Microengineered open tubular (MOT) columns with semi rectangular cross-sections have been designed and fabricated using microengineering techniques. The creation of 100-micrometers wide, 20-micrometers deep, and 125-cm long columns employed isotropic etching on (100) silicon and anodic bonding with a Pyrex 7740 glass cover plate. Column geometry has been optimized to achieve maximum efficiency and allow extreme operating conditions. The walls of the microcolumns were coated with a non-polar liquid stationary phase. Performances of the MOT columns have been demonstrated by their ability to completely separate a series of hydrocarbon mixture in less than 1.25 min under isothermal condition of 150 degrees C. The achievable column efficiencies as measured in terms of theoretical plate height ranged from 0.57 to 1.45 mm, which agreed well with theoretical predictions.
This paper describes the design and fabrication techniques of micro capillary columns as the main components in a microengineered gas chromatography 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, an open tubular column, a gas detector system, and an electronic circuit. Being designed in a modular structure, the system can be operated in a single and multidimensional configurations. The overall device measures 6 cm X 11 cm, making it very portable for field operation. The micromachined capillary columns are isotopically etched on silicon and sealed by Pyrex glass cover plate, measuring 125 cm long, and having rectangular shaped cross sections.