Single diaphragm pressure-balanced telemetric pressure sensing system

An in vivo differential pressure sensor adapted for implantation beneath the skin in the living body and sensing the pressure of a bodily fluid and adapted for in vivo calibration after implantation, said sensor comprising:

• (a) a housing;
• (b) a single flexible diaphragm means which is fluid pressure sealed with respect to said housing and having a first and a second side with at least a portion of said first side comprising at least a portion of the exterior surface of said sensor and being positioned so that after implantation, said portion of said first side is in mechanical pressure communication with the skin and whereby pressures external to the body can be communicated mechanically across the skin to said single flexible diaphragm means, said single flexible diaphragm means and said housing together defining a chamber such that the second side of said single flexible diaphragm means communicates mechanically with pressure inside said chamber so that changes in the difference in pressures on said two sides of said single flexible diaphragm means causes a motion of at least a portion of said single flexible diaphragm means;
• (c) inlet means to said chamber allowing the entrance of a bodily fluid from an internal bodily region to the inside of said chamber, thereby providing a fluid pressure communication between said internal bodily region and the inside of said chamber when said sensor is implanted in the living body, and enabling that a change in the pressure in said internal bodily region will cause a movement of at least a portion of said single flexible diaphragm means with respect to said housing;
• (d) contact means connected to said housing for contacting the single flexible diaphragm means for a predetermined relationship between the pressures on said single flexible diaphragm means thereby defining a mechanical contact reference position of said single flexible diaphragm means with respect to said housing at a predetermined relationship between said pressures on said single flexible diaphragm means;
• (e) means having a preselected parameter that is detectable by detection apparatus located outside the living body, said means having a preselected parameter being at least in part cooperatively connected to and movable with said single flexible diaphragm means so that said preselected parameter will change with movement of said single flexible diaphragm means, said parameter being detectable at least when said single flexible diaphragm means is at said mechanical contact reference position and said parameter changing upon at least:
• (i) a displacement of at least a portion of said single flexible diaphragm means from said mechanical contact reference position or (ii) displacements of at least a portion of said single flexible diaphragm means with respect to said housing;
• whereby when said sensor is implanted beneath the skin, said single 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 parameter can be determined at said mechanical contact reference position by a pressure external to the living body applied to the skin adjacent to said sensor and said preselected parameter can be determined at said mechanical contact reference position after implantation, and whereby the magnitude of the external pressure applied to the skin required to drive said single flexible diaphragm means to said mechanical contact reference position is a function of the pressure in said internal bodily region.

An in vivo differential pressure sensor adapted for implantation in the living body and adapted for in vivo calibration after implantation and sensing the pressure of a bodily fluid, said sensor comprising;

• (a) a housing having means defining an opening therein;
• (b) a single flexible diaphragm means extending over the end of the housing opening and being fluid pressure sealed with respect to said housing, said single flexible diaphragm means forming part of the exterior surface of the sensor whereby when said sensor is implanted beneath the skin, said single flexible diaphragm means is adjacent to and in pressure communication with the skin and whereby pressure external to the body applied to the skin is mechanically communicated to said single flexible diaphragm means, said single flexible diaphragm means and said housing forming a chamber with said single flexible diaphragm means communicating on one side with pressure inside the chamber and on the other side with pressure external to the sensor and adjacent to said single flexible diaphragm means;
• (c) inlet means to said chamber allowing the entrance of a bodily fluid from an internal bodily region to the inside of said chamber and thereby proving fluid pressure communication between said internal bodily region and said single flexible diaphragm so that a change in the difference of pressures on said single flexible diaphragm means will produce a movement of a portion of said single flexible diaphragm means with respect to said housing;
• (d) a magnetic material that is connected to and thus moves with said single flexible diaphragm means;
• (e) a 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 resonant circuit is varied in accordance with the position of the magnetic material relative to the inductor, said resonant frequency being detectable by apparatus external to the living body;
• (f) a mechanical stop for said single flexible diaphragm means against said housing when the pressure external to said sensor on said single flexible diaphragm means is equal to or greater than the pressure in said chamber whereby, when said sensor is implanted beneath the skin, said single flexible diaphgram means can be driven to said mechanical stop by a pressure applied externally to the skin and said resonant frequency can be determined at said mechanical stop after implantation and whereby the magnitude of the external pressure applied to the skin required to drive said single flexible diaphragm means to said mechanical stop is a measure of the pressure of said bodily fluid.

An in vivo differential pressure sensor adapted for implantation in the living body and adapted for in vivo calibration after implantation and sensing the pressure of a bodily fluid, said sensor comprising:

• (a) a housing having means defining an opening therein;
• (b) a single flexible diaphragm means extending over the end of the housing opening and being fluid pressure sealed with respect to said housing, said single flexible diaphragm means forming part of the exterior surface of the sensor whereby when said sensor is implanted beneath the skin said single flexible diaphragm means is adjacent to and in pressure communication with the skin and whereby pressure external to the body applied to the skin is mechanically communicated to said single flexible diaphragm means, said single flexible diaphragm means and said housing forming a chamber with said single flexible diaphragm means communicating on one side with pressure inside said chamber and on the other side with pressure external to said sensor and adjacent to said single flexible diaphragm means;
• (c) inlet means to said chamber allowing the entrance of a bodily fluid from an internal bodily region to the inside of said chamber and thereby proving fluid pressure communication between said internal bodily region and said single flexible diaphragm means so that a change in the difference of pressure or said single flexible diaphragm means will produce a movement of a portion of said flexible diaphragm means with respect to said housing;
• (d) a conductive material that is connected to and thus moves with said single flexible diaphragm means;
• (e) a 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 resonant circuit is varied in accordance with the postion of the conductive material relative to the inductor, said resonant frequency being detectable by apparatus external to the living body;
• (f) a mechanical stop for said single flexible diaphragm means against said housing when pressure external to said sensor on said single flexible diaphragm means is equal to or greater than the pressure in said chamber whereby, when said sensor is implanted beneath the skin, said single flexible diaphragm means can be driven to said mechanical stop by a pressure applied externally to the skin and said resonant frequency be determined at said mechanical stop after implantation and whereby the magnitude of the external pressure applied to the skin required to drive said single flexible diaphragm means to said mechanical stop is a measure of pressure of said bodily fluid.

An in vivo pressure detecting system comprising in combination:

• (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 therein;
• (2) a single flexible diaphragm means which extends across the housing opening and is secured with respect to said housing, said single flexible diaphragm means having a first and a second side, at least a portion of said first side comprising at least a portion of the exterior surface of said sensor, said housing and said single flexible diaphragm means being adapted so that when said sensor is implanted beneath the skin, the exterior surface of said single flexible diaphragm means is positioned to be adjacent to and facing an interior portion of skin whereby said exterior surface portion of said single flexible diaphragm means is in mechanical pressure communication with the skin and whereby pressures external to the body can be communicated mechanically across the skin to said single flexible diaphragm means;
• (3) means allowing the second side of said single flexible diaphragm means to be in contact, and thereby in pressure communication with a bodily medium the pressure of which is to be sensed when said sensor is implanted in the living body, so that changes in the difference in pressures on said two sides of said flexible diaphragm means cause motion of at least a portion of said single flexible diaphragm means with respect to said housing;
• (4) means connected to said housing for contacting the single flexible diaphragm means for a predetermined relationship between the pressures on said single flexible diaphragm means thereby defining a mechanical contact reference position of said single flexible diaphragm means with respect to said housing for a predetermined relationship between said pressures on said single flexible diaphragm means;
• (5) means having a preselected parameter that is detectable by detection apparatus located outside the living body, said means having a preselected parameter being at least in part cooperatively connected to and movable with said single flexible diaphragm means so that said preselected parameter will change with movement of said single flexible diaphragm means, said parameter being detectable at least when said single flexible diaphragm means is substantially at said mechanical contact reference position and said parameter changing upon at least:
• (i) a displacement of at least a portion of said single flexible diaphragm means from said mechanical contact reference position or (ii) displacement of at least a portion of said single flexible diaphragm means with respect to said housing;
• whereby when said sensor is implanted beneath the skin said single 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 parameter can be determined at said mechanical contact reference position after implantation and whereby the magnitude of the external pressure applied to the skin required to drive said single flexible diaphragm means to said mechanical contact reference position is a function of the pressure in said bodily medium;
• (b) a controllable pressure source means adapted to be located external to the living body and in cooperative relation with the living body and said single flexible diaphragm means for establishing said predetermined pressure relationship;
• and,
• (c) means for detecting said preselected parameter and the value of said preselected parameter at said mechanical contact reference position and any variation therefrom when said sensor is implanted in a living body, said detecting means being adapted to be located external to the living body and in cooperative relation with the living body and said sensor and without any connection to said sensor which requires a break in the skin of the living body.

An in vivo pressure detecting system comprising in combination:

• (a) an in vivo differential pressure sensor adapted for implantation beneath the skin in the living body and sensing the pressure of a bodily fluid, and adapted for in vivo calibration after implantation, said sensor comprising:
• (1) a housing;
• (2) a single flexible diaphragm means which is fluid pressure sealed with respect to said housing and has a first and a second side with at least a portion of said first side comprising at least a portion of the exterior surface of said sensor and being positioned so that after implantation, said portion of said first side is in mechanical pressure communication with the skin and whereby pressures external to the body can be communicated mechanically across the skin to said single flexible diaphragm means, said single flexible diaphragm means and said housing together defining a chamber such that the second side of said single flexible diaphragm means communicates mechanically with pressure inside said chamber so that changes in the difference in pressures on said two sides of said single flexible diaphragm means cause a motion of at least a portion of said single flexible diaphragm means;
• (3) inlet means to said chamber allowing the entrance of a bodily fluid from an internal bodily region to the inside of said chamber when said sensor is implanted in the living body, thereby providing a fluid pressure communication between said internal bodily region and the inside of said chamber when said sensor is implanted in the living body, and enabling that a change in pressure will cause a movement of at least a portion of said single flexible diaphragm means with respect to said housing;
• (4) contact means connected to said housing for contacting the single flexible diaphragm means for a predetermined relationship between the pressures on said single flexible diaphragm means thereby defining a mechanical contact reference position of said single flexible diaphragm means with respect to said housing at a predetermined relationship between said pressures on said single flexible diaphragm means;
• (5) means having a preselected parameter that is detectable by detection apparatus located outside the living body, said means having a preselected parameter being at least in part cooperatively connected to and movable with said single flexible diaphragm means so that said preselected parameter will change with movement of said single flexible diaphragm means, said preselected parameter being detectable at least when said single flexible diaphragm means is at said mechanical contact reference position and said parameter changing upon at least:
• (i) a displacement of at least a portion of said single flexible diaphragm means from said mechanical contact reference position or (ii) displacement of at least a portion of said single flexible diaphragm means with respect to said housing;
• whereby when said sensor is implanted beneath the skin said single 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 parameter can be determined at said mechanical contact reference position after implantation and whereby the magnitude of the external pressure applied to the skin required to drive said single flexible diaphragm means to said mechanical contact reference position is a function of the pressure of said bodily fluid;
• (b) a controllable pressure source means adapted to be located external to the living body and in cooperative relation with the living body and said single flexible diaphragm means for establishing said predetermined pressure relationship;
• and,
• (c) means for detecting said preselected 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 adapted to be located external to the living body and in cooperative relation with the livig body and said sensor and without any connection to said sensor which requires a break in the skin of the living body.

An in vivo differential pressure sensor adapted for implantation in the living body, said sensor comprising:

• (a) a housing having means defining an opening extending therethrough;
• (b) a single flexible diaphragm means extending across said housing opening and secured to said housing, said single flexible diaphragm means communicating with pressures in two separate regions external to the sensor that are separated by the single 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 so that opposite sides of said single flexible diaphragm means are in contact with and in mechanical pressure communication with two bodily media that are separated by said single flexible diaphragm means;
• (c) contact means connected to said housing for contacting the single flexible diaphragm means for a predetermined relationship between the pressure on said single flexible diaphragm means thereby defining a mechanical contact reference position of said single flexible diaphragm means with respect to said housing for a predetermined pressure relationship in said regions;
• and,
• (d) means having a preselected, detectable parameter that changes upon at least a displacement from said mechanical contact reference position of said single flexible diaphragm means upon a change from said predetermined pressure relationship.

An in vivo differential pressure sensor adapted for in vivo calibration after implantation, said sensor comprising:

• (a) a housing which defines a chamber therein, at least a portion of the wall of said housing being flexible so that changes in the pressures inside said chamber and outside said housing will cause movement of said flexible portion of said housing wall, said housing being adapted so that, when implanted beneath the skin in the living body, said flexible portion of said housing wall can be placed in mechanical pressure communication with an interior portion of skin and whereby pressures external to the body can be communicated mechanically across the skin to said flexible portion of said housing wall;
• (b) inlet means to said chamber allowing the entrance into said chamber of a bodily fluid, the pressure of which is to be measured when the sensor is implanted in the body;
• (c) stop means within said housing adapted to make contact with, and thereby stop the movement of, said flexible portion of said housing wall for a predetermined pressure relationship between pressures inside said chamber and outside said housing;
• (d) means within said housing having a preselected parameter that is detectable by apparatus outside the living body, said means having a preselected parameter being at least in part cooperatively connected to said flexible portion of said housing wall so that said preselected parameter will change with the movement of said flexible portion of housing wall, the preselected parameter being detectable at least when said flexible portion of the wall is in contact with said stop means and said parameter changing upon at least a movement of said flexible portion of wall away from said stop means, whereby when said sensor is implanted beneath the skin, said flexible portion of wall can be driven to contact said stop means by a pressure external to the living body applied to the skin adjacent to said sensor and said preselected parameter can be determined when said flexible portion of the wall is in contact with said stop means after implantation, and whereby the magnitude of the external pressure applied to the skin required to drive said flexible portion of wall to contact said stop means is a function of the pressure in said internal bodily region.