Massachusetts Institute of Technology

Innersea Technology

Other

David J Edell

Karen K Gleason

Herbert H Sawin

Joseph F Rizzo, Iii

John L Wyatt, Jr

Scott J Limb

Edward F Gleason

James C Weaver

Stephen K Burns

Sean V Sexton

Harry Frederick Bowman

Brian P Farrell

H Frederick Bowman

Bruce C Larson

Ying-Ping Liu

Lloyd D Clark, Jr

An apparatus and corresponding method for providing data communications to and from a location within a body cavity in which an internal transmitter receives a first data stream from an in vivo sensor, electrode, or transducer. The internal transmitter is configured and arranged to asynchronously modulate the first data stream and to provide as an output a first optical signal carrying the asynchronously modulated first data stream. The apparatus further includes an external receiver that is configured and arranged external to the body cavity such that an optical input to the external receiver is optically coupled to the internal transmitter output and receives the optical signal therefrom. The external receiver asynchronously demodulates the received optical signal and provides as an output at least one signal indicative of the first data stream.

Optical telemetry of data and power for wireless biomedical sensors and actuators

A precision current source is disclosed that includes a voltage setting circuit that precisely sets the voltage across a range setting resistor to set the current flowing in a load resistance connected in series with the range setting resistor. The voltage setting circuit precisely sets the voltage across the range setting resistor as a function of an input reference voltage. The voltage setting circuit includes an instrumentation amplifier that determines the voltage across the range setting resistor and the difference between this voltage and the reference voltage is used drive a drive voltage amplifier. The drive voltage amplifier output adjusts to minimize the difference between the reference voltage and the voltage across the range setting resistor. Other embodiments include the use of a DC blocking capacitor to allow only AC coupling and various nulling. circuits to remove any charge buildup on a DC blocking capacitor.

Analog bipolar current source

An implantable medical device (IMD) is disclosed that is formed on a substrate composed of liquid crystal polymer (LCP). In one embodiment, the IMD can be an interconnection module for interconnecting an electrode array to an equipment module. The interconnecting module includes conductors disposed on the LCP substrate and coupled to the electrode array, and wherein the conductors are encapsulated using a silicone or LCP encapsulant. In another embodiment, the IMD is an electrode array and interconnect module disposed on an integral LCP substrate. An equipment module can be coupled to the interconnect module. Alternatively, a hybrid electronic circuit can be coupled to the interconnect module for signal processing and conditioning signals received from the electrode array or for providing stimulus signals to the electrode array. In this embodiment, all of the conductors and at least a portion of the electrodes in the electrode array are encapsulated using a silicone or LCP encapsulant. In another embodiment, the IMD is an electrode array, an interconnecting module, and a hybrid circuit that are disposed on an LCP substrate. The interconnecting module is used to provide signal paths to and from the electrodes in the electrode array to the hybrid circuit. In this embodiment, all of the conductors, the hybrid electronic circuit and at least a portion of the electrodes in the electrode array are encapsulated using a silicone or LCP encapsulant.

Implantable devices having a liquid crystal polymer substrate

Provided are methods for forming a fluorocarbon polymer thin film on the surface of a structure. In one method, a monomer gas is exposed to a source of heat having a temperature sufficient to pyrolyze the monomer gas and produce a source of reactive CF.sub.2 species in the vicinity of the structure surface. The structure surface is maintained substantially at a temperature lower than that of the heat source to induce deposition and polymerization of the CF.sub.2 species on the structure surface. In another method for forming a fluorocarbon polymer thin film, the structure is exposed to a plasma environment in which a monomer gas is ionized to produce reactive CF.sub.2 species. The plasma environment is produced by application to the monomer gas of plasma excitation power characterized by an excitation duty cycle having alternating intervals in which excitation power is applied and in which no excitation power is applied to the monomer gas. The monomer gas employed in the methods preferably includes hexafluoropropylene oxide. The monomer gas pyrolysis and plasma excitation methods can be carried out individually, sequentially, or simultaneously. Flexible fluorocarbon polymer thin films can thusly be produced on wires, twisted wires, neural probes, tubing, complex microstructures, substrates, microfabricated circuits, and other structures. The thin films have a compositional CF.sub.2 fraction of at least about 50%, a dielectric constant of less than about 1.95, and a crosslinking density of less than about 35%.

Chemical vapor deposition of fluorocarbon polymer thin films

A low-pressure neural contact structure for contact with neural tissue, for example, neural tissue of the retina within which are ganglion cells to be electrically stimulated. The contact structure comprises a first portion for attachment to a first bodily location, such as the inner surface of the retina, and a second portion interconnected with the first portion via an interconnection and being held in contact with the neural tissue. The interconnection exhibits a weak restoring force which in conjunction with the geometry of said second portion provides a preselected desired pressure of contact against the neural tissue. As adapted for the retina, the interconnection exhibits a weak restoring force developed in response to curvature of the interconnection along the inner radius of the retina.

Low-pressure neural contact structure

Low pressure neural contact structure

The invention provides a method for preferentially stimulating neural somas over neural axons located around the somas but not integral with the somas. In the invention, a positive electrical pulse is applied to a region of neural tissue consisting of one or more neural somas to be stimulated and neural axons, and due to the physiology of the somas, they are preferentially stimulated by the electrical pulse over the neural axons not integral with the somas to be stimulated. The preferential soma stimulation provided by the invention achieves the advantage of locally focusing external stimulation such that it may be directed to particular soma locations for indicating location-dependent sensory information. Thus the pulse scheme of the invention may be employed in prosthetic applications directed to, for example, the retinal ganglia neural tissue.

Method and apparatus for preferential neuron stimulation

An aqueous solution of cesium hydroxide serves as a highly selective anisotropic etch for semiconductor crystals including silicon. The cesium hydroxide also has a high etch selectivity for tantalum with respect to semiconductor crystals.

Cesium hydroxide etch of a semiconductor crystal

A probe adapted for insertion in living tissue for measuring oxygen partial pressure and temperature at a plurality of sites in living tissue is provided. A temperature sensitive resistor is positioned adjacent each of a plurality of oxygen sensors so that the oxygen partial pressure measured can be adjusted for tissue temperature. The probe substrate has thermal properties similar to living tissue and the resistors are formed of a material having a temperature sensitive resistance. Temperature at each temperature sensitive resistor is obtained by measuring resistance with a four point measurement and correlating the resistance to temperature.

Apparatus for measuring oxygen partial pressure and temperature, in

A method of encapsulating a lead bonding pad region of an integrated circuit (such as a sensor used in an implantable medical device) is disclosed. The excapsulant (such as Teflon.TM.-TFE) is mechanically gripped on the surface of the circuit by anchor interlock portions which are held in undercut grooves, micromachined, in a predefined pattern, in the circuit substrate. The encapsulant is held down by the portions in the grooves, forms a tight mechanical seal with the substrate surface and with the insulation around an attached lead, and blocks intrusion of contaminants along the surfaces between these materials or through the encapsulant.

Micromachined bonding surfaces and method of forming the same

Flexible measurement probes are described for the determination of oxygen partial pressure; temperature and perfusion; and combined measurement of oxygen partial pressure, temperature, and perfusion. The probes are fabricated by patterning a metal coated substrate to form a conductive pattern of ribbon leads, insulating the conductive ribbon leads except for contact openings, and then attaching sensors to the conductive ribbon leads through noble metal plated open contacts. The plated contacts may be used directly to measure oxygen partial pressure.

Flexible measurement probes

Oxygen partial pressure and temperature are measured in living tissue by inserting a thin probe into living tissue. The probe includes a plurality of spatially separated thermal sensors secured to the probe substrate. A plurality of oxygen sensors is positioned along the length of the probe substrate and each oxygen sensor is associated with and positioned adjacent to or is an integral part of one of the thermal sensors. Electrical parameters of the sensors located on the probe are measured and used to determine oxygen partial pressure and to determine temperature at each of a plurality of sites along the probe.

Growing community of inventors

Lexington, MA, United States of America

David J Edell