Presentation: 2025 ND EPSCoR Annual conference 

October 21, 2025, NDSU Memorial Union, Fargo, North Dakota

Characterisation of the Dielectrophoresis Effect on Polystyrene Nanoparticles Using Electrochemical Impedance Spectroscopy

Abstract: Electrochemical impedance spectroscopy (EIS) provides a robust approach for characterizing nanoscale particle dynamics induced by dielectrophoresis. This study applies EIS to investigate the effect of positive dielectrophoresis (pDEP) on functionalised biotinylated polystyrene nanoparticles suspended in low-conductivity buffer. Interdigitated microelectrodes were used to apply a voltage source with alternating current, and impedance measurements were recorded before and after pDEP stimulation. Optical imaging confirmed nanoparticle accumulation at electrode tips during pDEP stimulation, while impedance spectra revealed distinct electrical markers of particle redistribution after pDEP removal. Significant shifts in impedance magnitude and phase were observed in the 10 Hz to 1 kHz frequency range, with magnitude increasing as nanoparticles dispersed. Equivalent circuit modelling identified the interfacial resistance as a sensitive electrical marker of particle dispersal, rising from 1.9 MΩ at 25 s to 19 MΩ at 100 s. These findings establish a clear relationship between impedance and nanoparticle dynamics, demonstrating EIS as a complementary, label-free alternative to microscopy. By establishing relationships between electrical markers such as interfacial resistance and pDEP-induced nanoparticle redistribution, EIS provides an electrical framework for profiling redistribution dynamics, supporting applications in biosensing, diagnostics, nanoparticle sorting, and scalable real-time nanomaterial characterization.