An improved micro-magnetic coil with cell-level F / C structure

Abstract

The present invention discloses an improved cell-level F / C structure micro-magnetic coil, which belongs to the field of biomedical engineering, realizes a cell-level micro-magnetic stimulation, has the advantages of accurate positioning and high spatial resolution, and can be applied to the diagnosis and treatment of neuropsychiatric diseases. The steps are: studying the line width, number of turns, thickness, and spacing of a fixed-size 100μm×100μm planar square spiral coil to determine the specific structural parameters of the coil; on the basis of determining the coil structure, studying the performance parameters of the micro-coil covered with a magnetic shielding layer under different structures, and determining that the structure of the coil covered with a magnetic layer is an F / C structure; studying the influence of different magnetic shielding layer patterns, the thickness, spacing, and width of the magnetic shielding layer pattern on the inductance L and magnetic induction intensity B of the micro-coil, thereby determining the specific geometric parameters of the cell-level F / C structure micro-coil.

Description

Technical Field

[0001] The invention belongs to the technical field of biomedical engineering, and in particular relates to a micro-magnetic coil with an improved cell-level F / C structure. Background Art

[0002] Mental illness is a type of disease in which abnormal brain function leads to cognitive, emotional, volitional and behavioral disorders, including Alzheimer's disease, schizophrenia, autism and depression. Electromagnetic stimulation technology is currently a major means of diagnosing, treating and studying neuropsychiatric diseases. The main technologies currently include electrical stimulation (ES) and transcranial magnetic stimulation (TMS); electrical stimulation includes deep brain stimulation (DBS) and transcranial direct current stimulation (tDCS). Clinical trials have shown that TMS has therapeutic benefits for treating many neurological diseases, such as major depression and Alzheimer's disease. Although there is a certain understanding of the effects of DBS and TMS on brain activity and how these effects change corresponding behaviors, there are still some technical and biological limitations in the application of the two. Magnetic resonance imaging examinations of patients treated with DBS may cause excessive heating at the end of the stimulating electrode, resulting in nerve damage. The DBS stimulating electrode directly contacts biological tissues, and the inflammation and immune response of the tissues may change the treatment effect. The TMS coil is relatively large (size: 10-20 cm), and the magnetic field strength decreases with the square of the distance from the field source, making it difficult to locate target areas deep in the brain and having a lower spatial resolution.

[0003] Micro-magnetic stimulation (μMS) is an emerging neurostimulation technology that is expected to revolutionize therapeutic stimulation of the human nervous system. The technology uses sub-millimeter-sized coils to stimulate neuronal tissue. Stimulation is achieved by passing a time-varying current through the microscopic coil to generate a dispersed magnetic flux density in the focal area of ​​the tissue. Due to its microscopic size, the μMS coil can be sharply implanted into deep brain structures to provide therapeutic stimulation with effects similar to those achieved by DBS. This new non-invasive neural μMS technology has recently demonstrated the feasibility of inducing neuronal activation in vitro. The μMS coil can be positioned adjacent to or in close proximity to neural tissue, so the power required to induce neuronal activity is significantly reduced compared to TMS technology.

[0004] In 2012, a team from Harvard University proposed that a spiral coil inductor (RF 0402 inductor) could be used to activate neuronal tissue; in 2017, a 0.316mm×0.316mm planar spiral coil structure was first proposed for stimulating brain neurons; in 2017, Seung Woo Lee proposed a single-layer planar coil that can be implanted for intracortical stimulation, with a stimulation intensity of 50,000V / m 2 ; In 2017, Giorgio Bonmassar et al. demonstrated that a single-layer planar spiral structure is more efficient than a solenoid microcoil in inducing neural activation, can generate up to 5 times the electric field in the tissue, and the energy is concentrated in the center area of ​​the coil. In 2016, MERizou et al. first proposed a 6×6 array micromagnetic stimulation coil structure based on a planar square spiral. In 2018, Giorgio Bonmassar et al. made a reinforced single-layer planar spiral coil structure with a size of 300μm×300μm×100μm. The magnetic flux generated by this structure is better than that of an ordinary planar spiral coil. In 2018, Yumei Wen et al. analyzed the parameters affecting the change of the coil inductance value by the structure of a coil sandwiched between soft magnetic layers. In 2018, Yao Wang et al. proposed a structure with superimposed multi-layer magnetic shielding layers for sensitive magnetic field detection, which can improve the value of coil inductance. In 2018, Fapeng Song et al. proposed a magnetic film / planar coil multilayer coupled inductor structure, which utilized strong mutual coupling to achieve high sensitivity of magnetic detection sensors at relatively low operating frequencies.

[0005] Micro-magnetic coils have problems such as small inductance L, high power consumption, weak magnetic induction intensity B and uneven distribution. Inductors with metal sandwich structures can improve the inductance of planar coils by using the high magnetic permeability of soft magnetic materials, but the efficiency is not high. At the same time, the structure introduces high AC conductor loss and high eddy current. Therefore, developing a micro-magnetic stimulator with high sensitivity and high spatial resolution to complete the directional activation of neuronal axons is of great significance for the treatment of mental illnesses such as epilepsy and depression. Summary of the invention

[0006] The purpose of the present invention is to solve the problem of directional magnetic stimulation of nerve cells and achieving high spatial resolution, and to provide a micro-magnetic coil with an improved cell-level F / C structure.

[0007] An improved cell-level F / C structure micro-magnetic coil is composed of a magnetic film, a coil and a pad. The magnetic film is a nickel-iron alloy with a magnetic film surrounded by four sides; the micro-coil is a planar square spiral coil; and the pad is a linear pad.

[0008] The F / C structure micro-magnetic coil is a micro-coil with a single magnetic layer surrounding it, and the gap between the coil and the magnetic shielding layer is g1 = 500 nm.

[0009] The material of the micro coil is one of Cu and Au, the linear dimension of the coil is 2 μm, the number of turns is 8, the spacing is 4 μm, the size of the micro magnetic coil is 100 μm×100 μm, and the coil thickness is 1.7 μm.

[0010] The pad has a size of 100 μm×100 μm, a shape of a linear pad, a material of one of Cu and Au, a line width of 2 μm, and a thickness of 1.7 μm.

[0011] The magnetic layer has a size of 100 μm×100 μm and a plane square shape, and the magnetic shielding layer has a thickness of tm=2 μm and a width of w=100 μm×100 μm.

[0012] The advantages and positive effects of the present invention are:

[0013] The improved cell-level F / C structure micro-magnetic coil of the present invention can achieve directional magnetic stimulation of nerve cells. The cell-level micro-coil has enhanced magnetic field strength and depth of action in the Z direction, and the magnetic field is more uniform. The coil inductance value is also greatly improved, thereby improving the quality factor of the micro-magnetic coil. This method is of great significance for designing a micro-magnetic stimulator with high sensitivity and high spatial resolution to complete directional activation of the direction of neuronal axons, and for treating mental diseases such as epilepsy and depression. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the micromagnetic coil structure of the cell-level F / C structure.

[0015] Figure 2 Schematic diagram of the micromagnetic coil of the cell-level F / C structure. DETAILED DESCRIPTION

[0016] The present invention is further described below with reference to the accompanying drawings and embodiments.

[0017] Implementation method 1:

[0018] Step 1: Through Comsol software modeling and simulation, determine the line width, number of turns, thickness, spacing and other parameters of the planar square microcoil with a fixed size of 100μm×100μm.

[0019] Step 2: Study the structures of four different cell-level micromagnetic coils, the performance parameters of the coils under different structures, and determine the F / C structure suitable for cell micromagnetic stimulation.

[0020] Step 3: Based on the F / C structure, the influence of different magnetic shielding layer patterns on the inductance L and B of the micromagnetic coil is studied, and the pattern of the magnetic shielding layer is determined.

[0021] Step 4: Study the inductance L and magnetic induction intensity B at different magnetic permeabilities at different distances g1 between the magnetic shielding layer and the micromagnetic coil, and determine the distance g1 between the magnetic shielding layer and the micro coil.

[0022] Step 5: Study different magnetic shielding layer thicknesses t when the spacing g1 is determined m The thickness t of the magnetic shielding layer is determined by the inductance L and magnetic induction intensity B under different magnetic permeabilities. m .

[0023] Step 6: Determine g1, t m Under the condition of different magnetic shielding layer width w m The inductance L and magnetic induction intensity B under different magnetic permeabilities determine the width w of the magnetic shielding layer m .

[0024] Step 7: Based on the above parameters, the specific structural parameters of the cell-level micromagnetic coil are finally determined.

Claims

1. An improved micro-magnetic coil of cell-level F / C structure, characterized in that: include: Structure of magnetic films, pads, and microcoils; The microcoil structure is a planar square spiral coil structure; the planar square spiral coil structure is a microcoil with a fixed size of 100 μm×100 μm; The fixed-size microcoil is a planar square spiral coil with a linear dimension of 2 μm, a wire thickness of 1.7 μm, a pitch of 4 μm, and a number of turns of 8; The magnetic film is a single magnetic layer surrounded by a belt; The cell-level F / C structure micro-magnetic coil is a micro-coil with a single magnetic layer surrounding it. The gap between the magnetic shielding layer and the coil of the cell-level F / C structure micro-magnetic coil is 500nm. The micro-magnetic coil of the cell-level F / C structure has a magnetic shielding layer with a thickness of 2 μm and a width of 100 μm×100 μm; The method for confirming the parameters of the micro-magnetic coil of the cell-level F / C structure comprises: S1: Determine the line width, number of turns, thickness, and spacing parameters of the planar square microcoil through modeling and simulation with Comsol software; S2: Covering the micro-coil with a magnetic shielding layer to form different structures, studying the parameters of the micro-coil under different structures, and determining that the structure of the micro-magnetic coil covered with the magnetic shielding layer is an F / C structure; S3: studying different magnetic shielding layer patterns in the micro-magnetic coil of the cell-level F / C structure; the studying different magnetic shielding layer patterns is to study the influence of different magnetic shielding layer patterns on the inductance L and B of the micro-magnetic coil, and determine the pattern of the magnetic shielding layer; S4: Study different distances gl between the magnetic shielding layer and the micromagnetic coil, including studying the inductance L and magnetic induction intensity B of different distances gl between the magnetic shielding layer and the micromagnetic coil under different magnetic permeabilities, and determining the distance gl between the magnetic shielding layer and the micro coil; S5: Study the influence of the thickness tm and width Wm of the magnetic shielding layer on the performance parameters of the coil, including studying the inductance L and magnetic induction intensity B of different magnetic shielding layer thickness tm under different magnetic permeabilities, determining the thickness tm of the magnetic shielding layer, studying the inductance L and magnetic induction intensity B of different magnetic shielding layer widths wm under different magnetic permeabilities, and determining the width wm of the magnetic shielding layer; S6: According to the influence of gl, tm and Wm on the performance parameters of the microcoil, the specific geometric parameters of the F / C structure are finally determined; The improved cell-level F / C structure micro-magnetic coil is used to achieve directional magnetic stimulation of nerve cells.

2. The improved cell-level F / C structure micro-magnetic coil according to claim 1, characterized in that: The pad size of the micro-magnetic coil of the cell-level F / C structure is 100 μm×100 μm, the shape is a linear pad, the material is one of Cu and Au, the line width is 2 μm, and the thickness is 1.7 μm.

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