Other

University of California

Ventritex, Inc.

Pacesetter, Inc.

M Dean Matthews

Pedro G Medrano

Benjamin D Pless

M Elizabeth Bush

Drew A Hoffmann

Alexander Pechnik

A capacitor optimized for use in an implantable medical device such as an implantable defibrillator is disclosed. In its simplest form, the capacitor comprises a thin planar dielectric sheet that has an array of cells open to one or both sides. Metallization is applied to the surface of the cells such that the walls of adjacent cells form a capacitor with the wall that separates the cells serving as the dielectric. The metallization pattern that forms the electrical connection to the cells may be patterned to limit the allowable current flow to each individual cell, thereby providing a fuse in the case of local dielectric failure.

Micro-cellular capacitor for use in implantable medical devices

An improved endocardial lead for electrocardial stimulation includes a sleeve that has a face surface. A conductor fitted into the sleeve, such that a distal end of the conductor passes completely through the sleeve, past the face surface, is electrically and mechanically connected to the face surface of the sleeve by mechanical means, e.g. crimping, and/or through the application of heat, e.g. welding or brazing. An electrode is integrated with the sleeve along an outer sleeve surface. A highly reliable, redundant joint is thereby provided between the sleeve and the conductor that secures the conductor against movement and therefore minimizes stress placed on the conductor, preventing fatigue to the conductor at the joint. A sleeve made in accordance with the present invention provides the narrowest and shortest possible conductor/electrode joint to minimize impact on the patient, while at the same time providing an endocardial lead that has excellent electrical properties, mechanical stability, and ease of manufacture, and that may be made from any desired material to thereby take advantage of new and/or improved materials.

Electrical connection for medical electrical stimulation electrodes

An electrochemical capacitor is prepared by assembling a stacked assembly of at least two bipolar electrodes, where each of the bipolar electrodes includes a metal foil electrode substrate having a porous, electronically conductive substrate coating, preferably porous platinum, on each surface. The stacked assembly further has a porous separator layer between each of the electrodes, made of a material that is electronically non-conductive. An ionic conductor electrolyte, preferably a polyoxometalate, that wets both the substrate coating and the separator layer at temperatures above the melting point of the solid ionic conductor electrolyte is provided, the ionic conductor electrolyte having a melting point above about 30.degree. C. The ionic conductor electrolyte is introduced into the stacked assembly, as by external infiltration with an optional applied pressure to assist the infiltration.

Solid state electrochemical capacitors and their preparation

A method for making an electrochemical capacitor is disclosed. A plurality of bipolar electrodes having porous conductive oxide coatings on opposite sides of a thin metal foil are first produced in a fixture assembly using sol-gel processing techniques. A dielectric oxide coating is then applied to one or both conductive coatings using the sol-gel process. A stack of a plurality of the bipolar electrodes with adjacent electrodes separated by a predetermined amount of a solid electrolyte is assembled. The stacked assembly is heated to a temperature above the electrolyte melting point allowing the molten electrolyte to infiltrate the porous coatings. Pressure is applied to the stacked assembly sufficient to produce intimate contact between adjacent surfaces of the bipolar electrodes while expelling excess liquid from between the electrode surfaces. The stacked assembly is cooled in a controlled fashion to produce a laminate structure. This laminate structure may be cut by a diamond saw along the edges and packaged to produce an electrochemical capacitor having the desired capacitance.

Method for producing multi-cell solid state electrochemical capacitors

A process for producing dense bodies from mixtures of materials with significantly different electrical resistivities. A mixture of electrically conducting powder and a dielectric or semiconducting powder is subjected to pressure and an intense electric current pulse of sufficiently short duration such that the heating is largely confined to the material of superior electrical conductivity. Densification is achieved under pressure prior to the attainment of thermal equilibrium within the mixture. Diamond/titanium diboride and boron carbide/titanium carbide composites are typical of the process.

Densification of powder compacts by fast pulse heating under pressure

An electric pulsed power vacuum press assembly for fast pulse heating of electrically conductive materials at high pressures is disclosed. The fast pulse capability is provided for by a current path (49) that is characterized by extremely low inductance and resistance. The low inductance of the press structure is achieved through the use of parallel plate (52), (56) and coaxial (64), (98) transmission line elements in the circuit. The use of a vacuum environment (46) reduces contamination of the material being processed. The press is useful for achieving fine scale adiabatic heating in dielectric/conductor mixtures (11) such as graphite and diamond, allowing for extreme heating of the conductive phase with minimal heat transfer to the dielectric phase during the heating pulse. Fine scale adiabatic heating enables phase changes and consolidation to be achieved in a composite with minimum energy input and minimum heating of the press structure.

Electric pulsed power vacuum press

A method for consolidating or densifying material selected from metal, ceramic or mixtures thereof to form a densified compact article, which process includes (a) arranging the sample to be consolidated or densified in a general configuration within a temperature controlled high pressure chamber completely surrounded by a pre-glass material which forms a glass at elevated temperature in close proximity and surrounded by a heating element within the pre-glass material and having at least one temperature measuring device in close proximity to the sample all located within a shell; (b) externally heating the arrangement produced in step (a) at an elevated temperature for a time effective to remove moisture, volatiles, impurities, volatile oxides or mixtures thereof; (c) heating the sample produced in step (c) to produce fusion of the pre-glass at between about 500.degree. to 1600.degree. C. to encapsulate the heating element; (d) using the encapsulated heating element, to locally heat the prearticle and sample to a temperature of between about 700.degree. and 2,200.degree. C., monitoring the sample temperature using the temperature measuring device, and simultaneously applying a pressure to the prearticle of between about 50,000 and 275,000 psi for a time effective to densify the material, wherein the external pressure chamber has a surface temperature in contact with the prearticle of not greater than 500.degree. C., and recovering the formed article. The brief localized heating makes it possible to use the high pressing pressures.

Method for localized heating and isostatically pressing of glass

A process for preparing ceramic-metal composites without melting the metal is disclosed. A compact or green body is made from a ceramic and a metal, and the compact is sealed in a vacuum in a container such as a glass envelope. The compact is then heated to a temperature below the melting point of the metal, but high enough so that the vapor pressure of the metal is significant, and the metal redistributes through the ceramic by evaporation and condensation. The composite thereby forms a body having ceramic particles uniformly coated by the metal. Products formed by the process and fabrication of a B.sub.4 C/Cr composite are also disclosed.

Growing community of inventors

Saratoga, CA, United States of America

M Dean Matthews