Micromachined ultrasonic transducers
First Claim
1. A capacitive micromachined ultrasonic transducer (CMUT) comprising:
- a substrate;
a first electrode coupled to the substrate;
a movable second electrode spaced apart from the first electrode; and
a structured membrane coupled to the movable second electrode, the structured membrane having a base portion and a structured portion, the base portion comprising a flat member, the structured portion including a feature formed across at least part of the base portion so that a ratio of a spring constant of the structured membrane over a mass of the structured membrane is greater than a ratio of a spring constant of the base portion over a mass of the base portion.
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Accused Products
Abstract
A capacitive micromachined ultrasonic transducer (CMUT) includes a structured membrane which possesses improved frequency response characteristics. Some embodiments provide CMUTs which include a substrate, a first electrode, a second movable electrode, and a structured membrane. The movable second electrode is spaced apart from the first electrode and is coupled to the structured membrane. The structured membrane is shaped to possess a selected resonant frequency or an optimized frequency response. The structured membrane can include a plate and a beam coupled to the plate such that the resonant frequency of the structured membrane is greater than the resonant frequency of the plate. Furthermore, the ratio of the resonant frequency of the structured membrane over the mass of the structured membrane can be greater than the ratio of the resonant frequency of the plate over the mass of the plate. In some embodiments, the CMUT is an embedded spring ESCMUT.
67 Citations
28 Claims
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1. A capacitive micromachined ultrasonic transducer (CMUT) comprising:
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a substrate; a first electrode coupled to the substrate; a movable second electrode spaced apart from the first electrode; and a structured membrane coupled to the movable second electrode, the structured membrane having a base portion and a structured portion, the base portion comprising a flat member, the structured portion including a feature formed across at least part of the base portion so that a ratio of a spring constant of the structured membrane over a mass of the structured membrane is greater than a ratio of a spring constant of the base portion over a mass of the base portion. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A capacitive micromachined ultrasonic transducer (CMUT) comprising:
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a substrate; a first electrode coupled to the substrate; a movable second electrode spaced apart from the first electrode; and a structured membrane coupled to the movable second electrode, the structured membrane including a plate and a first beam coupled to the plate and being shaped to result in an effective ratio of a resonant frequency of the structured membrane over a mass of the structured membrane greater than a ratio of a resonant frequency of the plate over a mass of the plate. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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20. A capacitive micromachined ultrasonic transducer (CMUT) comprising:
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a substrate; a first electrode coupled to the substrate; a movable second electrode spaced apart from the first electrode; and a structured membrane coupled to the movable second electrode and including; a plate, a first beam coupled to the plate and defining a void, and a second beam coupled to the plate and intersecting with the first beam, the structured membrane being shaped to result in an effective ratio of a resonant frequency of the structured membrane over a mass of the structured membrane greater than a ratio of a resonant frequency of the plate over a mass of the plate.
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21. An embedded spring CMUT (ESCMUT) comprising:
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a substrate; a first electrode coupled to the substrate; a spring plate coupled to and spaced apart from the first electrode; a movable second electrode coupled to the spring plate; and a structured surface plate coupled to the second electrode and having a base portion and a structured portion, the base portion comprising a flat member, the structured portion including a feature formed across at least part of the base portion so that an effective ratio of a resonant frequency of the structured surface plate over a mass of the structured surface plate is greater than a ratio of a resonant frequency of the base portion over a mass of the base portion. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28)
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Specification