No abstract

This paper describes the design and fabrication techniques of micro capillary columns as the main components in a microengineered gas chromatography (j.tGC) system. The system is to be developed using silicon micromachining technology, and is designed as a flexible device consisting of four basic modules: a sample injection system (module 1), an open tubular (capillary) column (module 2), a gas detector system (module 3), and an electronic circuit (module 4). Being designed in a modular structure, the system can be operated in a single and multidimensional configurations. The overall device measures 6 cm x 1 1 cm, making it very portable for field operation. The micromachined capillary columns are isotropically etched on silicon and sealed by Pyrex glass cover plate, measuring 125 cm long, and having rectangular shaped cross sections (100 .tm width and 20 tm height).

Pressure metrologists and other research workers have always aimed at the accurate determination of the distortion coefficient A characterizing the effective area of a pressure balance. This paper presents a novel and unique treatment which incorporates both the elastic distortions of the piston and the cylinder, and the pressure-viscosity effect. The Finite Element method is used to calculate the elastic distortions, but an iterative solution is obtained for the pressure-viscosity effect. An extensive validation of the developed computer models have been canied out and one new finding is reported. It is concluded that for balances with complex geometries the distortion coefficient depends on the geometrical and material properties of a balance as well as on its operating pressure.

No abstract

In this work, we proposed a direct bonding method using interlayers for single crystalline silicon wafers and glass wafers. Various materials were used for interlayers of thermal oxide, sputtered nitride, electron-beam(E-beam) evaporated silicon oxide and molybdenum. After hydrophilization, samples were spin dried and mated together without external forces. Three types of solutions were used for hydrophilizing the samples. Changes of average surface roughness after hydrophilization of the single crystalline silicon wafer, thermal oxide and E-beam silicon-oxide were inspected using atomic force microscope(AFM). Bonding interfaces of the bonded pairs were observed by scanning electron microscope(SEM). Voids and non-contact areas of the bonding pairs were also inspected using infrared(IR) transmission microscope. Surface energy, tensile strength measurements and breaking tests were also done.