Implantable capacitive absolute pressure and temperature sensor
First Claim
1. An implantable lead having a capacitive pressure sensor module for providing signals representative of the magnitude of body fluid pressure at a selected site and ambient operating conditions, including body temperature, at the site, said lead comprising:
- an elongated implantable lead body having proximal and distal end sections and having first and second electrical conductors extending from the proximal end section to the distal end section, said proximal end adapted to be coupled to a biasing signal source, and said distal end section adapted to be implanted in a body position for measuring a varying body fluid pressure; and
a pressure sensor module formed in the distal end section of the lead body and coupled to said first and second electrical conductors, the pressure sensor module of said lead comprising;
a module housing attached to said lead body adapted to be positioned in a body cavity and enclosing a hermetically sealed chamber;
pressure deformable pickoff capacitor means for varying in capacitance in response to variations in fluid pressure having a first plate formed of a pressure deformable diaphragm of said module housing and a second plate spaced apart therefrom;
reference capacitor means having a first plate formed of a relatively non-deformable portion of said diaphragm of said module housing and a second plate spaced apart therefrom;
a substrate supported within said module housing for supporting said second plates; and
pressure and temperature signal modulating circuit means supported on said substrate within said hermetically sealed chamber and electrically coupled to said first and second electrical conductors.
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Accused Products
Abstract
An endocardial lead for implantation in a right heart chamber for responding to blood pressure and temperature and providing modulated pressure and temperature related signals to an implanted or external hemodynamic monitor and/or cardiac pacemaker or pacemaker/cardioverter/defibrillator. The lead has a sensor module formed in its distal end and is coupled to a monitor that powers a sensor circuit in the sensor module. The sensor module is formed with a pickoff capacitor that changes capacitance with pressure changes and a reference capacitor that is relatively insensitive to pressure changes. The sensor circuit provides charge current that changes with temperature variation at the implant site, alternately charges and discharges the two capacitors, and provides timing pulses having distinguishable parameters at the end of each charge cycle that are transmitted to the demodulator. The demodulator detects and synchronizes the timing pulses and derives pressure and temperature analog voltage values representative of the intervals between the timing pulses which are digitized and stored in the monitor. The monitor may also be coupled with other sensors for measuring and storing related patient body parameters, e.g. blood gas, EGM, and patient activity.
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Citations
27 Claims
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1. An implantable lead having a capacitive pressure sensor module for providing signals representative of the magnitude of body fluid pressure at a selected site and ambient operating conditions, including body temperature, at the site, said lead comprising:
an elongated implantable lead body having proximal and distal end sections and having first and second electrical conductors extending from the proximal end section to the distal end section, said proximal end adapted to be coupled to a biasing signal source, and said distal end section adapted to be implanted in a body position for measuring a varying body fluid pressure; and
a pressure sensor module formed in the distal end section of the lead body and coupled to said first and second electrical conductors, the pressure sensor module of said lead comprising;a module housing attached to said lead body adapted to be positioned in a body cavity and enclosing a hermetically sealed chamber; pressure deformable pickoff capacitor means for varying in capacitance in response to variations in fluid pressure having a first plate formed of a pressure deformable diaphragm of said module housing and a second plate spaced apart therefrom; reference capacitor means having a first plate formed of a relatively non-deformable portion of said diaphragm of said module housing and a second plate spaced apart therefrom; a substrate supported within said module housing for supporting said second plates; and pressure and temperature signal modulating circuit means supported on said substrate within said hermetically sealed chamber and electrically coupled to said first and second electrical conductors. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. An implantable capacitive implantable lead for providing signals representative of the magnitude of body fluid pressure at a selected site and ambient operating conditions, including body temperature, at the site comprising:
an elongated implantable lead body having proximal and distal end sections and having first and second electrical conductors extending from the proximal end section to the distal end section, said proximal end adapted to be coupled to a biasing signal source, and said distal end section adapted to be implanted in a body position for measuring a varying body fluid pressure; and
a implantable module formed in the distal end section of the lead body and coupled to said first and second electrical conductors, the implantable module further comprising;a module housing attached to said lead body adapted to be positioned in a body cavity and enclosing a hermetically sealed chamber; pressure deformable pickoff capacitor means for varying in capacitance in response to variations in fluid pressure having a first plate formed of a pressure deformable diaphragm of said module housing and a second plate spaced apart therefrom; reference capacitor means having a first plate formed of a non-deformable portion of said module housing and a second plate spaced apart therefrom; and pressure and temperature signal modulating circuit means within said hermetically sealed chamber and electrically coupled to said first and second electrical conductors. - View Dependent Claims (20, 21, 22)
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23. A pressure sensor module having a housing enclosing a hermetically sealed chamber for implantation into a living body, said housing for attachment to an implantable device such that the housing is adapted to be positioned in a body so as to sense pressure therein and;
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pressure deformable pickoff capacitor means for varying in capacitance in response to variations in pressure exterior to said chamber having a first pressure deformable, substantially flat, diaphragm element with an interior surface and an exterior surface, said diaphragm element disposed on said housing so as to have said exterior surface thereof exposed to said body and the interior surface thereof facing interior to said chamber, said interior surface disposed to substantially parallel alignment with a second plate member spaced apart from the interior surface of said diaphragm and within said chamber, and having a conductive pickoff capacitor member lining or formed of a portion of said interior surface of said diaphragm element and having a second capacitor conductive member lining or formed of a portion of said second plate member spaced from said first conductive member; reference capacitor pressure sensing means having a first conductive capacitor member lining a relatively non-deformable portion of said diaphragm element of said interior surface and being electrically isolated from and non coincident with said pickoff capacitor first conductive member, and a second conductive capacitor member on said second plate spaced apart from said reference capacitor conductive member; pressure and temperature signal modulating circuit electrically coupled to said first and second electrical conductors. - View Dependent Claims (24, 25, 26, 27)
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Specification