SI25942A - Device for magnetic nerve muscle stimulation by measuring voltage variation on a capacitor - Google Patents

Abstract

Device (1) for magnetic nerve muscle stimulation, characterized in that it detects material in the space near the applicator (3). The device measures the voltage on the capacitor (2) in the device (1), and based on the change in voltage during operation, assumes the properties of materials near the applicator (3) and the change of materials near the applicator (3). Depending on the measured properties of the material in the vicinity of the applicator (3), it changes the operating parameters of the device (1).

Description

Device for magnetic nerve muscle stimulation by measuring voltage variation on a capacitor

Field of technology

Magnetic neuromuscular stimulation is used for diagnostic and therapeutic purposes and for the purpose of restoring original function to individual organs. In magnetic neuromuscular stimulation, the changing magnetic field of high magnetic field densities causes the activation of nerve cells and related muscle cells.

State of the art

The magnetic muscle stimulation device consists of a capacitor with stored electrical charge from which an electric current flows into a coil mounted in the applicator. Depending on the conditions on the capacitor and the inductance of the applicator system, we determine the properties of the electric current flowing through the wires into the coil. The changing electric current in and around the coil causes a magnetic field. Typical properties of a commonly used magnetic field are a magnetic field density of up to 3.5 T, with a monopolar or bipolar pulse length between 1 us and 10 ms, a coil inductance between 1 nH to 100 mH, a change in magnetic flux density of up to 1 MT / s. various modulations of the devices used in the operation, and a pulse frequency of up to 900 Hz. The inductance of the coil is between 1 nH to 100 mH, the voltage up to 10,000V and the currents up to 10,000 A. The changing magnetic field of the coil causes an electric current in the human body. The electric current generated by a magnetic field, like the much better known electrical stimulation, causes a change in the voltage across the membrane of nerve cells and consequently triggers the action potential of sensory or motor nerve cells. Triggering of motor nerve cells causes muscle activation and thus a response of the peripheral muscular system. To achieve this effect, electrical muscle stimulation is much better known and more commonly used, in which an electric current causes the activation of nerve cells. In electrical stimulation, an electric current is supplied to the body through electrically conductive electrodes. The electrodes are placed on the skin, subcutaneously, or along the peripheral nerve to be stimulated; with the placement of electrodes on the skin predominating. The electrodes can be attached to the skin through mounting with fixing tapes or self-adhesive electrodes. For electrical stimulation to work, we must always attach at least one pair of electrodes to the body.

The magnetic field generates an electric current flowing through the wire. The magnetic field is usually generated by a coil. The coil consists of a wire that is wound one or more times in the central part in a closed loop, while the two remaining ends of the wire are connected to a current generator. Thus, the coil is connected to the device by a pair of wires. The magnetic field that causes an electric field inside the body during magnetic neuromuscular stimulation depends on the size and shape of the electric current and the shape of the coil. Magnetic muscle stimulation devices are described in patents such as US6123658 and US 6123658, US9586057, US9974519, US9919161.

The electric charge flowing through the coil is stored, between two capacitor plates mounted inside the device. The electric charge can be measured as the electrical voltage between the capacitor terminals. Depending on the amount of electric current flowing through the capacitor, the amount of charge stored in the capacitor decreases, and thus the voltage on the capacitor. The amount of electric current at a given voltage on the capacitor depends on the inductance of the coil and the conditions around the coil. Depending on the electric current flowing through the wires in the coil, the voltage across the capacitor changes over time. The electric current depends on the conditions in the applicator and in the vicinity of the applicator.

Technical problem

The technical problem is the ignorance of the materials in the vicinity of the applicator. Depending on the properties and distances of biological material or material with different conductivity and inductance, therapy parameters could be adjusted, or therapy could be interrupted when the patient is not nearby, or parameters for which the device is not dimensioned occur.

Solution to a technical problem

The solution to the technical problem, the properties of the material in the vicinity of the applicator, can be recognized from the characteristics of the changing voltage of the capacitor when discharging the electric charge from the capacitor to the coil mounted in the applicator.

The properties of the applicator, the materials in the applicator and the materials in the vicinity of the applicator determine the inductance of the applicator system. The properties of the applicator and the materials in the applicator do not change during therapy. Any change in the inductance of the applicator system can thus be unambiguously associated with a change in the properties of the material in the vicinity of the applicator and the placement of the materials in the immediate vicinity of the applicator. The main properties are the inductance of materials and the electrical conductivity of these materials. The inductance of the applicator system affects the amount of current flowing through the coil in the applicator. Higher current discharges the electrical charge stored in the capacitor faster and reduces the voltage on the capacitor faster. A smaller current slows down the discharged electrical charge stored in the capacitor and slows down the voltage across the capacitor. By monitoring the speed and properties of the voltage change on the capacitor, we can thus infer the materials located near the applicator.

The amount of electric current that reduces the electric charge stored in the capacitor, and thus the reduction of the voltage across the capacitor can be estimated from the rate of change of the voltage across the capacitor.

From the properties of the materials, we can recognize whether the applicator works in an empty space, biological tissue, or in the vicinity of a material that greatly increases the inductance of the applicator system. In addition to the recorded extreme states, we can also recognize intermediate states (e.g., that part of the space near the applicator is filled with biological tissue), and that there has been a movement of material near the applicator.

The described placement of materials is necessary regardless of whether the applicator is located independently and is placed on the body with a stand, attached to the body with straps, held by the therapist, or is installed so that the patient can sit on it. , for example in a chair. In the case described, the applicator can be installed in the seat of the chair, the back of the chair, which allows targeted treatment of the pelvic floor, or elsewhere in the chair.

Figure 1: Implementation of a device for magnetic muscle stimulation with an applicator

Figure 2a: Figure 2a shows an embodiment of a magnetic muscle stimulation device with an applicator next to which there is an empty space, Figure 2b shows an embodiment of a magnetic muscle stimulation device with an applicator next to biological tissue, Figure 2c shows an embodiment of a magnetic muscle stimulation device stimulation with an applicator that greatly alters the inductance of the applicator system.

Figure 3: Figure 3a graphically shows the time course of voltage drop on the capacitor if there is empty space near the applicator, Figure 3b graphically shows the time course of voltage drop on the capacitor if near the applicator next to the biological tissue, Figure 3c is a graphical representation of the time course of the voltage drop across the capacitor, with a material located in the space near the coil that greatly alters the inductance of the applicator system.

Figure 1 shows a device (1) with a capacitor (2) connected to the applicator (3), inside which is a coil (4) that generates a magnetic field in the space near the coil (5).

Figure 2a shows a device (1) with a capacitor (2) connected to an applicator (3), inside which is a coil (4) that generates a magnetic field, the space near the coil being empty (6).

Figure 2b shows a device (1) with a capacitor (2) connected to an applicator (3), inside which is a coil (4) that generates a magnetic field, with biological tissue in the space near the coil (7). ).

Figure 2c shows a device (1) with a capacitor (2) connected to an applicator (3), inside which is a coil (4) that generates a magnetic field, with a material in the space near the coil that strongly changes the inductance of the applicator system (8).

Figure 3a graphically shows the time course of the voltage drop across the capacitor (U) as a function of time (t) if there is an empty space (6) near the applicator.

Figure 3b graphically shows the time course of the voltage drop across the capacitor (U) as a function of time (t) if biological tissue is located near the applicator (7).

Figure 3c graphically shows the time course of the voltage drop across the capacitor (U) as a function of time (t) if there is a material near the applicator that greatly alters the inductance of the applicator system (8).

Claims (9)

Patent claims 1. A device for magnetic neuromuscular stimulation, with a coil built into the applicator and a capacitor in the device, characterized in that the time course of the voltage change is monitored on the capacitor. Device according to Claim 1, characterized in that the changing properties of the coil voltage are monitored. Device according to Claims 1 and 2, characterized in that the properties of the material in the vicinity of the coil mounted in the applicator are inferred from the variation of the voltage. Device according to Claim 3, characterized in that the operating parameters of the device are changed on the basis of voltage changes. Device according to Claim 4, characterized in that the device is switched off if the current changes too rapidly. The device of claims 1-5, wherein the coil is mounted in a chair. The device of claims 1-6, wherein the coil is mounted in the seat of the chair. The device of claims 1-5, wherein the coil applicator is attached to the patient. The device of claims 1-5, wherein the applicator is designed to be held in the hand.