Figure 2.

Finite element simulation. (a) The electric field distribution of a quadruple electrode. (b) The simulation result for the electric field distribution at the assembled microparticles. (c) After concentrating the microparticles, the applied electric field is focused and locally amplified at the assembled bead-bead gaps wherein an extremely high electric field is produced. The amplified electric field can induce a positive DEP for manipulating nanocolloids into the gaps of the assembled microparticles. (d) The simulation result indicates that the local surface of the assembled microparticles also generates a secondary high electric field region. (e) The strength of the amplified electric field generated from the different electrode gaps. The dashed line indicates the threshold strength of electric field for effectively manipulating several tens nanometers colloids.