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J. Thomas Mortimer

Bio: J. Thomas Mortimer is an academic researcher from Case Western Reserve University. The author has contributed to research in topics: Diaphragm pacing & Motor nerve. The author has an hindex of 28, co-authored 58 publications receiving 4329 citations.


Papers
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Patent
11 Oct 1984
TL;DR: A self-curling sheet (A) of nonconductive material is biased to curl into a tight spiral as mentioned in this paper, and a cut out (22) is removed from one corner of the sheet such that, when the sheet spirals, a passage (28) defined axially therethrough has one portion with a smaller diameter and another portion having a larger diameter.
Abstract: A self-curling sheet (A) of non-conductive material is biased to curl into a tight spiral. A cut out (22) is removed from one corner of the sheet such that, when the sheet spirals, a passage (28) defined axially therethrough has one portion with a smaller diameter and another portion with a larger diameter. A pair of conductive strips (40, 50) are disposed on the self-curling sheet such that one extends peripherally around each of the larger and smaller diameter regions of the passage therethrough. The conductive segments may be electrically conductive for applying electrical impulses or fluid conductive for infusing medications. In use, a first edge (14) of the self-curling sheet is disposed adjacent a nerve trunk which is to receive the cuff therearound. The self-curling sheet is controllably permitted to curl around the nerve forming an annular cuff therearound.

374 citations

01 Jan 1998
TL;DR: In this paper, a blind volunteer with retinitis pigmentosa was chronically implanted with a self-sizing spiral cuff electrode around an optic nerve, which produced localized visual sensations that were broadly distributed throughout the visual field.
Abstract: A blind volunteer with retinitis pigmentosa was chronically implanted with a self-sizing spiral cuff electrode around an optic nerve. Electrical stimuli applied to the nerve produced localized visual sensations that were broadly distributed throughout the visual field and could be varied by changing the stimulating conditions. These results demonstrate the potential for constructing a visual prosthesis, based on electrical stimulation of the optic nerve, for blind subjects who have intact retinal ganglion cells. q 1998 Elsevier Science B.V. All rights reserved.

372 citations

Patent
11 Oct 1984
TL;DR: In this paper, a single electrode, asymmetric electrode cuff, is disposed around a nerve trunk to generate unidirectionally propagating action potentials on the nerve trunk, and a signal generator is connected between a cathode and an anode disposed asymmetrically in an electrically conductive relationship within the body tissue.
Abstract: A single electrode, asymmetric electrode cuff (B) is disposed around a nerve trunk (A). A signal generator (C) is connected between a cathode (20) disposed asymmetrically in the electrode cuff and an anode (22) disposed in an electrically conductive relationship within the body tissue. The signal generator applies a stimulus signal (FIG. 3) which generates unidirectionally propagating action potentials on the nerve trunk. The electrode cuff includes a dielectric sleeve (10) in which the cathode is positioned a first distance (L1) from an escape end (14) and a second distance (L2) from an arrest end (16). The first distance is at least 1.7, and preferably about 7, times the second distance. This asymmetry causes a primary or forward stimulus signal current (30) to be correspondingly greater than a secondary or reverse current (32).

357 citations

Journal ArticleDOI
TL;DR: Results of a nerve model investigation indicated that the threshold difference between different diameter nerve fibers would be dependent on pulse width, the choice between monophasic and biphasic stimuli, and the delay between the primary cathodic and secondary anodic pulses.
Abstract: The effect of stimulus parameters on the recruitment characteristics of motor nerve was studied for regulated current monophasic and balanced charge biphasic stimuli. Results of a nerve model investigation indicated that the threshold difference between different diameter nerve fibers would be dependent on pulse width, the choice between monophasic and biphasic stimuli, and the delay between the primary cathodic and secondary anodic pulses. Threshold difference increased with decreasing pulse width, the greatest effects evident for pulses less than 100 ?s. Biphasic stimulation with no delay between pulses provided greater threshold separation than monophasic stimulation or biphasic stimulation with delay. Animal experiments, in which recruitment in a nerve trunk composed of mixed diameter nerve fibers was examined, showed a decrease in recruitment slope with a decrease in pulse width and with the use of a biphasic, zero delay pulse. These results were examined through muscle force measurements using both a metal loop electrode encircling the nerve trunk and a nerve cuff electrode, i. e., a loop electrode in an insulating tube.

298 citations

Patent
04 Mar 1997
TL;DR: In this article, a customizable interactive educational system 30 includes an assembly of data modules 60 which control the inputting, categorizing, and formatting of educational data which have been determined to be well-accepted principles.
Abstract: A customizable interactive educational system 30 includes an assembly of data modules 60 which control the inputting, categorizing, and formatting of educational data which have been determined to be well-accepted principles. The well-accepted principles create a primary knowledge base stored as a professor customizable interactive textbook (CITbook) 40. The primary knowledge base is organized by at least subject matter, topic, and knowledge level and the data are linked to each other in predetermined sequences. Data managers 200 allow a professor teaching a course to select and manipulate portions of the primary knowledge base of the professor CITbook 40 to generate a customized student version 50 in accordance with the course being taught and personal data added by the professor. The data added or altered by the professor is visually distinguished from the well-accepted data. Maps are generated which include link sequences connecting the selected subjects and topics in a primary sequence based on the course being taught. Secondary links are generated interconnecting the selected subjects and topics in multiple directions allowing the student to access reference data by selecting one of the secondary links. A presentation manager 250 executes the primary sequence and presents the selected subjects and topics contained in the primary sequence to the student. The secondary links allow the student to dynamically change the primary sequence thereby accessing background or advanced topics.

287 citations


Cited by
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Journal ArticleDOI
TL;DR: The physical basis for electrical stimulation of excitable tissue, as used by electrophysiological researchers and clinicians in functional electrical stimulation, is presented with emphasis on the fundamental mechanisms of charge injection at the electrode/tissue interface.

1,875 citations

Patent
30 Oct 2007
TL;DR: An analyte monitor includes a sensor, a sensor control unit, and a display unit as discussed by the authors, which is used to display an indication of a level of an analyte, based on the data obtained using the sensor.
Abstract: An analyte monitor includes a sensor, a sensor control unit, and a display unit. The sensor has, for example, a substrate, a recessed channel formed in the substrate, and conductive material disposed in the recessed channel to form a working electrode. The sensor control unit typically has a housing adapted for placement on skin and is adapted to receive a portion of an electrochemical sensor. The sensor control unit also includes two or more conductive contacts disposed on the housing and configured for coupling to two or more contact pads on the sensor. A transmitter is disposed in the housing and coupled to the plurality of conductive contacts for transmitting data obtained using the sensor. The display unit has a receiver for receiving data transmitted by the transmitter of the sensor control unit and a display coupled to the receiver for displaying an indication of a level of an analyte. The analyte monitor may also be part of a drug delivery system to alter the level of the analyte based on the data obtained using the sensor.

1,856 citations

Journal ArticleDOI
TL;DR: Techniques for characterizing electrochemical properties relevant to stimulation and recording are described with examples of differences in the in vitro and in vivo response of electrodes.
Abstract: Electrical stimulation of nerve tissue and recording of neural electrical activity are the basis of emerging prostheses and treatments for spinal cord injury, stroke, sensory deficits, and neurological disorders. An understanding of the electrochemical mechanisms underlying the behavior of neural stimulation and recording electrodes is important for the development of chronically implanted devices, particularly those employing large numbers of microelectrodes. For stimulation, materials that support charge injection by capacitive and faradaic mechanisms are available. These include titanium nitride, platinum, and iridium oxide, each with certain advantages and limitations. The use of charge-balanced waveforms and maximum electrochemical potential excursions as criteria for reversible charge injection with these electrode materials are described and critiqued. Techniques for characterizing electrochemical properties relevant to stimulation and recording are described with examples of differences in the in vitro and in vivo response of electrodes.

1,843 citations

Patent
26 Jul 2001
TL;DR: A vascular anastomosis staple is used in coronary artery bypass surgery as mentioned in this paper to create a leak-proof seal between a vascular graft and the ascending aorta in CABG surgery.
Abstract: A system for performing an end-to-side vascular anastomosis, including an anastomosis device, an application instrument and methods for performing a vascular anastomosis. The system is applicable for performing an anastomosis between a vascular graft and the ascending aorta in coronary artery bypass surgery, particularly in port-access CABG surgery. A first aspect of the invention includes a vascular anastomosis staple. A first configuration has two parts: an anchor member, forming the attachment with the target vessel wall and a coupling member, forming the attachment with the bypass graft vessel. The anastomosis is completed by inserting the coupling member, with the graft vessel attached, into the anchor member. A second configuration combines the functions of the anchor member and the coupling member into a one-piece anastomosis staple. A second aspect of the invention includes an anastomotic fitting, having an inner flange over which the graft vessel is everted and an outer flange which contacts the exterior surface of the target vessel. A tailored amount of compression applied by the inner and outer flanges grips the target vessel wall and creates a leak-proof seal between the graft vessel and the target vessel. A third aspect of the invention has a flange to which the graft vessel attaches, by everting the graft vessel over the flange, and a plurality of staple-like members which attach the flange and the everted end of the graft vessel to the wall of the target vessel to form the anastomosis.

1,726 citations

Patent
22 May 1997
TL;DR: In this article, the authors present a system and method for interactive, adaptive, and individualized computer assisted instruction, which includes an agent (108) for each student, which adapts to its student, and provides individualized guidance to the student and controls to the augmented computer assisted instructional materials.
Abstract: This invention relates to a system and method for interactive, adaptive, and individualized computer assisted instruction. This invention includes an agent (108) for each student (101) which adapts to its student, and provides individualized guidance to the student and controls to the augmented computer assisted instructional materials. The instructional materials of this invention are augmented to communicate the student's performance and the material's pedagogical characteristics to the agent, and to receive control from the agent. In a preferred embodiment, the agent maintains data reflecting the student's pedagogic or cognitive characteristics in a protected and portable media in the personal control of the student. Preferably, the content of the communication between the agent and the materials conforms to specified interface standards, so that the agent acts independently of the content of the particular materials. Also preferably, the agent can project using various I/O modalities integrated engaging, lifelike display personna(e).

1,478 citations