# US 6,772,011 B2 · Transmission of information from an implanted medical device

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 6,772,011 B2
- Document ID: US6772011B2
- Status: Granted
- Kind: B2
- Application number: 10/224,118
- Filed: 2002-08-20
- Published: 2004-02-26
- Granted: 2004-08-03
- Earliest claimed: 2002-08-20
- Assignees: Thoratec Corporation
- Inventors: Alexander Dolgin
- Web page: https://patentgrep.com/patent/US6772011B2

## CPC

- A61N 1/3787: {from an external energy source}
- A61M 60/205: Non-positive displacement blood pumps
- A61M 60/873: specially adapted for wireless or transcutaneous energy transfer [TET], e.g. inductive charging
- A61N 1/37223: {Circuits for electromagnetic coupling}
- A61M 2205/3523: using telemetric means
- A61M 2205/8243: by induction
- A61N 1/3727: {characterised by the modulation technique}
- A61N: ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY (measurement of bioelectric currents A61B; surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body A61B18/00; anaesthetic apparatus in general A61M; incandescent lamps H01K; infrared radiators for heating H05B)
- A61M: DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY (introducing media into or onto the bodies of animals A61D7/00; means for inserting tampons A61F13/26; devices for administering food or medicines orally A61J; containers for collecting, storing or administering blood or medical fluids A61J1/05); DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY (surgery A61B; chemical aspects of surgical articles A61L); DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR {(Electrotherapy, e.g. producing anaesthesia by the use of alternating or intermittent currents A61N1/36021)}

## Abstract

An implanted medical apparatus and external power source use the same coils for energy transfer to the implanted medical device as used for transmission of control signals from the implanted device. In one example, implanted circuitry generates a feedback control signal indicative of the load voltage level of a load-generating medical device and superimposes the feedback signal on an inductor capacitor (LC) tank circuit for detection by the external powering apparatus. The external powering apparatus uses the feedback signal to control the energy transfer to the implanted medical device, thus regulating the load voltage at the load-generating medical device. The feedback control signal may be a sequence of pulses whose frequency indicates the load voltage level. Other information besides load voltage level may also be transmitted from the implanted device, such as telemetry and logic information.

## Claims

### Claim 1

An implantable device requiring electrical power from an external power source for operation, comprising:
an LC tank circuit that receives power from the external power source;
a load-generating device to which the received power is delivered; and
feedback circuitry that senses a load voltage level of the power delivered to the load-generating device, produces a pulsed feedback signal indicative of the bad voltage level, and superimposes the feedback signal on the LC tank circuit for communication to the external power source, wherein during a time that the feedback signal is superimposed on the LC tank circuit receipt of power from the external power source is interrupted.

### Claim 2 (depends on 1)

The implantable device of claim 1 wherein the feedback signal comprises a series of pulses, the frequency that the pulses are generated being indicative of the load voltage level.

### Claim 3 (depends on 2)

The implantable device of claim 2 wherein the feedback circuitry comprises:
an error amplifier that receives the load voltage level, compares the load voltage level to a reference voltage, and generates a difference signal indicative of the bad voltage level; and
a controller that receives the difference signal and generates the feedback signal.

### Claim 4 (depends on 2)

The implantable device of claim 2 wherein the pulses are generated at varying frequencies within a specified range with a center frequency, and that center frequency indicates that the load voltage level is the desired level and no adjustment needs to be made to the amount of power the external power source is delivering, while frequencies above and below the center frequency indicate that the amount of power the external power source is delivering needs to be adjusted to bring to load voltage level back to the desired level.

### Claim 5 (depends on 4)

The implantable device of claim 4 wherein the center frequency is about one kilohertz.

### Claim 6 (depends on 4)

The implantable device of claim 4 wherein the frequency range of the feedback signal differs from the frequency of a power signal produced by the external power source so that in the external power source, the power signal may be filtered to extract the feedback signal.

### Claim 7 (depends on 6)

The implantable device of claim 6 wherein the frequency tango of the feedback signal is less than the frequency of the power signal.

### Claim 8 (depends on 2)

The implantable device of claim 2 wherein the feedback circuitry comprises a switch that receives the feedback signal and is coupled with the LC tank circuit so that during the time the feedback signal is pulsed high the switch closes and the LC tank circuit is short-circuited to superimpose the feedback signal on the LC tank circuit.

### Claim 9 (depends on 8)

The implantable device of claim 8 farther comprising a rectifier that comprises:
first and second diodes, to first diode being coupled to a first terminal of the LC tank circuit and the second diode being coupled to a second terminal of the LC tank circuit, and the first and second diodes both having a forward bias directed toward a positive terminal of the load-generating device; and
first and second transistor switches whose current conducting terminals are coupled, respectively, between the first terminal of the LC tank circuit and the negative terminal of the load-generating device and between the second terminal of the LC tank circuit and the negative terminal of the load-generating device;
wherein the first and second transistor switches serve as the switch and each receives the feedback signal at its gate, and the first and second transistor switches ate activated by the pulses in the feedback signal.

### Claim 10

An implantable device requiring electrical power from an external power source for operation, comprising:
an LC tank circuit that receives a power signal from the external power source; a rectifier that rectifies the power signal;
a load-generating device to which the rectified power signal is delivered;
a voltage-to-frequency converter that senses a load voltage level of the power delivered to the load-generating device and produces a pulsed feedback signal comprising a series of pulses, the frequency that the pulses are generated being indicative of tit load voltage level; and
a switch that superimposes the pulsed feedback signal on the LC tank circuit for communication to the external power source.

### Claim 11 (depends on 10)

The implantable device of claim 10 wherein the rectifier and the switch utilize common components.

### Claim 12 (depends on 10)

The implantable device of claim 10 wherein the voltage-to-frequency converter comprises:
an error amplifier that receives the load voltage level, compares the load voltage level to a reference voltage, and generates a difference signal indicative of the load voltage level; and
a controller that receives the difference signal and generates the feedback signal.

### Claim 13 (depends on 10)

The implantable device of claim 10 wherein the pulses are generated at varying frequencies within a specified range with a center frequency, and that center frequency indicates that the load voltage level is the desired level and no adjustment needs to be made to the amount of power the external power source is delivering, while frequencies above and below the center frequency indicate that the amount of power the external power source is delivering needs to be adjusted to bring the load voltage level back to the desired level.

### Claim 14 (depends on 13)

The implantable device of claim 13 wherein the frequency range of the feedback signal differs from the frequency of the power signal so that in the external power source, the power signal may be filtered to extract the feedback signal.

### Claim 15 (depends on 10)

The implantable device of claim 10 wherein the rectifier comprises:
first and second diodes, the first diode being coupled to a first terminal of the LC tank circuit and the second diode being coupled to a second terminal of the LC tank circuit, and the first and second diodes both having a forward bias directed toward a positive terminal of the load-generating device; and
first and second transistor switches whose current conducting terminals are coupled, respectively, between the first terminal of the LC tank circuit and the negative terminal of the load-generating device and between the second terminal of the LC tank circuit and the negative terminal of the load-generating device;
wherein the first and second transistor switches serve as the switch and each receive the feedback signal at their gates, the first and second transistor switches being activated by the pulses in the feedback signal.

### Claim 16

A medical system with transcutaneous energy transfer comprising:
an external electrical power source having a power driver and a primary LC tank circuit; and
an implantable device requiring electrical power from an external power source for operation, comprising:
a secondary LG tank circuit that receives power from the external power source;
a load-generating device to which the received power is delivered; and
feedback circuitry that senses a load voltage level of the power delivered to the load-generating device, produces a pulsed feedback signal indicative of the load voltage level, and superimposes the feedback signal on the secondary LC tank circuit for communication to the external power source, wherein during a time that the feedback signal is superimposed on the LC tank circuit receipt of power from the external power source is interrupted.

### Claim 17 (depends on 6)

The medical system of claim 6 wherein the feedback signal comprises a series of pulses, the frequency that the pulses are generated being indicative of the load voltage level.

### Claim 18 (depends on 7)

The medical system of claim 7 wherein the power driver comprises: a sensor that senses the feedback signal communicated from the implantable device,
a decoder that receives the feedback signal sensed by the sensor, determines the frequency of the pulses in the feedback signal, and generates a voltage signal indicative of the frequency of the pulses; and
a pulse-width modulator and driver that receives the voltage signal and generates a power signal transferring a desired amount of energy to the implantable device.

### Claim 19 (depends on 18)

The medical system of claim 18 wherein the power signal is a rectangular pulse whose duty cycle varies the amount of energy transferred to the implanted device.

### Claim 20 (depends on 19)

The medical system of claim 19 wherein the frequency range of the feedback signal differs from the frequency of the power signal so that in to external power source, the power signal may be filtered to extract the feedback signal.

### Claim 21 (depends on 18)

The medical system of claim 18 wherein the power driver further comprises a tuning circuit that monitors a voltage component and a current component of the power signal and times the power signal so that the signal components have an ideal timing relationship.

### Claim 22 (depends on 17)

The medical system of claim 17 wherein the feedback circuitry comprises:
an error amplifier that receives the load voltage level, compares the load voltage level to a reference voltage, and generates a difference signal indicative of the load voltage level; and
a controller that receives the difference signal and generates the feedback signal.

### Claim 23 (depends on 17)

The medical system of claim 17 wherein the feedback circuitry comprises a switch that receives the feedback signal and is coupled with the secondary LC tank circuit so that during the time the feedback signal is pulsed high the switch closes and the secondary LC tank circuit is short-circuited to superimpose the feedback signal on the secondary LC tank circuit.

### Claim 24 (depends on 23)

The medical system of claim 23 further comprising a rectifier that comprises:
first and second diodes, the first diode being coupled to a first terminal of the secondary LC tank circuit and the second diode being coupled to a second terminal of the secondary LC tank circuit, and the first and second diodes both having a forward bias directed toward a positive terminal of the load-generating device; and
first and second transistor switches whose current conducting terminals are coupled, respectively, between the first terminal of the secondary LC tank circuit and the negative terminal of the load-generating device and between the second terminal of the secondary LC tank circuit and the negative terminal of the load-generating device;
wherein the first and second transistor switches serve as the switch and each receive the feedback signal at their gates, the first and second transistor switches being activated by the pulses in the feedback signal.

### Claim 25

An external power source for an implantable device requiring electrical power from an external power source for operation, the external power source comprising:
an electrical power supply;
a pulse-width modulator and driver for generating a power signal;
an LC tank circuit for transmitting electrical energy; and
a sensor that senses a feedback signal provided by the implantable device through the LC tank circuit, the feedback signal indicative of a load voltage level and comprising a series of pulses, the frequency that the pulses are generated being indicative of the load voltage level;
wherein the external power source varies the amount of power delivered to the implantable device in response to the feedback signal.

### Claim 26 (depends on 25)

external power source of claim 25 further comprising a decoder that receives the feedback signal sensed by the sensor, determines the frequency of the pulses in the feedback signal, and generates a voltage signal to be received by the pulsewidth modulator and driver that is indicative of the frequency of the pulses.

### Claim 27 (depends on 25)

The external power source of claim 25 wherein the power signal is a rectangular pulse whose duty cycle varies the amount of energy transferred to the implanted device.

### Claim 28 (depends on 27)

The external power source of claim 27 wherein the frequency range of the feedback signal differs from the frequency of the power signal so that the power signal maybe filtered to extract the feedback signal.

### Claim 29 (depends on 25)

The external power source of claim 25 further comprising a tuning circuit that monitors a voltage component and a current component of the power signal and tunes the power signal so that the signal components have an ideal timing relationship.

### Claim 30 (depends on 25)

The external power source of claim 25 further comprising a circuit that senses the rate of change of current through the LC tank circuit, and wherein the feedback signal further comprises a signal indicative of the rate of change of current though the LC tank circuit.

### Claim 31 (depends on 30)

The external power source of claim 30 wherein the circuit that senses the rate of change of current through the LC tank circuit is an R-C circuit that receives a current therethrough indicative of the current through the LC tank circuit and that has a capacitor with a voltage thereon indicative of the rate of change of current through the LC tank circuit.

### Claim 32

An implantable device requiring electrical power from an external power source for operation comprising:
an LC tank circuit that receives power from the external power source;
a load-generating device to which the received power is delivered; and
circuitry that senses a condition, produces a signal comprising one or more pulses and which is indicative of the condition, and superimposes the signal on the LC tank circuit for communication to die external power source.

### Claim 33 (depends on 32)

The implantable device of claim 32 wherein the load generating device is a blood pump.

### Claim 34 (depends on 33)

The implantable device of claim 33 wherein the condition being sensed is whether the blood pump is in an operating state or a fault state.

### Claim 35 (depends on 33)

The implantable device of claim 33 wherein the condition being sensed is whether the blood pump is operating on primary components or redundant components.

### Claim 36 (depends on 32)

The implantable device of claim 32 wherein the condition being sensed is a charge condition for an internal battery.

### Claim 37 (depends on 32)

The implantable device of claim 32 wherein the circuitry comprises a switch that receives the signal and is coupled with the LC tank circuit so that during the time the signal is pulsed high the switch closes and the LC tank circuit is short-circuited to superimpose the signal on the LC tank circuit.

### Claim 38 (depends on 32)

The implantable device of claim 32 further comprising a rectifier that comprises:
first and second diodes, the first diode being coupled to a first terminal of the LC tank circuit and the second diode being coupled to a second terminal of the LC tank circuit and the first and second diodes both having a forward bias directed toward a positive terminal of the load-generating device; and
first and second transistor switches whose current conducting terminals are coupled, respectively, between the first terminal of the LC tank circuit and the negative terminal of the load-generating device and between the second terminal of the LC tank circuit and the negative terminal of the load-generating device;
wherein the first and second transistor switches serve as the switch and each receive the signal at their gates, the first and second transistor switches being activated by the pulses in the signal.

### Claim 39

An implantable device requiring electrical power from an external power source for operation, comprising:
an LC tank circuit that receives power from the external power source;
a load-generating device to which the received power is delivered; and
feedback circuitry that senses a load voltage level of the power delivered to the load generating device, produces a feedback signal indicative of the load voltage level, and superimposes the feedback signal on the LC rank circuit for communication to the external power source, wherein the feedback signal comprises a series of pulses and the frequency that the pulses are generated is indicative of the load voltage level.

### Claim 40 (depends on 39)

The implantable device of claim 39 wherein the pulses are generated at varying frequencies within a specified range with a center frequency, and that center frequency indicates that the load voltage level is the desired level and no adjustment needs to be made to the amount of power the external power source is delivering, while frequencies above and below the center frequency indicate that the amount of power the external power source is delivering needs to be adjusted to bring the load voltage level back to the desired level.

### Claim 41 (depends on 40)

The implantable device of claim 40 wherein the center frequency is about one kilohertz.

### Claim 42 (depends on 39)

The implantable device of claim 39 wherein the frequency range of the feedback signal is less than the frequency of the power signal.

### Claim 43

An implantable device requiring electrical power from an external power source for operation, comprising:
an LC tank circuit that receives power from the external power source;
a load-generating device to which the received power is delivered; and
feedback circuitry that senses a load voltage level of the power delivered to the load-generating device, produces a feedback signal indicative of the load voltage level, and superimposes the feedback signal on the LC tank circuit the communication to the external power source, wherein the feedback circuitry comprises a switch that receives the feedback signal and is coupled with the LC tank circuit so that during the time the feedback signal is pulsed high the switch closes and the LC tank circuit is short-circuited to superimpose the feedback signal on the LC tank circuit.