Micro-electro-mechanical pressure sensor

Abstract

A pressure sensor is disclosed for measuring fluid pressure comprising a pressure sensing structure comprising a mass target suspended on a spring mechanism, wherein the mass target and the spring mechanism together exhibit high Q mechanical resonance, wherein the mass target has an area which is presented in a plane perpendicular to the direction of the mechanical oscillation of the structure, and further wherein the mass target and the spring mechanism are in the form of a membrane, and transducer means for measuring the fluid pressure by characterizing the effects that the fluid molecules produce on the motion of the structure.

Description

REFERENCE TO PENDING PRIOR PATENT APPLICATIONS [0001] This patent application claims benefit of: [0002] (1) pending prior U.S. Provisional Patent Application Ser. No. 60 / 440,154, filed Jan. 15, 2003 by Jakob Kogan et al. for MINIATURE RF / MEMS PRESSURE SENSOR (Attorney's Docket No. AHURA-4 PROV); and [0003] (2) pending prior U.S. Provisional Patent Application Ser. No. 60 / 534,089, filed Jan. 2, 2004 by Yakov Kogan for MICRO-ELECTRO-MECHANICAL VACUUM SENSOR (Attorney's Docket No. AHURA-17 PROV). [0004] The two above-identified patent applications are hereby incorporated herein by reference.FIELD OF THE INVENTION [0005] This invention relates to pressure sensors in general, and more particularly to micro-electro-mechanical pressure sensors. BACKGROUND OF THE INVENTION [0006] Gas pressure is a measure of the mechanical interaction of gas molecules with the surface of an object placed in that gas. Gas pressure is proportional to molecular concentration and gas temperature. [0007] Methods...

AI Technical Summary

Benefits of technology

"The present invention provides a pressure sensor with a mechanical portion and a transducer portion that can measure fluid pressure by inducing oscillation in a structure that has high Q mechanical resonance. The sensor has a mass target that is suspended on a spring mechanism, which together with the mass target exhibits high Q mechanical resonance. The mass target can have an area that is presented in a plane perpendicular to the direction of mechanical oscillation of the structure. The sensor can measure the fluid pressure by inducing the gas molecules to impact the structure and dampening their motion. The sensor can be designed to have a membrane or mirrors that reflect the impact of the gas molecules and convert the capacitance across electrodes into frequency. The sensor can be used to measure the fluid pressure in a variety of ways, including inducing oscillation in the mass target or tuning the frequency of the voltage applied across the electrodes."

Problems solved by technology

This makes sensor construction complicated and susceptible to damage when the sensor is subjected to pressures outside the intended measurement range.

However, both the thermocouple gauge and the ion gauge methods suffer from disadvantages.

The thermocouple gauge method is highly non-linear and has a limited dynamic range.

The ion gauge method can generally only be used at high levels of vacuum and will generally be damaged if turned on at higher pressures.

The ion gauge method also requires a high voltage electric source, which effectively prohibits its use in portable applications.

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