Abstract: An implantable system, such as a neural stimulator or a cochlear implant system, includes a rechargeable battery configuration having improved recharging and lifetime characteristics. The battery is housed within the implant's case and has first and second electrode plates. Each electrode plate has a plurality of slits that extend across a substantial portion of the plate's surface area. The slits in the electrode plates reduce the magnitude of eddy currents induced in the plates by external ac magnetic fields allowing faster battery recharging times. Alternatively, the electrode plates are wrapped in a spiral configuration such that, in the plane of the spiral, the electrode plates have a small cross-sectional area and no closed current loops. Additionally, the implant device may be housed in a case formed of a high-resistivity material and a circuit included in the implant device is configured to avoid large current loops that would result in eddy current heating.

Abstract: A protective, biocompatible coating or encapsulation material protects and insulates a component or device intended to be implanted in living tissue. The coating or encapsulation material includes a thin layer or layers of alumina, zirconia, or other ceramic, less than 25 microns thick, e.g., 5-10 microns thick. The alumina layer(s) may be applied at relatively low temperature. Once applied, the layer provides excellent hermeticity, and prevents electrical leakage. Even though very thin, the alumina layer retains excellent insulating characteristics. In one embodiment, an alumina layer less than about 6 microns thick provides an insulative coating that exhibits less than 10 pA of leakage current over an area 75 mils by 25 mils while soaking in a saline solution at temperatures up to 80.degree. C. over a three month period.

Abstract: An implantable living tissue stimulator avoids the use of conventional coupling capacitors in its output stage, yet still prevents an average dc current flow from flowing through living tissue in electrical contact with the stimulator. The output stage generates and applies a biphasic stimulating current pulse to selected paired output terminals. The terminals, in turn, are electrically connected to respective electrodes which are positioned so as to contact the living tissue to be stimulated. In one embodiment, special circuitry is employed within the output stage to block dc current flow through the living tissue and to balance the electrical charge that is delivered to the living tissue. In another embodiment, the electrodes themselves are made from a material that allows them to function as a capacitor. In yet an additional embodiment, the coupling capacitors are integrated into the leads that connect the output terminals of the output stage with the electrodes.

Abstract: An implantable sensor/stimulator is connectable to a controller using just two conductors, which two conductors carry both operating power and data (data commands and/or measured data) between the sensor/stimulator and control circuit. Each sensor/stimulator may be serially connected to another sensor/stimulator, again using only two conductors, thereby allowing a "daisy chain" of such sensors/stimulators to be formed. Each sensor/stimulator in the daisy chain is individually addressable by the control circuit. Input data is sent to the sensors over the two conductors using a phase-modulated biphasic modulation scheme, which scheme also provides operating power for each sensor/stimulator connected to the two conductors. Output data is sent from the sensors to the controller over the same two conductors using a pulse-position presence/absence modulation scheme. The data transmission schemes provide a very high signal-to-noise ratio.

Abstract: An implant stimulator device uses tantalum and tantalum pentoxide as a system for the conveyance of electrical stimulation pulses from stimulus-forming circuitry contained within an hermetic enclosure to the saline fluids of body tissue to be stimulated. Internal coupling capacitors are not used, yet the danger of having DC current flow to the saline fluids is eliminated. A preferred embodiment provides a multiplicity of electrode contacts made from sintered, anodized tantalum, connected via tantalum wire leads to tantalum feedthroughs into the hermetically sealed package containing the stimulus pulse-forming electronic circuitry. One or more counter electrode contacts (for monopolar or bipolar configurations, respectively) made of activated iridium, non-activated iridium, iridium in combination with a noble or non-noble metal, platinum, gold, or other metal which forms a low impedance contact with body fluids, is/are connected via platinum or other conductive metal leads to return feedthroughs.

Abstract: A cochlea stimulation system includes a patient wearable system comprising an externally wearable signal processor (WP) and a headpiece in electronic communication with an implanted cochlear stimulator (ICS). The ICS comprises eight output stages each having two electrically isolated capacitor-coupled electrodes, designated "A" and "B", circuits for monitoring the voltages on these electrodes, and circuits for both transmitting status information to and receiving control information from the WP. Based upon information received from the WP, a processor within the ICS can control both the frequency and the widths of the output stimulation pulses applied to the electrodes and may select which electrodes to monitor. The ICS receives power and data signals telemetrically through the skin from the WP. To save power, the ICS may be "powered down" by the WP based upon the absence of audio information or "powered up" if audio is present.

Abstract: A power control loop is established between an external control device and an implantable device so that only the amount of power needed by the implant device to sustain its present operating conditions is transmitted across a transcutaneous transmission link, thereby reducing the amount of power expended by the external control device. In one embodiment, the power control loop is used with a cochlea stimulating system that includes an externally wearable signal receiver and processor (WP) and an implanted cochlear stimulator (ICS). The power control loop is provided between the ICS and the WP such that power delivered to the ICS is precisely controlled in a closed loop manner, with a variable amount of RF energy (power) being transmitted across the transcutaneous link between the WP and ICS. The transmitted RF energy is received by the ICS and is converted to a voltage that is used as a power source within the ICS for stimulating electrode contacts of the ICS.

Abstract: A patient monitoring system measures the concentration of a particular substance in a patient's tissue, blood, or other bodily fluids, provides an indication of the rate of change of such concentration, and determines whether the measured concentration and rate of change are within certain preset limits. If not, an audible and/or visual alarm signal is generated. The patient monitoring system includes at least one enzymatic sensor adapted to be inserted into the patient, where it produces sensor signals related to the concentration of the substance being measured. The sensor signals are delivered through a suitable interconnect cable to a monitor. In one embodiment, the interconnect cable includes a contactless connector that electrically isolates the enzymatic sensor from the monitor, and reduces the number of conductors required to interface with a plurality of sensors.

Abstract: An implantable cochlear stimulator (ICS) has eight output stages (212), each having a current source (212B) connected to a pair of electrodes, designated "A" and "B", through respective output coupling capacitors and an electrode switching matrix (212C). An indifferent electrode is connected to each output stage by way of an indifferent electrode switch (212D). The current source generates a precise stimulation current as a function of an analog control voltage. The analog control voltage, in turn, is generated by a logarithmic D/A converter. The D/A converter serially converts data words, received in a data frame from an external source, to respective analog control voltages that are applied sequentially to the current sources of each output stage. An output mode register (208) controls the switching matrix of each stage, as well as the indifferent electrode switch, to configure the electrodes for a desired stimulation configuration, e.g.

Abstract: 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.

Abstract: A glucose monitoring system continuously measures the glucose concentration in a patient's blood, provides an indication of the rate of change of such concentration, and determines whether the measured concentration and rate of change are within certain preset limits. If not, an audible and/or visual alarm signal is generated. The glucose monitoring system includes a glucose sensor adapted to be inserted into the venous system of the patient, where it responds to blood glucose and produces sensor signals related to the glucose concentration. The sensor signals are delivered through a suitable interconnect cable to a glucose monitor. In one embodiment, the interconnect cable includes a contactless connector that electrically isolates the glucose sensor from the monitor, and reduces the number of conductors required to interface with a plurality of sensors. The glucose monitor interprets the sensor signals by applying a previously determined calibration to quantitatively determine the blood glucose value.

Abstract: A replaceable catheter system provides a way to replace an implantable sensor, electrode system, and/or fluid delivery/receiving system. The replaceable catheter system includes an implantable shunt, such as an arteriovenous shunt, attached to an implantable introducer. The introducer and implantable shunt are adapted for surgical implantation within a patient such that it extends from immediately below the patient's skin to the implantable shunt site. The replaceable catheter system further includes a replaceable catheter that is adapted to be contained within the introducer and properly aligned such that an implantable sensor, electrode system, and/or fluid delivery system that is carried by the replaceable catheter is placed in operative association with the implantable shunt and exposed to any fluids passing through the implantable shunt.

Abstract: A physician's tester provides for physician monitoring and control of an implantable human tissue stimulator system, such as an implantable cochlear stimulator (ICS) system. During normal operation, the tissue stimulator system includes an implantable stimulator and a wearable processor (WP). The physician's tester is designed around a microprocessor, and is basically a modification of the WP. The tester provides control over the selection of voltages and currents to be measured and the presetting of parameters in the implantable stimulator during testing of the implanted stimulator and/or a patient's response to data transmitted by the WP/tester to the implanted stimulator. The physician's testor is portable and utilizes telemetry coupling with the implanted stimulator to provide communication between the tester and stimulator for the monitoring, control and measurement of the stimulator parameters. The tester resides in a portable housing having a control panel and a visual display.

Abstract: A tissue stimulating system including an external transmitter for transmitting data to an implanted stimulator including a processor for generating stimulation signals for application to a plurality of tissue stimulating electrodes. The processor selectively monitors the electrodes and/or voltages generated in the stimulator and generates stimulator status indicating signals for transmission to the external transmitter. The external processor receives and processes such status indicating signals.

Abstract: A system and method for detecting failures in an auditory stimulation device includes, in one embodiment, a microphone; a signal processor; a supercutaneous transmitter; a subcutaneous receiver; a subcutaneous transmitter; and a supercutaneous receiver. The signal processor generates a stimulation signal in response to the microphone detecting an audio signal, and the supercutaneous transmitter couples the stimulation signal through a skin surface of a patient. The subcutaneous receiver receives the stimulation signal, and the subcutaneous transmitter generates a feedback signal in response to receipt of the stimulation signal by the subcutaneous receiver. The supercutaneous receiver receives the feedback signal. In one variation of the embodiment, the signal processor generates an alarm signal when the feedback signal is not received.

Abstract: A multichannel stimulation system includes a plurality of implantable microminiature stimulators (microstimulators), each being connected to a respective implanted electrode or electrode array. Each microstimulator is selectively operable as controlled by an external (non-implanted) control unit. The electrode or electrode array is implanted so as to contact nerves and/or tissue that is to be stimulated. Operating power is inductively coupled from the control unit to the microstimulators. An information signal is also coupled to the microstimulators to control which of the microstimulators is to be activated to provide a stimulation pulse to its respective electrode. In one embodiment, the invention provides a cochlear prosthesis with an intracochlear electrode array being implanted within the human cochlea, and with selected electrodes of the array being connected to individual ones of the plurality of microstimulators.

Abstract: An external wearable processor (WP) of a cochlear stimulating system transmits a data signal to an implanted cochlear stimulator (ICS). The ICS is controlled through the data signal so that cochlear stimulation is provided by the ICS only after a determination is made that the WP is in proper signal contact therewith, and that the ICS is functioning properly. The ICS extracts a raw power signal from the data signal and generates different operating voltages from the extracted raw power signal. A detector generates a power bad signal whenever one of the operating voltages is less than a reference voltage. The ICS also detects and generates a carrier detect signal when the data signal is being received. Clock signals are generated within the ICS, and a phase locked loop (PLL) lock signal is generated when the clock signals are phase locked to the data signal. ICS circuitry further checks the parity of the incoming data signal and generates a parity alarm signal whenever a parity error is detected.

Abstract: A transcutaneous coupling device having an implanted unit and an external unit uses VELCRO for attaching the external unit to the skin in a proper location for optimal electromagnetic coupling between the units. The VELCRO has two surfaces, which adhere to one another, one surface being affixed to the external unit, and the other surface being adhesively attached to the skin. In one embodiment, the VELCRO is a patch coextensive with the surface area of the side of the external unit. In another embodiment, where the thickness of the VELCRO interferes with the coupling, the VELCRO takes the form of a ring or set of smaller patches permitting projecting portions of the side of the external unit to directly contact the skin for better coupling.

Abstract: A fluidic infusion system introduces a select liquid chemical into the environment surrounding the functional end of an in vivo catheter or probe. The catheter/probe typically has a-sensor or electrode positioned near or at its closed distal end. A plurality of spaced radial openings are formed in an appropriate pattern adjacent to the end of the catheter/probe for introducing the select liquid chemical into the appropriate environment. The catheter/probe has at least one lumen extending through its length for directing the liquid chemical from a controlled pump to the radial openings. The openings are positioned within the catheter/probe so that when the catheter/probe is inserted into the appropriate environment, e.g.

Abstract: An implantable cochlear stimulator (ICS) has eight output stages (212), each having a programmable current source (212B) connected to a pair of electrodes, designated "A" and "B", through respective output coupling capacitors and an electrode switching matrix (212C). An indifferent electrode is connected to each output stage by way of an indifferent electrode switch (212D). An output mode register (208) controls the switching matrix of each stage, as well as the indifferent electrode switch, to configure the electrodes for: (1) bipolar stimulation (current flow between the pair of electrodes of the output stage), (2) monopolar A stimulation (current flow between the "A" electrode of the output stage and the indifferent electrode), (3) monopolar B stimulation (current flow between the "B" electrode of the output stage and the indifferent electrode), or (4) multipolar stimulation (current flow between the "A" or "B" electrode of one output stage and the "A" or "B" electrode of another output stage).