Dielectrophoretic assembly of single gold nanoparticle into nanogap electrodes

We report the optimization study of assembling single 20 nm gold nano-particle in 20 nm spaced electrode gap via ac dielectrophoresis (DEP) technique. It was observed that time, voltage, and frequency variations influenced significantly the assembly of gold nano-particle in the nano-gap electrodes. Frequency variation study revealed that at lower frequencies (< 1 MHz) the assembling was observed in low field regions; however, at a moderate frequency of 1 MHz, minimum number of nano-particles was assembled in high field region. Trapping of single 20 nm nano-particle in 20 nm spaced electrodes was successfully achieved under the optimized DEP parameters i.e., frequency, applied voltage and time of values corresponding to 1 MHz, 2 V, and 1 sec, respectively, with the yield of almost 66%. Our results show the promise of optimized dielectrophoresis in the future nano-engineering.