WO2007127831A2 - Systeme a energie thermoelectrique implantable - Google Patents

Systeme a energie thermoelectrique implantable Download PDF

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Publication number
WO2007127831A2
WO2007127831A2 PCT/US2007/067481 US2007067481W WO2007127831A2 WO 2007127831 A2 WO2007127831 A2 WO 2007127831A2 US 2007067481 W US2007067481 W US 2007067481W WO 2007127831 A2 WO2007127831 A2 WO 2007127831A2
Authority
WO
WIPO (PCT)
Prior art keywords
energy converter
thermoelectric energy
housing
capacitor
interior volume
Prior art date
Application number
PCT/US2007/067481
Other languages
English (en)
Other versions
WO2007127831A3 (fr
Inventor
Blair Erbstoeszer
Kristofer J. James
Glenn Morita
Original Assignee
Cardiac Pacemakers, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US11/681,976 external-priority patent/US8538529B2/en
Priority claimed from US11/681,995 external-priority patent/US8039727B2/en
Priority claimed from US11/681,985 external-priority patent/US8003879B2/en
Application filed by Cardiac Pacemakers, Inc. filed Critical Cardiac Pacemakers, Inc.
Publication of WO2007127831A2 publication Critical patent/WO2007127831A2/fr
Publication of WO2007127831A3 publication Critical patent/WO2007127831A3/fr

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N1/00—Electrotherapy; Circuits therefor
    • A61N1/18—Applying electric currents by contact electrodes
    • A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
    • A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
    • A61N1/372—Arrangements in connection with the implantation of stimulators
    • A61N1/378—Electrical supply
    • A61N1/3785—Electrical supply generated by biological activity or substance, e.g. body movement

Definitions

  • thermoelectric energy converters relate generally to thermoelectric energy converters, and more particularly to methods and apparatuses including in vivo thermoelectric power systems.
  • thermoelectric power system designs compatible with these applications, which can supplement the energy available from traditional power sources.
  • One embodiment of the present subject matter includes an apparatus, which includes an implantable housing which is thermally conductive and hermetically sealed and which defines an interior volume; electronics disposed in the interior volume and connected to a power source; and a thermoelectric energy converter disposed in the interior volume and connected to the power source, the thermoelectric energy converter including a hot pole and a cold pole, with the hot pole thermally conductive to a first portion of the housing, and the cold pole thermally conductive to a second portion of the housing.
  • Another embodiment of the present subject matter includes a method which includes connecting a hot pole of a thermoelectric energy converter to a first portion of a housing such that the hot pole and the first portion of a housing are thermally conductive to each other, connecting a cold pole of the thermoelectric energy converter to a second portion of a housing such that the cold pole and the second portion of a housing are thermally conductive to each other and powering an implantable device with the thermoelectric energy converter.
  • Still another embodiment of the present subject matter includes an apparatus which includes a thermoelectric energy conversion means for converting a temperature differential into energy and sealed housing means for housing the thermoelectric energy conversion means and cardiac rhythm management electronics.
  • thermoelectric energy converter is less than approximately 0.020 inches thick. Some embodiments are between 0.020 inches and 0.040 inches thick. Embodiments of the present subject matter are between 0.040 inches and 0.100 inches thick. Embodiments having a thickness which is greater than 0.100 inches thick are also contemplated. These combinations are provided for illustration and are not intended to be limiting as the present subject matter contemplates thicknesses which are not listed herein expressly. Some embodiments include a housing which is at least partially titanium, and/or using a housing which is at least partially stainless steel.
  • Some embodiments include a first shell which includes the first portion and a second shell which includes the second portion, the first shell having a first opening which is conformed to a second opening of the second shell.
  • a housing element is disposed between a first shell of the housing and a second shell of the housing, the housing element having a lower level of thermal conductivity than the first shell and the second shell.
  • Some embodiments use a thermally conductive grease to encourage conduction. Additional fillers which encourage conduction are also contemplated, including, but not limited to, epoxy and other adhesives.
  • the power source in various embodiments, includes a capacitor, a battery, or both.
  • the electronics in various embodiments, include pacemaker electronics, cardioverter defibrillator electronics, and/or other electronics.
  • the thermoelectric energy converter may interconnect with any of these subcomponents.
  • thermoelectric energy converter to a device housing, such that a hot pole of the thermoelectric energy converter is connected to a first housing portion, and a cold pole of the thermoelectric energy converter is connected to a second housing portion, with the connected first and second housing portions defining an interior volume in which the thermoelectric energy converter is disposed; positioning a power source in the device housing; positioning electronics in the interior volume; and powering the electronics with the thermoelectric energy converter.
  • One embodiment includes a method including connecting a thermoelectric energy converter to a device housing, such that a hot pole of the thermoelectric energy converter is connected to a first housing portion, and a cold pole of the thermoelectric energy converter is connected to a second housing portion, with the connected first and second housing portions defining an interior volume in which the thermoelectric energy converter is disposed; positioning a power source in the device housing; positioning electronics in the interior volume; and powering the power source with the thermoelectric energy converter.
  • the present subject matter includes implanting the thermoelectric energy converter in a patient.
  • Various embodiments additionally include positioning the first housing portion subcutaneously.
  • Embodiments of the present subject matter additionally include positioning a housing submuscularly.
  • One embodiment of the present subject matter includes an apparatus, which includes an implantable titanium housing, which is thermally conductive and hermetically sealed and which defines an interior volume; a housing element disposed between a first shell of the implantable titanium housing and a second shell of the implantable titanium housing, the housing element having a lower level of thermal conductivity than the first shell and the second shell; electronics disposed in the interior volume and connected to a primary battery; and a thermopile disposed in the interior volume, the thermoelectric energy converter including a hot pole and a cold pole, with the hot pole thermally connected to a first portion of the housing, and the cold pole thermally connected to a second portion of the housing, wherein the thermopile is less than approximately 0.100 inches thick, and is adapted to produce approximately 30 microwatts when exposed to a thermal gradient of approximately 1.0 degrees Celsius.
  • FIG. IA shows a self-powered device, according to one embodiment of the present subject matter.
  • FIG. IB shows a side view of the self-powered device of FIG. IA.
  • FIG. 2 shows a cross section of a self-powered device, according to one embodiment of the present subject matter.
  • FIG. 3 shows a side view of a self-powered device, according to one embodiment of the present subject matter.
  • FIG. 4 illustrates a schematic diagram of an apparatus for converting power from a thermoelectric energy converter, according to one embodiment of the present subject matter.
  • FIG. 5 shows a partial cross section side view of a self-powered device, according to one embodiment of the present subject matter.
  • FIG. 6 shows a cross section of a thermoelectric energy converter and additional components disposed in a shunt, according to one embodiment of the present subject matter.
  • FIG. 7 shows a cross section of a shunt and a thermoelectric energy converter, according to one embodiment of the present subject matter.
  • FIG. 8 is cross section or a self-powered device showing thermal gradients, according to one embodiment of the present subject matter.
  • FIG. 9 illustrates a schematic diagram of an apparatus for converting power from a thermoelectric energy converter, according to one embodiment of the present subject matter.
  • Thermoelectric devices convert thermal gradients to energy, and visa versa. These devices include an interface between dissimilar materials, hi some cases the dissimilar materials are metals, hi some instances the dissimilar materials are semiconductors. Additional materials which demonstrate the Seebeck effect fall within the present scope.
  • thermoelectric technology Despite the availability of materials which demonstrate the Seebeck effect, some applications have yet to benefit from thermoelectric technology. Problems include an inability for some applications to use available thermal gradients. Additionally, some existing designs are too large for practical implantation.
  • thermoelectric energy conversion system for a self-powered device.
  • Self-powered devices contemplated by the present subject matter include implantable devices.
  • Implantable devices contemplated by the present subject matter include, but are not limited to, cardiac rhythm management devices, neurostimulation devices, and other devices not expressly listed herein.
  • the thermoelectric energy conversion system of the present subject matter operates inside an implantable device, using a thermal gradient present at the implantable device. The embodiments provide enough energy to power electronics within the device.
  • FIG. IA shows a self-powered device, according to one embodiment of the present subject matter.
  • the self-powered device is suited for use as an implantable medical device.
  • the self-powered device is a cardiac rhythm management device.
  • the device is a neurostimulation device. These are only some of the self-powered devices contemplated by the present subject matter.
  • the present subject matter extends to additional devices not expressly listed herein.
  • This front view shows a header 102, and a housing 110.
  • the housing 110 includes titanium.
  • the housing 110 includes stainless steel. Other materials for the housing 110 which are compatible with implanting electronics can optionally be used.
  • Power source 104 includes a primary battery, in various embodiments. Some embodiments use one or more lithium ion batteries. Of these, some embodiments use one or more lithium manganese dioxide batteries. Other known primary battery compositions are also be used, in various embodiments. Additionally, power source 104, in various embodiments, includes a secondary battery. Secondary batteries within the present subject matter include rechargeable lithium ion types. Other known secondary batteries are also used. Also, in some embodiments, power source 104 includes a capacitor. Aluminum electrolytic capacitors are used in some embodiments of the present subject matter. Other capacitor compositions additionally fall within the present scope.
  • Power source 104 could include a combination of two or more of a primary battery, a secondary battery, or a capacitor. Power source 104, in various embodiments, provides a power source which is available for use in concert with thermoelectric energy converter 106. In various embodiments, power source 104 is used in applications where a power source is needed which delivers power at a rate different from a thermoelectric energy converter. In various embodiments, power source 104 is used for powering electronics when a thermal gradient is not available. Embodiments not including power source 104 additionally fall within the present scope.
  • housing 110 includes a first housing portion which is thermally conductive and which has a first housing opening.
  • Housing 110 additionally includes, in various embodiments, a second housing portion which is thermally conductive and which has a second housing opening, hi various embodiments, the second housing opening is hermetically sealed to the first housing opening.
  • the first housing portion and the second housing portion at least partially define an interior volume.
  • Thermoelectric energy converter 106 in various embodiments, is disposed in the interior volume.
  • Thermoelectric energy converter has a hot pole and a cold pole.
  • the hot pole is thermally connected to the first housing portion.
  • the cold pole is thermally connected to the second housing portion.
  • the self-powered device demonstrated in the present embodiment includes within its housing a thermoelectric energy converter, including the hot pole and the cold pole of the thermoelectric energy converter. Such a configuration is useful to power additional electronics 108, in various embodiments.
  • cardiac rhythm management electronics are disposed in the interior volume of housing 110.
  • neurostimulation electronics are disposed in the interior volume of housing 110.
  • Other electronics variants not expressly listed herein are additionally contemplated by the present subject matter.
  • the electronics include cardioverter defibrillator electronics, hi some embodiments, the additional electronics 108 are powered solely by the thermoelectric energy converter 106, and an additional power source 104 is not included in the device.
  • the thermoelectric energy converter 106 is adapted to power pacemaker electronics.
  • power source 104 is included in the device, but does not power pacemaker electronics.
  • power source 104 can provide power for a defibrillation capacitor.
  • power source 104 is not included.
  • the additional electronics 108 are powered by both the thermoelectric energy converter 106 and the power source 104.
  • the choice of what power source to use to power additional electronics 108 depends on the energy rate which should to be available.
  • the thermoelectric energy converter produces power at a rate too low to deliver energy for a defibrillation pulse.
  • power source 104 includes a capacitor used to provide a defibrillation pulse to a patient.
  • a power source 104 including a capacitor multiple capacitor pulses are needed to treat a patient. In these situations, some capacitors are not big enough to hold charge suitable for delivery of multiple pulses. Such housings require an additional power source which can discharge at a high rate to charge the capacitor between defibrillation pulses.
  • the thermoelectric energy converter 106 cannot discharge at a high enough rate to charge a capacitor in between defibrillation pulses.
  • additional power source 104 includes additional components, such as a battery, to charge the capacitor at a rate higher than is available from the thermoelectric energy converter 106.
  • a primary battery is used. Additional embodiments use a secondary battery. Some embodiments use a combination of a primary battery and a secondary battery.
  • the present subject matter enables a smaller battery to be used to charge a capacitor, in various embodiments.
  • a battery/capacitor combination may be called upon to deliver therapies multiple times, over multiple episodes.
  • a device may deliver 2 pulses during an episode, and may encounter one episode per year, for 5 years. Batteries in defibrillators are known to last between 3 and 7 years.
  • a battery should be sized to operate sufficiently during multiple episodes. However, if the battery need only be sized to function appropriately during one episode, it may be smaller. Battery discharge during the episode can be replenished using the thermoelectric device, in various embodiments of the present subject matter.
  • thermoelectric energy converter 106 should be able to harvest thermal energy from the human body and convert it into usable power.
  • Various embodiments of the present subject matter are configured to provide power when a thermal gradient exists which is between approximately 0.5 degrees Celsius, and approximately 5.0 degrees Celsius. Some embodiments provide power using a thermal gradient of approximately 4.3 degrees Celsius, hi some of embodiments, the thermoelectric energy converter is adapted to produce power when exposed to a thermal gradient of approximately 0.5 degrees Celsius to approximately 1.5 degrees Celsius.
  • Various embodiments of the present subject matter are configured such that the thermoelectric energy converter is adapted to produce from about 5 microwatts when exposed to a thermal gradient of approximately 0.5 degrees Celsius, to about 80 microwatts when exposed to a thermal gradient of approximately 4.3 degrees Celsius.
  • thermoelectric energy converter is adapted to produce approximately 30 microwatts when exposed to a thermal gradient of approximately 1.0 degrees Celsius.
  • power production examples are evinced in some of the configurations contemplated by the present subject matter, but are not intended to be limiting of the range of configurations contemplated by the present subject matter.
  • thermal gradients provided herein, and their relationship to power production are those of example embodiments which are illustrative of the present subject matter, but not demonstrative of the entire range of configurations contemplated by the present subject matter.
  • thermoelectric energy converters include thermopiles, hi some embodiments, the thermoelectric energy converter is a thin film thermoelectric energy converter. Some thermoelectric energy converters include a superlattice. Some thermoelectric energy converters operate using thermotunneling. Other known thermoelectric designs which meet packaging and power requirements of implantable self- powered devices additionally fall within the present scope.
  • FIG. IB shows a side view of the self-powered device of FIG. IA.
  • Pictured in the view are header 102 and housing 110.
  • the housing 110 is comprised, in various embodiments, of a first portion 112 and a second portion 114.
  • first portion 112 is cup shaped and includes a first aperture conformed to a second aperture of the second portion 114, wherein the first and second apertures are hermetically sealed at seam 150.
  • FIG. 2 shows a cross section of a self-powered device 224, according to one embodiment of the present subject matter.
  • Various embodiments of the present subject matter include a housing.
  • the housing includes a first housing portion 202 and a second housing portion 214.
  • Various embodiments additionally include electronics 210, an additional power source 212, and a thermoelectric energy converter system 204.
  • the first housing portion 202 is cup shaped and the second housing portion 214 is cup shaped.
  • the first housing portion and the second housing portion meet, with respective openings conforming to one another along plane 222.
  • the first housing portion 202 and the second housing portion 214 of the present subject matter demonstrate such a configuration, other configurations are possible, including ones in which first housing portion 202 and second housing portion 214 conform to one another along an irregular interface.
  • the first housing portion 202 and the second housing portion 214 are mechanically connected. Some embodiments are welded together. In some embodiments, a laser weld joins the first housing portion 202 and the second housing portion 214.
  • thermoelectric energy converter system 204 is thermally connected to the first housing portion 202 and the second housing portion 210. For example, some embodiments position a hot pole 218 of a thermoelectric energy converter system 204 adjacent a first housing portion 202, such that the hot pole and the first housing portion are in thermal conduction, In additional embodiments, the cold pole 220 of the thermoelectric energy converter system 204 is positioned adjacent the second housing portion 214, such that the cold pole 220 and the second housing portion 214 are in thermal conduction.
  • performance of the thermoelectric energy conversion system 204 is enhanced due to reduced thermal conduction between first housing portion 202 and second housing portion 214.
  • Some embodiments of the present subject matter utilize materials for the first housing portion 202 and/or the second housing portion 214 which are less thermally conductive.
  • Some embodiments, for example, use housing portions constructed of titanium. Titanium has a thermal conductivity of approximately 17 Watts per meter Kelvin, in various embodiments.
  • Additional embodiments use housing portions constructed of stainless steel.
  • Some embodiments of the present subject matter use 3161 stainless steel.
  • Some embodiments of the present subject matter use a stainless steel having a thermal conductivity of approximately 16 watts per meter Kelvin.
  • Other materials for the first and/or second housing portions fall within the present scope.
  • connection 216 in various embodiments, enhances thermal conductivity between second housing portion 214 and cold pole 220 using a thermally conductive grease.
  • a thermally conductive grease has a thermal conductivity of from about 4 Watts per meter Kelvin to about 5 Watts per meter Kelvin. Additional embodiments weld cold pole 220 to second housing portion 214.
  • Some embodiments include a thermally conductive filler material which thermally interconnects the second housing portion 214 and the cold pole 220. These configurations for connecting the cold pole 220 and the second housing portion 214 apply to connections to the first housing portion 202 and the hot pole 218, in various embodiments.
  • the thermoelectric energy converter system 204 has a thickness of Dl. In some embodiments, the thermoelectric energy converter is less than the thickness of the thermoelectric energy converter system. Some embodiments include a thermoelectric energy converter system 204 which is less than the thickness D2 of the device 224 in which it is housed. In some embodiments, the thickness Dl is less than 0.020 inches thick. Some embodiments are between 0.020 inches and 0.040 inches thick. Embodiments of the present subject matter are between 0.040 inches and 0.100 inches thick. Embodiments having a thickness Dl which is greater than 0.100 inches thick are also contemplated. These combinations are provided for illustration and are not intended to be limiting as the present subject matter contemplates thicknesses which are not listed herein expressly.
  • the connected first housing portion and second housing portion have a substantially plate shaped exterior.
  • the plate shaped exterior has a first planar surface and a second planar surface, wherein the thermoelectric energy converter system 204 is plate shaped and is disposed in the housing such that a thickness of the thermoelectric energy converter extends away from one of the first planar surface and the second planar surface.
  • the device 224 is exposed to a thermal gradient ⁇ T.
  • the thermal gradient ⁇ T is from about 0.5 degrees Celsius to about 4.3 degrees Celsius.
  • the thermal gradient ⁇ T is from about 0.5 degrees Celsius to about 1.5 degrees Celsius, hi some embodiments, the thermal gradient ⁇ T is about 1.0 degrees Celsius.
  • the hot pole is at 37.0 degrees Celsius
  • the cold pole is at 35.5 degrees Celsius.
  • a thermally insulative insert is disposed between first housing portion 202 and second housing portion 214.
  • the thermally insulative insert is epoxy.
  • the thermally insulative insert is conformed to first portion 202 and second portion 214 and is hermetically sealed to those portions.
  • thermoelectric energy converter to a device housing, such that a hot pole of the thermoelectric energy converter is connected to a first housing portion, and a cold pole of the thermoelectric energy converter is connected to a second housing portion, with the connected first and second housing portions defining an interior volume in which the thermoelectric energy converter is disposed. Additionally, various embodiments include disposing a converter inside an interior volume defined by a first housing portion and a second housing portion, such that of the thermoelectric energy converter are respectively connected to the first housing portion and the second housing portion.
  • Some embodiments include packaging, in the interior volume, a defibrillation capacitor powered by a battery.
  • the battery is a primary battery. In additional embodiments, the battery is a secondary battery.
  • thermoelectric energy converter to cardiac rhythm management electronics disposed in the interior volume.
  • some embodiments include connecting pacemaker electronics disposed in the interior volume to the thermoelectric energy converter, such that the pacemaker electronics are powered by the thermoelectric energy converter.
  • Some embodiments include connecting the thermoelectric energy converter to neurostimulation electronics disposed in the interior volume.
  • therapy electronics such as cardiac rhythm management electronics, neurostimulation electronics, etc.
  • a secondary battery powers the therapy electronics.
  • the thermoelectric energy converter powers the therapy electronics.
  • the thermoelectric energy converter powers the secondary battery exclusively.
  • Some embodiments include powering a capacitor with the secondary battery. Capacitors contemplated by the present subject matter include capacitors used as the primary power source for providing shocks for defibrillation.
  • Some embodiments of the present subject matter include methods of implanting a device having a thermoelectric energy converter of the present subject matter in a patient such that the first housing portion is positioned subcutaneously.
  • Embodiments of the present subject matter additionally include positioning a housing submuscularly.
  • the present subject matter includes additional embodiments, however, which position the device in other areas of the body.
  • FIG. 3 shows a side view of a self-powered device, according to one embodiment of the present subject matter.
  • a housing 310 includes a first portion 302, a second portion 306, and an insert 304. Transposing thermal gradient ⁇ T 2 to the thermoelectric energy converter system decrease in thermal gradient ⁇ T 2 is desirable.
  • insert 304 is disposed between first housing portion 302 and second housing portion 306. hi various embodiments, insert 304 is of a lower thermal conductivity than the first portion 302. In additional embodiments, the insert 304 is of a lower thermal conductivity than the second portion 306.
  • insert 304 includes a thermally insulative material. Some embodiments include a cured resin. In some embodiments, the thermally insulative insert 304 is epoxy. Various additional embodiments include other materials. In some embodiments, the thermally insulative insert is conformed to first portion 302 and second portion 306 and is hermetically sealed to those portions.
  • Some embodiments do not include an insert, and instead rely on a first portion of a housing and a second portion of a housing each having a low thermal conductivity.
  • some embodiments include a first portion of a housing and a second portion of a housing, with the two portions assembled to one another and defining an interior space.
  • a thermoelectric energy conversion system extends between the first and second housing portions, in various embodiments.
  • the first and second housing portions include a low conductivity material, in various embodiments. But because, in various embodiments, the first and second energy housings are thin, having a thickness of approximately 0.012 inches, heat passes through them, traveling to the thermoelectric energy conversion system. These embodiments create a thermal gradient which is sufficient to power a thermoelectric energy conversion device.
  • Various methods for assembly fall within the present subject matter.
  • thermoelectric energy converter to a device housing, such that a hot pole of the thermoelectric energy converter is connected to a first housing portion, and a cold pole of the thermoelectric energy converter is connected to a second housing portion, with the connected first and second housing portions defining an interior volume in which the thermoelectric energy converter is disposed. Additionally, various embodiments include disposing a converter inside an interior volume defined by a first housing portion and a second housing portion, such that of the thermoelectric energy converter are respectively connected to the first housing portion and the second housing portion.
  • Some embodiments include packaging, in the interior volume, a defibrillation capacitor powered by a battery, hi some embodiments, the battery is a primary battery, hi additional embodiments, the battery is a secondary battery.
  • Various embodiments include connecting the thermoelectric energy converter to cardiac rhythm management electronics disposed in the interior volume.
  • some embodiments include connecting pacemaker electronics disposed in the interior volume to the thermoelectric energy converter, such that the pacemaker electronics are powered by the thermoelectric energy converter.
  • cardiac rhythm management electronics and a secondary battery are connected to the thermoelectric energy converter.
  • the secondary battery powers the cardiac rhythm management electronics.
  • the thermoelectric energy converter powers the cardiac rhythm management electronics.
  • the thermoelectric energy converter charges the secondary battery exclusively.
  • FIG. 4 is a partial cross section of a self-powered implantable device having a thermal shunt, according to one embodiment of the present subject matter.
  • Various embodiments of the present subject matter include a first housing portion 414 which is thermally conductive and which has a first case opening.
  • Various embodiments include a second housing portion 402 which is thermally conductive and which has a second case opening, with the material defining the second case opening being hermetically sealed to the material defining the first case opening, and with the first housing portion and the second housing portion at least partially defining an interior volume.
  • the present subject matter includes additional electronics 408 disposed in the interior volume, in various embodiments. In some embodiments, the additional electronics include cardiac rhythm management electronics.
  • Various embodiments additionally include a thermal shunt 412 disposed in the interior volume.
  • the thermal shunt 412 is constructed such that heat at first housing portion 414 is conducted to the thermoelectric energy converter.
  • the thermal shunt is constructed from a material having a high thermal conductivity.
  • Materials contemplated by the present subject matter include, but are not limited to, copper, aluminum, silver, other materials and alloys thereof.
  • Another possible material is a carbon fiber composite having a structure which is anisotropic and which demonstrates a high level of thermal conductivity.
  • An anisotropic material is beneficial as it reduces the amount of energy conducted to an additional power source 410 and additional electronics 408.
  • the anisotropic material includes carbon fiber strands held in an orientation by a cured resin.
  • epoxy is the cured resin.
  • Diamond powder is an additional material which is suitable for construction of a shunt, according to various embodiments of the present subject matter. Other materials which are thermally conductive additionally fall within the present scope.
  • One embodiment uses a shunt which is a heat pipe.
  • Thermal shunt 412 is interconnected to other components in a variety of ways. In some examples, the shunt is interconnected to the first housing portion 414 using a weld. In additional examples, the shunt is interconnected to the first housing portion 414 with a thermal grease having a high thermal conductivity. In some embodiments, an adhesive interconnects thermal shunt 412 to other components. Additional mediums are also contemplated, including but not limited to, epoxy and additional adhesives.
  • thermoelectric energy converter 404 disposed in the interior volume and adjacent the thermal shunt, the thermoelectric energy converter having a first pole 416 and a second pole 418, with the first pole thermally connected to the first housing portion, and the second pole thermally connected to the shunt.
  • first pole 416 is a hot pole.
  • second pole 418 is a cold pole.
  • the thermoelectric energy converter 404 in various embodiments, is film shaped. In some embodiments, the thermoelectric energy converter 404 is a thin film device.
  • FIG. 5 shows a partial cross section side view of a self-powered device, according to one embodiment of the present subject matter.
  • Various embodiments of the present subject matter include a thermoelectric energy converter 504 which is in adjacent a thermal shunt having multiple beams 506A, 506B, . . . , 506X.
  • the multiple beams 506A, 506B, . . . , 506X are configured for passage through various components 514 of a self- powered device.
  • the multiple beams 506A, 506B, . . . , 506X pass through an additional power source.
  • 506X pass through a battery, hi some of these embodiments, the multiple beams 506A, 506B, . . . , 506X pass through a capacitor. In additional embodiments, the multiple beams 506A, 506B, . . . , 506X pass through electronics.
  • the multiple beams 506A, 506B, . . . , 506X are tubular columns of a conductive material.
  • Materials contemplated by the present subject matter include, but are not limited to, copper, aluminum, silver, other materials and alloys thereof. Other embodiments use additional shapes for the beams. Additional embodiments include alternate materials such as an anisotropic composite.
  • the illustration additionally shows a first case portion 502, a second case portion 512, an additional power source 510, and additional electronics 508.
  • the inclusion of the additional power source 510 as illustrated is not limiting, as some embodiments of the present subject matter integrate all additional power sources into additional components 514.
  • the inclusion of the additional electronics 508 as illustrated is not limiting, as some embodiments of the present subject matter integrate all additional electronics into additional components 514.
  • FIG. 6 shows a cross section of a thermoelectric energy converter and additional components disposed in a shunt, according to one embodiment of the present subject matter.
  • the illustration shows thermoelectric energy converter 602, shunt 606, and additional components 604.
  • additional components 604 include a battery.
  • additional components 604 include a capacitor.
  • Various embodiments dispose electronics in shunt 606. Electronics include one or more of pacemaker control circuits, cardioverter defibrillator circuits, and other circuits. A combination of components listed herein additionally are disposed in shunt 606, in various embodiments. Components not listed herein, or combinations of components not listed herein, may additionally be disposed in shunt 606.
  • Some embodiments include a solid shunt 606 having no components disposed within.
  • Some embodiments include a hollow shunt 606 having no components disposed within.
  • shunt 606 includes feedthrough provisions, in various embodiments.
  • battery electrodes are disposed in shunt 606.
  • the anode of the battery is connected to a feedthrough
  • the cathode is connected to the shunt
  • the cathode is connected to a feedthrough
  • the anode is connected to the shunt 606.
  • Some embodiments include a feedthrough for the battery anode and the capacitor cathode.
  • capacitor electrodes are disposed in shunt 606.
  • the anode of the capacitor is connected to a feedthrough, and the cathode is connected to the shunt.
  • the cathode is connected to a feedthrough, and the anode is connected to the shunt 606.
  • Some embodiments include a feedthrough for the capacitor anode and the capacitor cathode.
  • an electrolyte is in contact with the interior of the shunt 606, and functions as part of the components housed in the shunt 606.
  • a capacitor using the shunt 606 as a housing includes a thermally conductive electrolyte which further benefits the heat conducting properties of the shunt 606.
  • FIG. 7 shows a cross section of a shunt and a thermoelectric energy converter, according to one embodiment of the present subject matter, hi various embodiments, a thermoelectric energy converter 704 is disposed between a first shunt 702 and a second shunt 706.
  • the first shunt 702 and the second shunt 706 are respectively adjacent first and second portions of a self- powered device housing, in various embodiments.
  • First shunt 702 and second shunt 706 are solid in some embodiments. Additional embodiments include one or both of the first shunt 702 and the second 706 in a hollow configuration.
  • FIG. 8 is cross section or a self-powered device showing thermal gradients, according to one embodiment of the present subject matter.
  • the illustration shows a thermal representation of the temperature at a first housing portion 804, a thermoelectric device 808, a shunt 806, a second housing portion 812, an additional power source 810, and additional electronics 802.
  • Pictured is temperature gradient ⁇ T 2 , which in the illustrated example represents a temperature drop of approximately 0.9 degrees Celsius across the thermoelectric energy converter.
  • Such a temperature gradient is sufficient to provide power of around forty microwatts to one or both of the additional electronics 802 and the additional power source 810.
  • Other temperature gradients ⁇ T 2 and power outputs fall within the present scope.
  • Applications which could produce ⁇ T 2 include implantation below a patient's skin, with the first case portion 804 positioned subcutaneously.
  • Embodiments of the present subject matter additionally include positioning a housing submuscularly.
  • These power production examples are evinced in some of the configurations contemplated by the present subject matter, but are not intended to be limiting of the range of configurations contemplated by the present subject matter.
  • the thermal gradients provided herein, and their relationship to power production are those of example embodiments which are illustrative of the present subject matter, but not demonstrative of the entire range of configurations contemplated by the present subject matter.
  • Thermoelectric generators convert heat to electrical power.
  • This electrical power typically has current in the milliampere (mA) range and voltage in the microvolt ( ⁇ V) range.
  • the voltage required by a typical implantable medical device is several orders of magnitude larger. Additionally, excess energy can be stored for future use, but most energy storage systems require voltages higher than what is generated by a thermoelectric generator.
  • the present subject matter provides an apparatus and method for converting the output of a thermoelectric generator to voltages compatible with an implantable medical device.
  • FIG. 9 shows a circuit for converting power from a thermoelectric energy converter, according to one embodiment of the present subject matter.
  • an energy conversion circuit is provided.
  • the electronics of the present subject matter are adapted to control the conduction of energy between the thermoelectric energy converter and a power source. In some embodiments, these electronics control the transmission of energy to a secondary battery. In additional embodiments, the electronics control the transmission of energy between a battery and a defibrillation capacitor. In some embodiments, the thermoelectric energy converter powers a defibrillation capacitor concurrent with a battery.
  • FIG. 9 illustrates a schematic diagram of an apparatus for converting power from a thermoelectric energy converter, according to one embodiment of the present subject matter.
  • the apparatus 900 includes an input terminal 902 for receiving an input voltage generated by a thermoelectric energy converter 920 and a charging inductor 904 connected in series with the input terminal.
  • the apparatus also includes a switching Field Effect Transistor (FET, 906) connected to the inductor.
  • FET, 906 is connected to the FET and the input terminal via a diode 910.
  • the FET 906 is switched with a frequency and duty cycle such that a voltage level at the output terminal 912 is compatible with an implantable medical device.
  • Implantable medical devices refer to devices used for in situ sensing and/or therapy delivery. Examples include, but are not limited to, chronically implanted devices such as pacemakers, cardioverters/defibrillators, and neurostimulators.
  • the capacitor 908 has a capacitance of 1 ⁇ F, according to an embodiment.
  • the charging inductor 904 includes a hand- wrapped wire inductor.
  • the charging inductor 904 includes 22 turns of 34 gauge wire, according to an embodiment.
  • Other types and sizes of inductors are within the scope of this disclosure.
  • the apparatus provides power efficiency from the input terminal 902 to the output terminal 912 of 20 to 30%.
  • the FET 906 is switched with a frequency of 10kHz, according to one embodiment.
  • the FET 906 is switched using a closed loop feedback system that controls the frequency and duty cycle based on an observed voltage level at the output terminal 912.
  • the FET is switched with a duty cycle of at least 90%, according to various embodiments.
  • the apparatus functions as an inductive boost circuit.
  • the depicted implementation minimizes the number of circuit elements, and further reduces the need for customized circuit elements.
  • the circuit elements are appropriate for inclusion on an application-specific integrated circuit (ASIC).
  • ASIC application-specific integrated circuit
  • the low part count allows for easy implementation and minimizes package size.
  • the resistance of the inductor and FET are minimized to increase efficiency of the converter circuit.
  • the switching FET is selected to have a low resistance when switched "on". According to an embodiment, the FET has an "on" resistance of approximately 40 ohms.
  • the inductor is selected to have a low resistance as well, to improve the efficiency of the apparatus.
  • the apparatus takes as an input the relatively low voltage from the thermoelectric generator (8-100 ⁇ V, according to various embodiments) and builds the voltage on the capacitor.
  • the voltage level on the capacitor, or output voltage is determined by the loading of the output circuit, the heat flux across the thermoelectric generator, the efficiency of the thermoelectric generator, and the pulse frequency and duty cycle of the switching FET.
  • the frequency and duty cycle can by controlled using a closed loop system. According to an embodiment, the frequency and duty cycle are controlled using logic.
  • the frequency and duty cycle are controlled using pulse-width modulation, according to an embodiment.
  • An oscillating supply 914 connected to the gate of the FET 906 via logic 916 can be used to set and adjust frequency and duty cycle. In an embodiment, the oscillating supply is controlled using feedback from an observed output voltage.
  • the FET 906 includes circuit element model IRF7530, for example, in an embodiment.
  • the diode 910 includes circuit element model 1N4148, for example, in an embodiment.
  • Other circuit elements having the similar characteristics can be used without departing from the scope of the disclosure.
  • Some embodiments of the present subject matter include methods of implanting a device having a thermoelectric energy converter of the present subject matter in a patient such that the first housing portion is positioned subcutaneously.
  • Embodiments of the present subject matter additionally include positioning a housing submuscularly. Some of these embodiments position the housing of between the pectoral muscle and the skin.
  • the present subject matter includes additional embodiments, however, which position the device in other areas of the body.

Abstract

L'invention concerne un système à énergie thermoélectrique implantable comprenant une première partie de boîtier thermoconductrice pourvue d'une première ouverture de boîtier ; une deuxième partie de boîtier thermoconductrice pourvue d'une deuxième ouverture de boîtier, la deuxième ouverture de boîtier étant soudée hermétiquement sur la première ouverture de boîtier et la première partie de boîtier et la deuxième partie de boîtier définissant au moins partiellement un volume intérieur dans lequel sont disposés des circuits de régulation du rythme cardiaque ainsi qu'un convertisseur d'énergie thermoélectrique. Le convertisseur d'énergie thermoélectrique comporte un pôle chaud et un pôle froid, le pôle chaud étant relié thermiquement à la première partie de boîtier et le pôle froid étant relié thermiquement à la deuxième partie de boîtier.
PCT/US2007/067481 2006-04-26 2007-04-26 Systeme a energie thermoelectrique implantable WO2007127831A2 (fr)

Applications Claiming Priority (12)

Application Number Priority Date Filing Date Title
US74572406P 2006-04-26 2006-04-26
US74572006P 2006-04-26 2006-04-26
US74571506P 2006-04-26 2006-04-26
US60/745,724 2006-04-26
US60/745,720 2006-04-26
US60/745,715 2006-04-26
US11/681,976 2007-03-05
US11/681,995 2007-03-05
US11/681,985 2007-03-05
US11/681,976 US8538529B2 (en) 2006-04-26 2007-03-05 Power converter for use with implantable thermoelectric generator
US11/681,995 US8039727B2 (en) 2006-04-26 2007-03-05 Method and apparatus for shunt for in vivo thermoelectric power system
US11/681,985 US8003879B2 (en) 2006-04-26 2007-03-05 Method and apparatus for in vivo thermoelectric power system

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US8003879B2 (en) 2006-04-26 2011-08-23 Cardiac Pacemakers, Inc. Method and apparatus for in vivo thermoelectric power system
US8039727B2 (en) 2006-04-26 2011-10-18 Cardiac Pacemakers, Inc. Method and apparatus for shunt for in vivo thermoelectric power system
US8538529B2 (en) 2006-04-26 2013-09-17 Cardiac Pacemakers, Inc. Power converter for use with implantable thermoelectric generator
WO2021184084A1 (fr) * 2020-03-20 2021-09-23 Moroz Technologies Pty Ltd Système et procédé de charge thermoélectrique d'une batterie

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US8039727B2 (en) 2006-04-26 2011-10-18 Cardiac Pacemakers, Inc. Method and apparatus for shunt for in vivo thermoelectric power system
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WO2021184084A1 (fr) * 2020-03-20 2021-09-23 Moroz Technologies Pty Ltd Système et procédé de charge thermoélectrique d'une batterie

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