Resonance-enhanced impedance spectroscopy platform for label-free detection of biological particles.

Label-free electrical impedance sensing is promising for biological particle characterization, but high-frequency measurements are often limited by parasitic capacitance from the chip, interconnects, cables, and instrument inputs. Here, we present a resonance-enhanced impedance sensing platform that amplifies localized impedance changes in a dielectrophoresis (DEP)-integrated microelectrode array. External inductors were incorporated into the drive and sensing paths to tune both the resonance frequency and the resonance profile. DEP was used to localize yeast cells near the sensing electrodes before impedance measurement. The presence of yeast cells increased the resonance peak magnitude by approximately 57.86% and produced measurable changes in the real, imaginary, and phase responses of the measured impedance. At a fixed frequency of 10.8 MHz, the resonance-enhanced configuration provided a 14.35-fold increase in relative sensitivity and a 1.72-fold improvement in detection SNR compared with the non-resonant configuration. Parametric simulations further identified double-layer capacitance, parasitic capacitance, cytoplasm resistance, and membrane capacitance as key factors affecting sensitivity. These findings highlight the potential of the proposed platform to amplify particle-induced impedance changes and provide tunable, frequency-dependent electrical signatures for label-free, localized characterization of biological particles in microfluidic systems.