Detecting molecules using a surface impedance imaging technique

We demonstrate here a surface impedance imaging technique based on the local surface charge density influencing the surface plasmon resonance (SPR) measurement. Three images are captured of the entire surface: a DC steady-state image, an AC intensity image and an AC phase image. The DC image gives the standard SPR information on thickness. The AC intensity and phase images display information related to the surface impedance. This allows for the surface charge modulation created by the electrochemical potential modulation to be imaged optically.