Dielectrophoresis-Only Biosensing: Velocity and Cross-Over Frequency for Label-Free Bacterial Identification

Dielectrophoresis (DEP) has emerged as a powerful tool in bacterial detection, with recent research focusing on hybrid approaches incorporating acoustic, magnetic, optical, and thermal forces to enhance sensitivity. However, the complexity of these hybrid systems presents challenges in maintaining consistent and precise control, especially in long-term biosensor development. This study explores a streamlined alternative by employing DEP as the sole detection mechanism. We demonstrate successful differentiation of Escherichia coli and Staphylococcus aureus using two DEP-based parameters: cross-over frequency and movement velocity. E. coli and S. aureus exhibited distinct cross-over frequencies at 500-600 kHz and 1.0-1.5 MHz, respectively. Additionally, at 10 kHz, their movement velocities were measured at 0.00031 m/s and 0.00015 m/s, with the velocity curves showing strong resemblance to Clauscius-Mossotti Factor (CMF) profiles predicted by MyDEP simulations. These results not only validate the use of velocity as a complementary detection metric but also highlight the potential for developing simpler, cost-effective DEP biosensors. Expanding this approach to additional bacterial species may facilitate the creation of a comprehensive DEP-based detection database, supporting future applications in water quality monitoring and public health diagnostics.