Ph.D. Proposal Presentation by Andrew W. McFarland
Thursday, November 13, 2003

(Dr. Jon Colton, advisor)

"Production and Analysis of Polymer Micro-cantilever Parts"

Abstract

This research involves production of polymer microcantilevers (thickness-width-length dimensions of roughly 5 X 100 X 500 µm) used to detect antigen-antibody bonding in small-volume fluid samples. Numerous methods of production will be investigated, with a heavy focus on injection molding as preliminary results look quite promising. The main objective of the research is to examine length-scale effects exhibited by the microcantilevers, which will be accomplished via a two-pronged approach. The first approach will examine mechanical size-effects by employing strain gradient theories and comparing these theoretically-predicted values to values from the physical parts (obtained via AFM techniques). The second approach encompasses the main goal of the project, which is the development of a computer simulation of the entire injection molding process (from initial mold heating to part cooling), incorporating pressure-, temperature-, shear-rate-, and length-scale-dependent viscosity modeling, along with inclusion of surface tension and non-zero slip-velocity effects. This simulation code will predict the final part geometry and residual stress distribution based upon numerous manufacturing variables. Physical measurements will be taken (via interferometry, AFM techniques, and birefringence analysis) and compared to the code for validation. These small-scale effects have seen only modest attention in the literature and even less experimental validation; therefore this project will provide an important scientific tool for simulation of polymer flow at the small-scale, and for accurate, repeatable production of MEMS devices via injection molding techniques. The project will also validate the use of polymer microcantilevers as feasible and accurate biological sampling platforms by comparison of microcantilever-obtained values to those of commercially available sensing kits (specifically ELISA-type packages).