Clays

Clay-Coated Electroactive Planar Waveguides
Fundamental studies will lead to the smart development of sensors and nanocomposite materials.
   

Figure 1. Coating clays onto an electroactive planar waveguide allows investigation of the clay film in several dimensions for two reasons. The electrochemical perturbation probes the entire diffusion sampled depth of the clay film. The optical signal probes only within the evanescent wave depth which is of the order of 100 nm. The optical signal is composed of two parts the steady state signal and the electromodulated signal. The electromodulated signal responds only to a probe molecule that is within the evanescent wave depth AND confined (non-diffusing) to that depth. The planar waveguide was built by Azza Wagdy.

 

  Figure 2. Because probe molecules occupy different domains within the clay film their differential optical and current response to the potential modulation allows selective sampling of pinhole regions as compared to interlayer regions. This work is being pursued by graduate student Augustine Agyeman.

Figure 3. The data at the left show the variable optical and electrochemical responses of clay films which are in different expanded states.