Micromachined capacitive RF pressure sensor
First Claim
1. A micromachined capacitive pressure sensor including:
- a plurality of sealed micromachined capacitive cells of type 1, each cell including a rectangular membrane supported above a common conductive electrode by an insulating support and each membrane supporting a conductive electrode for movement therewith whereby each electrode forms with the common conductive electrode a capacitor whose capacitance varies with movement of the membrane relative to the common electrode;
a cavity region formed by the said membrane and the said conductive electrode; and
conductive lines interconnecting conductive electrodes of adjacent cells of type 1;
a plurality of micromachined capacitive cells of type 2, each cell including a rectangular film stack on a common conductive electrode by an insulating support and each stack supporting a conductive electrode therewith whereby each electrode forms with the common conductive electrode a capacitor whose capacitance does not vary with movement of the film stack; and
conductive lines interconnecting conductive electrodes of adjacent cells of type 2.
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Accused Products
Abstract
A Capacitive Micromachined Ultrasonic RF (CMURF) pressure sensor is described. This micromachined pressure sensor has: pressure sensitive capacitance elements including a scalable array of micromachined cells of the type including electrodes carried by a sealed membrane supported above a common electrode with conductive lines interconnecting the electrodes having an electrostatic capacitance ΔCm changing with a pressure to be detected; reference capacitance elements including a scalable array of micromachined cells of the type including electrodes carried by a stacked of membranes supported above a common electrode with conductive lines interconnecting the electrodes having an electrostatic capacitance Cm not changing with the pressure. A method of operating a pressure sensor array is also described.
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Citations
9 Claims
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1. A micromachined capacitive pressure sensor including:
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a plurality of sealed micromachined capacitive cells of type 1, each cell including a rectangular membrane supported above a common conductive electrode by an insulating support and each membrane supporting a conductive electrode for movement therewith whereby each electrode forms with the common conductive electrode a capacitor whose capacitance varies with movement of the membrane relative to the common electrode;
a cavity region formed by the said membrane and the said conductive electrode; and
conductive lines interconnecting conductive electrodes of adjacent cells of type 1;
a plurality of micromachined capacitive cells of type 2, each cell including a rectangular film stack on a common conductive electrode by an insulating support and each stack supporting a conductive electrode therewith whereby each electrode forms with the common conductive electrode a capacitor whose capacitance does not vary with movement of the film stack; and
conductive lines interconnecting conductive electrodes of adjacent cells of type 2. - View Dependent Claims (2)
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3. The method of operating a micromachined capacitive pressure sensor of the type that includes:
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a plurality of micromachined capacitive cells of type 1 arranged in a two-dimensional matrix over a broad frequency band, said cells each comprising a membrane supported by an insulating support above a common conductive electrode with a conductive electrode on each of said membranes to form with said spaced common electrode a capacitor;
a plurality of micromachined capacitive cells of type 2 arranged in a two-dimensional matrix over a broad frequency band, said cells formed with film stacks on a common conductive electrode by an insulating support and each stack supporting a conductive electrode therewith whereby each electrode forms with the common conductive electrode a capacitor;
said method comprising connecting said cells of type 1 and type 2 in series with conductive connecting lines whereby said connecting lines and said capacitors form a high frequency transmission line whose length varies with changes in the capacitance of said cells type 1 and type 2 and inductance of said lines, applying a high frequency RF voltage to said high frequency transmission lines, and determining the change in electrical length of the lines responsive to a received pressure signal to provide an output signal representative of the pressure signal.
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4. A micromachined capacitive pressure sensor including:
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a plurality of micromachined capacitive pressure sensor cells of type 1 arranged in a two-dimensional matrix, each cell including a membrane supported above a common conductive electrode by an insulating support and each membrane supporting a conductive electrode for movement therewith whereby each electrode forms with the common conductive electrode a capacitor whose capacitance varies with movement of the membrane relative to the common electrode, a plurality of micromachined capacitive cells of type 2 arranged in a two-dimensional matrix, each cell including a rectangular film stack on a common conductive electrode by an insulating support and each stack supporting a conductive electrode therewith whereby each electrode forms with the common conductive electrode a capacitor whose capacitance does not vary with movement of the film stack;
a conductive line interconnecting all conductive electrodes of cells of type 1 in said array in series, whereby the inductance of said conductive line and the capacitance of said capacitors form a high frequency transmission line whose electrical length changes in responsive to movement of said membrane. a conductive line interconnecting all conductive electrodes of cells of type 2 in said array in series, whereby the inductance of said conductive line and the capacitance of said capacitors form a high frequency transmission line whose electrical length does not change in responsive to movement of said film stack. a co-planar structure forming a high frequency transmission line interconnecting all conductive electrodes of cells of types 1 and 2 in said array in series. - View Dependent Claims (5, 6)
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7. The method of operating a micromachined capacitive pressure sensor of the type which includes a plurality of micromachined capacitive cells of type 1 and type 2 arranged in a two-dimensional matrix over a broad frequency band, said cells of type 1 each comprising a membrane supported by an insulating support above a common conductive electrode with a conductive electrode on each of said membranes to form with said spaced common electrode a capacitor, said cells of type 2 comprising a rectangular film stack supported by an insulating support on a common conductive electrode with a conductive electrode on each of said film stack to form with said spaced common electrode a capacitor,
said method comprising: -
connecting said cells of type 1 and type 2 in series with conductive connecting lines whereby said connecting lines and said capacitors form a high frequency transmission line whose length varies with changes in the capacitance of said cells of type 1 and type 2 and inductance of said lines, applying a high frequency RF voltage to said high frequency transmission lines, determining the change in electrical length of the line formed by said cells of type 1 in responsive to a received pressure signal to provide an output signal representative of the pressure signal, and means of connected to said transmission lines for determining the absolute pressure level.
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8. The method of operating a micromachined capacitive pressure sensor of the type which includes a plurality of micromachined capacitive cells of type 1 and type 2 arranged in a two-dimensional matrix over a broad frequency band, said cells of type 1 each comprising a membrane supported by an insulating support above a common conductive electrode with a conductive electrode on each of said membranes to form with said spaced common electrode a capacitor, said cells of type 2 comprising a rectangular film stack supported by an insulating support on a common conductive electrode with a conductive electrode on each of said film stack to form with said spaced common electrode a capacitor,
said method comprising: -
connecting said cells of type 1 in series with conductive connecting lines whereby said connecting lines and said capacitors form a high frequency transmission line whose length varies with changes in the capacitance of said cells of type 1 and inductance of said lines, connecting said cells of type 2 in series with conductive connecting lines whereby said connecting lines and said capacitors form a high frequency transmission line whose length varies with changes in the capacitance of said cells of type 2 and inductance of said lines, applying a high frequency RF voltage to said high frequency transmission lines, determining the change in electrical length of the lines formed by said cells of type 1 relative to the lines formed by said cells of type 2 in responsive to a received pressure signal to provide an output signal representative of the pressure signal, and means of connected to said transmission lines for determining the absolute pressure level. - View Dependent Claims (9)
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Specification