Figure 1. Electrical Impedance Microscopy.

(a) Schematic illustration of the experimental setup. A laser beam is directed onto a gold-coated glass coverslip via an oil immersion objective to create surface plasmon resonance (SPR) on the gold surface, which is imaged with a CCD. On the coverslip cells are cultured for study. An AC modulation potential is applied to the gold electrode relative to a reference electrode inserted in the solution, and the impedance image (EIM) was created from the potential-induced SPR signal changes. In addition to the SPR and EIM images, a conventional optical image of the same sample is also available. (b) Example of optical, SPR and EIM images of 200 nm-silica nanoparticles to demonstrate spatial resolution. The optical image cannot resolve the nanoparticles, and the SPR image shows each nanoparticle as a bright spot with a long tail in the SPR propagation direction. The EIM image has similar spatial resolution as the SPR image.