Magnetic switching device

A magnetic switching device includes an electromagnetic component adapted to be arranged proximate to an exterior surface of an object having a magnetically-switchable device therein and a control circuit electrically connected to the electromagnetic component. The electromagnetic component is constructed to generate a magnetic field of sufficient strength and orientation to engage a switch in the magnetically-switchable device. The invention further includes an electrocautery system, including an electrocautery device, a control circuit electrically connected to the electrocautery device, and an electromagnetic component electrically connected to the control circuit. The electromagnetic component is adapted to be arranged proximate to an exterior surface of an object having a magnetically-switchable device therein. Operation of the electrocautery device causes the electromagnetic component to generate a magnetic field of sufficient strength to engage a switch in the magnetically-switchable device.

BACKGROUND

1. Field of Invention

This application relates to magnetic switching devices and systems, and more particularly to magnetic switching devices and systems for controlling embedded electrical devices.

2. Discussion of Related Art

Currently in the United States, there are thousands of patients implanted with electrical devices, for example, but not limited to, pacemakers and/or implantable cardioverter-defibrillators (ICDs). A pacemaker, also called an artificial pacemaker, is a device which uses electrical impulses, delivered by electrodes contacting the heart muscles, to regulate the beating of the heart. An ICD is a small battery-powered electrical impulse generator which is implanted in patients who are at risk of sudden cardiac death due to ventricular fibrillation and ventricular tachycardia. The ICD is programmed to detect cardiac arrhythmias and correct it by delivering a jolt of electricity.

Many patients with such electrical devices will require non-cardiac surgery or procedures at some point during their lifetime which may interfere with their electrical devices. Non-cardiac surgery may include the use of electrocautery during surgery, lithotripsy, for treatment of kidney stones, the use of a transcutaneous electrical nerve stimulation (TENS) device, or radiation therapy in the treatment of cancer. This presents a serious problem, as many electrical devices are sensitive to electromagnetic interference (EMI) from other electrical devices used during surgery. Consequently, many implantable devices are designed with a magnetically operable switch to shut off the device or switch it to a “backup mode” when a magnetic field is applied. For example, a patient's pacemaker exposed to EMI may malfunction. Similarly, a patient's ICD may mischaracterize EMI as ventricular fibrillation (VF) and may deliver a shock to the patient. VF is a condition in which there is an uncoordinated contraction of the cardiac muscle of the ventricles in the heart, making them quiver rather than contract properly.

Several methods have been adopted to avoid the influence of EMI on an imbedded electrical device during surgery. However, these methods have some serious limitations. For example, one solution in avoiding EMI is to reprogram the magnetically-switchable device. However, reprogramming generally requires a technically skilled person to be present to reprogram each device, making reprogramming an expensive option.

Another known solution is to place a magnet over a magnetically-switchable, electrical device to inactivate or place the device in a backup mode. The type of magnet used is usually a large permanent magnet, such as a donut magnet. Needless to say, it is difficult to position and to ensure that the magnet stay in place during surgery. Shifting of the magnet during an operation could reactivate the magnetically-switchable, electrical device, for example the pacemaker or ICD, and put the patient at risk.

SUMMARY

There thus remains a need for devices and/or systems to facilitate control of embedded electrical devices. One embodiment of the present invention relates to a magnetic switching device that includes an electromagnetic component adapted to be arranged proximate to an exterior surface of an object comprising a magnetically-switchable device therein; and a control circuit electrically connected to the electromagnetic component, wherein the electromagnetic component is constructed to generate a magnetic field of sufficient strength to engage a switch in the magnetically-switchable device.

Another embodiment of the present invention relates to an electrocautery system that includes an electrocautery device; a control circuit electrically connected to the electrocautery device; and an electromagnetic component electrically connected to the control circuit, wherein the electromagnetic component is adapted to be arranged proximate to an exterior surface of an object comprising a magnetically-switchable device therein, and wherein operation of the electrocautery device causes the electromagnetic component to generate a magnetic field of sufficient strength to engage a switch in the magnetically-switchable device.

This summary is provided merely to introduce certain concepts and not to identify any key or essential features of the claimed subject matter. Further features and advantages of embodiments of the invention, as well as the structure and operation of various embodiments of the invention, are described in detail below with reference to the accompanying drawings.

DETAILED DESCRIPTION

FIG. 1Ais schematic illustration of a top view of a magnetic switching device100, in accordance with at least some embodiments of the present invention. The magnetic switching device100may include an electromagnetic component10in electrical connection to a control circuit12. The electromagnetic component10may include a patch14adapted to be arranged proximate to an exterior surface of an object20(seeFIG. 2A), for example a human medical patient, having an embedded magnetically-switchable device22(seeFIG. 2A), for example a pacemaker or ICD. However, the general concepts of the current invention are not limited to only pacemakers and ICDs implanted in people. Other types of magnetically-switchable devices could be implanted in the patient or even some non-human object. When activated, the control circuit12delivers a current I to the electromagnetic component10which, in turn, generates a magnetic field B (seeFIG. 2B) of sufficient strength and orientation to engage a switch (not shown) in the magnetically-switchable device22of the object20. According to one embodiment, the electromagnetic component10will generate a magnetic field of approximately 0.1 to 45 Gauss when activated.

According to another embodiment, the magnetic field B generated by the electromagnetic component10may cause the magnetically-switchable device22, here a pacemaker, to go VOO, i.e. to revert into back-up mode. According to a further embodiment, the magnetic field B generated by the electromagnetic component10may cause the magnetically-switchable device22, here an ICD, to turn of its sensing function and to go into a backup pacing mode. In either embodiment, deactivation of the electromagnetic component10, which stops the generation of the magnetic field B, can re-engage the switch of the magnetically-switchable device22, causing the magnetically-switchable device22to revert back to its original settings and to resume normal operation.

According to one embodiment, the patch14may be an adhesive patch adapted to be affixed to the exterior surface of the object20. In that case, the adhesive patch may prevent the electromagnetic component10from accidentally shifting during surgery potentially moving the electromagnetic component10out of the necessary proximity to the magnetically-switchable device22, thus failing to switch the magnetically-switchable device22to a backup mode or some other desired mode of operation during EMI. For these same reasons, the patch width may include additional tolerance to compensate for error during surgery. Alternatively, other fastening devices may be used, such as straps, clips, stickers, suction devices and/or medical tape. The patch14may further be reusable or disposable.

According to another embodiment, the electromagnetic component10further includes a core16that is coupled to or positioned on the patch14. A wire18, for example an enamel-covered wire, may be wound around the core16to produce an electromagnetic coil11(seeFIG. 1B). The wire18may provide the electrical connection of the electromagnetic component10to the control circuit12. The wire18may be in the range of approximately 0.3 to 1.3 millimeters in diameter, for example. According to another embodiment, the wire thickness may range from approximately 0.25 centimeters to 0.6 centimeters.

According to a further embodiment of the current invention, the core16may be embodied as a plastic donut, a plastic cylinder, a metal cylinder and/or a metal donut. The embodiment of the metal cylinder core16, for example a ferromagnetic core, may provide a maximum magnetic field, however weight may become a consideration. For example, it may be advisable to limit the weight of the core16to approximately eight pounds.

According to one embodiment, the electromagnetic component10may include a heat absorber and/or heat dissipater (not shown) to absorb/dissipate the heat generated by the coil11. The heat absorber may be embodied as a single-piece insulating layer, a multi-piece insulating layer, or passive/active heat dissipation system, such as a layer of gel. The heat absorber may be coupled to or positioned on the patch14.

FIG. 1Bis a side view of the electromagnetic coil11of the magnetic switching device100ofFIG. 1A. Generally, an electromagnetic coil11may refer to a coil of wire that is formed to produce a magnetic field B when current I flows through the coil. One loop of wire18is generally referred to as a “turn,” and a coil11consists of one or more turns. In other words, the coil11may be accomplished with a minimum of one loop or turn. As seen inFIG. 1B, the wire18is wound around the core16eight times to produce eight turns. As such, the control circuit12may send a current I through the wire18to the coil11of the electromagnetic component10to generate the magnetic field B over the magnetically-switchable device22embedded in the object20.

According to one embodiment, the control circuit12may transmit approximately five Amperes of current I to the electromagnetic component10via the wire18. Five Amperes is used only as an example of a current I. The current I could be more than five Amperes or it could be less. A smaller current I may reduce the heat generated by the coil11. In this embodiment, the five Amperes of current I through a wire18, where the wire18is approximately 0.5 millimeters in diameter, may generate approximately 12 Watts of power. The 12 Watts of power may generate approximately 172 calories/minute.

According to another embodiment, the portion of the patch14affixed or positioned in close proximity to the exterior surface of the object20may be dimensioned as 15 centimeters by 15 centimeters. The coil11may have a radius R of approximately 7 centimeters and a height H of approximately 3 centimeters. The current I transmitted from the control circuit12to the electromagnetic component10may be approximately five Amperes (A).

FIG. 2Ais a schematic diagram of the magnetic switching device100during a “power off stage,” in accordance with some embodiments of the present invention. As shown inFIG. 2A, the electromagnetic component10has been positioned on the exterior surface of an object20, for example a medical patient, above the object's magnetically-switchable device22. Here, the control circuit12, also called a “electrocautery generator,” may comprise a DC or AC power supply24electrically connected to the electromagnetic component10via a wire18having a switch26, also called an “electrocautery pen.” In other embodiments, the switch26may be an “on/off” switch, a foot petal and/or any other activation device. In the embodiment ofFIG. 2A, the switch26is open, thus preventing the power supply24from supplying a current Ito the coil11of the electromagnetic component10. The coil11of the electromagnetic component10, therefore, cannot generate a magnetic field B. This may be referred to as the “power off stage.”

FIG. 2Bis a schematic diagram of the magnetic switching device100during a “power on stage,” in accordance with some embodiments of the present invention. InFIG. 2B, the switch26is closed, thus transmitting current I from the power supply24to the coil11of the electromagnetic patch10which then generates a magnetic field B of sufficient strength to engage the switch in the embedded magnetically-switchable device22. This may be referred to as the “power on stage.”

According to one embodiment, approximately eight Gauss may be required to effectuate a backup mode on the magnetically-switchable device22. Furthermore, the coil11may be adapted to generate a magnetic field B that is perpendicular to the skin surface of the object20. The coil radius R may be sized to accommodate magnetically-switchable devices22of different types, sizes and shapes. The coil radius R may be, for example, but not limited to, between 4.2 and 9.5 centimeters. The coil11may be embodied as a dot magnet with a highly concentrated and directed magnetic field B. Alternatively, the coil11may be provided with a slightly larger radius R for additional tolerance to compensate for the spacing between the coil11and the magnetically-switchable device22embedded in the object20. Additional tolerance may be desirable when the center of the magnetically-switchable device22is unknown. Furthermore, additional tolerance may compensate for any shifting of the magnetically-switchable device22within object20due to body movement during surgery.

According to another embodiment, the current I is approximately five Amperes, the skin thickness of the object20is approximately 5 centimeters, and the magnetic field B is at least eight Gauss during operation. The skin thickness of the object20may be used to determine the distance of the magnetically-switchable device22from the coil11of the electromagnetic component10. This distance may be calculated by adding the skin thickness of the object20, or medical patient, and the patch14thickness, where the patch14is directly affixed to the exterior surface, or skin, of the object20.

FIG. 3is a graphical diagram showing simulation results for the strength of the magnetic field B delivered at the magnetically-switchable device22based on the number of wire turns of the electromagnetic coil11, in accordance with some embodiments of the present invention. As described above, the wire18may be wound around the circumference of the core16a pre-determined number of times to produce an electromagnetic coil11adapted to generate an appropriate magnetic field B during the power on stage. The pre-determined number of turns, for example, but not limited to, may be between 30 and 50 turns of wire18.FIG. 3depicts a graph of the simulation results of the magnetic switching device100based on varying numbers of turns of the wire18.

The embodiment ofFIG. 3, assumes that an ideal circular coil11is used, including, for example, an air or cylindrical/donut fixture that does not generate any magnetic field other than that which is generated by the coil11. For example, the coil11may include a plastic cylinder, as seen inFIGS. 1A,1B,2A and2B. Such an ideal circular coil11is depicted to the right of the graph inFIG. 3. The embodiment assumes that the skin thickness of the object20is approximately five centimeters. Skin thickness may be used to calculate the depth of the magnetically-switchable device22in the object20, which may in turn be used to calculate the strength of the magnetic field B experienced at the magnetically-switchable device22. The embodiment further assumes that the current through the wire18is approximately five Amperes. In this embodiment, the electromagnetic component10requires a minimum magnetic field B of eight Gauss to generate a magnetic field B of sufficient strength to engage the switch (not shown) of the magnetically-switchable device22. A coil11having 40 turns of wire and a coil radius of approximately eight centimeters would produce a magnetic field B of approximately 9.6 Gauss, as shown in Example A. Meanwhile, a coil11having 50 turns of wire and a coil radius of approximately seven centimeters would produce a magnetic field of B of approximately 12 Gauss, as shown in Example C. This embodiment shows that the strength of the magnetic field B at the magnetically-switchable device22is proportional to the number wire turns and depends on the coil radius. The coil11is not limited to 40 or 50 turns of the wire18, other embodiments, for example 30 turns of wire, are also possible.

FIG. 4is a graphical diagram showing simulation results for the strength of the magnetic field B delivered at the magnetically-switchable device22based on the skin thickness of the object20, in accordance with some embodiments of the present invention. As described above, an object's20skin thickness may be used to determine the depth of the magnetically-switchable device22within the object20and, thus, the strength of the magnetic field B at that depth. According to one embodiment, the depth of the magnetically-switchable device22will not exceed a depth of five inches from the skin surface.

In Example D ofFIG. 4, an object's20, or patient's, skin thickness is approximately seven centimeters. Under Example D, an approximately 9.5 centimeter coil radius will generate a magnetic field B of approximately 8.75 Gauss. In Example E, an object's20, or patient's, skin thickness is approximately five centimeters. Under Example E, an approximately seven centimeter coil radius will produce a magnetic field B of approximately 12 Gauss. Likewise, when an object's20, or patient's, skin thickness is one centimeter, an approximately 4.2 centimeter coil radius will produce the maximum magnetic field B at the given skin thickness (not shown).FIG. 4demonstrates the need to optimize the radius of the coil11depending on depth of the magnetically-switching device22within the object.

FIG. 5is a chart comparing various characteristics of the core16of the magnetic switching device100, in accordance with some embodiments of the present invention. According to one embodiment, the coil11may include an insulator or air core16′, as depicted to the top left of the chart. An insulator core refers to an insert that is positioned within the coil11and that is constructed from plastic or another insulating material. An air core simply refers to the coil11having a non-existent hollow core, i.e. it uses open spaces between the loops of the coil11for air. An insulator/air core16′ is light-weight, low-cost, easy to fabricate and produces an acceptable amplitude of the magnetic field B. Any wire18may be used with the insulator/air core16′. However, the insulator/air core16′ does not allow for precise control of the direction of the magnetic field B and produces a smaller amplitude of magnetic field B than would the metal/ferromagnetic core16″ inFIG. 5. The example shown inFIG. 5is a cylinder, however other shapes, such as a donut, may be used.

According to another embodiment, the coil11may include a metal/ferromagnetic core16″, as depicted to the top right of the chart. The metal/ferromagnetic core16″ may be constructed from iron, nickel, or any other ferromagnetic material. The metal/ferromagnetic core16″ has an acceptable amplitude of the magnetic field B and has a better control of the direction of the magnetic field B than the insulator/air core16′ Specifically, the metal/ferromagnetic core16″ is better able to concentrate or focus the magnetic field B towards the magnetically-switchable device22embedded in the object20. However, the metal/ferromagnetic core16″ is heavy, more expensive and harder to fabricate. Further, the metal/ferromagnetic core16″ must be used in conjunction with a wire18which is coated with an insulator or, alternatively, the surface of the core16″ itself must be coated with an insulator.

FIG. 6is a schematic illustration of a top view of an electrocautery system600, in accordance with some embodiments of the present invention. In this embodiment, a control circuit12, including a power unit62and switch box64, is in electrical connection with both an electromagnetic component10and an electrocautery device66. The electrocautery device66may be any device used for electrocauterization, i.e. the process of destroying tissue using heat conduction from a metal probe heated by an electric current, and may be referred to as an electrocautery pen. In this embodiment, when in use, the electrocautery device66triggers an input into the switch box64, which switches on the power unit62to send an output current Ito the electromagnetic component10. As with the prior embodiments, the electromagnetic component10is adapted to be arranged proximate to an exterior surface of an object20having an embedded magnetically-switchable device22(seeFIGS. 2A and 2B). When current I is transferred from the power unit62to the electromagnetic component10, the electromagnetic component10is adapted to generate a magnetic field B of sufficient strength to engage a switch in the magnetically-switchable device22.

This embodiment prevents EMI from interfering with the object's20magnetically-switchable device22during surgery. Examples of non-cardiac surgery may include the use of electrocautery during surgery, lithotripsy, the use of a TENS device, or radiation therapy. Each time the surgeon uses the electrocautery device66, the control circuit12activates the electromagnetic component10to generate a magnetic field B over the magnetically-switchable device22, thus halting or modifying the normal operation of the magnetically-switchable device22and preventing a disruption or malfunction due to EMI. This is again shown inFIG. 7, in which a simplified circuit diagram of the electrocautery system is shown.

As seen inFIG. 7, control circuit12, including a power source62, is electrically connected to both an electromagnetic component10and an electrocautery device66. When the electrocautery device66is in use during an operation, the circuit loop closes, thus connecting the control circuit20, the electromagnetic component10and the electrocautery device66in series. This connection enables the power source62to transmit a current I to the electromagnetic component10for generation of a magnetic field B. When the electrocautery device66is not in use, the loop remains open and no current I may pass to the electromagnetic component10.

According to one embodiment, the control circuit12may optionally include a protective circuit70to prevent electrical shock generated while turning the electrocautery device66on and off. The protective circuit70may be positioned between the power source62and the electrocautery device66and/or switch26. Alternatively, the protective circuit may be positioned between the electrocautery device66and/or switch26and the electromagnetic component10.

According to one embodiment, the electrocautery system600may include a lock-out at ten seconds or some other programmable period of time to prevent an accidental reprogramming of an ICD. Some ICD models reprogram if a magnet is applied for more than several seconds. This embodiment may be able to control the duration of the magnet application in such a case or leave this setting off if reprogramming is not an obstacle. In addition, it is possible that the electromagnet may generate too much heat and such a lock-out system may set a duration of the electromagnetism to prevent this.

According to another embodiment, either the magnetic switching device100or the electrocautery system600may include a lighting device or LED device to show a user, for example a surgeon, that the electromagnetic component10is in use.

According to a further embodiment, the electrocautery device66may be directly plugged into the control circuit12of the electrocautery system600. Since the electrocautery device66may act as the electrocautery system600on/off switch, according to one embodiment the electrocautery device66should plug into the electrocautery system600prior to operation.

FIG. 8is a schematic diagram of the electrocautery system600, in accordance with some embodiments of the present invention. In this embodiment, a ground patch80may be coupled to the patch14to ground the object20, i.e. the patient during surgery. The ground patch80may be a separate pad connected to a bypass, which may be positioned on an extremity of the object20and away from the patch14of the electromagnetic component10. The ground patch80, according to one embodiment, need not be incorporated with the bypass.

FIG. 9is a schematic diagram of the magnetic switching device100having a plurality of coils11connected in series to a power source24, in accordance with at least some embodiments of the present invention. In this embodiment, five coils11are connected via wire18to power source24. The coils11may each be coupled to and/or positioned on the patch14and may have, for example, a radius R of 4.2 centimeters. The coils11may be positioned at a distance S from one another, which may be, for example, 0.2 centimeters apart. The plurality of coils11may concentrate a stronger and more directed magnetic field B on the magnetically-switchable device22. The plurality of coils11may increase the tolerance to compensate in the case where the center of the magnetically-switchable device22is unknown or where the magnetically-switchable device22shifts within object20due to body movement during surgery.

FIG. 10is a schematic diagram of the magnetic switching device100having a plurality of coils11connected in parallel to a plurality of power sources24, in accordance with at least some embodiments of the present invention. In this embodiment, five coils11are positioned on or coupled to the patch14of the electromagnetic component10. Each coil11is connected to a separate power source24. Each coil11may further be connected to a separate trigger and/or switch26. The power sources24may optionally be external power sources to the system. A connecting module (not shown) may be used to correlate the operation of each coil11of the magnetic switching device100. Here again, the coils11may have a radius R, for example 4.2 centimeters, and may be positioned at a distance S from one another, for example 0.2 centimeters. The plurality of coils11may increase the tolerance to compensate in the case where the center of the magnetically-switchable device22is unknown or where the magnetically-switchable device22shifts within object20due to body movement during surgery.

According to a further embodiment, a hybrid system may be used (not shown). The hybrid system may use both an electromagnetic coil11and a permanent magnet to generate a magnetic field B of sufficient strength and orientation to engage a switch in the magnetically-switchable device22of the object20. In this embodiment, a thinly sliced static or permanent magnet may be combined with an electromagnet coil11to produce a more powerful magnetic field B over the magnetically-switchable device22. Meanwhile, the magnetic field B generated only by the static or permanent magnet may be smaller than eight Gauss so that it cannot turn on the the magnetically-switchable device22of the object20, unless the coil11is activated. The permanent magnet may either be looped together with the electromagnet coil11using wire18or may be layered on top of the electromagnet coil11. This embodiment may reduce the amount of electricity needed to effectively operate the electromagnetic component10of the magnetic switching device100.

The present invention, in various embodiments, includes components, methods, processes, systems and/or apparatuses substantially as depicted and described herein, including various embodiments, subcombinations, and subsets thereof. The present invention, in various embodiments, includes providing devices and processes in the absence of items not depicted and/or described herein or in various embodiments hereof, including in the absence of such items as may have been used in previous devices or processes, e.g., for improving performance, achieving ease and\or reducing cost of implementation.

The foregoing discussion of the invention has been presented for purposes of illustration and description. The foregoing is not intended to limit the invention to the form or forms disclosed herein. In the foregoing Detailed Description for example, various features of the invention are grouped together in one or more embodiments to facilitate a description of some concepts of the current invention. This method of disclosure is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the following claims are hereby incorporated into this Detailed Description, with each claim standing on its own as a separate preferred embodiment of the invention.