Qing He

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.

Ion liquid chromatography on-a-chip with beads-packed parylene column

A parylene-MEMS ion-exchange Liquid Chromatography (LC) chip is presented here. The chip is integrated with microfluidic I/O ports, a separation column, frits/filters, and a conductivity detector. The column is packed with conventional LC stationary phase support materials, i.e. micro-beads with surface functional groups. To withstand high pressure normally encountered in high performance liquid chromatography (HPLC), a self-aligned, channel-anchoring technique is developed to increase the pressure rating of the parylene microfluidic devices from 30 to at least 800psi. On-chip injection, separation and detection of anions in water, with /spl sim/25 ppm concentration, have been successfully demonstrated. To our knowledge, this is the first demonstration of microbeads-packed column ion liquid Chromatography (LC) on a chip.

Integrated Micro/Nano Fluidics for Mass-spectrometry Protein Analysis

Over the past decade there has been increasing interest in the development of miniaturized chemical analysis systems using MEMS technology to handle a small amount of liquid from mL down to nL, or even pL. However, due to the diversified process of chemical/biochemical analysis and a wide range of samples involved, a self-contained mass-produced lab-on-a-chip with the same economy of scale as electrical components has yet to be realized. Here, we report an effort to produce such a chip that can couple to a mass spectrometer for biomolecule analysis.

Integrated Electrospray Chip for Mass Spectrometry

We report here a novel micromachined fluid dispensing system for ESI-MS (Electrospray Ionization - Mass Spectrometry) that has integrated electrolysis-based micro pump, micro mixer and ESI nozzle on a single chip. The whole structure is built by multi-layer Parylene surface micromachining technology. Using this system, precise and multi-sample dispensing for ESI-MS can be achieved on a single chip.