance analysis method provides additional information to characterize the electrical properties of solutions and strange objects moving in the fluidic channel, thus enhancing the sensitivity of conventional C 4 D structure. In addition, the effects of the fluidic properties, object size, excitation frequency, and sensor geometry on the performance of the proposed C 4 D sensor were investigated. The proposed sensor system used the finite element method analysis to investigate the performance of the proposed method. The simulation results show that the largest resistance change is approximately 27 kΩ while the largest reactance change is about 10 kΩ according to the passage of a 400 μ m radius oil droplet over the sensing area in the NaCl solution channel. Furthermore, this work indirectly verifies the possibility and feasibility of the proposed impedance analysis method by utilizing the conventional C 4 D structure thanks to its advantages and lays a good foundation for future research work.