Pressure-balanced telemetric pressure sensing system and method therefore
First Claim
1. A differential pressure sensor adapted for implantation beneath the skin in the living body and for in vivo calibration after implantation, said sensor comprising:
- a. a housing having means defining an opening, extending therethrough;
b. a first flexible diaphragm extending across the housing opening and being secured with respect to said housing, at least a portion of said first flexible diaphragm defining a portion of the exterior surface of said sensor and being positioned so that after implantation beneath the skin said portion of said first flexible diaphragm is in mechanical pressure communication with the skin and whereby pressurs external to the body can be communicated mechanically across the intact skin to said first flexible diaphragm;
c. a second flexible diaphragm extending across the housing opening and being secured with respect to said housing, said diaphragms and opening defining means defining a chamber within said sensor and the side of said second flexible diaphragm that is external to said chamber being positioned to be in contact with and in mechanical pressure communication with a bodily medium, the pressure of which is to be sensed when said sensor is implanted in the living body;
d. solid coupling means located within said chamber and secured to both of said flexible diaphragms for coupling the motion of one of said flexible diaphragms to the other of said flexible diaphragms so that, when said sensor is implanted in the living body, changes in the difference in pressures in said bodily medium and on said exterior portion of said first flexible diaphragm will cause motion of said flexible diaphragms and said solid coupling means;
e. contact means connected to said housing for contacting (i) at least one of said diaphragms or (ii) said solid coupling means thereby defining a mechanical contact reference position with respect to said housing of (i) at least one of said diaphragms or (ii) of said solid coupling means for a predetermined pressure relationship between said pressure in communication with said two flexible diaphragms when said sensor is implanted in the living body; and
,f. means having a preselected, detectable parameter that is detectable by detection means located outside the living body, said means having a preselected, detectable parameter being at least in part cooperatively connected to and movable with at least one of said flexible diaphragms or said solid coupling means so that said preselected detectable parameter will change with movement of displacement of (i) at least one of said flexible diaphragms or (ii) of said solid coupling means and the value of said preselected, detectable parameter can be detected at said mechanical contact reference position, said at least one flexible diaphragm or said solid coupling means and said means having a preselected detectable parameter being so constructed and cooperatively connected that the value of said preselected detectable parameter changes upon a change from said predetermined pressure relationship;
whereby, when said sensor is implanted beneath the skin, (i) at least one of said flexible diaphragms or (ii) said solid coupling means can be driven to said mechanical contact reference position by a pressure external to the living body applied to the skin adjacent to said sensor, and said preselected detectable parameter can be determined at said mechanical contact reference position after implantation, and whereby the magnitude of the external pressure applied to the skin that is required to drive (i) at least one of said flexible diaphragms or (ii) said solid coupling means to said mechanical contact reference position is a function of the pressure in said bodily medium.
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Accused Products
Abstract
A differential pressure sensing device is fully implanted in the body of a patient to monitor internal pressure such as intracranial pressure. A movable element in the sensor communicates on one side with the internal pressure to be measured and on the other side with an external pressure which is applied by an external pressurizer-control system and which is communicated to the sensor through the intact skin. An imbalance of the two opposing pressures causes a displacement of the movable element which changes a physical characteristic of the sensor, such as the resonant frequency of a tuned L-C circuit. This change is detected outside the body by an external detection system, such as a frequency swept radio frequency oscillator. The external pressure is varied until the external detector senses that the pressures are balanced on the movable element, at which point the external pressure equals the internal pressure, and the former is measured and read out.
221 Citations
110 Claims
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1. A differential pressure sensor adapted for implantation beneath the skin in the living body and for in vivo calibration after implantation, said sensor comprising:
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a. a housing having means defining an opening, extending therethrough; b. a first flexible diaphragm extending across the housing opening and being secured with respect to said housing, at least a portion of said first flexible diaphragm defining a portion of the exterior surface of said sensor and being positioned so that after implantation beneath the skin said portion of said first flexible diaphragm is in mechanical pressure communication with the skin and whereby pressurs external to the body can be communicated mechanically across the intact skin to said first flexible diaphragm; c. a second flexible diaphragm extending across the housing opening and being secured with respect to said housing, said diaphragms and opening defining means defining a chamber within said sensor and the side of said second flexible diaphragm that is external to said chamber being positioned to be in contact with and in mechanical pressure communication with a bodily medium, the pressure of which is to be sensed when said sensor is implanted in the living body; d. solid coupling means located within said chamber and secured to both of said flexible diaphragms for coupling the motion of one of said flexible diaphragms to the other of said flexible diaphragms so that, when said sensor is implanted in the living body, changes in the difference in pressures in said bodily medium and on said exterior portion of said first flexible diaphragm will cause motion of said flexible diaphragms and said solid coupling means; e. contact means connected to said housing for contacting (i) at least one of said diaphragms or (ii) said solid coupling means thereby defining a mechanical contact reference position with respect to said housing of (i) at least one of said diaphragms or (ii) of said solid coupling means for a predetermined pressure relationship between said pressure in communication with said two flexible diaphragms when said sensor is implanted in the living body; and
,f. means having a preselected, detectable parameter that is detectable by detection means located outside the living body, said means having a preselected, detectable parameter being at least in part cooperatively connected to and movable with at least one of said flexible diaphragms or said solid coupling means so that said preselected detectable parameter will change with movement of displacement of (i) at least one of said flexible diaphragms or (ii) of said solid coupling means and the value of said preselected, detectable parameter can be detected at said mechanical contact reference position, said at least one flexible diaphragm or said solid coupling means and said means having a preselected detectable parameter being so constructed and cooperatively connected that the value of said preselected detectable parameter changes upon a change from said predetermined pressure relationship;
whereby, when said sensor is implanted beneath the skin, (i) at least one of said flexible diaphragms or (ii) said solid coupling means can be driven to said mechanical contact reference position by a pressure external to the living body applied to the skin adjacent to said sensor, and said preselected detectable parameter can be determined at said mechanical contact reference position after implantation, and whereby the magnitude of the external pressure applied to the skin that is required to drive (i) at least one of said flexible diaphragms or (ii) said solid coupling means to said mechanical contact reference position is a function of the pressure in said bodily medium. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An in vivo pressure detecting system comprising:
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a. a differential pressure sensor adapted for implantation in a living body, said sensor comprising; (1) a housing having means defining an opening extending therethrough; (2) flexible diaphragm means extending across said housing opening and being fluid pressure sealed with respect to said housing, said flexible diaphragm means communicating with pressures in two separate regions external to the sensor that are separated by the flexible diaphragm means with the pressure in one of the regions being an internal bodily pressure when the sensor is implanted in a living body; (3) contact means connected to said housing for contacting said flexible diaphragm means thereby defining a mechanical contact reference position of said flexible diaphragm means with respect to said housing for a predetermined pressure relationship in said regions when said sensor is implanted in the living body; and
,(4) means having a preselected, detectable parameter that is detectable by detection means located outside the living body, said means having a preselected, detectable parameter being at least in part cooperatively connected to and movable with said flexible diaphragm means so that said preselected detectable parameter will change with movement of said flexible diaphragm means and the value of said preselected detectable parameter can be detected at said mechanical contact reference position, said flexible diaphragm means and said means having a preselected, detectable parameter being so constructed and cooperatively connected that the value of said preselected detectable parameter changes upon a change from said predetermined pressure relationship;
whereby, when said sensor is implanted beneath the skin and flexible diaphragm means can be driven to said mechanical contact reference position by a pressure external to the living body applied to the skin adjacent to said sensor and said preselected detectable parameter can be determined at said mechanical contact reference position after implantation, and whereby the magnitude of the external pressure applied to the skin that is required to drive said flexible diaphragm means to said mechanical contact reference position is a function of the internal bodily pressure;b. a controllable pressure source means external to the living body for establishing said predetermined pressure relationship and for applying and measuring the external pressure applied to the skin and, c. means for detecting said sensor parameter and the value of the parameter at the reference position and any variation therefrom when said sensor is implated in a living being, said detecting means being located externally of the living body and without any connection to said sensor which requires a break in the skin of the living body. - View Dependent Claims (16, 17, 18, 19)
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20. An in vivo pressure detecting system comprising:
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a. a differential pressure sensor adapted for implantation in a living body and in in vivo calibration after implantation, said sensor comprising; (1) a housing having means defining an opening extending therethrough; (2) a first flexible diaphragm extending across said housing opening and being secured with respect to said housing, at least a portion of said first flexible diaphragm defining a portion of the exterior surface of said sensor and being positioned so that after implantation beneath the skin said portion of said first flexible diaphragm is in mechanical pressure communication with the skin and whereby pressures external to the body can be communicated mechanically across the intact skin to said first flexible diaphragm; (3) a second flexible diaphragm extending across the housing opening and being securd with respect to said housing, said flexible diaphragms and opening defining means defining a chamber within said sensor and the side of said second flexible diaphragm that is external to said chamber being positioned to be in contact with and in mechanical pressure communication with a bodily medium, the pressure of which is to be sensed when the sensor is implanted in a living body; (4) solid coupling means located within said chamber and secured to both of said flexible diaphragms for coupling the motion of one of said flexible diaphragms to the other of said flexible diaphragms so that when said sensor is implanted in the living body, changes in the difference in pressures in said bodily medium and on said exterior portion of said first flexible diaphragm will cause motion of said flexible diaphragms and said solid coupling means; (5) contact means connected to said housing for contacting (i) at least one of said diaphragms or (ii) said solid coupling means thereby defining a mechanical contact reference position with respect to said housing of (i) at least one of said diaphragms or (ii) of said solid coupling means for a predetermined pressure relationship between said pressures in communication with said two flexible diaphragms when said sensor is implanted in the living body; (6) means having a preselected, detectable parameter that is detectable by detecting means located outside the living body, said means having a preselected, detectable parameter being at least in part cooperatively connected to and movable with at least one of said flexible diaphragms or said solid coupling means so that said preselected detectable parameter will change with movement of (i) at least one of said diaphragms or (ii) of said solid coupling means and the value of said preselected, detectable parameter can be detected at said mechanical contact reference position, said at least one flexible diaphragm or said solid coupling means and said means having a preselected, detectable parameter being so constructed and cooperatively connected that the value of said preselected, detectable parameter changes upon a change from said predetermined pressure relationship;
whereby said sensor is implanted beneath the skin, (i) at least one of said flexible diaphragms or (ii) said incompressible means sensor can be driven to said mechanical contact reference position by a pressure external to the living body applied to the skin adjacent to said sensor, and said preselected detectable parameter can be determined at said mechanical contact reference position after implantation, and whereby the magnitude of the external pressure applied to the skin that is required to drive (i) at least one of said flexible diaphragms or (ii) said solid means sensor to said mechanical cntact reference position is a function of the pressure in said bodily medium;b. controllable pressure source means external to the living body adapted to apply and measure an external pressure to the intact skin adjacent to said sensor, and thereby transmitting said external pressure to said first flexible diaphragm for establishing said predetermined pressure relationship; and
,c. means for detecting said preselected, detectable parameter and the value of the parameter at said mechanical contact reference position and any variation therefrom when said sensor is implanted in a living body, said detecting means being located externally of the living body and without any connection to said sensor which requires a break in the skin of the living body. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
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41. An in vivo pressure detecting system comprising:
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a. a balanced differential pressure sensor adapted for implantation in a living body, said sensor comprising; (1) a housing having means defining an opening extending therethrough; (2) a flexible diaphragm extending across said housing opening and being fluid pressure sealed with respect to said housing, said diaphragm communicating with pressures in two separate regions external to the sensor that are separated by the flexible diaphragm with one side of the diaphragm communicating with a pressure source and the other side of the diaphragm communicating with an internal bodily pressure when the sensor is implanted in a living body; (3) means for defining a reference position of said diaphragm with respect to said housing for a predetermined pressure relationship between the pressure of the pressure source and the internal bodily pressure; (4) means having a preselected, detectable variable parameter that changes with displacement of said diaphragm means from the reference position upon a change from said predetermined pressure relationship; b. pressure source means external to the living body for establishing said predetermined pressure relationship; and
,c. means for detecting said sensor parameter and the value of the parameter at the reference position and any variation therefrom when said sensor is implanted in a living being, said detecting means being located externally of the living body and without any connection to said sensor which requires a break in the skin of the living body. - View Dependent Claims (42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54)
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55. An in vivo differential pressure sensor adapted for implantation beneath the skin in the living body and for in vivo calibration after implantation, said sensor comprising:
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a. a housing having means defining an opening therethrough; b. a first flexible diaphragm having an interior side and an exterior side, said first flexible diaphragm extending across the housing opening at substantially one end thereof and being secured to said housing, at least a portion of said exterior side of said flexible diaphragm defining a portion of the exterior surface of said sensor and being positioned so that after said sensor is implanted beneath the skin said portion of said exterior side of said first flexible diaphragm is in mechanical pressure communication with the skin whereby pressures external to the living body can be communicated mechanically across the intact skin to said first flexible diaphragm; c. a second flexible diaphragm having an interior side and an exterior side, said second flexible diaphragm extending across said housing opening at substantially the other end thereof and being secured to said housing, said first and second flexible diaphragm interior sides and said housing opening defining a chamber within said sensor and, when said sensor is implanted in a living body, said exterior side of said second flexible diaphragm being positioned to be in contact with and in mechanical pressure communication with a bodily medium, the pressure of which is to be sensed; d. solid coupling means located within said chamber and secured to both of said flexible diaphragms for coupling the motion of one of said flexible diaphragms to the other of said flexible diaphragms, the motion of said flexible diaphragms being in response to changes in the difference in pressures on said exterior sides of said two flexible diaphragms; e. contact means connected to said housing for contacting (i) at least one of said diaphragms or (ii) said solid coupling means thereby defining a mechanical contact reference position within said sensor and with respect to said housing of (i) at least one of said flexible diaphragms or (ii) said solid coupling means, said reference position corresponding to a predetermined pressure relationship between said pressure on the exterior side of the first flexible diaphragm and the pressure on the exterior side of the second flexible diaphragm; and
,f. means having a preselected, detectable parameter that is detectable by detection means located outside the living body, said means having a preselected, detectable parameter being at least in part cooperatively connected to and movable with at least one of said flexible diaphragms or said solid coupling means so that said preselected, detectable parameter will change with movement of (i) at least a portion of one of said flexible diaphragms or (ii) said solid coupling means and the value of said preselected, detectable parameter can be detected at said mechanical contact reference position, said at least one flexible diaphragm or said solid coupling means and said means having a preselected, detectable parameter being so constructed and cooperatively connected that the value of said preselected detectable parameter changes upon a change from said predetermined pressure relationship;
whereby said sensor is implanted beneath the skin, (i) at least one of said flexible diaphragms or (ii) said solid coupling means can be driven to said mechanical contact reference position to said mechanical contact reference position by a pressure external to the living body applied to the skin adjacent to said sensor, and said preselected detectable parameter can be determined at said mechanical contact reference position after implantation, and whereby the magnitude of the external pressure applied to the skin that is required to drive (i) at least one of said flexible diaphragms or (ii) said solid coupling means to said mechanical contact reference position is a function of the pressure in said bodily medium. - View Dependent Claims (56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78)
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79. An in vivo differential pressure sensor adapted for implantation beneath the skin in the living body and for in vivo calibration after implantation, said sensor comprising:
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a. a housing having means defining an opening therethrough; b. first flexible diaphragm having an interior side and an exterior side, said first flexible diaphragm extending across the housing opening at one end thereof and being secured to said housing, at least a portion of said exterior side of first flexible diaphragm defining a portion of the exterior surface of said sensor and being positioned so that after said sensor is implanted beneath the skin said portion of said exterior side of said first flexible diaphragm is in mechanical pressure communication with the skin, whereby pressures external to the living body can be communicated mechanically across the intact skin to said first flexible diaphragm; c. a second flexible diaphragm having an interior side and an exterior side, said second flexible diaphragm extending across said housing opening at the other end thereof and being secured to said housing, said first and second flexible diaphragm interior sides together with said housing opening defining a chamber within said sensor and, when said sensor is implanted in a living body, said exterior side of said second flexible diaphragm being positioned to be in contact with and in mechanical pressure communication with a bodily medium, the pressure of which is to be sensed; d. a rigid piston located within said chamber, the rigid piston extending between and being secured to the interior sides of said flexible diaphragms, so that changes in said pressures on said exterior sides of said flexible diaphragms will cause a motion of said flexible diaphragms and said rigid piston, said piston including a magnetic material portion; e. parallel resonant circuit means comprising an inductor and a capacitor that are mounted within said housing so that the inductance of said inductor and thus the resonant frequency of said parallel resonant circuit means is varied in accordance with the position of the magnetic material portion relative to the inductor, the resonant frequency of said parallel resonant circuit means being detectable by detection apparatus located external to the living body, whereby said resonant frequency changes in accordance with changes in said pressures on said exterior sides of said flexible diaphragms; and
,f. a mechanical stop for said piston against said housing when the pressures on said exterior sides of said flexible diaphragms are equal;
whereby, when said sensor is implanted beneath the skin, said rigid piston can be driven to said mechanical stop by a pressure external to the living body applied to the skin adjacent to said sensor, and said resonant frequency can be detected at the position of said rigid piston at said mechanical stop after said sensor has been implanted in the living body, and whereby the value of the external pressure applied to the skin required to drive said rigid piston to said mechanical stop, as indicated by said resonant freqency, is equal to the pressure in said bodily medium. - View Dependent Claims (80, 81, 82)
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83. An in vivo differential pressure sensor adapted for implantation beneath the skin in the living body and for in vivo calibration after implantation, said sensor comprising:
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a. a housing having means defining an opening therethrough; b. a first flexible diaphragm having an interior side and an exterior side, said first flexible diaphragm extending across the housing opening at one end thereof and being secured to said housing, at least a portion of said exterior side of said first flexible diaphragm defining a portion of the exterior surface of said sensor and being positioned so that after said sensor is implanted beneath the skin said portion of said exterior side of said first flexible diaphragm is in mechanical pressure communication with the skin, whereby pressures external to the living body can be communicated mechanically across the intact skin to said first flexible diaphragm; c. a second flexible diaphragm having an interior side and an exterior side, said second flexible diaphragm extending across said housing opening at the other end thereof and being secured to said housing, said first and second flexible diaphragm interior sides together with said housing opening defining a chamber within said sensor and, when said sensor is implanted in a living body, said exterior side of said second flexible diaphragm being positioned to be in contact with and in mechanical pressure communication with a bodily medium, the pressure of which is to be sensed; d. a rigid piston located within said chamber, the rigid piston extending between and being secured to the interior sides of said flexible diaphragms, so that changes in said pressures on said exterior sides of said flexible diaphragms will cause a motion of said flexible diaphragms and said rigid piston, said piston including an electrically conductive portion; e. parallel resonant circuit means comprising an inductor and a capacitor that are mounted within said housing so that the inductance of said inductor and thus the resonant frequency of said parallel resonant circuit means is varied in accordance with the position of the electrically conductive portion of said rigid piston relative to the inductor, the resonant frequency of said parallel resonant circuit means being detectable by detection apparatus located external to the living body, whereby said resonant frequency changes in accordance with changes in said pressures on said exterior sides of said flexible diaphragms; and
,f. a mechanical stop for said piston against said housing when the pressures on said exterior sides of said flexible diaphragms are equal;
whereby, when said sensor is implanted beneath the skin, said rigid piston can be driven to said mechanical stop by a pressure external to the living body applied to the skin adjacent to said sensor, and said resonant frequency can be detected at the position of said rigid piston at said mechanical stop after said sensor has been implanted in the living body, and whereby the value of the external pressure applied to the skin required to drive said rigid piston to said mechanical stop, as indicated by said resonant frequency, is equal to the pressure in said bodily medium. - View Dependent Claims (84, 85, 86)
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87. An in vivo differential pressure sensor adapted for implantation beneath the skin in the living body and for in vivo calibration after implantation, said sensor comprising:
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a. a housing having means defining an opening therethrough; b. a first flexible diaphragm having an interior side and an exterior side, said first flexible diaphragm means extending across said opening at one end thereof and being secured to said housing, at least a portion of said exterior side of said first flexible diaphragm defining a portion of the exterior surface of said sensor and being positioned so that after said sensor is implanted beneath the skin said portion of said exterior side of said first flexible diaphragm is in mechanical pressure communication with the skin, whereby pressures external to the body can be communicated mechanically across the intact skin to said first flexible diaphragm; c. a second flexible diaphragm having an interior side and an exterior side, said second flexible diaphragm extending across said opening and being secured to said housing, said first and second flexible diaphragms interior sides and a portion of said housing defining a chamber within said sensor, and said sensor being so adapted that, when said sensor is implanted in a living body, said exterior side of said second flexible diaphragm can be placed in mechanical pressure communication with a bodily medium, the pressure of which is to be sensed; d. rigid means located within said chamber and secured to both of said flexible diaphragms for coupling the motion of one of said flexible diaphragms to the other of said flexible diaphragms, the motion of said flexible diaphragms being in response to changes in the difference in said pressures on said exterior sides of said flexible diaphragms; e. contact means connected to said housing for contacting (i) at least one of said diaphragms or (ii) said rigid coupling means thereby defining a mechanical contact reference position within said sensor and with respect to said housing of (i) at least one of said flexible diaphragms or (ii) said rigid coupling means, said mechanical contact reference position corresponding to a predetermined pressure relationship between said pressures on said exterior sides of said flexible diaphragms; and
,f. means having a preselected, detectable parameter that is detectable by detection means located outside the living body, said means having a preselected, detectable parameter being at least in part cooperatively connected to and movable with at least one of said flexible diaphragms or said rigid means so that said preselected, detectable, parameter will change with movement of (i) at least a portion of one of said flexible diaphragms or (ii) said rigid coupling means and the value of said preselected, detectable parameter can be detected at said mechanical contact reference position, said at least one flexible diaphragms or said rigid coupling means and said means having a preselected, detectable parameter being so constructed and cooperatively connected that the value of said preselected, detectable parameter changes upon a change from said predetermined pressure relationship;
whereby, when said sensor is implanted beneath the skin, said sensor can be driven to said mechanical contact reference position by a pressure external to the living body applied to the skin adjacent to said sensor, and said preselected, detectable parameter can be determined at said mechanical contact reference position after implantation, and whereby the magnitude of the external pressure applied to the skin that is required to drive said sensor to said mechanical contact reference position is a function of the pressure in said bodily medium. - View Dependent Claims (88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110)
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Specification