The opportunity to create design and manufacturing protocols for the creation of engineered polymeric ultrathin film systems (PUFS) may rest to a great degree on the development of sophisticated, in-situ diagnostics. The Langmuir/Blodgett (L/B) deposition technique offers the possibility of providing the foundation for the application of organics to important emerging fields, such as optics, electronics, and biotechnology. These applications depend on precise control of materials properties such as positional and orientational order of active molecular structures, alternation of layers, and thickness. For L/B deposition, surface pressure and Langmuir-layer area have remained the only necessary diagnostic techniques because L/B methods were confined to simple organics. The investigators have shown that it is possible to detect the thickness of a single L/B monolayer using a capacitance sensor composed of interdigitated metal electrodes. The sensor is fabricated on the substrate that is to be coated with the L/B film. It is proposed to extend this work to examine other promising applications of the capacitance sensor. It has been necessary to redesign the sensor to eliminate or minimize subphase entrainment by the sensor itself. This was achieved by coating the sensor with a hydrophobic monolayer and designing the sensor so that the electrodes are normal to the interface during dipping. The sensor also allows the study of the role of film drying on deposition quality. In addition to quantifying subphase incorporation, the sensor is used to study how L/B films coat over complex topography.
