Telemetric differential 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 pressures 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 pressures on said two flexible diaphragms when said sensor is implanted in the living body; and
,f. means having a preselected, detectable, variable parameter that is detectable by detection means located outside the living body, said means having a preselected, detectable variable parameter being at least in part cooperatively connected to and movable with at (i) least one of said flexible diaphragms or (ii) said solid coupling means so that said preselected, detectable, variable parameter will change as a known function of the displacement from said mechanical contact reference position of (i) at least one of said diaphragms or (ii) of said solid coupling means, said displacement being a known function of the difference of the external pressures on said diaphragms;
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 thereby the value of said preselected, detectable, variable parameter at said mechanical contact reference position corresponding to said predetermined pressure relationship can be determined in vivo after implantation; and
whereby the difference in the value of said preselected, detectable, variable parameter from said value determined at said mechanical contact reference position is a measure 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 with the internal pressure of the body to be measured on one side and the atmospheric pressure on the other, the latter communicated through the intact skin and a nearly coplanar membrane. The movable element'"'"'s differential pressure dependent displacement changes a physical characteristic of the sensor, such as the resonant frequency of a tuned L-C circuit, and the change is detected external to the body by a radiating detector system, such as a frequency swept radio frequency oscillator, by which the internal pressure is read out.
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Citations
92 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 pressures 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 pressures on said two flexible diaphragms when said sensor is implanted in the living body; and
,f. means having a preselected, detectable, variable parameter that is detectable by detection means located outside the living body, said means having a preselected, detectable variable parameter being at least in part cooperatively connected to and movable with at (i) least one of said flexible diaphragms or (ii) said solid coupling means so that said preselected, detectable, variable parameter will change as a known function of the displacement from said mechanical contact reference position of (i) at least one of said diaphragms or (ii) of said solid coupling means, said displacement being a known function of the difference of the external pressures on said diaphragms;
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 thereby the value of said preselected, detectable, variable parameter at said mechanical contact reference position corresponding to said predetermined pressure relationship can be determined in vivo after implantation; and
whereby the difference in the value of said preselected, detectable, variable parameter from said value determined at said mechanical contact reference position is a measure of the pressure in said bodily medium. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 19, 22)
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18. An in vivo pressure detecting system comprising:
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a. a differential pressure sensor adapted for implantation in a living body and for 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, said first flexible diaphragm being in pressure communication with and mechanical contact with a first bodily medium when said sensor is implanted; (3) a second flexible diaphragm extending across the housing opening and being secured 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 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, changes in the pressure in said two bodily media will cause movement 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 corresponding to the condition that the pressure in said first medium exceeds the pressure in said second medium by a predetermined pressure relationship; (6) means having a preselected, detectable, variable 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 (i) at least one of said flexible diaphragms or (ii) said solid coupling means so that said preselected detectable, variable parameter will change with movement 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 variable parameter being so constructed and cooperatively connected that the said parameter changes as a known function of displacement with respect to said mechanical contact reference position and said displacement is a known function of the difference in said pressures in communication with said flexible diaphragms;
whereby when said sensor is implanted, (i) at least one of said flexible diaphragms or (ii) said solid coupling means will be driven to said mechanical contact reference position when the pressure in said first medium exceeds the pressure in said second medium by said predetermined pressure relationship, and thereby the value of said preselected parameter corresponding to said mechanical contact refernce position can be determined in vivo, and whereby changes in the value of said predetermined parameter from said value of said mechanical contact reference position will be a measure of the difference in pressure in said two bodily media;b. means for detecting said preselected, detectable, variable parameter and any variation therein 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 (20, 21, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39)
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40. An in vivo differential pressure sensor adapted for implantation 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 side 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 flexible diaphragms or (ii) said incompressible coupling means thereby defining a mechanical contact reference position 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, variable 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 (i) at least one of said flexible diaphragms or (ii) said solid coupling means so that said preselected, detectable variable 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, variable parameter being so constructed and cooperatively connected that said parameter changes as a known function of displacement with respect to said mechanical contact reference position and said displacement is a known function of the difference of the external pressure on said diaphragms;
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 thereby the value of said preselected, detectable variable parameter at said mechanical contact reference position corresponding to said predetermined pressure relationship can be determined in vivo after implantation, and whereby the difference in the value of said preselected, detectable, variable parameter from said value determined at said mechanical contact reference position is a measure of the pressure in said bodily medium. - View Dependent Claims (41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66)
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67. 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 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 in the two bodily regions are equal;
whereby when said sensor is implanted beneath the skin in the living body, 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 thereby the value of said resonant frequency can be determined in vivo at the position of said rigid piston against said mechanical stop corresponding to the equality of pressures on said exterior sides of said flexible diaphragms; and
whereby the difference in the value of said resonant frequency from said value determined at said mechanical stop position is a measure of the pressure in said bodily medium. - View Dependent Claims (68, 69, 70)
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71. 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 an in mechanical pressure communication with a bodily medium, the pressure of which is to be sensed; d. 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 in the living body, 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 thereby the value of said resonant frequency can be determined in vivo at the position of said rigid piston against said mechanical stop corresponding to the equality of pressures on said exterior sides of said flexible diaphragms; and
whereby the difference in the value of said resonant frequency from said value determined at said mechanical stop position is a measure of the pressure in said bodily medium. - View Dependent Claims (72, 73)
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74. 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 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 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, variable parameter that is detectable by detection means located outside the living body, said means having a preselected, detectable variable parameter being at least in part cooperatively connected to and movable with (i) at least one of said flexible diaphragms or (ii) said rigid coupling means so that said preselected, detectable, variable parameter will change with movement of (i) at least one 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 diaphragm or said rigid coupling means and said means having a preselected, detectable, variable parameter being so constructed and cooperatively connected that said parameter changes as a known function of displacement with respect to said mechanical contact reference position and said displacement is a known function of the difference in the external pressures on said diaphragms;
whereby, when said sensor is implanted beneath the skin (i) at least one of said flexible diaphragms or (ii) said rigid 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 thereby the value of said preselected, detectable variable parameter at said mechanical contact reference position corresponding to said predetermined pressure relationship can be determined in vivo after implanation and whereby the difference in the value of said preselected, detectable variable parameter from said value determined at said mechanical contact reference position is a measure of the pressure in said bodily medium. - View Dependent Claims (75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92)
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Specification