Electrostatic modes of atomic force microscopy have shown to be non-destructive and relatively simple methods for imaging conductors embedded in insulating polymers. Here we use electrostatic force microscopy to image the dispersion of carbon nanotubes in a latex-based conductive composite, which brings forth features not observed in previously studied systems employing linear polymer films. A fixed-potential model of the probe-nanotube electrostatics is presented which in principle gives access to the conductive nanoparticle's depth and radius, and the polymer film dielectric constant. Comparing this model to the data results in nanotube depths that appear to be slightly above the film-air interface. This result suggests that water-mediated charge build-up at the film-air interface may be the source of electrostatic phase contrast in ambient conditions.
Proceedings of SPIE - The International Society for Optical Engineering
Skinner, Jack L.; Andriolo, Jessica M.; Beisel, Josh D.; Ross, Brandon M.; Purkett, Lance M.; Murphy, John P.; Kyeremateng, Jerry; Franson, Marvin J.; Kooistra-Manning, Emily A.; Hill, Bryce E.; Loyola, Bryan L.
Traditional fabrication methods for the integrated circuit (IC) and the microelectromechanical systems (MEMS) industries have been developed primarily for two-dimensional fabrication on planar surfaces. More recently, commercial electronics are expeditiously emerging with non-planar displays and rapid prototype machines can be purchased for the price of a modern laptop. While electrospinning (ES) has been in existence for over 100 years, this fabrication method has not been adequately developed for commercial fabrication of electronics or the rapid prototyping industries. ES provides many benefits as a fabrication method including tunability of fiber size and affordable hardware. To realize the full potential of ES as a commonplace fabrication method for modern devices, precise control, real-time fiber morphology monitoring, and the creation of a comprehensive databank of accurate models for prediction is essential. The aim of this research is to accomplish these goals through several avenues. To improve fiber deposition control, both passive and active methods are employed to modify electric field lines during the ES process. COMSOL models have been developed to meticulously mimic experimental results for predictive planning, and an in situ laser diagnostic tool was developed to measure real-time fiber morphology during electrospinning. Further, post-processing data was generated through the use of two-dimensional fast Fourier transform (2D-FFT) to monitor alignment, and four-point conductivity measurements were taken via four independently-positioned micromanipulator probes. This article describes the devices developed to date, the a priori modeling approach taken, and resultant capabilities which complement ES as an attractive fabrication method for the electronic and photonic industry.