Resonant photo acoustic system
First Claim
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1. A device comprising:
- a resonator having an oscillating portion formed as a single-prong suspended beam having a supported end;
a light source to provide light along a length of the oscillating portion, the light being directed toward the supported end; and
a detector to detect a change in oscillation of the resonator responsive to the light source heating a gas, wherein the detector comprises a piezoelectric layer split into two adjacent portions along the length of the single-prong suspended beam supported by a ground electrode, and further comprises a pair of electrodes extending along the lengths of and coupled to respective adjacent portions of the piezoelectric layer, wherein one electrode is positioned to collect positive electrical charges from one portion of the piezoelectric layer and the other electrode is positioned to collect negative electrical charges from the other portion of the piezoelectric layer, such that the adjacent portions along the length of the single-prong suspended beam prevent charge compensation.
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Abstract
A device includes a resonator having an oscillating portion with dimensions chosen to lead to a desired resonant frequency. A light source is positioned to provide light along the length of the oscillating portion at a specific wave length. A detector detects a change in oscillation of the resonator responsive to the wave pressure produced by the light source heating a gas. The light source is modulated with a frequency the same as the resonant frequency of the resonator.
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Citations
14 Claims
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1. A device comprising:
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a resonator having an oscillating portion formed as a single-prong suspended beam having a supported end; a light source to provide light along a length of the oscillating portion, the light being directed toward the supported end; and a detector to detect a change in oscillation of the resonator responsive to the light source heating a gas, wherein the detector comprises a piezoelectric layer split into two adjacent portions along the length of the single-prong suspended beam supported by a ground electrode, and further comprises a pair of electrodes extending along the lengths of and coupled to respective adjacent portions of the piezoelectric layer, wherein one electrode is positioned to collect positive electrical charges from one portion of the piezoelectric layer and the other electrode is positioned to collect negative electrical charges from the other portion of the piezoelectric layer, such that the adjacent portions along the length of the single-prong suspended beam prevent charge compensation. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method comprising:
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providing light adjacent to a length of a micro electromechanical systems (MEMS) cantilever single-prong suspended beam resonant oscillator, the light being provided along the single-prong suspended beam toward a supported end of the beam; exposing a gas to be detected to the light to create a pressure wave; and detecting oscillation of the single-prong suspended beam resonant oscillator responsive to the pressure wave via a detector having a piezoelectric layer split into two adjacent portions supported by a ground electrode, along the length of the single-prong suspended beam resonant oscillator and further comprising a pair of electrodes extending along the lengths of and coupled to respective adjacent portions of the piezoelectric layer, wherein one electrode is positioned to collect positive electrical charges from one portion of the piezoelectric layer and the other electrode is positioned to collect negative electrical charges from the other portion of the piezoelectric layer, such that the adjacent portions along the length of the single-prong suspended beam resonant oscillator prevent charge compensation. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. A sensor comprising:
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a device wafer formed of silicon; a microelectricalmechanical single crystal cantilevered single-prong beam resonator released from the silicon on insulator device wafer and having a single-prong beam oscillating portion with dimensions chosen to lead to a desired resonant frequency; an optical fiber light source to provide light along the length of the oscillating single-prong beam portion in a cavity formed in the device wafer, the light having a frequency tuned to a resonant frequency of the resonator and to an absorption line of a gas to be detected, and wherein the light is directed toward a supported portion of the cantilevered single-prong beam; a handle wafer supporting the device wafer and the optical fiber light source; and a transducer to detect a change in oscillation of the single-prong beam resonator responsive to the light source heating the gas, wherein the transducer comprises a piezoelectric layer split into two adjacent portions supported by a ground electrode, along the length of the single-prong beam resonator and further comprising a pair of electrodes extending along the lengths of and coupled to respective adjacent portions of the piezoelectric layer, wherein one electrode is positioned to collect positive electrical charges from one portion of the piezoelectric layer and the other electrode is positioned to collect negative electrical charges from the other portion of the piezoelectric layer, such that the adjacent portions along the length of the single-prong beam of the resonator prevent charge compensation.
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Specification