Ph.D. Proposal Presentation by Nathan D. Masters
Tuesday, July 6, 2004

(Dr. Wenjing Ye, Chair)

"Multiscale Modeling and Design with Application to Thermal Sensing Atomic Force Microscopy"


The fields of Micro- and NanoElectroMechanical Systems (MEMS and NEMS) have created the need for new modeling techniques that can deal efficiently with geometric complexity and the scale dependent effects that may arise. The goal of this work is to develop multiscale modeling techniques and tools treating continuum and non-continuum effects to facilitate the system level modeling, characterization and design of Micro- and NanoElectroMechanical Systems (MEMS and NEMS). Continuum descriptions may become invalid as length scales decrease. Thus, methods based on first principles (molecular, atomistic, or quantum mechanical) are required. Furthermore, non-continuum effects are often localized to small regions of (relatively) large systems—precluding the global application of detailed models due to computational expense. Multiscale modeling seeks to couples efficient continuum solvers with detailed models to providing accurate and efficient models of complete systems.

This study will focus on multiscale modeling of micro- and nanoscale gas phase heat transfer and apply the developed techniques to the modeling of Thermal Sensing Atomic Force Microscopy (TSAFM). This will allow more accurate characterization of TSAFM operation for improved scanning sensitivity and optimized system design. The proposed approach will use 1. Boundary Element Method (BEM) for continuum analysis, 2. Direct Simulation Monte Carlo (DSMC) for non-continuum regions, and 3. A suitable (but currently undetermined) flux-conserving coupling scheme.

Coupling will be a significant area of the research as appropriate boundary conditions and sampling techniques need to be developed to interface with the various models. Finally, the multiscale modeling tools developed in this research will facilitate the exploration of nanoscale phenomena (e.g., the Knudsen's force) with the goal of developing novel micro- and nanoscale devices.