Patent ID: 12246185

DETAILED DESCRIPTION

Briefly described, wireless energy is transmitted by means of a primary coil in an external energy source located outside a mammal patient and is received inductively by means of a secondary coil in an internal energy receiver located inside the patient. The internal energy receiver is connected to an electrically operable medical device implanted in the patient, for directly or indirectly supplying received energy to the medical device. Feedback control information is transferred from the secondary coil to the primary coil by switching the secondary coil on and off to induce a detectable impedance load variation in the primary coil encoding the feedback control information. The feedback control information relates to the energy for operating the medical device and is used for controlling the transmission of wireless energy from the external energy source

An energy balance may be determined between the energy received by the internal energy receiver and the energy used for the medical device, and the transmission of wireless energy is then controlled based on the determined energy balance and in response to the feedback control information. The energy balance thus provides an accurate indication of the correct amount of energy needed, which is sufficient to operate the medical device properly, but without causing undue temperature rise.

InFIG.1, an arrangement is schematically illustrated for supplying an accurate amount of energy to an electrically operable medical device100implanted in a patient, whose skin is indicated by a vertical line S separating the interior “Int” of the patient from the exterior “Ext”. The medical device100is connected to an internal energy receiver102, likewise located inside the patient, preferably just beneath the skin S. Generally speaking, the energy receiver102may be placed in the abdomen, thorax, muscle fascia (e.g. in the abdominal wall), subcutaneously, or at any other suitable location. The energy receiver102is adapted to receive wireless energy E transmitted from an external energy source104located outside the skin S in the vicinity of the energy receiver102.

The wireless energy E is transferred by means of a primary coil arranged in the energy source104and an adjacent secondary coil arranged in the energy receiver102. When an electric current is fed through the primary coil, energy in the form of a voltage is induced in the secondary coil which can be used to operate the medical device100, e.g. after storing the incoming energy in an energy storing device or accumulator, such as a battery or a capacitor, not shown in this figure.

The internal energy receiver102is adapted to transfer suitable feedback control information FB from the secondary coil to the primary coil by switching the secondary coil on and off to induce a detectable impedance load variation in the primary coil. This load variation is created and controlled to encode the feedback control information in a useful manner. The feedback control information thus communicated from the energy receiver102over to the energy source104, generally relates to the energy for operating the medical device100. The feedback control information is then used for controlling the transmission of wireless energy from the external energy source104. The amount of transferred energy is regulated by means of an external control unit106controlling the energy source104.

An internal control unit108may be implanted in the patient connected to the medical device100. The internal control unit108is used to control the on and off switching of the secondary coil. The feedback control information FB may include at least one predetermined parameter relating to the received energy. The predetermined parameter may further be variable. When using the internal control unit108, the feedback control information may relate to the received energy and may also require artificial intelligence to be generated.

The on and off switching of the secondary coil may be executed by means of an implantable switch110(SW) at the energy receiver102, and the switch110is connected to and controlled by the internal control unit108. The switch may be an electronic switch such as a transistor. Further, the internal control unit108may comprise a memory108afor storing the transferred feedback control information FB.

The energy balance mentioned above may be determined by means of the internal control unit108, and the feedback control information will then relate to the determined energy balance. In that case, the external control unit.106may be used to control the transmission of wireless energy E from the external energy source104based on the determined energy balance and using the received feedback control information FB.

Alternatively, the external control unit106may be used to determine the energy balance above, based on the feedback control information FB which in that case comprises measurements relating to characteristics of the medical device. The external control unit106is then further used to control the transmission of wireless energy from the external energy source104based on the determined energy balance and using the received feedback control information FB.

The internal control unit108may be arranged to receive various measurements obtained by suitable sensors or the like, not shown, measuring certain characteristics of the medical device100, somehow reflecting the energy needed for proper operation of the medical device100. Moreover, the current condition of the patient may also be detected by means of suitable measuring devices or sensors, in order to provide parameters reflecting the patient's condition. Hence, such characteristics and/or parameters may be related to the current state of the medical device100, such as power consumption, operational mode and temperature, as well as the patient's condition reflected by, e.g., body temperature, blood pressure, heartbeats and breathing.

Furthermore, an energy storing device or accumulator, not shown here, may also be connected to the energy receiver102for accumulating received energy for later use by the medical device100. Alternatively or additionally, characteristics of such an energy storing device, also relating to the energy, may be measured as well. The energy storing device may be a battery, and the measured characteristics may be related to the current state of the battery, such as voltage, temperature, etc. In order to provide sufficient voltage and current to the medical device100, and also to avoid excessive heating, it is clearly understood that the battery should be charged optimally by receiving a correct amount of energy from the energy receiver102, i.e. not too little or too much. The energy storing device may also be a capacitor with corresponding characteristics.

For example, battery characteristics may be measured on a regular basis to determine the current state of the battery, which then may be stored as state information in a suitable storage means in the internal control unit108. Thus, whenever new measurements are made, the stored battery state information can be updated accordingly. In this way, the state of the battery can be “calibrated” by transferring a correct amount of energy, so as to maintain the battery in an optimal condition.

Thus, the internal control unit108may be adapted to determine the energy balance and/or the currently required amount of energy, (either energy per time unit or accumulated energy) based on measurements made by the above-mentioned sensors or measuring devices on the medical device100, or the patient, or an energy storing device if used, or any combination thereof. The amount of energy transmitted from the energy source104may then be regulated in response to the received feedback control information.

Alternatively, sensor measurements can be transmitted to the external control unit106wherein the energy balance and/or the currently required amount of energy can be determined by the external control unit106, thus basically integrating the above-described function of the internal control unit108in the external control unit106. In that case, the internal control unit108can be omitted and the sensor measurements are comprised in the feedback control information FB. The energy balance and the currently required amount of energy can then be determined by the external control unit106based on those sensor measurements.

Hence, the present solution employs the feed back of information indicating the required energy, which is more efficient than previous solutions because it is based on the actual use of energy that is compared to the received energy, e.g. with respect to the amount of energy, the energy difference, or the energy receiving rate as compared to the energy rate used by the medical device. The medical device may use the received energy either for consuming or for storing the energy in an energy storage device or the like. The different parameters discussed above would thus be used if relevant and needed and then as a tool for determining the actual energy balance. However, such parameters may also be needed per se for any actions taken internally to specifically operate the medical device.

The feedback control information FB may further be modulated with respect to frequency, phase or amplitude.

To conclude, the energy supply arrangement illustrated inFIG.1may operate basically in the following manner, in the case when the transmission of wireless energy is controlled based on the energy balance described above. The energy balance may first be determined by the internal control unit108. Feedback control information FB relating to the energy is also created by the internal control unit108, and the feedback control information FB is transmitted from the energy receiver102to the energy source104. Alternatively, the energy balance can be determined by the external control unit106instead depending on the implementation, as mentioned above. In that case, the feedback control information FB may carry measurement results from various sensors. The amount of energy emitted from the energy source104can then be regulated by the external control unit106, based on the determined energy balance, e.g. in response to the received feedback control information FB. This process may be repeated intermittently at certain intervals during ongoing energy transfer, or may be executed on a more or less continuous basis during the energy transfer.

The amount of transferred energy can generally be regulated by adjusting various transmission parameters in the energy source104, such as voltage, current, amplitude, wave frequency and pulse characteristics.

FIG.2illustrates different embodiments for how received energy can be supplied to and used by a medical device200. Similar to the example ofFIG.1, an internal energy receiver202receives wireless energy E from an external energy source204which is controlled by a transmission control unit206. The internal energy receiver202may comprise a constant voltage circuit, indicated as a dashed box “constant V” in the figure, for supplying energy at constant voltage to the medical device200. The internal energy receiver202may further comprise a constant current circuit, indicated as a dashed box “constant C” in the figure, for supplying energy at constant current to the medical device200.

The medical device200comprises an energy consuming part200awhich may be a motor, pump, restriction device, or any other medical appliance that requires energy for its electrical operation. The medical device200may further comprise an energy storage device200bfor storing energy supplied from the internal energy receiver202. Thus, the supplied energy may be directly consumed by the energy consuming part200aor stored by the energy storage device200b, or the supplied energy may be partly consumed and partly stored. The medical device200may further comprise an energy stabilizing unit200cfor stabilizing the energy supplied from the internal energy receiver202. Thus, the energy may be supplied in a fluctuating manner such that it may be necessary to stabilize the energy before consumed or stored.

The energy supplied from the internal energy receiver202may further be accumulated and/or stabilized by a separate energy stabilizing unit208located outside the medical device200, before being consumed and/or stored by the medical device200. Alternatively, the energy stabilizing unit208may be integrated in the internal energy receiver202. In either case, the energy stabilizing unit208may comprise a constant voltage circuit and/or a constant current circuit.

It should be noted thatFIG.1andFIG.2illustrate some possible but non-limiting implementation options regarding how the various shown functional components and elements can be arranged and connected to each other. However, the skilled person will readily appreciate that many variations and modifications can be made within the scope of the present invention.

A method is thus provided for controlling transmission of wireless energy supplied to an electrically operable medical device implanted in a patient. The wireless energy is transmitted from an external energy source located outside the patient and is received by an internal energy receiver located inside the patient, the internal energy receiver being connected to the medical device for directly or indirectly supplying received energy thereto. An energy balance is determined between the energy received by the internal energy receiver and the energy used for the medical device. the transmission of wireless energy from the external energy source is then controlled based on the determined energy balance.

An apparatus is also provided for controlling transmission of wireless energy supplied to an electrically operable medical device implanted in a patient. The apparatus is adapted to transmit the wireless energy from an external energy source located outside the patient which is received by an internal energy receiver located inside the patient, the internal energy receiver being connected to the medical device for directly or indirectly supplying received energy thereto. The apparatus may further be adapted to determine an energy balance between the energy received by the internal energy receiver and the energy used for the medical device, and control the transmission of wireless energy from the external energy source, based on the determined energy balance.

A change in the energy balance may be detected to control the transmission of wireless energy based on the detected energy balance change. A difference may also be detected between energy received by the internal energy receiver and energy used for the medical device, to control the transmission of wireless energy based on the detected energy difference.

When controlling the energy transmission, the amount of transmitted wireless energy may be decreased if the detected energy balance change implies that the energy balance is increasing, or vice versa. The decrease/increase of energy transmission may further correspond to a detected change rate.

The amount of transmitted wireless energy may further be decreased if the detected energy difference implies that the received energy is greater than the used energy, or vice versa. The decrease/increase of energy transmission may then correspond to the magnitude of the detected energy difference.

As mentioned above, the energy used for the medical device may be consumed to operate the medical device, and/or stored in at least one energy storage device of the medical device.

In one alternative, substantially all energy used for the medical device is consumed (e.g. by the consuming part200aofFIG.2) to operate the medical device. In that case, the energy may be consumed after being stabilized in at least one energy stabilizing unit of the medical device.

In another alternative, substantially all energy used for the medical device is stored in the at least one energy storage device. In yet another alternative, the energy used for the medical device is partly consumed to operate the medical device and partly stored in the at least one energy storage device.

The energy received by the internal energy receiver may be stabilized by a capacitor, before the energy is supplied directly or indirectly to the medical device.

The difference between the total amount of energy received by the internal energy receiver and the total amount of consumed and/or stored energy may be directly or indirectly measured over time, and the energy balance can then be determined based on a detected change in the total amount difference.

The energy received by the internal energy receiver may further be accumulated and stabilized in an energy stabilizing unit, before the energy is supplied to the medical device. In that case, the energy balance may be determined based on a detected change followed over time in the amount of consumed and/or stored energy. Further, the change in the amount of consumed and/or stored energy may be detected by determining over time the derivative of a measured electrical parameter related to the amount of consumed and/or stored energy, where the derivative at a first given moment is corresponding to the rate of the change at the first given moment, wherein the rate of change includes the direction and speed of the change. The derivative may further be determined based on a detected rate of change of the electrical parameter.

The energy received by the internal energy receiver may be supplied to the medical device with at least one constant voltage, wherein the constant voltage is created by a constant voltage circuitry. In that case, the energy may be supplied with at least two different voltages, including the at least one constant voltage.

The energy received by the internal energy receiver may also be supplied to the medical device with at least one constant current, wherein the constant current is created by a constant current circuitry. In that case, the energy may be supplied with at least two different currents including the at least one constant current.

The energy balance may also be determined based on a detected difference between the total amount of energy received by the internal energy receiver and the total amount of consumed and/or stored energy, the detected difference being related to the integral over time of at least one measured electrical parameter related to the energy balance. In that case, values of the electrical parameter may be plotted over time as a graph in a parameter-time diagram, and the integral can be determined from the size of the area beneath the plotted graph. The integral of the electrical parameter may relate to the energy balance as an accumulated difference between the total amount of energy received by the internal energy receiver and the total amount of consumed and/or stored energy.

The energy storage device in the medical device may include at least one of: a rechargeable battery, an accumulator or a capacitor. The energy stabilizing unit may include at least one of: an accumulator, a capacitor or a semiconductor adapted to stabilize the received energy.

When the energy received by the internal energy receiver is accumulated and stabilized in an energy stabilizing unit before energy is supplied to the medical device and/or energy storage device, the energy may be supplied to the medical device and/or energy storage device with at least one constant voltage, as maintained by a constant voltage circuitry. In that case, the medical device and energy storage device may be supplied with at least two different voltages, wherein at least one voltage is constant, maintained by the constant voltage circuitry.

Alternatively, when the energy received by the internal energy receiver is accumulated and stabilized in an energy stabilizing unit before energy is supplied to the medical device and/or energy storage device, the energy may be supplied to the medical device and/or energy storage device with at least one constant current, as maintained by a constant current circuitry. In that case, the medical device and energy storage device may be supplied with at least two different currents wherein at least one current is constant, maintained by the constant current circuitry.

The wireless energy may be initially transmitted according to a predetermined energy consumption plus storage rate. In that case, the transmission of wireless energy may be turned off when a predetermined total amount of energy has been transmitted. The energy received by the internal energy receiver may then also be accumulated and stabilized in an energy stabilizing unit before being consumed to operate the medical device and/or stored in the energy storage device until a predetermined total amount of energy has been consumed and/or stored.

Further, the wireless energy may be first transmitted with the predetermined energy rate, and then transmitted based on the energy balance which can be determined by detecting the total amount of accumulated energy in the energy stabilizing unit. Alternatively, the energy balance can be determined by detecting a change in the current amount of accumulated energy in the energy stabilizing unit. In yet another alternative, the energy balance, can be determined by detecting the direction and rate of change in the current amount of accumulated energy in the energy stabilizing unit.

The transmission of wireless energy may be controlled such that an energy reception rate in the internal energy receiver corresponds to the energy consumption and/or storage rate. In that case, the transmission of wireless energy may be turned off when a predetermined total amount of energy has been consumed.

The energy received by the internal energy receiver may be first accumulated and stabilized in an energy stabilizing unit, and then consumed or stored by the medical device until a predetermined total amount of energy has been consumed. In that case, the energy balance may be determined based on a detected total amount of accumulated energy in the energy stabilizing unit. Alternatively, the energy balance may be determined by detecting a change in the current amount of accumulated energy in the energy stabilizing unit. In yet another alternative, the energy balance may be determined by detecting the direction and rate of change in the current amount of accumulated energy in the energy stabilizing unit.

As mentioned in connection withFIG.1, suitable sensors may be used for measuring certain characteristics of the medical device and/or detecting the current condition of the patient, somehow relating to the energy needed for proper operation of the medical device. Thus, electrical and/or physical parameters of the medical device and/or physical parameters of the patient may be determined, and the energy can then be transmitted with a transmission rate which is determined based on the parameters. Further, the transmission of wireless energy may be controlled such that the total amount of transmitted energy is based on said parameters.

The energy received by the internal energy receiver may be first accumulated and stabilized in an energy stabilizing unit, and then consumed until a predetermined total amount of energy has been consumed. The transmission of wireless energy may further be controlled such that an energy reception rate at the internal energy receiver corresponds to a predetermined energy consumption rate.

Further, electrical and/or physical parameters of the medical device and/or physical parameters of the patient may be determined, in order to determine the total amount of transmitted energy based on the parameters. In that case, the energy received by the internal energy receiver may be first accumulated and stabilized in an energy stabilizing unit, and then consumed until a predetermined total amount of energy has been consumed.

The energy is stored in the energy storage device according to a predetermined storing rate. The transmission of wireless energy may then be turned off when a predetermined total amount of energy has been stored. The transmission of wireless energy can be further controlled such that an energy reception rate at the internal energy receiver corresponds to the predetermined storing rate.

The energy storage device of the medical device may comprise a first storage device and a second storage device, wherein the energy received by the internal energy receiver is first stored in the first storage device, and the energy is then supplied from the first storage device to the second storage device at a later stage.

When using the first and second storage devices in the energy storage device, the energy balance may be determined in different ways. Firstly, the energy balance may be determined by detecting the current amount of energy stored in the first storage device, and the transmission of wireless energy may then be controlled such that a storing rate in the second storage device corresponds to an energy reception rate in the internal energy receiver. Secondly, the energy balance may be determined based on a detected total amount of stored energy in the first storage device. Thirdly, the energy balance may be determined by detecting a change in the current amount of stored energy in the first storage device. Fourthly, the energy balance may be determined by detecting the direction and rate of change in the current amount of stored energy in the first storage device.

Stabilized energy may be first supplied from the first storage device to the second storage device with a constant current, as maintained by a constant current circuitry, until a measured voltage over the second storage device reaches a predetermined maximum voltage, and thereafter supplied from the first storage device to the second storage energy storage device with a constant voltage, as maintained by a constant voltage circuitry. In that case, the transmission of wireless energy may be turned off when a predetermined minimum rate of transmitted energy has been reached.

The transmission of energy may further be controlled such that the amount of energy received by the internal energy receiver corresponds to the amount of energy stored in the second storage device. In that case, the transmission of energy may be controlled such that an energy reception rate at the internal energy receiver corresponds to an energy storing rate in the second storage device. The transmission of energy may also be controlled such that a total amount of received energy at the internal energy receiver corresponds to a total amount of stored energy in the second storage device.

In the case when the transmission of wireless energy is turned off when a predetermined total amount of energy has been stored, electrical and/or physical parameters of the medical device and/or physical parameters of the patient may be determined during a first energy storing procedure, and the predetermined total amount of energy may be stored in a subsequent energy storing procedure based on the parameters.

When electrical and/or physical parameters of the medical device and/or physical parameters of the patient are determined, the energy may be stored in the energy storage device with a storing rate which is determined based on the parameters. In that case, a total amount of energy may be stored in the energy storage device, the total amount of energy being determined based on the parameters. The transmission of wireless energy may then be automatically turned off when the total amount of energy has been stored. The transmission of wireless energy may further be controlled such that an energy reception rate at the internal energy receiver corresponds to the storing rate.

When electrical and/or physical parameters of the medical device and/or physical parameters of the patient are determined, a total amount of energy may be stored in the energy storage device, the total amount of energy being determined based on said parameters. The transmission of energy may then be controlled such that the total amount of received energy at the internal energy receiver corresponds to the total amount of stored energy. Further, the transmission of wireless energy may be automatically turned off when the total amount of energy has been stored.

When the energy used for the medical device is partly consumed and partly stored, the transmission of wireless energy may be controlled based on a predetermined energy consumption rate and a predetermined energy storing rate. In that case, the transmission of energy may be turned off when a predetermined total amount of energy has been received for consumption and storage. The transmission of energy may also be turned off when a predetermined total amount of energy has been received for consumption and storage.

When electrical and/or physical parameters of the medical device and/or physical parameters of the patient are determined, the energy may be transmitted for consumption and storage according to a transmission rate per time unit which is determined based on said parameters. The total amount of transmitted energy may also be determined based on said parameters.

When electrical and/or physical parameters of the medical device and/or physical parameters of the patient are determined, the energy may be supplied from the energy storage device to the medical device for consumption with a supply rate which is determined based on said parameters. In that case, the total amount of energy supplied from the energy storage device to the medical device for consumption, may be based on said parameters.

When electrical and/or physical parameters of the medical device and/or physical parameters of the patient are determined, a total amount of energy may be supplied to the medical device for consumption from the energy storage device, where the total amount of supplied energy is determined based on the parameters.

When the energy received by the internal energy receiver is accumulated and stabilized in an energy stabilizing unit, the energy balance may be determined based on an accumulation rate in the energy stabilizing unit, such that a storing rate in the energy storage device corresponds to an energy reception rate in the internal energy receiver.

When a difference is detected between the total amount of energy received by the internal energy receiver and the total amount of consumed and/or stored energy, and the detected difference is related to the integral over time of at least one measured electrical parameter related to said energy balance, the integral may be determined for a monitored voltage and/or current related to the energy balance.

When the derivative is determined over time of a measured electrical parameter related to the amount of consumed and/or stored energy, the derivative may be determined for a monitored voltage and/or current related to the energy balance.

When using the first and second storage devices in the energy storage device, the second storage device may directly or indirectly supply energy to the medical device, wherein the change of the difference corresponds to a change of the amount of energy accumulated in the first storage unit. The energy balance may then be determined by detecting a change over time in the energy storing rate in the first storage device, the energy balance corresponding to the change. The change in the amount of stored energy may also be detected by determining over time the derivative of a measured electrical parameter indicating the amount of stored energy, the derivative corresponding to the change in the amount of stored energy. A rate of change of the electrical parameter may also be detected, the derivative being related to the change rate. The electrical parameter may be a measured voltage and/or current related to the energy balance.

The first storage device may include at least one of: a capacitor and a semiconductor, and the second storage device includes at least one of: a rechargeable battery, an accumulator and a capacitor.

As mentioned above, the wireless energy may be transmitted inductively from a primary coil in the external energy source to a secondary coil in the internal energy receiver. However, the wireless energy may also be transmitted non-inductively. For example, the wireless energy may be transmitted by means of sound or pressure variations, radio or light. The wireless energy may also be transmitted in pulses or waves and/or by means of an electric field.

The wireless energy may also be transmitted in pulses or waves and/or by means of an electric field. The transmission of wireless energy may be controlled by adjusting the width of the pulses.

When the difference between the total amount of energy received by the internal energy receiver and the total amount of consumed energy is measured over time, directly or indirectly, the energy balance may be determined by detecting a change in the difference. In that case, the change in the amount of consumed energy may be detected by determining over time the derivative of a measured electrical parameter related to the amount of consumed energy, the derivative corresponding to the rate of the change in the amount of consumed energy, wherein the rate of change includes the direction and speed of the change. A rate of change of the electrical parameter may then be detected, the derivative being related to the detected change rate.

When using the first and second storage devices in the energy storage device, the first storage device may be adapted to be charged at a relatively higher energy charging rate as compared to the second storage device, thereby enabling a relatively faster charging. The first storage device may also be adapted to be charged at multiple individual charging occasions more frequently as compared to the second storage device, thereby providing relatively greater life-time in terms of charging occasions. The first storage device may comprise at least one capacitor. Normally, only the first storage may be charged and more often than needed for the second storage device.

When the second storage device needs to be charged, to reduce the time needed for charging, the first storage device is charged at multiple individual charging occasions, thereby leaving time in between the charging occasions for the first storage device to charge the second storage device at a relatively lower energy charging rate. When electrical parameters of the medical device are determined, the charging of the second storage device may be controlled based on the parameters. A constant current or stabilizing voltage circuitry may be used for storing energy in the second storage device.

The transmission of wireless energy from the external energy source may be controlled by applying to the external energy source electrical pulses from a first electric circuit to transmit the wireless energy, the electrical pulses having leading and trailing edges, varying the lengths of first time intervals between successive leading and trailing edges of the electrical pulses and/or the lengths of second time intervals between successive trailing and leading edges of the electrical pulses, and transmitting wireless energy, the transmitted energy generated from the electrical pulses having a varied power, the varying of the power depending on the lengths of the first and/or second time intervals.

In that case, the frequency of the electrical pulses may be substantially constant when varying the first and/or second time intervals. When applying electrical pulses, the electrical pulses may remain unchanged, except for varying the first and/or second time intervals. The amplitude of the electrical pulses may be substantially constant when varying the first and/or second time intervals. Further, the electrical pulses may be varied by only varying the lengths of first time intervals between successive leading and trailing edges of the electrical pulses.

A train of two or more electrical pulses may be supplied in a row, wherein when applying the train of pulses, the train having a first electrical pulse at the start of the pulse train and having a second electrical pulse at the end of the pulse train, two or more pulse trains may be supplied in a row, wherein the lengths of the second time intervals between successive trailing edge of the second electrical pulse in a first pulse train and leading edge of the first electrical pulse of a second pulse train are varied.

When applying the electrical pulses, the electrical pulses may have a substantially constant current and a substantially constant voltage. The electrical pulses may also have a substantially constant current and a substantially constant voltage. Further, the electrical pulses may also have a substantially constant frequency. The electrical pulses within a pulse train may likewise have a substantially constant frequency.

When applying electrical pulses to the external energy source, the electrical pulses may generate an electromagnetic field over the external energy source, the electromagnetic field being varied by varying the first and second time intervals, and the electromagnetic field may induce electrical pulses in the internal energy receiver, the induced pulses carrying energy transmitted to the internal energy receiver.

The electrical pulses may be released from the first electrical circuit with such a frequency and/or time period between leading edges of the consecutive pulses, so that when the lengths of the first and/or second time intervals are varied, the resulting transmitted energy are varied. When applying the electrical pulses, the electrical pulses may have a substantially constant frequency.

The circuit formed by the first electric circuit and the external energy source may have a first characteristic time period or first time constant, and when effectively varying the transmitted energy, such frequency time period may be in the range of the first characteristic time period or time constant or shorter.

The feedback signal may be related to the amount of energy being received in the internal energy receiver. The external energy source may then further comprise an electronic circuit for comparing the feedback signal with the amount of energy transmitted by the external energy source. The electronic circuit may comprise an analyzer adapted to analyze the amount of energy being transmitted and adapted to receive the feedback signal related to the amount of energy received in the receiver, and further adapted to determine the special energy balance by comparing the amount of transmitted energy and the feedback signal related to the amount of received information. The external energy source may be adapted to use the feedback signal to adjust the level of the transmitted energy.

The external energy source may be adapted to transfer data related to the amount of transmitted energy to the receiver, and wherein the feedback signal is related to the amount of energy received in the receiver the receiver compared to the amount of the transmitted energy. The external energy source may also be adapted to use the feedback signal to adjust the level of the transmitted energy.

When the energy is transferred inductively, the feedback signal may be related to a coupling factor between the primary coil and the secondary coil. The external energy source may then be adapted to increase the amount of transferred energy to the internal energy receiver until a predetermined response of the coupling factor is detected. The external energy source may further comprise an indicator adapted to indicate a level of the coupling factor. The external energy source may further comprise an indicator adapted to indicate an optimal placement of the secondary coil in relation to the primary coil to optimize the coupling factor.

While the invention has been described with reference to specific exemplary embodiments, the description is in general only intended to illustrate the inventive concept and should not be taken as limiting the scope of the invention. In particular, the skilled person will readily understand that the above-described embodiments and examples can be implemented both as a method and an apparatus. The present invention and various possible embodiments are generally defined by the following claims.

DESCRIPTION OF POSSIBLE IMPLEMENTATION EXAMPLES

The schematicFIG.3shows a circuit diagram of one of the proposed designs of the invented apparatus for controlling transmission of wireless energy, or energy balance control system. The schematic shows the energy balance measuring circuit that has an output signal centered on 2.5V and that is proportional to the energy imbalance. A signal level at 2.5V means that energy balance exists, if the level drops below 2.5V energy is drawn from the power source in the implant and if the level rises above 2.5V energy is charged into the power source. The output signal from the circuit is typically feed to an A/D converter and converted into a digital format. The digital information can then be sent to the external transmitter allowing it to adjust the level of the transmitted power. Another possibility is to have a completely analog system that uses comparators comparing the energy balance level with certain maximum and minimum thresholds sending information to an external transmitter if the balance drifts out of the max/min window.

The schematicFIG.3shows a circuit implementation for a system that transfers power to the implant from outside of the body using inductive energy transfer. An inductive energy transfer system typically uses an external transmitting coil and an internal receiving coil. The receiving coil, L1, is included in the schematicFIG.3; the transmitting parts of the system are excluded.

The implementation of the general concept of energy balance and the way the information is transmitted to the external energy transmitter can of course be implemented in numerous different ways. The schematicFIG.3and the above described method of evaluating and transmitting the information should only be regarded as examples of how to implement the control system.

Circuit Details

In the schematicFIG.3the symbols Y1, Y2, Y3and so on symbolize test points within the circuit. References to the test points are found on the graphs in the diagrams following later in the text. The components in the diagram and their respective values are values that work in this particular implementation which of course is only one of an infinite number of possible design solutions.

Energy to power the circuit is received by the energy receiving coil L1. Energy to the implant is transmitted in this particular case at a frequency of 25 kHz. The energy balance output signal is present at test point Y1.

The diagram inFIG.4shows the voltage, Y7x, over the receiving coil L1and the input power, Y9, received by the coil from the external transmitter. The power graph, Y9, is normalized and varies between 0-1 where 1 signifies maximum power and 0 no power; hence Y9does not show the absolute value of the received power level. The power test point Y9is not present in the schematic, it is an amplitude modulation signal on the transmitter signal power. In the diagram it can be seen that the Y7xvoltage over the receiving coil L1increases as the power from the external transmitter increases. When the Y7xvoltage reaches the level where actual charging of the power source, C1, in the implant commences the Y7xlevel increases at a much slower rate as the input power is increased because of the load that the power source impart on the receiving coil.

The receiving coil L1is connected to a rectifying bridge with four Schottky diodes, D1x-D4x. The output voltage from the bridge, Y7, is shown in the diagram ofFIG.5. The capacitor C6absorbs the high frequency charging currents from the bridge and together with the Schottky diode D3prevents the 25 kHz energy transmission frequency from entering into the rest of the circuit. This is beneficial since the energy balance of the system is measured as the voltage across R1, which with out the C6-D3combination would contain high level of 25 kHz alternating charge current. The power source in the implant is the capacitor C1. The capacitor C3is a high frequency decoupling capacitor. The resistor named LOAD is the fictive load of the power source in the implant. The voltage over the power source, Y5, is also shown in the diagram ofFIG.5together with the power graph Y9.

The voltage Y3in the diagram ofFIG.6is a stabilized voltage at about 4.8V used to power the operational amplifier X1. The Y3voltage is stabilized by a fairly standard linear voltage regulator consisting of the MosFet X2, zenerdiode D5, capacitor C4and resistor R3. The capacitor C2is a high frequency decoupling capacitor. In the diagram ofFIG.6the input voltage to the regulator is seen as Y5and the output voltage is Y3.

The X1operational amplifier is used to amplify the energy balance signal together with R6and R7that set the gain of the amplifier circuit to 10 times. The input signals to the circuit are shown in the diagram ofFIG.7. Y4is fixed at a more or less constant level of approximately 2.74V by the zenerdiode D1. The voltage Y4is shunted and high frequency filtered by the capacitor C5. A part of the DC voltage at Y4is coupled into the Y2voltage by the resistor R8in order to center the Y1output voltage at 2.5V when energy is balanced. The voltage Y2is basically the same voltage as the voltage, Y6, over R1, only slightly high frequency filtered by R9and C7and shifted in DC level by the current going through R8. To compare Y6and Y2look in the diagram ofFIG.7.

The energy balance output signal of the circuit, Y1in the diagram ofFIG.8, also closely correspond to the Y6voltage. The Y1voltage is an amplified, 10 times, and DC shifted to center around 2.5V instead of 0V version of the Y6voltage. The higher signal level at Y1and the DC center point around 2.5V is much easier to interface to for the circuits connected to the energy balance output signal.

The diagram ofFIG.9shows the relationship between the energy balance signal Y1and the actual voltage over the power source of the implant. The energy balance signal is the derivative of the voltage level over the power source, Y5. When the energy balance signal, Y1, is negative relative to 2.5V the voltage level, Y5, drops off and when the energy balance signal is positive relative to 2.5V the Y5voltage increases. The more negative or positive relative to 2.5V the energy balance signal Y1is the more rapidly the Y5voltage over the power source increases or decreases.

The diagram ofFIG.10, of another circuit condition, perhaps even more clearly shows how the energy balance signal corresponds to the derivative of the Y5voltage over the power source. The traces shows a situation where the energy put into the power source is held at a constant level and the load is varied between 5 mA and 30 mA in four discrete steps. During the first 25 ms the load is 30 mA, the following 25 ms it is 5 mA then followed by the same 30 mA and 5 mA sequence. When the Y5voltage over the power source decreases at a constant level due to the 30 mA load the derivative level is at a constant level below 2.5V and when the Y5voltage increases the derivative voltage is positive at a constant level.

The two diagrams ofFIG.11show the relation ship between the energy balance signal Y1and the energy imbalance in the circuit in a complex situation where both the load is varied and the amount of power put into the implant is varied. The two traces in the first diagram ofFIG.11shows the charging current into the power source and the load current. The charging current is represented by the IY12trace and the load current is the IY10trace. The second diagram ofFIG.11shows the Y1voltage generated by the altering currents shown in the first diagram. When the amount of stored energy in the power source is changed due to the energy imbalance the derivative signal Y1rapidly responds to the imbalance as shown in the diagram.

In a system where the energy balance signal is used as a feedback signal to an external power transmitter, enabling it to regulate the transmitted power according to the energy imbalance, it is possible to maintain an optimal energy balance and to keep the efficiency at maximum. The diagram ofFIG.12shows the charging current into the power source and the load current, the charging current are represented by the IY12trace and the load current is the IY10trace, as well as the voltage level over the power source, Y5, and the energy balance signal Y1in such a system. It can clearly be seen that this system rapidly responds to any load current changes by increasing the charging current. Only a small spike in the energy balance signal can be seen right at the edges where the load is rapidly changed due to the finite bandwidth of the feedback loop. Apart from those small spikes the energy is kept in perfect balance.

FIGS.13a-13cschematically illustrate different states of operation of a generally designed apparatus according to one embodiment, when the apparatus is applied on a wall portion of a bodily organ designated BO. The apparatus includes a constriction device and a stimulation device, which are designated CSD, and a control device designated CD for controlling the constriction and stimulation devices CSD.FIG.9ashows the apparatus in an inactivation state, in which the constriction device does not constrict the organ BO and the stimulation device does not stimulate the organ BO.FIG.13bshows the apparatus in a constriction state, in which the control device CD controls the constriction device to gently constrict the wall portion of the organ BO to a constricted state, in which the blood circulation in the constricted wall portion is substantially unrestricted and the flow in the lumen of the wall portion is restricted.FIG.13cshows the apparatus in a stimulation state, in which the control device CD controls the stimulation device to stimulate different areas of the constricted wall portion, so that almost the entire wall portion of the organ BO contracts (thickens) and closes the lumen.

FIGS.13dand13eshow how the stimulation of the constricted wall portion can be cyclically varied between a first stimulation mode, in which the left area of the wall portion (seeFIG.13d) is stimulated, while the right area of the wall portion is not stimulated, and a second stimulation mode, in which the right area of the wall portion (seeFIG.13e) is stimulated, while the left area of the wall portion is not stimulated, in order to maintain over time satisfactory blood circulation in the constricted wall portion.

It should be noted that the stimulation modes shown inFIGS.13dand13eonly constitute a principle example of how the constricted wall portion of the organ BO may be stimulated. Thus, more than two different areas of the constricted wall portion may be simultaneously stimulated in cycles or successively stimulated. Also, groups of different areas of the constricted wall portion may be successively stimulated.

FIGS.13f-13hillustrate different states of operation of a modification of the general embodiment shown inFIGS.13a-13e, wherein the constriction and stimulation devices CSD include several separate constriction/stimulation elements, here three elements CSDE1, CSDE2and CSDE3.FIG.13fshows how the element CSDE1in a first state of operation is activated to both constrict and stimulate the organ BO, so that the lumen of the organ BO is closed, whereas the other two elements CSDE2and CSDE3are inactivated.FIG.13gshows how the element CSDE2in a second following state of operation is activated, so that the lumen of the organ BO is closed, whereas the other two elements CSDE1and CSDE3are inactivated.FIG.13hshows how the element CSDE3in a following third state of operation is activated, so that the lumen of the organ BO is closed, whereas the other two elements CSDE1and CSDE2are inactivated. By shifting between the first, second and third states of operation, either randomly or in accordance with a predetermined sequence, different portions of the organ can by temporarily constricted and stimulated while maintaining the lumen of the organ closed, whereby the risk of injuring the organ is minimized. It is also possible to activate the elements CSDE1-CSDE3successively along the lumen of the organ to move fluids and/or other bodily matter in the lumen.

FIGS.13i-13killustrate an alternative mode of operation of the modification of the general embodiment. Thus,FIG.13ishows how the element CSDE1in a first state of operation is activated to both constrict and stimulate the organ BO, so that the lumen of the organ BO is closed, whereas the other two elements CSDE2and CSDE3are activated to constrict but not stimulate the organ BO, so that the lumen of the organ BO is not completely closed where the elements CSDE2and CSDE3engage the organ BO.FIG.13jshows how the element CSDE2in a second following state of operation is activated to both constrict and stimulate the organ BO, so that the lumen of the organ BO is closed, whereas the other two elements CSDE1and CSDE3are activated to constrict but not stimulate the organ BO, so that the lumen of the organ BO is not completely closed where the elements CSDE1and CSDE3engage the organ BO.FIG.13kshows how the element CSDE3in a following third state of operation is activated to both constrict and stimulate the organ BO, so that the lumen of the organ BO is closed, whereas the other two elements CSDE1and CSDE2are activated to constrict but not stimulate the organ BO, so that the lumen of the organ BO is not completely closed where the elements CSDE1and CSDE2engage the organ BO. By shifting between the first, second and third states of operation, either randomly or in accordance with a predetermined sequence, different portions of the organ can by temporarily stimulated while maintaining the lumen of the organ closed, whereby the risk of injuring the organ is reduced. It is also possible to activate the stimulation of the elements CSDE1-CSDE3successively along the lumen of the organ BO to move fluids and/or other bodily matter in the lumen.

FIGS.14-16show basic components of an embodiment of the apparatus for controlling a flow of fluid and/or other bodily matter in a lumen formed by a tissue wall of a patient's organ. The apparatus comprises a tubular housing1with open ends, a constriction device2arranged in the housing1, a stimulation device3integrated in the constriction device2, and a control device4(indicated inFIG.16) for controlling the constriction and stimulation devices2and3. The constriction device2has two elongate clamping elements5,6, which are radially movable in the tubular housing1towards and away from each other between retracted positions, seeFIG.15, and clamping positions, seeFIG.16. The stimulation device3includes a multiplicity of electrical elements7positioned on the clamping elements5,6, so that the electrical elements7on one of the clamping elements5,6face the electrical elements7on the other clamping element. Thus, in this embodiment the constriction and stimulation devices form a constriction/stimulation unit, in which the constriction and stimulation devices are integrated in a single piece.

The constriction and stimulation devices may also be separate from each other. In this case, a structure may be provided for holding the electrical elements7in a fixed orientation relative to one another. Alternatively, the electrical elements7may include electrodes that are separately attached to the wall portion of the patient's organ.

FIG.17ashows an example of transmitted pulses, according to one embodiment. The pulses have a constant frequency and amplitude. However, the relation between the times t1and t2varies.

FIG.17bshows another example of transmitted pulses, according to another embodiment. During the time t1a train of pulses is transmitted, and during the time t2no pulses are transmitted. The pulses have a constant frequency and amplitude. However, the relation between the times t1and t2varies.