Decoupling Diffusive Transport Phenomena in Microgravity
Principal Investigator: Mauro Ferrari, Ph.D.
The University of Texas Health Science Center
The emergent properties of materials and devices fabricated with critical dimensions in the nanoscale present significant opportunities in the fields of medicine and biology for engineering of pharmaceutical delivery vehicles, therapeutic and imaging agents, and biological sensors. Despite the increasing focus on nanofluidics in many of these applications, the laws governing molecular transport through nanoscale fluidic channels have not been fully realized. As the size of the channel is reduced to the molecule size, classical continuum theories fail to predict even basic characteristics of fluid transport. New transport mechanisms are observed whereby channel surface properties begin to dominate over volume properties. At the theoretical level the major challenge in analyzing these systems arises from the difficulty in decoupling the interactive effects of charge distribution, space constraints and molecular adsorption. At the experimental level this decoupling becomes nearly impossible. We propose an experiment capable of analyzing nanoscale confinement on molecular diffusion through simulation at the microscale. The objective of this study is to provide insight into the aforementioned decoupled interaction effects by overcoming experimental limitations specific to the nanoscale. In the absence of significant gravitational forces, micron sized particles should constitute a reliable substitute for molecules at nanoscale once the appropriate microscale channel size is determined. This substitution allows for greater control of the geometric design, size distribution, and surface modification of the diffusing constituents and decreases the complexity of quantifying the experimental results. The analysis will focus on understanding how particle and channel properties, such as surface charge, coupled with particle-to-particle and particle-to-channel interactions affect the diffusive transport. The insight into nanoscopic diffusive transport gleaned from this study will be relevant for “on-Earth” applications including drug delivery, molecular sieving and particle filtration. Moreover, the study will provide an understanding of microparticle diffusive transport in view of future technological applications for space exploration.