Design, Fabrication, and Characterization of a Micro Vapor-Jet Vacuum Pump

Abstract

A microelectromechanical system (MEMS) vapor-jet pump for vacuum generation in miniaturized analytical systems, e.g., micro-mass-spectrometers (Wapelhorst, E., Hauschild, J., and Mueller, J., 2005, “A Fully Integrated Micro Mass Spectrometer,” in Fifth Workshop on Harsh-Environment Mass Spectrometry;Hauschild, J., Wapelhorst, E., and Mueller, J., 2005, “A Fully Integrated Plasma Electron Source for Micro Mass Spectrometers,” in Ninth International Conference on Miniaturized Systems for Chemistry and Life Sciences (μTAS), pp. 476–478), is presented. A high velocity nitrogen or water vapor jet is used for vacuum generation. Starting from atmospheric pressure, a high throughput of more than 23ml∕min and an ultimate pressure of 495mbars were obtained with this new type of micropump. An approach for the full integration of all components of the pump is presented and validated by experimental results. The pump is fabricated from silicon and glass substrates using standard MEMS fabrication techniques including deep reactive ion etching, trichlorosilane molecular vapor deposition, and metal-assisted chemical etching for porous silicon fabrication. Micromachined pressure sensors based on the Pirani principle have been developed and integrated into the pump for monitoring.

Experimental results for a microscale ethanol vapor jet ejector

“…The ethanol ejector, however, produces a greater suction draft. For reference, at closed throttle the maximum vacuum pressures achieved by the ejector using nitrogen gas and ethanol vapor are 0.647 atm and 0.473 atm, respectively, which are comparable to other pumps using supersonic nozzles such as the 0.489 atm (495 mbars) vacuum reported in [12].…”

“…The laser generates hydrogen peroxide steam by catalytic decomposition, driving an ejector-based pressure recovery system that pumps low pressure fluid to the atmosphere [10]. Other investigators have micromachined 2D single-and multi-stage water-vapor-driven vacuum pumps for use in miniaturized analytical systems such as mass spectrometers [11,12]. These vacuum pumps demonstrated jet pump operation at the microscale, achieving a vacuum of 495 mbar, and presented a system with an integrated heater and a Pirani pressure sensor.…”

MEMS mass spectrometers: the next wave of miniaturization

“…As part of a broader effort to develop fully integrated mass spectrometers, a vapour jet pump has been developed at TU Hamburg-Harburg [200,201]. The micromachined silicon pump incorporates a Laval nozzle to generate a supersonic jet of a working fluid.…”

Cathode Design Optimization toward the Wide-Pressure-Range Miniature Discharge Ion Source for a Vacuum Micropump

“…The main types of vacuum micropumps include micro diaphragm pumps [22,23], micro vapour-jet pumps [24,25], micro cryopumps [26], Knudsen pumps [27,28,29] and micro ion pumps [30,31,32,33,34]. Micro diaphragm pumps, micro vapour-jet pumps and micro cryopumps can start working at atmospheric pressure and pump gas continuously.…”