Chi-Yuan Shih

Residual stress in thin-film parylene-c

This paper reports the influence of thermal annealing on the residual stress in parylene-c thin-films on silicon. Although recently others have used the diaphragm bulge testing method to measure the residual stress in parylene, this is the first extensive study of residual stress in parylene using the load-deflection method and rotating tip strain gages. This paper supports the hypothesis that stress is relaxed in parylene-c films at elevated temperatures (>100/spl deg/C) and that thermal stress accounts for 90% of the residual stress in films that have undergone annealing at these elevated temperatures. It was found that this held true up to 180/spl deg/C which is above the glass transition temperature of the material.

Nano-to-micro self-assembly using shear flow devices

This work aims at developing a new technique to precisely assemble nano-materials into micro-or even meso-scale devices. For example, our long-term goal is to use massively architected motor-molecules to build muscle-like actuators in which these molecules work in parallel to output large forces. As an important first step, we report here the successful development of a much improved shear-flow-enhanced self-assembly method over the baseline spontaneous assembly method in test tubes. More specifically, we have engineered special thiolated model molecules (bisdisulfide/C/sub 28/H/sub 34/O/sub 4/S/sub 4/) and demonstrated the nano-to-micro self-assembly through flow interface using thiol-gold bonding chemistry. Our method has produced gold/molecule aggregates as big as 50 /spl mu/m that are completely made of 30 nm gold nanoparticles and 3 nm model molecules.