Alfred E. Mann Foundation for Scientific Research

Kate E Purnell

Guangqiang Jiang

Gary D Schnittgrund

Joseph H Schulman

Yitzhak Zilberman

David L Canfield

Andrew J Szyszkowski

Martin J Vogel

Adam Vogel, Legal Representative

Jiang Guangqiang

The invention is directed to an apparatus substantially eliminating destructive low-temperature, humidity-enhanced phase transformation of yttria-stabilized zirconia in general, as well as eliminating low-temperature degradation of yttria-stabilized tetragonal zirconia polycrystalline ceramic (Y-TZP). The martensitic-type phase transformation from tetragonal to monoclinic is accompanied by severe strength degradation in a moist environment at low-temperature, specifically at room temperature as well as at body temperature. This class of materials has been chosen as the packaging material for small implantable neural-muscular sensors and stimulators because of the high fracture toughness and high mechanical strength. This destructive phase transformation has been substantially eliminated, thus ensuring the safety of long-term implants, by subjecting the sintered components to post-machining hot isostatic pressing, such that the average grain size is less than about 0.5 microns.

Low temperature degradation resistant yttria stabilized zirconia

A method of removing an implantable electronic microdevice by an integral removal loop or circumferential ring to facilitate removal of the implanted microdevice without additional surgery. The device is removed by pulling it along the surgically created implantation path. Optionally a radio-opaque tether provides a method of locating the implantable microdevice without additional surgery and attachment of one end of the tether to a radio-opaque marker provides a method of locating the end of the tether to facilitate removal of the implantable microdevice from living tissue.

Method for removing surgically implanted devices

The invention is directed to a material and a method of substantially eliminating destructive low-temperature, humidity-enhanced phase transformation of yttria-stabilized zirconia in general, as well as eliminating low-temperature degradation of yttria-stabilized tetragonal zirconia polycrystalline ceramic (Y-TZP). The martensitic-type phase transformation from tetragonal to monoclinic is accompanied by severe strength degradation in a moist environment at low-temperature, specifically at room temperature as well as at body temperature. This class of materials has been chosen as the packaging material for small implantable neural-muscular sensors and stimulators because of the high fracture toughness and high mechanical strength. This destructive phase transformation has been substantially eliminated, thus ensuring the safety of long-term implants, by subjecting the sintered components to post-machining hot isostatic pressing, such that the average grain size is less than about 0.5 microns.

Material and method of forming yttria-stabilized zirconia to minimize low-temperature degradation

A method of bonding a ceramic part to a metal part by heating a component assembly including the metal part, the ceramic part, and a thin essentially pure interlayer material placed between the two parts heated at a temperature that is greater than the temperature of the eutectic formed between the metal part and the interlayer material, but that is less than the melting point of the interlayer material, the ceramic part or the metal part is disclosed. The component assembly is held in intimate contact at temperature in a non-reactive atmosphere for a sufficient time to develop a hermetic and strong bond between the ceramic part and the metal part. The bonded assembly is optionally treated with acid to remove any residual free nickel and nickel salts to assure a biocompatible assembly for implantation in living tissue.

Manufacturing method for a ceramic to metal seal

A housing for an implantable medical device in the shape of a hollow magnetic field concentrating tube about which an electrically conductive wire coil is wound and within which medical device electronics is housed. The tube, preferably made of ferrite, is encased in a protective sleeve formed of a material that is impervious to body fluids. The coil provides an electrical output as a result of being exposed to a varying magnetic field that is concentrated around the coil by virtue of the field concentrating tube. The output of the coil is utilized as part of a power supply for the medical device electronics. The sleeve has a generally cylindrical cross-section having an outside diameter of about 3.175 mm and an axial length in the range of about 3.2 mm to 8 mm.

Housing for an implantable medical device

The invention is a method of qualifying an implantable ceramic component made of high-purity dense yttria tetragonal zirconium oxide polycrystal (Y-TZP) by application of non-destructive tests. Specifically, a qualified Y-TZP ceramic component or witness sample is examined by X-ray diffraction to determine the initial monoclinic phase content. The component or witness sample is exposed to steam at 127&#xb0; C. for a predetermined period of time, preferably six hours. The monoclinic phase content is determined for the post-exposure sample. The absolute difference between the initial monoclinic phase content and the post-exposure monoclinic phase content is calculated by difference. If the difference is less than 2.1% the sample is accepted. In an alternate embodiment, the components that pass the screening test are examined by ultrasonic testing to evaluate soundness of the ceramic component. Any component that presents a flaw of greater than three microns is rejected.

Non-destructive method of predicting performance of ceramic components

The invention is a method of bonding a ceramic part to a metal part by heating a component assembly comprised of the metal part, the ceramic part, and a very thin essentially pure interlayer material of a compatible interlayer material placed between the two parts and heated at a temperature that is greater than the temperature of the eutectic formed between the metal part and the metal interlayer material, but that is less than the melting point of either the interlayer material, the ceramic part or the metal part. The component assembly is held in intimate contact at temperature in a non-reactive atmosphere for a sufficient time to develop a hermetic and strong bond between the ceramic part and the metal part. The bonded component assembly is optionally treated with acid to remove any residual free nickel and nickel salts, to assure a biocompatible component assembly for implantation in living tissue.

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Valencia, CA, United States of America

Kate E Purnell