Device for transcranial magnetic stimulation

Abstract

The invention relates to a device (10) for transcranial magnetic stimulation of a target region in a body part of a patient, comprising a stimulation unit (20) having at least one magnetic coil (30), wherein the device (10) comprises at least one contact sensor (40) which is designed to detect a contact point (60) between the stimulation unit (20) and a surface (50) of the body part in order to align the stimulation unit (20) with the target region.

Description

[0001] December 19, 2025 FORBENCAP GmbH M / FOR-009-WO

[0002] title

[0003] Device for transcranial magnetic stimulation

[0004] The invention relates to a device for transcranial magnetic stimulation of a target area in a part of a patient's body.

[0005] State of the art

[0006] Transcranial magnetic stimulation (TMS) is a non-invasive method for activating neurons, particularly in the human brain, and has become an important tool in both experimental neuroscience and clinical medicine. Through electromagnetic induction, TMS generates short but intense magnetic fields that induce electrical fields in targeted brain regions. These fields enable precise stimulation of neuronal circuits and modulation of neuronal activity, which is of great importance for understanding brain function and for therapeutic approaches in various neurological and psychiatric disorders.

[0007] The state of the art of TMS and its functionality are described in detail in the literature, for example Goetz et al. [SM Goetz and ZD Deng (2017). The development and modelling of devices and paradigms for transcranial magnetic stimulation. International Review of Psychiatry, 29(2), 115-145. DOI:

[0008] [10.1080 / 09540261.2017.1305949] and patent literature, for example, publications US 2005 / 0256,539, US 7,494,458, US 2013 / 0267,763, US 2010 / 033,160, or US 9,486,639. In particular, publication US 7,087,008 discloses a TMS system with a treatment coil, or simply coil, for bringing the coil close to or into contact with the body, i.e., tissue, and delivering signals via pulses into the tissue and to the neurons located therein. A special aspect of the publication is a focal application and the corresponding orientation of the coil.

[0009] The process begins with a current pulse in the coil, which generates a transient magnetic field. This magnetic field, in turn, induces a magnetic flux in the brain tissue, creating an electric field strong enough to activate neurons. Neuronal activation occurs primarily through the response of ion channels in the axon membranes to the induced electric field, thus mimicking physiological neuronal activity.

[0010] Specific protocols such as repetitive transcranial magnetic stimulation (rTMS), theta burst stimulation, or quadripulse stimulation can alter the excitability of specific neural circuits, thereby enabling neuromodulation. These protocols can either suppress or enhance the activity of neural networks, thus shifting the balance between opposing neural circuits. Neuromodulation has far-reaching implications for restoring functional balance in neurological disorders and for studying cortical excitability in the healthy brain.

[0011] TMS is also used therapeutically, for example in the treatment of depression, where it helps to recalibrate dysregulated neural networks. Furthermore, it serves as a diagnostic tool for neurological disorders and is an indispensable instrument in brain research, particularly in the investigation of functional connectivity and neuronal plasticity. Nevertheless, there are challenges in its therapeutic application, as success rates for remission of depression with TMS currently range only between 14% and 33%.

[0012] Recent studies emphasize the importance of pulse shape and duration for optimizing the selectivity and efficacy of TMS-induced neuromodulation. Asymmetric pulses have been shown to produce stronger and more precise neuromodulation than conventional biphasic pulses. These findings have driven the development of power electronics technologies capable of generating rapid series of near-monophasic pulses with variable shapes and durations. This allows for further optimization of stimulation protocols and enables more effective applications in both research and clinical practice.

[0013] A particular challenge in the application of TMS is the precise positioning of the stimulation coil. It must be aligned exactly with six degrees of freedom – three for position and three for orientation. The rounded surface of the head further complicates this task, as the coil's focal point must be precisely aligned with the desired cortical target. Errors in alignment or positioning can significantly reduce the effectiveness of the stimulation. The alignment of the coil, i.e., its orientation, poses considerable difficulties for most users, especially positioning the coil tangentially, for example, on the curved, though not perfectly spherical, head surface above the target and keeping it there. No known technical aid currently solves this problem satisfactorily, and its quality and extent are not described in scientific publications, such as Lin et al. [Y.-Y.Lin et al. (2022). Impact of operator experience on transcranial magnetic stimulation. Clinical Neurophysiology Practice, 7:42-8. DOI: 10.1016 / j.cnp.2022.01.002] and Koehler et al. [M. Koehler et al. (2024). How coil misalignment and mispositioning in transcranial magnetic stimulation affect the stimulation strength at the target. Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology, 162, 159-161. DOI: 10.1016 / j.clinph.2024.03.037] reveal that even machine or robotic positioning of the treatment coils fails in the current state of the art, according to studies [SM Goetz et al. (2019). Accuracy of robotic coil positioning during transcranial magnetic stimulation. Journal of Neural Engineering, 16(5), 054003. DOI: 10.1088 / 1741-2552 / ab2953] less in terms of position, but noticeably in terms of orientation. Furthermore, the scientific paper by Goetz and Kammer [S. Goetz, T. Kammer (2021). Neuronavigation.In: The Oxford Handbook of Transcranial Stimulation, second edition, pp. 183-226, Oxford University Press. DOI:.

[0014] [10.1093 / oxfordhb / 9780198832256.013.7] that previous solutions are indirect, complex, difficult for users to handle and expensive.

[0015] Neuronavigation systems assist users by providing real-time feedback on the coil's position and orientation relative to the patient's head and brain anatomy. These systems often use stereotactic cameras and retroreflective markers to track and display the coil and head positions on a computer screen. Despite their advantages, these systems are often bulky, require a high level of operator skill, and can be tiring during prolonged use.

[0016] To overcome these challenges, more user-friendly spool designs and advanced technologies such as transparent visual aids or virtual windows are being developed, allowing users to align the spool more intuitively. Furthermore, spool designs such as branded iron-style handles, aligned with the spool's normal axis to facilitate positioning, are being developed. However, even these innovations have their limitations, particularly with inexperienced users.

[0017] The further development of TMS systems aims to reduce reliance on manual operation and maximize stimulation precision. By refining pulse shapes, improving coil designs, and integrating intuitive navigation aids, the next generation of TMS devices has the potential to revolutionize both clinical and research applications, making neuromodulation more effective and accessible.

[0018] Documents US 2013 / 0003,242 and US 11,658,476, for example, disclose protective circuits using diodes, pn junctions, and elements that conduct current above certain voltages.

[0019] These prior art solutions can completely dissipate exhaustible overvoltages, such as the source charge, and convert them into heat, but they are entirely unsuitable for the present problem. The inventors recognized that the source impedance of TMS is low for electromagnetic coupling, unlike other prior art voltage couplings with high source impedance. In the prior art, the induced energy is dissipated due to the high source impedance upon short-circuiting or dissipation of all charge at a voltage higher than, for example, the supply voltage of the sensor circuit. With TMS, however, the energy is not dissipated when the voltage is dissipated at low impedance. Instead, the induced voltage remains relatively constant due to the low source impedance and increases the current, thus also increasing the energy.While the electronics may detect a lower overvoltage with this approach, the current rises to levels that can damage the electronics. The source impedance of TMS can be less than 100 mΩ, and induced currents can exceed 100 A. Accordingly, electronics located near the coil are problematic according to the prior art and sometimes even dangerous due to the high induced energies. The object of the invention is to provide an improved device for transcranial magnetic stimulation of a target area in a patient's body part.

[0020] Disclosure of the invention

[0021] The problem is solved by a device according to the features of claim 1.

[0022] According to a preferred aspect, a device for transcranial magnetic stimulation of a target area in a body part of a patient is proposed, comprising a stimulation device with at least one magnetic coil, wherein the device includes at least one touch sensor configured to detect a point of contact between the stimulation device and a surface of the body part in order to align the stimulation device with the target area.

[0023] The device comprises a stimulation unit with at least one magnetic coil designed to generate a magnetic field to induce an electric field in the target area of ​​a body part, particularly the brain. The magnetic coil is designed to preferably generate precise and focused stimulation signals. A feature of the device is the at least one touch sensor, preferably integrated in close proximity to the underside of the magnetic coil. The touch sensor is preferably configured to detect the point of contact between the magnetic coil and the surface of the body part, for example, the scalp. The sensor can be capacitive, resistive, or a combination of both technologies to enable high-resolution detection of the point of contact. This allows not only the determination of touch but also the detection of deviations in the orientation of the magnetic coil.

[0024] The touch sensor can take various forms, such as a single sensor in the area of ​​the coil's hotspot, multiple discrete sensors that detect the touch point with high accuracy, or a high-resolution sensor grid that enables detailed 2D or 3D analysis of the touch points. Preferably, the sensor data is processed in real time and displayed to the operator via a display device to ensure precise positioning and alignment of the magnetic coil.

[0025] A particular challenge is posed by the electromagnetic conditions for electronics located near, and especially on the direct underside of, a coil. Due to its design, the treatment coil emits a strong electromagnetic field for excitation, typically in the form of intense, short pulses often lasting around 1 ms or less. The electric field strength at the location of the touch sensor can exceed 100 V / m, 200 V / m, and even 300 V / m. The magnetic flux density can be one or more Tesla. Consequently, there is a risk that the pulse intended for stimulation will induce high voltages in the electronics, exceeding not only the measurement voltage but also the destruction voltage of the evaluation electronics. Conventional protection methods, such as those for electrostatic discharge (ESD), are unsuitable for this invention.ESD protection circuits typically use diodes to divert overvoltages into the supply voltage, usually less than 5 V, and often as low as 3.3 V or less. Alternatively, Zener diodes or transient voltage suppressors are sometimes used; these become conductive at a voltage above a certain limit, dissipating the charge and preventing higher voltages.

[0026] The device offers several technical advantages. The integration of a touch sensor significantly facilitates the precise alignment of the stimulation device with the target area, thereby increasing the effectiveness of the magnetic stimulation. The touch sensor makes it possible to detect deviations in coil position and / or inclination, particularly in real time, and to display them visually if necessary, which is a considerable help, especially for inexperienced operators.

[0027] The use of thin sensor materials, such as polymer films, ensures, for example, that the distance between the magnetic coil or its magnetically effective conductor windings and the target area remains minimal, thereby maximizing the strength of the induced electric field.

[0028] Compared to expensive and bulky neuronavigation systems, this device offers a cost-effective, compact, and easily integrated solution that increases user comfort and improves stimulation outcomes. Furthermore, the real-time display of touch points on a screen or in an augmented reality headset enables intuitive operation and reduces the likelihood of errors in positioning the magnetic coil.

[0029] The device may "comprise a magnetic coil equipped with a touch sensor that detects the contact area between the coil and the surface of the target area." Another formulation could be: "The device comprises a magnetic coil with an integrated or removable touch sensor that serves to determine the position of the magnetic coil relative to the patient's head surface." Alternatively, the claim could read: "The device has a high-resolution touch sensor that detects the contact points between the magnetic coil and the body part and contributes to optimal positioning."

[0030] In another aspect, it is proposed that the touch sensor be capacitive and / or resistive, and preferably provide a submillimeter resolution for detecting the touch point.

[0031] The capacitive touch sensor preferably utilizes changes in the electric field caused by contact with the patient's head surface to accurately detect touch points. Alternatively, a resistive sensor preferably detects touches through changes in electrical resistance when the upper and lower sensor layers meet. Both sensor types can be configured to provide high sensitivity and resolution to maximize the precision of magnetic coil positioning. Submillimeter resolution enables the high-precision alignment required for focused stimulation applications. This allows for improved touch point detection and thus more precise control of magnetic coil positioning. The technical advantage is that high-resolution detection increases stimulation accuracy and, consequently, the effectiveness of neurostimulation.

[0032] In another aspect, it is proposed that the stimulation device has a bottom surface facing the body part and a top surface opposite the bottom surface, and that the touch sensor is located on the bottom surface or integrated into the bottom surface, enabling touch detection along the bottom surface within a range of at least 2 cm in every direction along the bottom surface around the point of touch.

[0033] The underside of the magnetic coil is preferably designed for placement on the body part, while the top side is preferably oriented towards the user. The placement of the touch sensor on the underside preferably allows for direct and precise detection of the point of contact with the head surface. A range of at least 1 to 2 cm in each direction preferably ensures that even larger deviations from the ideal position can be detected. Alternatively, the touch sensor could be detachable for attachment to different coil types. This offers the possibility of detecting positional deviations over a wide range, increasing the flexibility of the stimulation. Technical advantages include improved usability and / or a reduction in incorrect placement.

[0034] A touch sensor according to the invention could detect biological material and indicate and / or locate contact with tissue. For example, conductive material due to the ionic solution of usually over 100 mmol / L sodium, potassium, or calcium in the body, in contrast to, for example, insulating plastic on the underside of the coil, or due to the electrical polarization of the high water content of tissue as well as the organic acids and salts contained in tissue cells, such as phospholipids, can be measured, for example, by electrically separated but adjacent contact structures made of electrically conductive material on or in the surface of the coil, which become electrically conductive to a greater or lesser extent upon contact with tissue, since the tissue establishes an electrical contact.Furthermore, electrical polarization, and thus contact with ground, can be measured via at least one electrical conductor or between at least two electrical conductors, for example, conductor pairs, which need not be in contact with tissue. Polarization can be measured, for example, via a pulse response or a detuning of a resonance if the electrical conductors are part of an electrical resonator, for example, together with an inductor. In contrast to the prior art, this can be done, in particular, through a layer of hair.

[0035] In another aspect, it is proposed that the touch sensor includes several sensor segments which, for the purpose of aligning the stimulation device, enable the detection of deviations of the touch point from an ideal contact point, usually on the underside of the coil.

[0036] Multiple sensor segments preferably enable the detection of contact points in different areas of the coil's underside, allowing deviations from the ideal position to be detected preferably immediately. This allows the operator to be prompted with targeted corrections. Alternatively, the sensor segments could preferably be configured as a ring-shaped or grid-like arrangement to ensure complete coverage or a large proportion of the underside, for example, at least 10% of the area, preferably at least 20%, and particularly preferably at least 40%. This offers greater accuracy in coil alignment, as even small positional or tilt errors are detected. The technical advantage lies in the improved precision of the stimulation, which is particularly important for complex target areas.

[0037] In another aspect, it is proposed that the device has a display device, and that the information from the touch sensor can be visualized on the display device, the display device preferably being arranged on a top side of the stimulation device or as a separate display near an operator of the stimulation device.

[0038] The display device preferably serves to show the data acquired by the touch sensor, particularly in real time, thus assisting the operator in correct positioning. An arrangement on the top of the coil preferably offers a direct line of sight, while a separate display allows for greater handling flexibility. Alternatively, the display device could preferably be implemented as a mobile app or software solution on an external device. This enables intuitive and user-friendly visualization of the coil position. Technical advantages include reduced error rates and more efficient handling by the operator.

[0039] In a further aspect, it is proposed that the display device graphically represent the information as a vector, numerical angular deviations, and / or a point on a 2D grid to assist the operator in correcting the alignment of the stimulation device. The graphical representation preferably allows for immediate interpretation of the data by the operator. A vector preferably shows the direction of the deviation, numerical values ​​provide specific information about the angular deviation, and a 2D grid shows the relative position of the coil to the target surface. Alternatively, the display could preferably be visualized as a 3D model to clarify the spatial orientation. This enables improved and faster alignment of the coil. The technical advantage lies in the increased efficiency and accuracy of the neurostimulation.

[0040] In another aspect, it is proposed that the touch sensor is designed to detect a curvature of the surface of the body part and to calculate 2D or 3D orientation information from this in order to determine an inclination of the stimulation device relative to the surface of the body part.

[0041] Capturing the curvature preferably allows for precise adjustment of the coil orientation to the individual anatomical characteristics of the patient. Alternatively, the touch sensor could be combined with a camera or other optical scanning systems to collect additional geometric data. This offers the possibility of precisely considering complex surfaces, thus making the stimulation more targeted. The technical advantage lies in the improved adaptability to different patients and target areas.

[0042] In another aspect, it is proposed that the display device be integrated as part of a head-up display or an augmented reality headset in order to provide the operator of the stimulation device with visual support, particularly intuitive support, in positioning the stimulation device relative to the body part.

[0043] Integration into a head-up display allows the operator to see the coil position and / or the acquired data directly in their field of vision without having to change their gaze. Alternatively, an augmented reality headset could display additional virtual instructions or assistance. This offers seamless operation and reduced cognitive load for the operator. Technical advantages include increased precision and improved ergonomics during use. Furthermore, it is proposed that the touch sensor be arranged on or encompass a polymer film, and that the touch sensor have a height of less than 2 mm, preferably less than 1 mm, and further preferably less than 300 µm.

[0044] The use of thin polymer films preferably reduces the device's overall height and minimizes the distance between the magnetic coil and the target area. This preferably ensures maximum field strength and stimulation efficiency. Alternatively, flexible materials could be used to facilitate adaptation to curved surfaces. This offers improved signal strength and stimulation precision. Technical advantages include higher effectiveness while maintaining a compact design.

[0045] In another aspect, it is proposed that the device includes a signal processing unit designed to analyze the data acquired by the touch sensor and transmit it via an electromagnetically isolated interface.

[0046] The signal processing unit preferably processes the sensor data in real time and preferably ensures its interference-free transmission, even with the high electromagnetic pulses generated by the magnetic coil. Alternatively, signal isolators or special filters could be integrated to make the transmission even more robust. This enables reliable data analysis and interference-free communication, for example, for transmission to the display device. Technical advantages include increased operational reliability and the avoidance of malfunctions due to electromagnetic interference.

[0047] The at least one touch sensor used in the device can preferably combine various technologies, such as capacitive or resistive sensors, to ensure high flexibility and precision. Capacitive sensors utilize changes in the electrostatic field caused by the patient's conductive scalp to detect touch. Preferably, such sensors can also be multi-touch capable, allowing them to detect multiple touch points simultaneously. This provides the possibility of obtaining detailed information about the contact area between the magnetic coil and the head surface, which is particularly advantageous for complex surface geometries of the body part. Alternatively, resistive sensors could be used, which detect touch through changes in electrical resistance and represent a robust solution for applications where mechanical stress may occur.

[0048] Additionally, the device can be equipped with a signal processing unit that analyzes the data from the touch sensors and transmits it to the operator in real time. Preferably, the signal transmission is electromagnetically isolated to minimize interference caused by the high voltage rise rates (dV / dt) typically found in TMS systems. This electromagnetic isolation can preferably be achieved by using signal isolators and / or isolated DC-DC converters, thereby increasing the operational reliability of the device. Ferrite cores can preferably be used as an additional measure to further suppress residual interference in common-mode mode.

[0049] Another optional feature of the device is the ability to position touch sensors near the hotspot of the magnetic coil.

[0050] Preferably, sensors can be arranged directly in the hotspot or in a ring-shaped pattern around the hotspot to ensure precise coil alignment. This allows the operator to accurately detect both the contact point and deviations from the optimal position. Preferably, a high-resolution sensor grid could also be used that detects contact points with submillimeter resolution, further improving alignment accuracy.

[0051] The hotspot of the coil preferably refers to the point or area on the magnetic coil where the induced electric field is strongest. This point is preferably located in the center or at a characteristic location on the coil, depending on the coil's design. In a typical figure-of-eight coil, such as those preferably used in transcranial magnetic stimulation, the hotspot is located at the overlap of the two loops, as the magnetic fields of both coil sections constructively overlap there. The hotspot is the area where the magnetic stimulation is most effective, since the maximum field strength here enables targeted and focal stimulation of neurons. The precise positioning of the hotspot is important for effectively stimulating the desired target area in the brain. If the hotspot is not precisely aligned over the target area, the stimulation may be less effective or even ineffective.Therefore, the hotspot is a central reference point for positioning the coil. The device described in the invention addresses this problem by integrating touch sensors in the area of ​​the hotspot. This means that touch sensors are preferably located below and / or more or less laterally to the side of the hotspot in order to detect both a correct position and any deviation, and even to quantify it metrically, for example in millimeters or centimeters, or in degrees of rotation. Well-defined positions or distances from the hotspot are particularly preferred in order to quantify both the direction and extent of the deviation in well-defined units, such as metric units. These sensors detect the point of contact between the coil and the head surface and provide the operator with real-time information on the coil's position and orientation.

[0052] By directly detecting touch at and around the hotspot, the system ensures that the coil is correctly aligned with the target area. The operator receives feedback on any deviations, allowing the coil to be adjusted as needed until the hotspot is optimally positioned. This enables more precise and effective stimulation and minimizes the risk of misplacement. The integration of such sensors significantly improves coil handling, as alignment can be controlled intuitively and user-friendly. The hotspot thus remains the central point where maximum efficiency and effectiveness of the stimulation is achieved.

[0053] The device also offers easy integration into existing systems. The touch sensor can preferably be either permanently integrated into the underside of the magnetic coil or designed as a removable component that can be attached to various coil types. This allows for flexible adaptation to different applications and user requirements without requiring significant modification of the coil itself. One application example demonstrates how the device improves the alignment of the magnetic coil with the patient's head. Preferably, the touch sensor detects which point of the coil is in contact with the head and transmits this information to the display device in real time.If the coil is misaligned, for example due to tilt or lateral displacement, the display device graphically indicates the deviation to the operator, for instance, by a vector pointing in the direction of the deviation (or alternatively, 180° opposite it). The length and / or line thickness and / or color represent the quantitative extent of the deviation, and the direction indicates either the direction of the deviation, the direction in which an operator would need to correct, or numerical angular deviations. The operator can then correct the position and orientation of the coil until the sensor registers the optimal contact point. This real-time feedback significantly improves alignment precision, resulting in more effective stimulation of the target area. This is particularly beneficial for inexperienced operators, as the intuitive visual support reduces training requirements and greatly simplifies operation.

[0054] Additionally, the device is preferably robust against external influences, such as hair on the patient's scalp. Preferably, the touch sensor ignores interference from hair and focuses exclusively on contact with the scalp. This ensures that the sensors retain their functionality even with varying hair lengths and / or densities, further simplifying its use with different patients. These features make the device a versatile and reliable solution for transcranial magnetic stimulation in clinical and experimental settings.

[0055] A touch sensor can be constructed in various ways, depending on the technology and application requirements. Preferably, it comprises a sensitive layer and / or structure that detects touch and converts it into an electrical signal that can then be processed. A capacitive touch sensor preferably consists of a conductive layer that generates an electrostatic field. When a conductive object, such as the scalp, comes into contact with or is near the sensor surface, the local capacitance preferably changes. This change is measured by a control chip or oscillator, which converts it into a digital signal. Capacitive sensors can be implemented as a continuous layer or in the form of a grid of transparent conductive materials, such as indium tin oxide (ITO), on a polymer film.

[0056] Alternatively, a resistive touch sensor can be constructed, comprising at least two conductive layers separated by an insulating intermediate layer. When pressure is applied to the upper layer, the two conductive layers make contact, creating a closed circuit. This contact results in a measurable change in electrical resistance, which is evaluated by a microcontroller. Such sensors are robust and can operate reliably even under mechanical stress.

[0057] A high-resolution touch sensor can preferably be configured as a grid structure, for example with row and column arrays, in which individual sensor elements detect local touches. In the described device, this structure could be designed to cover the entire area around the coil's hotspot. Preferably, the sensor is mounted on a thin polymer film with a thickness of less than 2 mm, ideally less than 1 mm, and more preferably less than 300 pm, to minimize the distance between the coil and the target area. The film could be provided with capacitive or resistive sensor elements arranged either as individual points or as a complete grid to enable precise detection of the touch point.

[0058] The conductors can be applied to one side of the substrate, for example a film, a substrate, or a carrier film, to establish electrical contact with the fabric and thus a temporary circuit between at least one conductor and, for example, ground, or between at least two conductors. This allows for the identification of the conductors causing the circuit and / or a change in impedance, and thus for the localization of the contact point(s). The electrical conductors can preferably be arranged such that, under normal contact with a fabric, at least two contacts interact electrically with the fabric, for example, by conducting more or less effectively and / or changing their electrical impedance relative to each other.The conductors can be arranged, for example, as points in a regular grid or an irregular structure where, for instance, the area beneath the hotspot has a higher density of points capable of making contact. If the exact location of each point is known, a contact point with coordinates on the underside of the coil can be determined when a current is detected through a point or when the electrical impedance of that point changes relative to another potential, such as ground, or to another point. For multiple contact points, these can be averaged mathematically. Preferably, they are then grouped into contiguous areas to identify several separate contact points, with at least one of these contact points being assigned a location, for example, by calculating the mathematical mean of the positions of the associated contacts.Alternatively, the conductors can also be designed as surfaces with larger dimensions, for example to improve the contact resistance to fabric and / or to take into account the accuracy required depending on the deviation.

[0059] For example, if the contact point deviates significantly from the hotspot, a more precise quantification of the deviation is no longer necessary than when the contact point is very close to the hotspot. Therefore, the points or areas at a distance from the hotspot can become larger. The radial extent from the hotspot thus influences the metrological resolution of the coil's radial orientation error. The transverse extent, i.e., on the surface perpendicular to the radial direction, determines the measurement accuracy of the direction of the coil's orientation error. Ideally, the extent of the respective planar contact over a wide area in both directions is directly and linearly related to the corresponding measurement accuracy. Alternatively, a contact pattern consisting of rings or ring segments can also be used, in accordance with the basic concept of the invention.Rings allow the magnitude of an alignment error to be quantified as soon as a contact is detected, for example, via current flow or an impedance change. Segmentation, in turn, allows the direction from the center of the ring, preferably the hotspot of the coil, to be specified. The impedance change can relate to resistance and / or capacitance. If the impedance primarily involves capacitance, a non-conductive material, such as a lacquer layer, film, glass, or plastic, can be placed between the conductors and the surface contacting the fabric. Preferably, the material is non-conductive and has well-defined dielectric properties, i.e., a constant, preferably known, dielectric constant.Similarly, the conductors can be arranged on multiple sides, for example, on both sides of a substrate, such as a film, or on several separate layers of a film or a comparable material, for example, three. The conductors on different layers or sides are preferably at least locally at a large angle to each other, for example, at least 30°, more preferably at least 45°, more preferably at least 60°, or even perpendicular. This can, for example, represent a pattern of parallel, straight lines over large areas, which, for example, run in one direction on one side or layer and at an angle to this direction on a second side or layer. If these conductors run at a large angle to each other, for example, even perpendicularly, corresponding row and column conductor patterns result.Similarly, conductors extending radially from a center, preferably the hotspot, are arranged on a first side or plane, and conductors extending as rings or ring segments at varying distances from a center point are arranged on a second side or plane. If the substrate, for example the film, is compressible, a contact point can be identified and located by a change in the impedance, for example capacitance and / or resistance, of the conductors relative to each other. For example, by applying pressure with fabric to a specific point, the distance between at least one conductor on a first side or layer on or in the substrate, for example a film, is forced against at least one second conductor on a second side or layer on or in the substrate, such that their electrical properties, preferably in the form of impedance, change between them, while the electrical properties between other conductors, for example, remain unchanged.Given a known location where the at least one first conductor and the at least one second conductor come close to each other, preferably lying one above the other separated by a substrate such as a film, the invention allows a location, and thus a contact point, to be assigned to such a change in the electrical properties between the two. For example, the substrate can have a fixed electrical conductivity per unit distance and cross-sectional area, whereby a local pressure and, if the substrate material is elastic, a subsequent change in thickness, an increased current flow and / or a reduced resistance, can be measured and localized by two conductors arranged as described above.Furthermore, the substrate can exhibit a fixed electrical capacitance per unit distance and cross-sectional area, caused, for example, by dielectric properties. This can result in local pressure and, if elastic, a subsequent change in thickness, leading to an increased current flow under AC voltage and / or an increased capacitance, which can be measured and localized by two conductors arranged as described above. A change in capacitance can also be detected, for example, by the detuning, i.e., the change in a resonant frequency, of a component whose capacitance is affected, together with another electrical element, such as an inductor. Furthermore, both the resistance and the capacitance can be changed by contact and / or pressure and preferably measured simultaneously.

[0060] Alternatively, micromechanical switches can be placed between different conductors on the substrate, for example, a film. Upon contact, these switches transform a less electrically conductive connection between a first and second conductor into a more conductive one. This variant has the advantage of allowing the use of well-defined and inert substrate materials, which also do not require precisely controlled mechanical properties. Furthermore, such switches can prevent destructive current flow caused by induced voltages.

[0061] Additionally, touch sensors can be combined with signal processing units that measure voltage or capacitance changes and calculate the precise position of the touch point. Such systems can be equipped with oscillators that are detuned by capacitive changes or with a capacitive divider that uses threshold circuits. These signals are converted into digital data and forwarded to the control unit or a display for further processing. Thanks to the use of modern materials and electronics, touch sensors can be manufactured to be very thin, flexible, and cost-effective, while simultaneously ensuring high precision and robustness.

[0062] The electronics are preferably designed such that no conductor generates low-impedance current loops below the coil, which could then carry the flux of its winding through the coil. Depending on the coupling into the sensor electronics, the induced voltage can be the coil voltage, usually less than 2600 V, often less than 2200 V, and sometimes less than 1700 V, divided by the coil's voltage transfer factor, for example, 7 to 15. Therefore, for small resulting currents, the invention should provide an impedance of at least 100 Ω, preferably at least 1 kΩ, particularly preferably at least 10 kΩ, 50 kΩ, or even 100 kΩ between contacts and in loops. Furthermore, the conductors are preferably arranged such that they have lengths in the centimeter range, for example, more than 2 cm, preferably more than 4 cm, and particularly preferably more than 5 cm, but do not cover a large area.Preferably, the area spanned by a conductor with a return conductor is less than 10 cm. 2 , especially preferred to be smaller than 5 cm 2 and preferably smaller than 1 cm 2 The impedance can be increased by adding resistors to the conductor or between a conductor and the evaluation electronics. Furthermore, the impedance can be increased by the substrate on or in which the conductors are located, for example, a foil, so that the paths from one conductor to another exhibit a high impedance within the limits mentioned above. Preferably, the resistance from at least one first conductor to another conductor is at least 100 Ω, more preferably at least 1 kΩ, and more preferably at least 10 kΩ or even at least 100 kΩ. Ideally, the substrate and conductors are designed such that the resistance from the majority of the conductors to another majority of the conductors reaches at least the resistance values ​​mentioned above.

[0063] Furthermore, the invention allows conductors to be disconnected from the evaluation electronics during a coil stimulus by means of switches, for example, mechanical switches, micromechanical switches, or semiconductor switches. For example, the impedance can also be significantly increased during a pulse using transistors. After a pulse, a conductive connection can be re-established to resume measurement operation. The inventors have recognized that measurement information can usually be dispensed with during the short duration of a pulse if measurement information is available before and after. Preferably, the conductors, which alone or together with other conductors form current loops with a resistance of less than 1 kΩ, do not have clipping diodes, for example, for power supply, or Zener diodes or similar elements that dissipate a voltage above a threshold.Preferably, leakage and clipping diodes are only present in conductor loops resulting from individual or combinations of conductors and the contact between them (for example, through the substrate or through fabric in contact with the conductors), and which have a loop resistance of at least 100 Ω, preferably at least 1 kΩ, particularly preferably at least 10 kΩ or even 100 kΩ, such that the induced current, which can be leaked via the diodes, is limited accordingly by the resistance. If leakage or clipping diodes are present, at least one further resistor of at least 100 Ω, preferably at least 1 kΩ, particularly preferably at least 10 kΩ or even 100 kΩ, is connected between the terminal of a leakage or clipping diode (for example, leaking to ground or another reference potential such as the supply voltage) and the evaluation electronics of the touch sensor. Particularly preferably, they contain no leakage or clipping diodes at all.

[0064] Alternatively, the voltage induced in the (electrical) conductors of the touch sensor can be shielded from the evaluation electronics by capacitors connected in series with the evaluation electronics, thus preventing damage. Furthermore, a capacitor connected in series with the evaluation electronics can be combined on the evaluation electronics side with a connection to at least one resistor connected to the supply voltage, ground, or another preferably stable and robust potential. Additionally, at least one further capacitor on the evaluation electronics side can be connected to a supply voltage, ground, or another preferably stable and robust potential to form a dynamic capacitive voltage divider with the at least one series capacitor. Finally, another resistor can be connected in series between the capacitors and the evaluation electronics to isolate the latter from the capacitors.The latter capacitor is preferably larger than the former. Preferably, it is larger by more than a factor of two, and particularly preferably by a factor of 5, 10, 20, or even 50. The arrangement forms a bandpass filter. The time constants of the bandpass filter can be tuned so that TMS pulses are not within the passband but are filtered out, preferably by a factor of more than ten, and particularly preferably by a factor of more than 50 or even 100.

[0065] To further reduce the induced voltage, the electrical connections of conductors in the substrate, for example on or within a foil, to the evaluation electronics can be arranged in such a way that they absorb little or no induced voltage from the coil. This can be achieved, for example, by having the connections, also called leads, run locally approximately perpendicular to the winding in the coil. In typical figure-eight coils, for instance, two ring structures are present, allowing the leads to run radially to the circular winding of the coil in order to absorb as little induced voltage as possible. The leads can run radially from the center or from one side. Furthermore, a figure-eight coil generates a predominant electric field that lies perpendicular to the line connecting the two centers of the figure eight.Accordingly, the leads of the touch sensor can preferably run predominantly in the direction of the connecting line of the centers of the figure eight and as little as possible perpendicular to it, for example, at least 60% in the direction of the connecting line and only a maximum of 40% perpendicular to it, preferably at least 80% in the direction of the connecting line, and particularly preferably at least 90% in the direction of the connecting line. This design is particularly advantageous for touch sensors that provide at least two conductors on the surface of a substrate, which come into electrically conductive contact with the tissue, for example, of a person's head, in order to measurably change an electrical connection between the conductors via the tissue or an impedance in the form of a resistance and / or a capacitance between the two conductors by the evaluation electronics.

[0066] To avoid absorbing induced voltage as much as possible, conductors and combinations of conductors are preferably arranged in such a way that no large areas, especially not exceeding 1 cm², are affected. 2 , 2 cm 2 or even 5 cm 2 , in a plane approximately parallel to the underside of the coil or a surface projected onto such a parallel plane.

[0067] Preferably, such resulting areas are further compensated by the opposing course of the corresponding conductors, for example on another plane or on the back of the touch sensor, so that the induced voltages in the loop add up to the induced voltage in the compensation preferably to approximately zero or to a value below the supply voltage.

[0068] For example, conductors can have an active part and a compensation part to reduce this loop area. The active part corresponds to the part mentioned above, which, accordingly, forms an impedance (e.g., capacitance and / or resistance) with other active parts of conductors upon local contact with tissue. The compensation part of a conductor preferably does not have electrical interaction with another compensation part of a second conductor via an impedance and can, for example, run on an isolated plane of the touch sensor, such as on the back of the touch sensor facing the coil. Preferably, the path of the compensation part approximately follows the path of the electrically isolated active part located next to or below it.

[0069] The invention preferably does not require optoelectronic components, which are highly prone to failure in real-world environments, cannot handle hair, and are expensive. Furthermore, it preferably does not require ultrasonic components, for example, to measure distances to surfaces. The solution generally preferably does not measure the distance between points on the underside of the coil and the head surface, which would be complicated, for example, by hair, braids, or other medical systems such as electroencephalography electrodes. In particular, the solution is not dependent on the optical properties of the surface, which can vary considerably between individuals due to pigmentation and therefore already leads to problems and inconsistent results from person to person, or excludes certain individuals, in the prior art of optical medical technology.The presented solution, in contrast, can in principle distinguish between biological tissue and technical surfaces, since these exhibit different electrical properties, particularly conductivity and dielectric strength. For coil alignment and correct contact positioning near the hotspot, the solution primarily or exclusively considers body tissue and the body surface, such as the scalp. Similarly, the solution can differentiate between hair and tissue. Preferably, the solution is designed such that the measuring electronics have a threshold for changes in impedance, for example, a resistance and / or capacitance. This threshold is preferably chosen such that hair is not recognized as a contact, but tissue is. Due to the numerous problems associated with this method, the solution preferably avoids detecting a contact point by measuring a distance.

[0070] In one embodiment, the device comprises evaluation electronics and / or impedance measurement electronics configured to operate with a supply voltage and / or signal voltages above a certain, particularly expected, induced voltage in the conductors. For example, the evaluation electronics and / or impedance measurement electronics operate in a voltage range of at least 5 volts, with operation of the evaluation electronics and / or impedance measurement electronics at voltages of 10 volts, preferably 15 volts, is provided.The evaluation electronics and / or impedance measurement electronics preferably use an integrated circuit based on a semiconductor process specifically designed for higher voltages. This results in increased robustness compared to the usual voltage ranges of 1 to 3.3 volts, and in particular, ensures that the voltage induced in the conductors during a pulse remains below the operating voltage and / or the supply voltage and / or the usual operating voltage range. This design specifically prevents induced voltages from exceeding the supply voltage, as such a condition would lead to a collapse of the input impedance and a rapid increase in current.This results from the technologically unavoidable pn junctions, which, acting as diodes, divert voltages above the positive supply of signals and / or input pins to the power supply and divert voltages below ground and / or the negative supply of signals and / or input pins to ground and / or the chip substrate. Adapting the evaluation electronics and / or impedance measurement electronics to higher voltage ranges ensures that such effects are avoided, thus guaranteeing the functionality and reliability of the evaluation electronics and / or impedance measurement electronics even under induced voltages.

[0071] The described configurations and training programs can be combined in any way desired.

[0072] Further possible embodiments, developments and implementations of the invention also include combinations of features of the invention described previously or subsequently with regard to the exemplary embodiments that are not explicitly mentioned.

[0073] Brief description of the drawings

[0074] The accompanying drawings are intended to provide a further understanding of the embodiments of the invention. They illustrate embodiments and serve in the context of describing and explaining the principles and concepts of the invention.

[0075] Other embodiments and many of the aforementioned advantages become apparent with reference to the drawings. The elements depicted in the drawings are not necessarily shown to scale.

[0076] Fig. 1 shows a schematic representation of the device according to one embodiment.

[0077] Fig. 2 shows a schematic diagram of the device according to one embodiment.

[0078] Fig. 3A-3D shows schematic representations of touch sensors.

[0079] Figs. 4A, 4B show schematic circuit diagrams of the device according to

[0080] Embodiments. Fig. 5 shows a schematic structure of a touch sensor.

[0081] Fig. 6 shows a schematic representation of the device according to one embodiment.

[0082] Fig. 7 shows a schematic sectional view of the structure of a touch sensor.

[0083] Fig. 8 shows a schematic diagram of a touch sensor.

[0084] Fig. 9 shows a schematic diagram of a touch sensor.

[0085] Fig. 10 shows a schematic diagram of a touch sensor.

[0086] Fig. 11 shows a schematic diagram of a touch sensor.

[0087] Fig. 12 shows a schematic sectional view of the structure of a touch sensor.

[0088] Detailed description of the drawings

[0089] In the figures of the drawings, identical reference symbols denote identical or functionally equivalent elements, parts or components, unless otherwise stated.

[0090] Fig. 1 shows a schematic representation of a device 10 for transcranial magnetic stimulation. A different embodiment of the device 10 is also shown in Fig. 6 and may, for example, also include a handle 11 for guiding the device 10. In Fig. 6, the device is shown during a tilting movement and is therefore drawn accordingly. The device 10 comprises a stimulation unit 20 with a magnetic coil 30. Furthermore, the device 10 includes a touch sensor 40. The touch sensor 40 is, for example, designed as a capacitive sensor. The device 10, by means of the touch sensor 40, is designed, for example, for the precise positioning of the stimulation unit 20 or the magnetic coil 30 on the head surface 50 of a patient. According to Fig. 1, the touch sensor 40 is shown to be significantly oversized in relation to the stimulation unit 20.

[0091] The touch sensor 40 is, for example, composed of several layers to detect a point of contact 60 between a bottom surface 21 of the stimulation device 20 and the head surface 50. The touch sensor 40 comprises, for example, a conductive layer 41 in the X-direction and another conductive layer 42 in the Y-direction, which are electrically separated from each other by an intervening dielectric or insulating layer 43. These two conductive layers 41 and 42 preferably form a capacitive sensor grid that serves to detect changes in capacitance at specific points when the head surface 50 touches the touch sensor 40. The precise localization of the point of contact 60 is preferably achieved by superimposing the measurement data from both layers 21 and 22.

[0092] The touch sensor 40 further comprises an insulating front layer 44, which forms the outer layer of the touch sensor 40 oriented towards the head surface 50. This front layer 44 protects the underlying components and preferably ensures that the touch sensor 40 does not make direct electrical contact with the scalp. Preferably, the front layer 44 is made of a flexible, thin material to ensure the lowest possible overall height and to facilitate adaptation to the contours of the head surface 50.

[0093] On the reverse side of the touch sensor 40, which faces the underside 21 of the stimulation device 20, a support layer or substrate 45 is provided, which ensures the structural stability of the entire touch sensor 40. This substrate preferably serves as a mechanical basis for the conductive layers 441 and 42 as well as the insulating intermediate layer 43.

[0094] The head surface 50 of the patient is shown schematically in Fig. 1, with the point of contact 60 being detected by the capacitive properties of the skin.

[0095] As soon as the head surface 50 touches the touch sensor 40, the residual charge of the scalp induces a local change in the electrostatic field in the touch sensor 40. This change is analyzed, for example, by a signal processing unit 70 (Fig. 2) to determine the exact position of the point of contact 60 and to visualize it for the operator via a display device 80. The signal processing unit 70 can, for example, include the evaluation electronics and / or impedance measurement electronics mentioned earlier in the text.

[0096] The display device 80 can preferably be arranged either directly on a top surface 22 of the stimulation device 20 or as a separate element to provide the operator with intuitive visual feedback. The sensor data are preferably processed graphically and can be displayed, for example, as a point 81 on a grid 82 or as numerical values ​​to optimize the coil alignment.

[0097] Figure 2 shows a schematic representation of the operation and data processing within the device 10 for transcranial magnetic stimulation. Figure 2 illustrates the signal flow from the touch sensor 40 of the stimulation device 20 via a signal processing unit 70 to the display device 80, which provides the operator with precise feedback on the position and orientation of the magnetic coil 30 on the patient's head surface 50.

[0098] The touch sensor 40 is designed to detect the point of contact 60 between the underside 21 of the stimulation device 20 and the head surface 50. The signals generated by the touch sensor 40 are transmitted to the signal processing unit 70 via an isolated interface 90. To protect the sensitive signals from electromagnetic interference from the magnetic coil 30, the interface 90 has an isolator 91 integrated into the signal flow. The isolator 91 ensures galvanic isolation and minimizes interference caused by the high voltage rise rates (dV / dt) that can occur during stimulation.

[0099] Preferably, the isolator 91 could be implemented by signal isolators or optical couplers to ensure reliable data transmission.

[0100] The signal processing unit 70 receives the isolated signals from the touch sensor 40 and analyzes them to determine the exact position of the touch point 60. The analyzed data is then forwarded to the display device 80, which provides visual feedback to the operator. The display device 80 includes, by way of example, a screen on which the data from the touch sensor 40 is graphically displayed. In Fig. 2, this is illustrated by a grid 82 on which the current touch point 60 is displayed as point 81. This visual feedback enables the operator to precisely correct the orientation of the magnetic coil 30 and optimally align the touch point 60 over the target area.

[0101] The grid 82 on the display device 80 provides the operator with an intuitive orientation aid. The displayed point 81 shows the current position of the contact point 60 relative to the ideal position on the head surface 50. Alternatively, the sensor data could also be displayed as numerical values ​​or vectors representing the direction and distance of the coil alignment relative to the target position.

[0102] Figures 3A to 3D show schematic representations of different possible arrangements of conductive layers in the touch sensor 40 of the transcranial magnetic stimulation device 10. These different designs illustrate how the conductive layers 41 and 42 within the touch sensor 40 can be configured to enable precise detection of the touch point 60 and optimal adaptation to the contours of the head surface 50.

[0103] Figure 3A shows a first arrangement in which the conductive layers of the touch sensor 40 are arranged in concentric circles and radial segments. The central conductive zone preferably corresponds to the hotspot of the magnetic coil 30, where the electric field is strongest. The radial segments enable the detection of deviations of the coil in various directions relative to the target area. This arrangement provides a clear delineation of the individual sectors, which facilitates the localization of contact points.

[0104] Fig. 3B shows an extended version of the arrangement from Fig. 3A. Additional concentric rings are integrated here to achieve higher resolution in the detection of touch points. The finer segmentation enables more precise determination of the touch points and thus more detailed feedback on the orientation of the magnetic coil 30. This configuration is particularly advantageous when high spatial resolution is required. Fig. 3C shows an alternative arrangement in which the touch sensor 40 is located in a central area and adjacent radial sectors. Here, the conductive layers of the sensor are more focused on the central area, enabling particularly precise detection at the hotspot. The radial sectors support the detection of lateral deviations, and the segmentation simplifies data analysis.

[0105] Fig. 3D shows a variant with overlapping concentric rings and radial segments. This arrangement combines the advantages of the concentric rings from Fig.

[0106] 3B with the radial sectors from Fig. 3C to achieve maximum spatial resolution and coverage of the touch sensor 40. The central area remains the point with the highest detection accuracy, which is particularly important for the precise positioning of the coil at the hotspot.

[0107] Fig. 4A shows a schematic representation of an electronic circuit 400 for capacitive touch detection, which can be used as part of the touch sensor 40 in the device 10 for transcranial magnetic stimulation. The circuit shown illustrates how touches are detected by changes in capacitance or impedance and how the resulting signals are forwarded for further processing.

[0108] The circuit is based on a capacitive input element that measures the electrical capacitance between a conductive surface and a contacting object, such as the surface of the head 50. When a conductive surface, such as human skin, is brought near the sensor or touches it, the local capacitance changes.

[0109] The capacitive sensor is schematically represented here as a conductive plate connected to a pull-up resistor RP. This resistor RP serves to keep the capacitive sensor in a defined state when no touch is detected. Additionally, a base resistor RB is present, which regulates the current supply to the base of the transistor. The transistor itself acts as a switching amplifier, converting small changes in capacitance into amplified electrical signals. The voltage source +V provides the necessary operating voltage for the circuit, while GND serves as the ground connection. When the sensor's capacitance is increased by a touch, this leads to a change in the potential at the base of the transistor. This change is amplified by the transistor and provided as an output signal, which can then be forwarded to the signal processing unit 70.

[0110] The circuit is robust and simple in design, making it cost-effective and easy to integrate. By using a transistor for signal amplification, the circuit can reliably detect even small changes in capacitance. This is particularly important for precisely capturing and analyzing the contact points 60 on the head surface 50 in real time. Preferably, the circuit shown could be supplemented with additional elements such as filters to minimize interference from electromagnetic pulses of the magnetic coil 30.

[0111] Fig. 4B shows an extended circuit 402 for capacitive touch detection, which offers improved signal processing and noise suppression. This circuit is part of the touch sensor 40 of the transcranial magnetic stimulation device 10 and serves to precisely detect changes in capacitance upon touching the head surface 50 and to process the signals for further processing.

[0112] The circuit begins with a capacitive sensor element, represented by a conductive surface. This surface is held in a defined state by a pull-up resistor RP. When the conductive head surface 50 touches or comes near the sensor, this causes a change in capacitance, which is detected by the subsequent circuit section.

[0113] A key component of the circuit is an amplifier module, depicted in the circuit diagram as a differential amplifier. This module amplifies the capacitance change signals and prepares them for further processing. Preferably, the gain is adjusted by resistors RI and R2, which regulate the sensitivity and output level of the circuit. Additionally, a capacitor C is integrated into the circuit, acting as a filter element to suppress high-frequency interference, such as that which might be caused by the magnetic coil 30. The amplified output of the differential amplifier is fed to the base of a transistor, which functions as a switching amplifier. This transistor further amplifies the signal and passes it to the circuit's output, which is connected to the signal processing unit 70. An additional resistor R3 is used to limit the current flow to the transistor and prevent overloading.

[0114] A characteristic feature of this circuit is its ability to reliably detect even small changes in capacitance while effectively minimizing external interference. The integration of the differential amplifier and capacitor C ensures that the output signal remains clear and stable, even when the magnet coil 30 generates electromagnetic interference.

[0115] Fig. 5 shows the schematic structure of a two-layer touch sensor 40, which can be used for the transcranial magnetic stimulation device 10. The illustration shows how two conductive layers 41 and 42 are arranged in the X and Y directions to detect capacitive or resistive touch points. Each layer 41, 42 is electrically isolated from each other (not shown here), thus enabling precise two-dimensional localization of the touch.

[0116] The upper layer 41 (X-direction) is equipped with connection points X1 and X2 and has a resistance RI distributed along the conductive surface. This layer serves to detect touches along the horizontal axis. As soon as a touch point 60 is detected on the head surface 50, the resistance value changes proportionally to the position of the touch point along the X-axis. The measured resistance value can be translated into a precise position by a signal processing unit.

[0117] The lower layer (Y-direction) has a similar structure, but with connection points Y1 and Y2 and a resistor R2 along the conductive surface. This layer measures touches along the vertical axis. Analogous to the upper layer, the change in resistance value is used to determine the position of the touch point along the Y-axis. Between the two layers 41 and 42 is an insulating intermediate layer (not shown) that ensures electrical isolation. This isolation allows the signals from the X and Y layers to be evaluated independently, enabling precise two-dimensional localization of the touch point 60.

[0118] Preferably, this intermediate layer is made of a thin, flexible material to minimize the height of the sensor and to facilitate adaptation to the contours of the head surface 50.

[0119] By superimposing the measurement data from both layers 41 and 42, the exact position of the contact point can be determined in a 2D coordinate system. This enables precise feedback on the positioning of the magnetic coil 30 relative to the head surface 50. Preferably, the signals from the two layers could be forwarded to a signal processing unit 70 and analyzed there to display the position of the contact point in real time on a display device 80.

[0120] Fig. 7 shows an embodiment of the touch sensor 40 in a sectional view. Here, electrical conductors 46 are formed on a first layer El. The conductors 46 can, for example, be embedded in a non-conductive substrate 47 and arranged on the carrier layer 45 or on another non-conductive substrate. The conductors are connected to conductors 49 on a second layer E2 by means of vias 48. Alternatively, the connection between the conductors 46 of the first layer El and the conductors 49 of the second layer E2 can also be made by crimping.

[0121] Figs. 8 and 9 show two further embodiments of the motion sensor 40, which essentially correspond to the structure shown in Fig. 7.

[0122] As can be seen in Fig. 8, the conductors 46 of the first layer are embedded throughout the substrate 47 and arranged on the support layer 45, which is not explicitly shown in Fig. 8. The arrangement of the conductors 49 extends around a center Z of the touch sensor 40. The contact point 60 is located at the center Z. The conductors 46 can be arranged, for example, as points in a regular grid or an irregular structure, where, for instance, the area under the hotspot has a higher density of points that can make contact. If the exact location of each point is known, a contact point with coordinates on the underside 21 can be determined accordingly when a current is detected through a point or when the electrical impedance of this point changes relative to another potential, for example, ground, or relative to another point. For multiple contact points, these can be averaged mathematically, for example.The conductors 49 of the second level extend partially outwards from the center Z in a star-shaped pattern. Furthermore, the touch sensor 40 has a region 900 in which the conductors 49 run parallel to each other, in particular essentially, i.e., ± 20%, in order to be directed to a common electrical terminal 902.

[0123] As can be seen in Fig. 9, the conductors 46 of the first layer are arranged segmentally on the carrier film. The segmented arrangement of the conductors 46 extends around a center Z of the touch sensor 40. The arrangement of the conductors 49 extends around the center Z of the touch sensor 40. The contact point 60 is located at the center Z. The conductors 46 can be applied, for example, as points in a regular grid, but also in an irregular structure, where, for example, the area under the hotspot has a higher density of points that can make contact. If the exact location of each point is known, a contact point with coordinates on the underside 21 can be determined accordingly when a current is detected through a point or when the electrical impedance of this point changes relative to another potential, for example, ground, or relative to another point.Furthermore, in a modification of this embodiment, an impedance change at the connection between one of the conductors 46, which, for example, is electrically connected to an associated conductor 49 and serves as a lead for an impedance measurement, and another conductor 46, which is electrically connected to another associated conductor 49 and serves as a further lead for an impedance measurement, can be determined via skin contact. Alternatively, there can be no electrical contact between conductors 46 and conductors 49, but upon contact with a target, pressure can be applied locally to deform a separating dielectric in order to change and measure the impedance between conductors 46 and associated conductors 49.In both cases, at least one electrical or mechanical contact point, preferably to a head, can be located by assigning conductors 49 to conductors 46 and their known spatial arrangement, and in particular the locations where they electrically contact each other resistively or, separated by a dielectric, are closest to each other (and therefore form a capacitance). If there are multiple contact points, these can, for example, be averaged mathematically. The conductors 49 of the second plane extend partially outwards from the center Z in a star-shaped pattern. Furthermore, the touch sensor 40 has a region 900 in which the conductors 49 run parallel to each other, in particular substantially, i.e., ± 20%, in order to be routed to a common electrical connection 902.In particular, the illustrated arrangement generates only a very small area for current flow (whether resistive, capacitive, or inductive) from conductors 49 to conductors 46, or from conductors 49 via conductors 46 to other conductors 46 and back to other conductors 49, for example, driven by a measuring device that measures the electrical impedance between at least one of the conductors 49 and another potential, for example, ground, or between at least two of the conductors 49. Specifically, the area parallel to the underside of the coil, and thus for magnetic field lines perpendicular to this area, is very small, so that only a very small change in flux during a pulse of the TMS coil penetrates the resulting conductor loop, and thus only a very small voltage is induced, which would damage or even destroy prior art electronics.

[0124] Figures 10 and 11 show schematic representations of a low-inductance arrangement of conductors 46, 49 within the touch sensor 40 of the transcranial magnetic stimulation device 10. This arrangement is specifically designed to minimize electromagnetic interference while simultaneously enabling precise detection of touch points 60.

[0125] As shown in Figures 10 and 11, the touch sensor 40 is constructed from two layers El, E2, between which a compressible dielectric 51 is arranged. The first layer El comprises the conductors 46 in the form of circular segments, while the second layer E2 has star-shaped counter-conductors 49. This combination reduces the inductance of the touch sensor 40 by minimizing the area between the conductors 46, 49. This minimization, in turn, reduces the induced voltage and thus enables measurement without damaging or even destroying the measuring electronics.This minimization can be improved in particular if circular segments are kept small, because if the conductors 46 can generate electrical contact with a body part, for example to locate the point of contact, in particular by means of an impedance measurement, only a few segments form a more or less electrically conductive contact over the head surface due to the curved head surface, and thus the area spanned by the conductors 46 and their respective associated conductors 49, which are electrically more or less conductively connected over the head surface, is very small and therefore only permeated by a small flux.

[0126] Of particular note is that the connecting conductors 53 (see also Fig. 12) to the conductors 46 are also arranged in a star-shaped pattern around the center of the conductor arrangement in the form of circular segments. This symmetrical geometry further contributes to minimizing parasitic inductances by reducing the length of the conductor paths and effectively suppressing electromagnetic interference.

[0127] In other embodiments, the conductors 46 of the upper level El can be arranged in rectangular segments, while the conductors 49 of the second level E2 run perpendicular to them. A compressible dielectric 51 can be located between these two levels El, E2, enabling precise mechanical adaptation to the head surface 50. This embodiment offers similar electromagnetic performance to the circular segment arrangement shown and allows for simple fabrication and integration into rectangular sensor geometries.

[0128] Both designs shown are conceived to ensure precise and interference-free detection of the touch points 60 by combining the advantages of area-reduced geometries and compressible dielectrics. They are therefore particularly suitable for use in highly sensitive applications such as transcranial magnetic stimulation.

[0129] Fig. 12 shows a detailed sectional view of an exemplary layer structure of the touch sensor 40 of the device 10 for transcranial magnetic stimulation, as shown, for example, in Figs. 10 and 12. This structure is designed to enable precise capacitive detection of touch points 60 while simultaneously ensuring mechanical adaptation to the head surface 50.

[0130] One of the star-shaped conductors 49 of plane E2 is shown as the uppermost layer. The conductors 49 of plane E2 are arranged on the compressible dielectric 51. The compressible dielectric 51 is shown, by way of example, arranged on a layer of an incompressible dielectric 52. The circular segment-shaped conductors 46 of plane El are arranged in the layer of incompressible dielectric 52. The conductors 46, or the conductor segments, each run approximately perpendicular to the conductors 49 of plane E2. The connecting conductors 53 are also arranged in the incompressible dielectric 52, or at least partially surrounded by it, and preferably run radially, in particular parallel to the respective conductors 49, outwards in order to cover the smallest possible area.

[0131] 10 Device for transcranial magnetic stimulation

[0132] 11 Handle

[0133] 20 Stimulation device

[0134] 21 Underside of the stimulation device

[0135] 22 Top of the stimulation device

[0136] 30 magnetic coil

[0137] 40 touch sensors

[0138] 41 conductive layer in the X direction

[0139] 42 conductive layers in the Y direction

[0140] 43 Insulating intermediate layer

[0141] 44 Insulating front layer

[0142] 45 Carrier layer / substrate

[0143] 46 ladders

[0144] 47 Substrat

[0145] 48 vias

[0146] 49 leaders

[0147] 50 Head surface

[0148] 51 Dielectric

[0149] 52 Dielectric

[0150] 53 supply lines

[0151] 60 Point of contact

[0152] 70 Signal processing unit

[0153] 80 Display device

[0154] 81 points on the grid of the display device

[0155] 82 grids on the display device

[0156] 90 isolated interface

[0157] 91 Insulator

[0158] 400 Electronic circuit for capacitive touch detection (Fig. 4A) 402 Extended circuit for capacitive touch detection (Fig. 4B) 900 Range

[0159] 902 connection

[0160] C capacitor

[0161] El EbeneE2 Ebene

[0162] RP Pull-up Resistor

[0163] RB base resistor

[0164] RI resistance in X-layer

[0165] R2 resistor in Y-layer

[0166] R3 resistor for current limiting

Claims

- 38 - Patent claims 1. Device (10) for transcranial magnetic stimulation of a target area in a body part of a patient, comprising a stimulation device (20) with at least one magnetic coil (30), wherein the device (10) comprises at least one touch sensor (40) configured to detect at least one point of contact (60) between the stimulation device (20) and a surface (50) of the body part in order to align the stimulation device (20) with the target area.

2. Device (10) according to claim 1, wherein the touch sensor (40) is capacitive and / or resistive, and preferably provides a submillimeter resolution for detecting the touch point (60).

3. Device (10) according to one of the preceding claims, wherein the stimulation device (20) has a bottom surface (21) facing the body part and a top surface (22) opposite the bottom surface (21), and wherein the touch sensor (40) is arranged on the bottom surface (21) or integrated into the bottom surface (21), and enables touch detection along the bottom surface (21) within a range of at least 2 cm in every direction along the bottom surface (21) around the point of contact (60).

4. Device (10) according to claim 3, wherein the touch sensor (40) comprises several sensor segments which enable the detection of deviations of the touch point (60) from an ideal contact point for aligning the stimulation device (20).

5. Device (10) according to one of the preceding claims, wherein the device (10) comprises a display device (80), and wherein the information from the touch sensor (40) is visualizable on the display device (80), the display device (80) preferably being arranged on a top surface (22) of the stimulation device (20) or as a separate display near an operator of the stimulation device (20). - 39 - 6. Device (10) according to claim 5, wherein the display device (80) graphically represents the information as a vector, numerical angular deviations and / or a point (81) on a 2D grid (82) to assist the operator in correcting the alignment of the stimulation device (20).

7. Device (10) according to one of the preceding claims, wherein the touch sensor (40) is configured to detect a curvature of the surface (50) of the body part and to calculate 2D or 3D orientation information from it in order to determine an inclination of the stimulation device (20) relative to the surface (50) of the body part.

8. Device (10) according to claim 5 or 6, wherein the display device (80) is integrated as part of a head-up display or an augmented reality headset to provide the operator of the stimulation device (20) with, in particular, intuitive visual support in positioning the stimulation device (20) relative to the body part.

9. Device (10) according to one of the preceding claims, wherein the touch sensor (40) is arranged on or comprises a polymer film, and wherein the touch sensor (40) has a height of less than 2 mm, preferably less than 1 mm, and further preferably less than 300 pm.

10. Device (10) according to one of the preceding claims, wherein the device (10) comprises a signal processing unit (70) configured to analyze the data acquired by the touch sensor (40) and to transmit it via an electromagnetically isolated interface (90).

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