High resolution solid state pressure sensor
First Claim
Patent Images
1. A pressure sensing catheter comprising:
- a plurality of pressure sensors, each comprising;
a rigid inner tubular member having an electrically conductive layer defining an inner tubular electrode, the rigid inner tubular member further comprising a first annular raised structure and a second annular raised structure; and
a deformable, outer tubular membrane comprising an electrically conductive layer formed on a dielectric polymer and defining an outer tubular electrode, the outer tubular electrode being attached to the first annular raised structure and the second annular raised structure such that the outer tubular electrode is spaced from the inner tubular electrode by an annular gap, said pressure sensors being disposed along the catheter, wherein each pressure sensor is configured to produce an electrical signal varying in response to the capacitance between the outer tubular electrode and the inner tubular electrode such that the electrical signal is representative of a circumferential pressure that is radially acting and distributed along a circumference of the sensor applied to the catheter tube at a location along the catheter;
flexible material between pressure sensors of the plurality of pressure sensors; and
a signal bus extending through the inner tubular member of each of the plurality of sensors and electrically connected to the electrically conductive layer of each outer tubular membrane and the inner tubular electrode of each pressure sensor, said signal bus extending to terminal connectors at a terminal end of said catheter, said terminal connectors configured to allow access to signals from said pressure sensors whereby a change in capacitance between the inner tubular electrode and the outer tubular electrode may be sensed.
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Abstract
A pressure sensor and pressure-sensing catheter in which a deformable pressure sensing membrane is separated from an inner metalized surface on a rigid support by an air gap. An input allows a voltage to be applied to an electrode on the sensing membrane and an output allows reading of the signal modulation from the support surface. An outer sleeve overlays the membrane and a wire bus transmits the signals to a terminal connector. The catheter may include a vented air gap, a multiplexing wire bus, and an internal cable to maintain tension.
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Citations
37 Claims
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1. A pressure sensing catheter comprising:
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a plurality of pressure sensors, each comprising; a rigid inner tubular member having an electrically conductive layer defining an inner tubular electrode, the rigid inner tubular member further comprising a first annular raised structure and a second annular raised structure; and a deformable, outer tubular membrane comprising an electrically conductive layer formed on a dielectric polymer and defining an outer tubular electrode, the outer tubular electrode being attached to the first annular raised structure and the second annular raised structure such that the outer tubular electrode is spaced from the inner tubular electrode by an annular gap, said pressure sensors being disposed along the catheter, wherein each pressure sensor is configured to produce an electrical signal varying in response to the capacitance between the outer tubular electrode and the inner tubular electrode such that the electrical signal is representative of a circumferential pressure that is radially acting and distributed along a circumference of the sensor applied to the catheter tube at a location along the catheter; flexible material between pressure sensors of the plurality of pressure sensors; and a signal bus extending through the inner tubular member of each of the plurality of sensors and electrically connected to the electrically conductive layer of each outer tubular membrane and the inner tubular electrode of each pressure sensor, said signal bus extending to terminal connectors at a terminal end of said catheter, said terminal connectors configured to allow access to signals from said pressure sensors whereby a change in capacitance between the inner tubular electrode and the outer tubular electrode may be sensed. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. A method of manufacturing a tubular capacitive pressure sensor, the pressure sensor comprising:
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a pair of spaced apart, co-axially aligned surfaces comprising an outer deformable, electrically conductive membrane having a tubular structure around an inner axially aligned non-deformable support structure having an electrically conductive surface separated from the deformable membrane by a gap having a characteristic gap dimension; and electrical signal leads positioned proximate to said membrane surface, making separate contact with the deformable conductive membrane surface and the non-deformable conductive surface, adapted for coupling to a signal source having a frequency to measure capacitive impedance across the electrical signal leads, wherein the capacitive impedance varies as circumferential pressure that is radially acting and distributed along a circumference of the sensor changes the dimension of the gap, and the method comprising; rolling the deformable, electrically conductive membrane into the tubular structure; and attaching the deformable, electrically conductive membrane around the circumference of the tubular structure at a first location and a second location, with the electrically conductive membrane separated from the tubular structure between the first location and the second location to form the gap. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34)
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35. A method of operating a capacitive pressure sensor,
the capacitive pressure sensor comprising: -
a cylindrical outer sensing membrane comprising a flexible dielectric member with a metallic coating on an inner surface forming a first electrode, said sensing membrane having a plurality of slits through the flexible dielectric member and the metallic coating defining a plurality of elongated conductive regions in a first portion of the metallic coating, each elongated conductive region being disposed between adjacent slits of the plurality of slits, the metallic coating having a second portion interconnecting elongated conductive regions of the plurality of elongated conductive regions; a cylindrical inner rigid structure having at least two spacer elements creating an inner air gap between said outer sensing membrane and an underlying metallic layer on said inner rigid structure, said underlying metallic layer forming a second electrode; a first conductive trace, the first conductive trace coupling the first electrode to a first contact terminal; and a second conductive trace, the second conductive trace allowing connection to the second electrode; and the method comprising; providing a voltage between the first electrode and the second electrode; exposing the sensor to a circumferential pressure that is radially acting and distributed along a circumference of the sensor from outside of the cylindrical outer sensing membrane; deforming, under the circumferential pressure, the flexible dielectric member towards the cylindrical inner structure; and sensing a change in capacitance between the plurality of elongated conductive regions defined by the plurality of slits in the metallic coating of the first electrode and the second electrode to measure the circumferential pressure. - View Dependent Claims (36, 37)
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Specification