Alfred E. Mann Foundation for Scientific Research

Alfred E. Mann Foundation

Pacesetter, Inc.

Medtronic Minimed, Inc.

Lyle Dean Canfield

Joseph H Schulman

Rajiv Shah

John Charles Gord

Charles L Byers

Michael Steven Colvin

An implantable sensor includes electronic circuitry for automatically performing on a periodic basis, e.g., every 1 to 24 hours, specified integrity tests which verify proper operation of the sensor.

Implantable sensor and integrity tests therefor

An implantable substrate sensor has electronic circuitry and electrodes formed on opposite sides of a substrate. A protective coating covers the substrate, effectively hermetically sealing the electronic circuitry under the coating. Exposed areas of the electrodes are selectively left uncovered by the protective coating, thereby allowing such electrodes to be exposed to body tissue and fluids when the sensor is implanted in living tissue. The substrate on which the electronic circuitry and electrodes are formed is the same substrate or 'chip' on which an integrated circuit (IC) is formed, which integrated circuit contains the desired electronic circuitry. Such approach eliminates the need for an hermetically sealed lid or cover to cover hybrid electronic circuitry, and allows the sensor to be made much thinner than would otherwise be possible. In one embodiment, two such substrate sensor may be placed back-to-back, with the electrodes facing outward. As required, capacitors that form part of the sensor's electronic circuits are formed on the substrate by placing metalization layers and a dielectric in vacant areas of the substrate surface.

Implantable substrate sensor with back-to-back electrodes

An implantable substrate sensor has electronic circuitry and electrodes formed on opposite sides of a substrate. A protective coating covers the substrate, effectively hermetically sealing the electronic circuitry under the coating. Exposed areas of the electrodes are selectively left uncovered by the protective coating, thereby allowing such electrodes to be exposed to body tissue and fluids when the sensor is implanted in living tissue. The substrate on which the electronic circuitry and electrodes are formed is the same substrate or 'chip' on which an integrated circuit (IC) is formed, which integrated circuit contains the desired electronic circuitry. Such approach eliminates the need for an hermetically sealed lid or cover to cover hybrid electronic circuitry, and allows the sensor to be made much thinner than would otherwise be possible. In one embodiment, two such substrate sensors may be placed back-to-back, with the electrodes facing outward. As required, capacitors that form part of the sensor's electronic circuits are formed on the substrate by placing metalization layers and a dielectric in vacant areas of the substrate surface.

Substrate sensor

Improved implantable monitoring systems suitable for long-term in vivo use to measure the concentration of one or more prescribed substances, such as glucose, are described herein. In particular, an implantable enzyme-based glucose monitoring system is described that includes at least one of the following: means for replenishing the enzyme solution as it is consumed by the enzymatic reaction; means for replenishing the electrolyte solution bathing the electrode assembly; and microprocessing means proximal the electrode assembly. In preferred embodiments, a microprocessor assembly is hermetically associated with the substrate to which the electrode assembly is affixed. Further, the monitoring systems employ one or more reservoir systems in fluid communication with enzyme and electrolyte chambers wherein the enzyme and electrolyte solutions are used. In a further embodiment, the monitoring systems use enzyme and electrolyte reservoir bulbs in fluid communication with the enzyme and electrolyte reservoirs, respectively, and positioned near the skin surface, thereby providing ready access to the enzyme and electrolyte solutions without the need for explantation of the device. Further provided herein is an enzyme solution comprising microspheres in association with the enzyme; whereby the enzyme is immobilized by the microspheres and the microspheres are in a fluid, flowable solution. Also provided herein is a method of extending the useful life of an implantable enzyme-based monitoring system, which method comprises providing means, within the system, to replenish the enzyme and/or electrolyte solution.

Implantable enzyme-based monitoring systems adapted for long term use

An implantable substrate sensor has electronic circuitry and electrodes formed on opposite sides of a substrate. A protective coating covers the substrate, effectively hermetically sealing the electronic circuitry under the coating. Exposed areas of the electrodes are selectively left uncovered by the protective coating, thereby allowing such electrodes to be exposed to body tissue and fluids when the sensor is implanted in living tissue. The substrate on which the electronic circuitry and electrodes are formed is the same substrate or &ldquo;chip&rdquo; on which an integrated circuit (IC) is formed, which integrated circuit contains the desired electronic circuitry. Such approach eliminates the need for an hermetically sealed lid or cover to cover hybrid electronic circuitry, and allows the sensor to be made much thinner than would otherwise be possible. In one embodiment, two such substrate sensors may be placed back-to-back, with the electrodes facing outward. As required, capacitors that form part of the sensor's electronic circuits are formed on the substrate by placing metalization layers and a dielectric in vacant areas of the substrate surface.

Implantable substrate sensor

Improved implantable monitoring systems suitable for long-term in vivo use to measure the concentration of one or more prescribed substances, such as glucose are described herein. In particular, an implantable enzyme-based glucose monitoring system is described that includes at least one of the following: means for replenishing the enzyme solution as it is consumed by the enzymatic reaction; means for replenishing the electrolyte solution bathing the electrode assembly; and microprocessing means proximal the electrode assembly. In preferred embodiments a microprocessor assembly is hermetically associated with the substrate to which the electrode assembly is affixed. Further, the monitoring systems employ one or more reservoir systems in fluid communication with enzyme and electrolyte chambers wherein the enzyme and electrolyte solutions are used. In a further embodiment, the monitoring systems use enzyme and electrolyte reservoir bulbs in fluid communication with the enzyme and electrolyte reservoirs, respectively, and positioned near the skin surface, thereby providing ready access to the enzyme and electrolyte solutions without the need for explantation of the device. Further provided herein is an enzyme solution including microspheres in association with the enzyme; whereby the enzyme is immobilized by the microspheres and the microspheres are in a fluid, flowable solution. Also provided herein is a method of extending the useful life of an implantable enzyme-based monitoring system, which method includes providing means, within the system, to replenish the enzyme and/or electrolyte solution.

A low power switched rectifier circuit is realized using P-MOS and N-MOS FET switches that are turned ON/OFF at just the right time by a detector and inverter circuit (which form an integral part of the rectifier circuit) to rectify an incoming ac signal in a highly efficient manner. Parasitic diodes and transistors that form an integral part of the FET circuitry respond to and rectify the incoming signal during start up, i.e., when no supply voltage is yet present, thereby providing sufficient operating voltage for the FET switches to begin to perform their intended rectifying function. In the absence of an incoming ac signal, i.e., during the time between biphasic pulses, the rectifier circuit is biased with an extremely small static bias current; but in the presence of an incoming ac signal, at a time when the positive and negative phases of the incoming signal are to be connected to positive and negative supply lines, a much larger dynamic bias current is automatically triggered.

Low power rectifier circuit for implantable medical device

A thin hermetically sealed electrical feedthrough suitable for implantation within living tissue permits electrical connection between electronic circuits sealed within an hermetically sealed case and electrical terminals or contacts on the outside of the case. The hermetically sealed case is made by hermetically bonding a cover to an insulating layer. The hermetically sealed electrical feedthrough is made by depositing a conductive trace on the insulating layer and then depositing another insulating layer thereover, so that the conductive trace is hermetically encapsulated within the insulating layers. At least two spaced-apart openings are formed in the insulating layers before bonding the cover thereto, exposing the conductive trace. Additional conductive material is then inserted within each of the openings or holes so as to form conductive vias that make electrical contact with the conductive trace. The cover is then hermetically sealed to the insulating layer so that at least one conductive via resides inside of an hermetically sealed cavity formed under the cover, and the other conductive via resides outside of the hermetically sealed cavity. An electrical feedthrough is thus formed through the respective conductive vias and conductive trace so that electrical contact may be made between the outside and inside of the hermetically sealed cavity.

Hermetically sealed electrical feedthrough for use with implantable

An active discharge circuit for use within an implantable medical device, such as a pacemaker, rapidly discharges a coupling capacitor connected between a therapy circuit and body tissue. The active discharge circuit has a switching device, a charge transfer capacitor, and a clock. The clock is coupled to a control input of the switching device and provides a clock signal thereto. In response to the clock signal, the switching device sequentially and repeatedly couples the charge transfer capacitor to a discharge voltage supply so that charge transfers therebetween, and then couples the charge transfer capacitor to the coupling capacitor so that charge transfers therebetween. As the switch oscillates in response to the clock signal, the coupling capacitor is actively discharged.

Growing community of inventors

Lake Hughes, CA, United States of America

Lyle Dean Canfield