Dielectrophoretic force characteristics toward Lactobacillus casei on an oblique-patterned electrode

Abstract

Dielectrophoresis-based biochips with various microelectrode configurations have been extensively studied within the last five deca des. However, wide-field application is still challenging. This study aims to fabricate an oblique-configuration microelectrode and then utilizes it to determine the dielectrophoretic (DEP) characteristics of Lactobacillus casei based on the generated non-uniform electric field. The electric field distribution on microelectrodes was simulated with Quickfield 6.6 student version. The microelectrodes were fabricated using a copper film on a glass substrate. The DEP characteristic of Lactobacillus casei was investigated by applying a sinusoidal AC signal to microelectrodes in medium solution with an electrical conductivity of 0.05 S/m. The electric-field simulations show that the strongest electric-field was generated on the tip of electrodes spacing, and the weakest electric-field was generated on the inner of electrodes spacing. The negative-DEP force on Lactobacillus casei was observed at the frequency of 60–130 kHz, while the positive-DEP force was observed at the frequency of 380–700 kHz, both at voltage of 2–6 Vpp. The nDEP force led Lactobacillus casei to be pushed toward the weak electric field on the inner of electrodes spacing, and the pDEP force induced Lactobacillus casei to be attracted toward the strong electric-field on the tip of electrodes spacing. This study implies that the proposed oblique-microelectrode platform has promising application for bioparticles separation.