Neural microprobes for dual-mode functional localization and precise electrical stimulation of deep brain nuclei in non-human primates

Abstract

This invention discloses a neural microprobe for bimodal functional localization and precise electrical stimulation of deep brain nuclei in non-human primates. It comprises a basal layer, a conductive metal layer, and an insulating layer. The conductive layer includes a set of detection sites and stimulation sites. This invention employs a dry etching process on the back of the silicon basal layer using two insulating layers with opposite stresses, balancing the stress differences between the different materials. This overcomes the technological challenges of extending silicon microprobes and solves the problems of probe bending and low mechanical stress caused by the large aspect ratio of silicon probes in non-human primates. The detection sites acquire bimodal signals using modified nanomaterials and polymer anti-interference ion-exchange membranes as localization markers for functional localization. The detection sites are arranged between the positive and negative electrodes of the electrical stimulation, controlling the stimulation range to be near the detection sites, thus achieving precise electrical stimulation. This invention provides a new research method and means for deep brain stimulation therapy of diseases such as Parkinson's disease.

Description

Technical Field

[0001] This invention relates to the fields of deep brain stimulation therapy for diseases such as Parkinson's disease and the field of microelectromechanical systems (MEMS) technology, and in particular to neural microprobes for dual-mode functional localization and precise electrical stimulation of deep brain nuclei in non-human primates. Background Technology

[0002] Deep brain stimulation (DBS) has become an effective treatment for diseases such as Parkinson's disease, epilepsy, and dystonia. To achieve optimal treatment results without damaging surrounding brain nuclei, precise localization and electrical stimulation of these deep brain nuclei are necessary. Since the physiological structures of non-human primates are closer to those of humans, using non-human primates as animal models will play an important role in the study of human diseases.

[0003] The combined detection of neurophysiological and neuroelectrochemical signals is of great significance for the identification and differentiation of brain nuclei and the diagnosis and regulation of the nervous system. To achieve precise target localization, it is necessary to improve the spatial resolution of the detection, thereby acquiring more neural information. Multi-channel detection tools that simultaneously detect electrophysiological and electrochemical signals will contribute to the precise localization of brain regions.

[0004] Traditional forms of brain stimulation primarily use millimeter- and centimeter-scale electrodes, which can cause significant damage to brain tissue and easily harm other nuclei. Using localization and stimulation electrodes independently can lead to deviations in the stimulation site, making precise electrical stimulation difficult and hindering real-time monitoring of changes in neurophysiological and neurochemical signals under electrical stimulation.

[0005] Compared to rat models, primate models have larger brain volumes, requiring longer silicon probes. However, due to the stress buildup from the different materials, long silicon probes are prone to curling, making them unsuitable for implantation in primates.

[0006] Therefore, there is currently a lack of a tool that can achieve dual-mode functional localization of deep brain nuclei in non-human primates and can precisely electrically stimulate target nuclei. Summary of the Invention

[0007] (a) Technical problems to be solved

[0008] To address the aforementioned technical problems, this invention proposes a neural microprobe for dual-mode functional localization and precise electrical stimulation of deep brain nuclei in non-human primates, thus resolving these issues.

[0009] (II) Technical Solution

[0010] This invention provides a neural microprobe for dual-mode functional localization and precise electrical stimulation of deep brain nuclei in non-human primates, wherein the microelectrode array comprises:

[0011] Substrate layer: The material is an insulating material; preferably, the substrate layer is a rigid insulating material.

[0012] Metal conductive layer: Located on the above-mentioned base layer, including: electrophysiological detection sites and electrochemical detection sites located between the positive and negative electrostimulation electrodes; a reference electrode and a counter electrode located on both sides of the lower end of the detection sites; the detection sites, the positive and negative electrostimulation electrodes are connected to the pads through wires.

[0013] Insulating layer: The material is a double insulating layer with opposite stresses, located above the conductive layer.

[0014] Preferably, there are 12 electrophysiological detection sites and 4 electrochemical detection sites.

[0015] Furthermore, the microprobe is made of SOI substrate material. To avoid the problem of excessively long silicon probes used in non-human primates causing easy bending of electrodes and low mechanical strength, dry etching is used to remove silicon oxide on the back of the microprobe. At the same time, a double insulating layer with opposite stresses is used to balance the stress difference between different materials, thereby realizing a long probe for implantation in non-human primates.

[0016] The electrophysiological and electrochemical detection sites are densely arranged, allowing multiple sites to simultaneously contact or approach the same nerve cell. This facilitates contact between the detection sites and neurons in the non-human primate brain, enabling the acquisition of electrophysiological and electrochemical signals. Electrophysiological leads are connected to the electrophysiological detection sites. Electrochemical leads are connected to the electrochemical detection sites.

[0017] The electrochemical detection sites are modified with nanomaterials and polymer anti-interference ion membranes to detect neurotransmitters and obtain neuroelectrochemical signals; the electrophysiological detection sites are modified with nanomaterials to detect nerve cell firing signals and obtain neuroelectrophysiological signals.

[0018] The reference electrode and counter electrode are 20 micrometers wide and 300 micrometers long, and are used to provide a reference point and maintain a stable potential.

[0019] The positive and negative electrodes of the electrical stimulation are 150 micrometers wide and 200 micrometers long, encompassing the electrophysiological detection site and the electrochemical detection site. Both the positive and negative electrodes are located inside the target nucleus, and the electric field formed is limited to the inside of the target nucleus.

[0020] The electrical stimulation leads are 80 micrometers wide and consist of two wires, one connected to the positive electrode and the other to the negative electrode. The wire width is positively correlated with the applicable current, and the maximum current that can be passed is 3.2 mA, which can meet the electrical stimulation current required for disease treatment.

[0021] The present invention also provides a method for preparing a neural microprobe for any of the above-described embodiments, comprising:

[0022] Operation S1: Using SOI front-side silicon as the substrate, the first photolithography process is performed. Nanoscale platinum is sputtered and then stripped to form the conductive layer pattern;

[0023] Operation S2: Silicon nitride and silicon oxide with opposite stresses are deposited as a double insulating layer using plasma chemical vapor deposition (PECVD) to balance the stress difference between the different materials. A second photolithography step is then performed to etch and expose the sites and pads.

[0024] Operation S3: Third photolithography, deeply etching the top silicon layer to form a probe pattern;

[0025] Operation S4: Wet etching of the bottom silicon structure of SOI, silicon probe detaches from substrate;

[0026] Operation S5: Place the released silicon probe face side onto a silicon wafer with uniformly spin-coated photoresist, and etch the silicon oxide on the back side of the probe to avoid stress superposition between different materials, thereby solving the problems of large aspect ratio, small electrode thickness, easy bending, and low mechanical strength of silicon probes used for non-human primates.

[0027] This disclosure also provides a method of using any of the neural microprobes described above, comprising:

[0028] The microprobe was implanted into the subthalamic nucleus (STN) as the target area. Neurophysiological and electrochemical signals from the reticular thalamus (Rt), zona incerta (ZI), and subthalamic nucleus (STN) of non-human primates, as well as the substantia nigra (SN) beneath the STN, were received through the detection site. Based on the emission patterns of neurophysiological signals and the concentration characteristics of neuroelectrochemical signals in each brain region, precise functional localization of the subthalamic nucleus was achieved. Electrical stimulation of the localized brain region was then performed, and changes in neurophysiological and neuroelectrochemical signals before and after stimulation were detected to explore the electrical stimulation regulation mechanism. The stimulation parameters were then adjusted in reverse to achieve long-term closed-loop precise electrical stimulation regulation.

[0029] (III) Beneficial Effects

[0030] As can be seen from the above technical solution, the neural microprobe proposed in this invention for functional localization and electrical stimulation modulation of deep brain nuclei has the following beneficial effects:

[0031] (1) It can locate and stimulate deep brain nuclei in non-human primates;

[0032] (2) It can realize the synchronous detection of neurophysiological signals and neuroelectrochemical signals, which is conducive to obtaining more comprehensive neural information;

[0033] (3) The small diameter of the electrode detection site is conducive to obtaining neural information at the single-cell level and improving the positioning accuracy;

[0034] (4) The integration of electrophysiological and electrochemical detection and electrical stimulation can achieve precise electrical stimulation of localized nuclei, reducing damage to brain tissue;

[0035] (5) Simultaneous realization of electrical stimulation and detection of changes in neurophysiological and neurochemical signals is beneficial for exploring the regulatory mechanism of electrical stimulation and provides a basis for long-term closed-loop regulation. Attached Figure Description

[0036] To gain a more complete understanding of the invention and its advantages, reference will now be made to the following description taken in conjunction with the accompanying drawings, which are incorporated in and form part of this specification, wherein:

[0037] Figure 1 It is a neural microprobe for dual-mode functional localization and precise electrical stimulation of deep brain nuclei in non-human primates;

[0038] Figure 2 This is a magnified view of the detection and stimulation portion of a neural microprobe used for dual-mode functional localization and precise electrical stimulation of deep brain nuclei in non-human primates.

[0039] Figure 3 A schematic diagram of the fabrication process of a neural microprobe for dual-mode functional localization and precise electrical stimulation of deep brain nuclei in non-human primates;

[0040] Figure 4 This is a schematic diagram of the functional localization of the subthalamic nucleus of a rhesus monkey using a neural microprobe that achieves dual-mode functional localization and precise electrical stimulation of deep brain nuclei in non-human primates.

[0041] Figure 5 It is a simulation of the electric field generated by the electrical stimulation of a neural microprobe used for dual-mode functional localization and precise electrical stimulation of deep brain nuclei in non-human primates.

[0042] In the above figures, the meanings of the reference numerals are as follows:

[0043] 1-Electrophysiological detection site; 2-Electrochemical detection site; 3-Positive electrostimulation electrode; 4-Negative electrostimulation electrode; 5-Reference electrode; 6-Counter electrode; 7-Electrophysiological lead; 8-Electrochemical lead; 9-Electrostimulation lead; 10-Pad site; 11-Pad lead; 12-Substrate. Detailed Implementation

[0044] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the invention. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the invention for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0045] In the disclosed embodiments, neural microprobes are provided for bimodal functional localization and electrical stimulation modulation of deep brain nuclei, such as... Figure 1 and Figure 2 As shown, a neural microprobe for dual-mode functional localization of deep brain nuclei using electrostimulation is described. The microprobe includes: an electrophysiological detection site 1, an electrochemical detection site 2, a positive electrostimulation electrode 3, a negative electrostimulation electrode 4, a reference electrode 5, a counter electrode 6, an electrophysiological lead 7, an electrochemical lead 8, an electrostimulation lead 9, a pad site 10, a pad lead 11, and a substrate 12. The electrophysiological detection site 1 and the electrochemical detection site 2 are located between the positive electrostimulation electrode 3 and the negative electrostimulation electrode 4. The pad site 10 is connected to the electrophysiological lead 7, the electrochemical lead 8, and the electrostimulation lead 9, respectively. The electrophysiological detection site 1, the electrochemical detection site 2, the positive electrostimulation electrode 3, the negative electrostimulation electrode 4, the reference electrode 5, the counter electrode 6, the electrophysiological lead 7, the electrochemical lead 8, the electrostimulation lead 9, the pad site 10, and the pad lead 11 are all located on the substrate 12.

[0046] The microprobe is made of SOI substrate 12. To avoid the problem of the electrode being easy to bend and the mechanical strength being low due to the excessive length of the silicon probe used for non-human primates, the silicon oxide on the back of the microprobe is removed by dry etching. At the same time, a double insulating layer with opposite stress is used to balance the stress difference of different materials, thereby realizing a long probe for implantation in non-human primates.

[0047] The electrophysiological detection site 1 and the electrochemical detection site 2 are circular with a diameter of 10 micrometers; there are 12 electrophysiological detection sites and 4 electrochemical detection sites, for a total of 16 detection sites, all located between the positive electrode 3 and the negative electrode 4 of the electrical stimulation.

[0048] The electrochemical detection site 2 is modified with nanomaterials and polymer anti-interference ion membranes to detect neurotransmitters and obtain neuroelectrochemical signals; the electrophysiological detection site 1 is modified with nanomaterials to detect nerve cell firing signals and obtain neuroelectrophysiological signals.

[0049] The electrophysiological detection site 1 and the electrochemical detection site 2 are densely arranged, allowing multiple sites to simultaneously contact or approach the same nerve cell. This makes it easier for the detection sites to contact neurons in the brains of non-human primates, facilitating the acquisition of electrophysiological and electrochemical signals.

[0050] The reference electrode 5 and the counter electrode 6 are 20 micrometers wide and 300 micrometers long, and are used to provide a reference point and maintain a stable potential.

[0051] The electrostimulation positive electrode 3 and electrostimulation negative electrode 4 are 150 micrometers wide and 200 micrometers long, respectively, and contain the electrophysiological detection site and the electrochemical detection site.

[0052] The electrophysiological lead 7 has a width of 4 micrometers and a length of 4 centimeters, and its number is equal to that of the electrophysiological detection site 1. The electrophysiological lead 7 is connected to the electrophysiological detection site 1. The electrochemical lead 8 has a width of 4 micrometers and a length of 4 centimeters, and its number is equal to that of the electrochemical detection site 2. The electrostimulation lead 9 has a width of 80 micrometers, and there are two of them. One is connected to the positive electrostimulation electrode 3, and the other is connected to the negative electrostimulation electrode 4.

[0053] The pads 10 are square and there are 20 of them.

[0054] The pad wires 11 are connected to the electrophysiological wires 7, the electrochemical wires 8, and the electrostimulation wires 9, respectively.

[0055] The electrophysiological wire 7, electrochemical wire 8, electrical stimulation wire 9, and pad wire 11 are covered with silicon nitride as an insulating layer with a thickness of 800 nanometers.

[0056] In the disclosed embodiments, such as Figure 3 As shown, this disclosure also provides a method for preparing the neural microprobe for any of the above-described methods, comprising:

[0057] Operation S1: Using SOI front-side silicon as the substrate, the first photolithography process is performed. Nanoscale platinum is sputtered and then stripped to form the conductive layer pattern;

[0058] Operation S2: Silicon nitride and silicon oxide with opposite stresses are deposited as a double insulating layer using plasma chemical vapor deposition to balance the stress difference between the different materials. A second photolithography is then performed to etch and expose the sites and pads.

[0059] Operation S3: Third photolithography, deeply etching the top silicon layer to form a probe pattern;

[0060] Operation S4: Wet etching of the bottom silicon structure of SOI, silicon probe detaches from substrate;

[0061] Operation S5: Place the released silicon probe face side onto a silicon wafer with uniformly spin-coated photoresist, and etch the silicon oxide on the back side of the probe to avoid stress superposition between different materials, thereby solving the problems of large aspect ratio, small electrode thickness, easy bending, and low mechanical strength of silicon probes used for non-human primates.

[0062] In the disclosed embodiments, such as Figure 4 As shown, the neural microprobes for dual-mode functional localization and electrical stimulation modulation of deep brain nuclei described in this disclosure are implanted in the bilateral brain regions of macaques, with the subthalamic nucleus as the target brain region, to acquire neurophysiological and neurochemical signals of neural nuclei along the route, thereby achieving precise localization of the STN.

[0063] Specifically, MPTP was injected unilaterally into macaques to create a lesion model. When the macaques exhibited Parkinson's symptoms, the model was applied to functional localization and electrical stimulation experiments.

[0064] This invention demonstrates the localization of neural information functions and the modulation of electrical stimulation in the subthalamic nucleus (STN) of a rhesus monkey, using it as a target area. Through the detection sites, signals from the reticular thalamic nucleus (Rt) and zona incerta (ZI) of a non-human primate reach the subthalamic nucleus (STN) and penetrate the STN into the substantia nigra (SN). Feature extraction of neurophysiological and neurochemical signals from each brain region ultimately achieves precise localization of the subthalamic nucleus.

[0065] In the disclosed embodiments, such as Figure 5 As shown, the effect of electrical stimulation after applying a voltage of 0.2 volts is illustrated. The arrows indicate the direction of the electric field. It can be seen that the electrical stimulation area is completely covered and confined to the vicinity of the electrophysiological detection site.

[0066] Specifically, after the microprobe reaches the target nucleus STN, a bidirectional voltage or current pulse is applied between the positive and negative electrical stimulation electrodes 3 and 4 to stimulate the subthalamic nucleus in situ to regulate the treatment of Parkinson's disease in rhesus monkeys. The changes in the neurophysiological and neurochemical signals of the subthalamic nucleus regulated by electrical stimulation are detected by electrophysiological and electrochemical detection sites to explore its regulatory mechanism.

[0067] Those skilled in the art will understand that although the invention has been shown and described with reference to specific exemplary embodiments thereof, they should understand that various changes in form and detail may be made to the invention without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents. Therefore, the scope of this disclosure should not be limited to the above embodiments, but should be determined not only by the appended claims but also by their equivalents.

Claims

1. A neural microprobe for deep brain nuclei dual-mode functional localization and precise electrical stimulation in non-human primates, characterized in that, It comprises: a substrate layer made of rigid insulating material; a metal conductive layer on the substrate layer, comprising: an electrophysiological detection site and an electrochemical detection site between the positive and negative electrodes of electrical stimulation; a reference electrode and a counter electrode on the lower end of the detection site on both sides, the detection site, the positive and negative electrodes of electrical stimulation are connected to the pads through wires; the electrophysiological detection site and the electrochemical detection site are densely arranged, so that multiple sites simultaneously contact or approach the same nerve cell, the detection site contacts the neurons in the brain of non-human primates, and the electrophysiological and electrochemical signals are obtained; the electrochemical detection site is modified by nanomaterial and polymer anti-interference ion membrane for detecting neurotransmitters and obtaining nerve electrochemical signals; the electrophysiological detection site is modified by nanomaterial for detecting nerve cell discharge signals and obtaining nerve electrophysiological signals; an insulating layer made of double insulating layers with opposite stresses on the conductive layer; 12 electrophysiological detection sites and 4 electrochemical detection sites; The microprobe uses SOI as the substrate manufacturing material, uses double insulating layers with opposite stresses, and removes the silicon oxide on the back of the microprobe by dry etching to balance the differences in stress of different materials, thereby realizing the probe for implantation in non-human primates.

2. The microprobe according to claim 1, wherein The reference electrode and the counter electrode have a size of 20 microns wide and 300 microns long, which are used to provide reference points and maintain stable potential.

3. The microprobe of claim 1, wherein The positive and negative electrodes of electrical stimulation have a width of 150 microns and a length of 200 microns, which contain the electrophysiological detection site and the electrochemical detection site, and the positive and negative electrodes of electrical stimulation are located inside the target nucleus and form an electric field limited to the inside of the target nucleus.

4. The microprobe of claim 1, wherein The electrical stimulation wires have a line width of 80 microns and two wires, one connected to the positive electrode of electrical stimulation and the other connected to the negative electrode of electrical stimulation; the line width is positively correlated with the maximum current that can be applied, which is up to 3.2 mA.

5. A preparation method of the microprobe according to claim 1, comprising: Operation S1: selecting SOI front silicon as the substrate and performing the first photoetching process; Sputtering nanometer platinum to form a conductive layer pattern by peeling off; Operation S2: depositing silicon nitride and silicon oxide as double insulating layers with opposite stresses by plasma chemical vapor deposition method to balance the stress differences between different materials, performing the second photoetching, and etching to expose the sites and pads; Operation S3: third photoetching, deep etching the top silicon to form the probe pattern; Operation S4: wet etching the SOI bottom silicon structure, and the silicon probe is separated from the substrate; Operation S5: sticking the released silicon probe front to the silicon wafer with spin-coated uniform photoresist, etching the silicon oxide on the back of the probe to avoid stress superposition of different materials.

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