A wearable flexible EEG cap for measuring magnetic field signals in the human brain.

Abstract

This invention discloses a wearable flexible magnetoencephalogram (MEG) cap for measuring magnetic field signals in the human brain, belonging to the field of biomedical engineering. It relates to a medical device comprising a flexible cap body, supporting ribs, and a probe holder. The outer surface of the flexible cap body is mapped with a gridded MEG measurement pattern, corresponding to the sensitive points of the probe's magnetic field measurement, according to internationally accepted standards for EEG acquisition lead systems and the physiological functional zones of the human brain. The probe holder is arranged according to the MEG measurement pattern to fix the probe, ensuring reliable close-range fixation between the sensor and the scalp surface. The supporting ribs are made of high-strength polyester wire and are evenly distributed throughout the flexible cap body to support it. The proposed flexible MEG cap is a more universal, accurate, low-cost, and reliable tool for detecting magnetic field signals.

Description

Technical Field

[0001] This invention belongs to the field of biomedical engineering, and specifically relates to a wearable flexible brain magnetic cap for measuring magnetic field signals in the human brain. Background Technology

[0002] Magnetoencephalography (MEG) is a powerful functional neuroimaging technique that can measure brain neural activity in a completely non-invasive manner. It has been widely used in the study of higher brain functions and the diagnosis of neurological diseases.

[0003] In the past, the most commonly used instrument for magnetoencephalography (MEG) was the superconducting quantum interference device (SQIUID). However, because the SQUID magnetometer needs to operate under liquid nitrogen cooling conditions, it limits the distance between the instrument and the subject's scalp, resulting in a small signal detection amplitude and limiting the instrument's application range. At the same time, the requirement for liquid nitrogen cooling also greatly increases operating costs, reaching hundreds of thousands of dollars annually.

[0004] With the development of laser technology, the sensitivity of optically pumped atomic magnetometers based on laser interactions has reached the femtotes level. Among them, the sensitivity of atomic magnetometers based on spin-exchange relaxation-free (SERF) reached [a certain level] in 2010. Where fT is a physical unit and Hz represents a frequency unit, the sensitivity of the SERF magnetometer almost surpasses that of the SQUID magnetometer, thus beginning to enter the field of biomagnetic field measurement, forming a trend of gradually replacing the SQUID magnetometer, and becoming the internationally recognized development direction of the next generation of magnetoencephalography (MEG) instruments.

[0005] Compared to SQUID, the SERF atomic magnetometer is smaller and can be arrayed on the human head, meeting wearable design requirements. Currently, many atomic magnetometer research institutions at home and abroad rely on 3D printing technology to customize personalized magnetic field caps or helmets for measuring magnetic field signals in local or whole brain regions. This process is lengthy and expensive; almost no research institutions currently use flexible magnetic field caps for experimental verification or measurement.

[0006] Existing magnetic resonance imaging (MRI) caps used in research environments are mostly personalized rigid MRI caps customized using 3D printing technology. This involves using a high-precision scanning device to scan the subject's head to obtain three-dimensional data, and then using 3D printing technology to complete the personalized helmet body. Due to the personalized customization, the rigid MRI cap can only be used by one subject, resulting in poor universality and high experimental costs. In current research processes, the arrangement of the slots in the tested brain regions is mostly based on standard model data. There is a certain positional error between different populations (such as adults and children). Since the slots are printed as a single piece with the helmet body, their positions are fixed and cannot be adjusted, which leads to inaccurate data and further increases testing costs.

[0007] If the position of the slot can be flexibly adjusted, it will facilitate the experiment and further reduce the testing cost; due to the difficulty in designing the curved structure of the human head, the slot of the 3D printed helmet is designed and processed as an integral part of the helmet body, which cannot realize the adjustment and measurement of the subject's head at any position. Summary of the Invention

[0008] To overcome the shortcomings of existing technologies, this invention provides a wearable flexible brain magnetic field cap for measuring the magnetic field signal of the human brain. It is a highly universal, reliable sensor fixation, low detection cost, and reliable brain magnetic signal detection tool.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] A wearable flexible EEG cap for measuring magnetic field signals in the human brain comprises a flexible cap body, supporting ribs, and a probe bracket. The supporting ribs are fixed inside the flexible cap body, and the probe bracket is fixed to the flexible cap body. The supporting ribs are made of high-strength polyester wire, which is evenly distributed inside and outside the flexible cap body, avoiding the probe mounting area, to support the flexible cap body. The probe bracket includes a main probe fixing part and a base. The main probe fixing part is designed in a four-sided encircling shape according to the shape of a femtosla level extremely weak magnetic field measurement sensor. The four clamping plates for holding the probe have a 3-5 degree taper in the vertical direction to ensure tight clamping of the probe. Two of the clamping plates only serve a clamping function, while the other two clamping plates are provided with hook-shaped protrusions to ensure the probe is fixed in the vertical direction and prevent it from falling off. Two reinforcing ribs are designed on the outer wall of the two clamping plates with hook-shaped protrusions to improve the strength of the plates and prevent the plates from breaking when the probe is pulled out.

[0011] The probe holder consists of a main probe mounting section designed according to the sensor's external dimensions and a base. The main probe mounting section reliably secures the sensor, reducing sensor displacement and rotation during magnetoencephalography (MEG) measurements. The base secures the sensor mounting bracket to the cap. The probe holder design offers greater reliability compared to other mounting structures.

[0012] Furthermore, one of the probe supports is a fixed probe support, which includes a main probe fixing part and a base sewn to the flexible cap, with the base and the main probe fixing part being an integral design. Four limiting members are provided at the bottom end of the probe and the fixed probe support near the scalp to ensure that the probe does not directly contact the scalp and prevent burns. Sewn sections are provided at the four corners of the base of the fixed probe support; these sections are semi-circular thin plates with four symmetrically distributed circular holes, each 1-2 mm in diameter, for thread to pass through. If necessary, the probe can be sewn to fix the entire probe to the outer surface of the flexible cap according to the array-type magnetoencephalography (MEG) measurement pattern on the surface of the flexible cap. The fixed probe support is used for MEG signal acquisition between different subjects, and the cap's contraction can adaptively maintain consistency in the measured brain regions among different subjects.

[0013] Furthermore, one of the probe supports is a detachable probe support, comprising a detachable main probe fixing part and a base. These two parts are designed to be separate, with a slot and a buckle working together to ensure a reliable connection. The slot has a clamp-like structure with a central part that engages with the buckle. The buckle has a pointed hook-like structure, distributed diagonally on the base. Sewn-in sections are located at the four corners of the inner rectangle of the base, allowing for sewing at specific positions when necessary. Thanks to the connection method of the slot and buckle, the detachable probe support can not only fix the sensor according to the marked gridded EEG measurement map on the EEG cap, but also allow the buckles to be arbitrarily arranged on the flexible cap body according to the data acquisition needs, enabling arbitrary dense arrangement of EEG sensors in any brain region. The main probe fixing part is 3D printed with tolerances maintained according to the sensor size.

[0014] Furthermore, the flexible cap is made based on a standard human head model; the surface of the flexible cap adopts the EEG acquisition lead system and the physiological structure and functional division of the human brain to draw a gridded magnetoencephalogram of the arrayed probe support, so that the position of the probe magnetic field sensitive source on the gridded magnetoencephalogram corresponds to the standardized brain region and acupoint, which facilitates subsequent signal acquisition and processing.

[0015] Furthermore, the EEG acquisition lead system adopts the internationally recognized 10-20, 10-10, or 10-5 international EEG lead standards.

[0016] Furthermore, the flexible cap is made of elastic fabric such as nylon Oxford cloth, and the flexible cap fits tightly against the subject's scalp to ensure that the extremely weak magnetic sensor inserted into the probe holder is at the minimum distance from the subject's actual scalp.

[0017] Furthermore, the flexible EEG cap equipped with a fixed probe holder is used for EEG measurement of a brain model that has already been constructed. During whole-brain EEG measurement, multiple probes are inserted into the fixed probe holder, and the one-to-one correspondence between the probe and the cerebral cortex position is obtained according to the standard positioning marks on the flexible EEG cap.

[0018] Furthermore, a flexible EEG cap equipped with a detachable probe holder is used for EEG measurements before a brain model scan has been performed. Before performing EEG measurements, the main probe fixing part is removed from the buckle. An optical scanner is used to scan and construct the human brain without sensors. A position marker extraction algorithm is used to extract the position and orientation of optical position markers on the brain. The position and orientation information is used and certain calculations are performed to obtain the position and orientation of the sensor at the corresponding location.

[0019] Further, after the sensor position and orientation are determined, the probe, together with the main probe fixing part, is installed on the buckle to carry out the acquisition and measurement of the brain magnetic signal.

[0020] This invention, employing the above technical solutions, offers the following advantages: By eliminating rigid contact between the helmet and the subject's scalp, the probe can be positioned as close as possible to the subject's actual scalp, improving the quality of the EEG signal; the flexible cap possesses a certain degree of elasticity, making it more universally applicable compared to rigid helmets; moreover, the flexible cap material is readily available, simple to process, and less expensive; the flexible cap utilizes an internationally recognized standard EEG acquisition lead system and depicts the physiological structure and functional zones of the human brain, featuring a gridded EEG measurement map with an array of probe supports, enabling more accurate positioning of the probe relative to brain regions and enhancing its research reference value; this invention provides two connection methods between the flexible cap and the probe, corresponding to different application scenarios and meeting various needs; the detachable probe support allows for flexible adjustment of the presence, position, and number of probes according to testing requirements, improving the accuracy of sensor position and orientation, while also adapting to the measurement of magnetic field signals at any position on the complex curved surface of the human head. Attached Figure Description

[0021] Figure 1 A schematic diagram of a wearable flexible EEG cap equipped with a fixed probe support and the fixed probe support.

[0022] Figure 2 A schematic diagram of a wearable flexible EEG cap equipped with a detachable probe support and the detachable probe support. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0024] like Figure 1 , Figure 2 As shown, the wearable flexible EEG cap for measuring magnetic field signals in the human brain according to the present invention consists of a flexible cap body A, supporting ribs B, and a probe bracket C. The probe bracket C includes two forms: a fixed probe bracket C1 and a detachable probe bracket C2. The supporting ribs B are fixed inside the flexible cap body A, and the fixing method can be sewing or inserting into the inner or outer parts of the cap body. The probe bracket C is fixed based on the flexible cap body A, and the fixing method of the probe bracket C can be sewing or a sandwich-like structure, with the flexible cap body A fixed within the inner and outer components of the probe bracket C.

[0025] like Figure 1 As shown, the base and probe clamping part of the fixed probe bracket C1 are integrated and cannot be separated. The fixed probe bracket C1 includes a main probe fixing part D and a part E sewn to the flexible cap. The main probe fixing part D is designed to be surrounded by a quadrant based on the shape of a felisle-level extremely weak magnetic measurement sensor. The four clamping plates L holding the probe have a 3-5 degree taper in the vertical direction to ensure a tight clamping of the probe. Two of the clamping plates L only serve a clamping function, while the other two clamping plates L are provided with hook-shaped protrusions K to ensure the probe is fixed in the vertical direction and prevent it from falling off. Two reinforcing ribs M are designed on the outer wall of the two clamping plates L with hook-shaped protrusions K to improve the strength of the plates and prevent the plates from breaking when the probe is pulled out. Four limiting pieces are provided at the bottom end of the probe and the fixed probe bracket C1 near the scalp to ensure that the probe does not directly contact the scalp and prevent burns. The flexible cap sewing section E is designed at the four corners of the fixed probe bracket C1, i.e., around the perimeter of the base, through pre-drilled sewing holes. This allows the probe to be fixed to the outer surface of the flexible cap A by sewing, following the array-like magnetoencephalography (MEG) pattern on the surface of the flexible cap A. The flexible cap sewing section E is a semi-circular thin plate with four symmetrically distributed circular sewing holes, each 1-2 mm in size, large enough for needle and thread to pass through. The supporting ribs B of the fixed probe bracket C1 are made of high-strength polyester thread, which is evenly distributed inside and outside the flexible cap A, avoiding the probe mounting area, to support the cap.

[0026] like Figure 2As shown, the detachable probe holder C2 consists of a base H and a main probe fixing part D, which are connected and fixed using a combination of clips and slots. The detachable probe holder C2 is an improvement on the fixed probe holder C1. The upper main probe fixing part D is similar to that of the fixed probe holder C1, but with four partially hollowed-out corners N, which provides some heat dissipation while ensuring reliable probe fixation. The lower base H adopts a detachable structure, with slots F and clips G working together to ensure connection. Slot F is a clamp-like structure with a central part that engages with clip G. Clips G are pointed hook-like structures, distributed diagonally on the base H. To reduce volume, sewn-in parts I are designed at the four corners of the inner rectangle of the base H. That is, small sewn-in holes are left inside the base H, allowing the base H to be fixed to the inner surface of the flexible cap A according to the array-type magnetoencephalography (MEG) measurement pattern. The buckle G is designed as a needle-like structure, piercing the fabric of the flexible cap A, with the exposed outer surface fitting into the main probe fixing part D. The main probe fixing part D is 3D printed according to the size tolerance of the sensor. The supporting ribs B are made of high-strength polyester wire, which are evenly distributed inside and outside the flexible cap A, avoiding the probe installation area, to support the cap body.

[0027] The two types of main probe fixing parts (D) are largely the same, both designed as a four-sided enclosure based on the shape of a femtosla level extremely weak magnetic field measurement sensor. The four clamping plates (L) fixing the probe have a 3-5 degree taper in the vertical direction to ensure a tight grip. Two of the clamping plates (L) not only clamp the probe but also utilize hook-shaped protrusions (K) to maintain its vertical fixation and prevent it from falling off. Additionally, two reinforcing ribs are designed on the outer wall of these two vertical plates to increase their strength and prevent breakage when the probe is removed. The four corners are partially hollowed out (N), ensuring reliable probe fixation while also providing some heat dissipation.

[0028] The flexible cap A is made based on a standard human head model. The surface of the flexible cap A adopts the internationally recognized 10-20 standard EEG acquisition lead system and the physiological structure and functional division of the human brain to draw a gridded magnetoencephalogram of the arrayed probe support C. This makes the position of the probe magnetic field sensitive source on the gridded magnetoencephalogram correspond to the standardized brain regions and acupoints, which facilitates subsequent signal acquisition and processing. The number of magnetoencephalograms can also be expanded according to EEG acquisition lead systems such as 10-10 and 10-5.

[0029] The flexible cap A is made of nylon Oxford cloth. The flexible cap A fits snugly against the subject's scalp to minimize the distance between the extremely weak magnetic sensor inserted into the probe holder C and the subject's actual scalp. The flexible cap equipped with a fixed probe holder C1 can be used for magnetoencephalography (MEG) measurements on a pre-constructed brain model. During whole-brain MEG measurements, multiple probes are inserted into the fixed probe holder C1. The one-to-one correspondence between the probes and the cerebral cortex or acupoints can be obtained based on the standard positioning marks on the flexible cap, making it convenient and quick. The flexible cap equipped with a detachable probe holder C2 is suitable for MEG measurements before a brain model scan. Before MEG measurements, the main probe fixing part D and the slot F of the detachable probe holder C2 are removed from the buckle G. An optical scanner is used to scan and construct the human brain model. After the brain model is constructed, the probes, along with the main probe fixing part D and the slot F, are then installed on the buckle G for MEG measurements. Based on the MEG cap markings in the optical scan model, a one-to-one correspondence between the probes and the cerebral cortex or acupoints is obtained through certain calculations. When optical registration is required, the probe and base are removed to reduce interference with optical scanning registration. After registration, the probe and base are installed on the protruding clips on the surface of the flexible cap for the next experimental operation. This significantly reduces the interference of the base on optical registration, resulting in an order-of-magnitude improvement in registration accuracy and reducing systematic errors in the localization and tracing of magnetoencephalogram (MEG) signals.

[0030] The flexible cap A is made in four models based on a standard human head model, corresponding to underage males and females, and adult males and females, respectively, to accommodate a wider range of head sizes and greatly reduce testing costs in practical applications. The surface of the flexible cap adopts an internationally recognized standard EEG acquisition lead system and the physiological structure and functional divisions of the human brain to draw a gridded magnetoencephalogram of the arrayed probe support. Compared with the 3D-printed one-piece helmet with densely arranged slots all over the head, the data obtained based on the gridded magnetoencephalogram has certain medical reference value and is more convenient for subsequent signal acquisition and processing.

[0031] Furthermore, it should be noted that the names and shapes of the components described in this invention may differ, and any modifications, additions, and improvements made based on the structure, features, and principles described in this invention should be considered within the scope of protection of this invention.

Claims

1. A wearable flexible EEG cap for measuring magnetic field signals in the human brain, characterized in that: It consists of a flexible cap (A), supporting ribs (B), and a probe bracket (C); the supporting ribs (B) are fixed inside the flexible cap (A), and the probe bracket (C) is fixed to the flexible cap (A); the supporting ribs (B) are high-strength polyester wires, which are evenly distributed inside and outside the flexible cap (A), avoiding the probe installation area, to support the flexible cap (A); the probe bracket (C) includes a main probe fixing part (D) and a base; the main probe fixing part (D) is based on the Feltes water... The flat, extremely weak magnetic field measuring sensor is designed with a four-sided enclosed shape. The four clamping plates (L) that hold the probe have a 3-5 degree taper in the vertical direction to ensure a tight grip on the probe. Two of the clamping plates (L) only serve a clamping function, while the other two clamping plates (L) are equipped with hook-shaped protrusions (K) to ensure that the probe is fixed in the vertical direction and prevent it from falling off. Two reinforcing ribs (M) are designed on the outer wall of the two clamping plates (L) with hook-shaped protrusions (K) to improve the strength of the plates and prevent the plates from being broken when the probe is pulled out. The four clamps (L) that fix the probe have a taper of 3 to 5 degrees to the vertical direction; A flexible EEG cap equipped with a detachable probe holder (C2) is used for EEG measurements before a brain model scan has been performed. Before EEG measurements, the main probe fixing part (D) and the slot (F) are removed from the buckle (G). An optical scanner is used to scan and construct a human brain model. After the brain model is constructed, the probe, together with the main probe fixing part (D) and the slot (F), is installed on the buckle (G) for EEG measurements. The one-to-one correspondence between the probe and the standard positioning is obtained based on the human brain model constructed by the optical scanner and the marking points on the flexible EEG cap. The probe holder (C) is a fixed probe holder (C1), which includes a main probe fixing part (D) and a flexible cap sewn part (E). Its base and the main probe fixing part (D) are designed as an integral part. Four limiting parts are set at the bottom of the probe and the fixed probe holder (C1) near the scalp to ensure that the probe does not directly contact the scalp and prevent burns. The flexible cap sewn part (E) is set at the four corners of the base of the fixed probe holder (C1). It is a semi-circular thin plate with four symmetrically distributed round holes, each 1-2 mm in size, for thread to pass through. The probe is fixed to the outer surface of the flexible cap (A) by sewing according to the array of magnetoencephalography measurement patterns on the surface of the flexible cap (A). Alternatively, the probe holder (C) can be a detachable probe holder (C2), which includes a detachable main probe fixing part (D) and a base (H). The two are connected detachably by a slot (F) and a buckle (G). The slot (F) is a clamp-like structure with a mating part with the buckle (G) in the middle. The buckle (G) is a pointed hook-like structure, which is distributed diagonally on the base (H). Stitching parts (I) are set at the four corners of the inner rectangle of the base (H). The main probe fixing part (D) is 3D printed with tolerance according to the size of the sensor.

2. The wearable flexible EEG cap for measuring magnetic field signals in the human brain according to claim 1, characterized in that: The flexible cap (A) is made based on a standard human head model. The surface of the flexible cap (A) adopts the EEG acquisition lead system and the physiological structure and functional division of the human brain to draw a gridded magnetoencephalogram of the arrayed probe support (C), so that the position of the probe magnetic field sensitive source on the gridded magnetoencephalogram corresponds to the standardized brain region and acupoint, which facilitates the subsequent signal acquisition and processing.

3. A wearable flexible EEG cap for measuring magnetic field signals in the human brain according to claim 2, characterized in that: The EEG acquisition lead system adopts the 10-20, 10-10, or 10-5 international EEG lead standards established by the International Federation for Clinical Neurophysiology.

4. A wearable flexible EEG cap for measuring magnetic field signals in the human brain according to claim 1, characterized in that: The flexible cap (A) is made of nylon Oxford cloth. The flexible cap fits tightly against the subject's scalp to ensure that the extremely weak magnetic sensor inserted into the probe holder (C) is at the minimum distance from the subject's actual scalp.

5. A wearable flexible EEG cap for measuring magnetic field signals in the human brain according to claim 1, characterized in that: The flexible cap for magnetoencephalography (MEG) equipped with a fixed probe holder (C1) is used for MEG measurement of a brain model that has been constructed. During whole-brain MEG measurement, multiple probes are inserted into the fixed probe holder (C1), and the positional relationship between the probes and the cerebral cortex regions or acupoints is obtained directly according to the standard positioning marks on the flexible cap for MEG.

6. A wearable flexible EEG cap for measuring magnetic field signals in the human brain according to claim 1, characterized in that: After the sensor position and orientation are determined, the probe, together with the main probe fixing part (D), is installed on the buckle (G) to carry out the acquisition and measurement of the brain magnetic signal.

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