Implantable spinal cord neural signal acquisition electrode array based on ZnO thin film transistor

Abstract

The invention discloses an implantable spinal cord neural signal acquisition electrode array based on a ZnO thin film transistor. A flexible circuit board of the signal acquisition electrode array comprises a ZnO layer, the electrode modules are arranged on the flexible circuit board in an array mode, and the first wires are arranged at intervals in the length direction of the flexible circuit board and electrically connected with the adjacent electrode modules. The second wires are arranged at intervals in the width direction of the flexible circuit board and electrically connected with the adjacent electrode modules, the first wires sequentially transmit pulse signals and then conduct the adjacent electrode modules in sequence, and the second wires output collected spinal cord neuromyoelectricity signals. According to the electrode array, the circumferential distribution of the electrodes distributed around the spinal cord can be maximized, meanwhile, crosstalk pollution is minimized, and noise is effectively reduced. Due to the design of the array electrodes, spinal cord signals can be collected in a high-density mode, on-site amplification of the signals can be achieved, and noise interference borne by weak signals in the transmission process is reduced.

Description

Technical Field

[0001] The invention relates to a signal acquisition electrode array, and relates to the technical field of electrode structures, and in particular to an implantable spinal cord nerve signal acquisition electrode array based on a ZnO thin film transistor. Background Art

[0002] The spinal cord is a major component of the nervous system and is essential for transmitting motor and sensory information between the brain and peripheral systems. Spinal cord injury can lead to serious consequences including paralysis and autonomic dysfunction. Patients with spinal cord injuries have a poor quality of life and urgently need to address pain, ambulation, and various basic functions. Traditional spinal cord stimulation devices are mainly designed to treat chronic pain rather than directly restore motor function. Implantable spinal cord bridging technology is expected to solve the problems caused by spinal cord injury, such as interrupting the connection between the brain and spinal cord areas, leading to paralysis, cardiovascular and gastrointestinal dysfunction.

[0003] Whether collecting signals from damaged upstream spinal nerves or applying electrical stimulation signals to downstream spinal nerves, suitable electrodes are required as interface devices. Since the signals from damaged upstream spinal nerves are relatively weak and multiple nerve lines are gathered together, collecting and analyzing such signals is a major challenge.

[0004] Electrodes implanted in the human body need to face the harsh biological environment caused by inflammation after implantation, that is, the electrodes must be able to resist corrosion, delamination, expansion, dissolution and mechanical strain under continuous electrical stimulation. Traditional metal substrates cannot meet the safety requirements of implantable electrodes. The existing implantable electrode designs, such as the microneedle (wire) structure of the Utah array electrode and the probe structure of the Michigan electrode, cannot be deployed on the spinal cord; spiral electrodes and skin-attaching electrodes cannot meet the needs of tightly wrapping the spinal cord. Summary of the invention

[0005] In order to solve the problems in the background technology, the present invention provides an implantable spinal cord nerve signal collection electrode array based on ZnO thin film transistors. The design of the ZnO thin film transistors in the present invention enables the electrode array to completely wrap the entire spinal cord, maximizing the circumferential distribution of the electrodes around the spinal cord while minimizing crosstalk pollution.

[0006] The technical solution adopted by the present invention is:

[0007] 1. An implantable spinal cord nerve signal collection electrode array based on ZnO thin film transistors:

[0008] The signal collection electrode array includes a flexible circuit board containing a zinc oxide ZnO layer.

[0009] The signal collection electrode array includes a plurality of electrode modules, and each electrode module array is arranged on one side of the flexible circuit board.

[0010] The signal acquisition electrode array includes a plurality of first wires and second wires. Each first wire is arranged at intervals in each electrode module along the length direction of the flexible circuit board and is electrically connected to each electrode module adjacent to itself. Each second wire is arranged at intervals in each electrode module along the width direction of the flexible circuit board and is electrically connected to each electrode module adjacent to itself. Each first wire transmits a pulse signal in sequence and then turns on an adjacent row of electrode modules in sequence. Each second wire collects the neuromyographic electromyographic signal of the spinal cord and transmits it to an external signal processing device.

[0011] The flexible circuit board adopts a top gate structure with an active layer covered inside. The flexible circuit board includes a glass substrate, a source-drain electrode layer, an active layer, a gate oxide layer and a gate electrode layer stacked in sequence. The active layer adopts a zinc oxide ZnO layer, and an aluminum oxide protective layer is deposited between the active layer and the gate oxide layer.

[0012] The electrode modules are arrayed and arranged at intervals on the gate electrode layer of the flexible circuit board, a row of electrode modules is arranged between every two adjacent first wires, a column of electrode modules is arranged between every two adjacent second wires, and an electrode module is arranged in the gap between every two adjacent first wires and the second wire as an array unit; the electrode module includes an electrode, a first thin film transistor TFT A, a second thin film transistor TFT B and a third thin film transistor TFT C, the gate of the first thin film transistor TFT A is electrically connected to the electrode and works as a source follower, the drain of the first thin film transistor TFT A is electrically connected to the gate of the second thin film transistor TFT B and a first wire adjacent to the electrode module, the source of the first thin film transistor TFT A is electrically connected to the source of the second thin film transistor TFT B and the drain of the third thin film transistor TFT C, the drain of the second thin film transistor TFT B is electrically connected to a second wire adjacent to the electrode module, and the source and gate of the third thin film transistor TFT C are short-circuited and electrically connected to another first wire adjacent to the electrode module.

[0013] The third thin film transistor TFT C is a depletion type TFT with a gate and a source short-circuited, and its gate-source voltage is constant at 0V. After being turned on, the current is almost unchanged, and it can be regarded as a constant current source load. Therefore, when the gate terminal voltage of the third thin film transistor TFT C fails to reach the turn-on voltage, the reverse resistance is large, and it can be regarded as a large resistor at this time.

[0014] Each of the three adjacent electrode modules forms a three-electrode structure, which collects the neuromyographic electrogram of the spinal cord in a double differential manner, can effectively reduce noise, and is used to collect the neuromyographic electrogram of the part to be tested or to apply an electrical stimulation signal to the part to be stimulated.

[0015] The two ends of the flexible circuit board are provided with positioning anchors respectively. When the flexible circuit board is wrapped around the spinal cord, the positioning anchors are overlapped to confirm the position and fix it. In specific implementation, two hollow positioning anchors can be provided along the width direction of the flexible circuit board.

[0016] 2. A signal acquisition method of an implantable spinal cord nerve signal acquisition electrode array, comprising:

[0017] When the acquisition electrode array is collecting signals, it first inputs a pulse signal to each first wire at intervals, and the conduction of the second thin film transistor TFT B is determined by the input signal. When the pulse signal SCAN of the nth first wire n When the pulse signal SCAN of the n+1th first wire reaches the nth first wire, the second thin film transistor TFT B of an electrode module connected to the nth first wire is turned on. n+1 When arriving, the last turned-on second thin-film transistor TFT B is turned off, and the second thin-film transistor TFT B of an electrode module connected to the n+1th first wire is turned on, and the neuromyographic signal of the spinal cord is output to an external signal processing device via a second wire connected to the drain of the second thin-film transistor TFT B; when the voltage of the neuromyographic signal of the spinal cord is less than the preset threshold voltage, the signal output by the second wire is only a pulse signal, and when the voltage of the neuromyographic signal of the spinal cord is greater than or equal to the preset threshold voltage, the signal output by the second wire is a signal obtained by superimposing the pulse signal and the neuromyographic signal of the spinal cord.

[0018] The beneficial effects of the present invention are:

[0019] The implantable spinal cord nerve signal efficient collection electrode array of the present invention can adapt to the complex human body environment after implantation and will not cause harm to the human body; the electrode is made of transparent material, so the spinal cord condition can be monitored at any time; it can be completely attached to the spinal cord surface and will not cause direct damage to the spinal cord, while being more sensitive to nerve signals; the size of the electrode can be adjusted according to the specific spinal cord condition and attachment position of the experimental subject, and is suitable for all vertebrates.

[0020] Compared with the prior art, the present invention creatively proposes a flexible circuit array electrode solution based on flexible integrated circuit technology, which can maximize the circumferential distribution of electrodes distributed around the spinal cord, while minimizing crosstalk pollution and effectively reducing noise. The design of the array electrode can not only collect spinal cord signals at a high density, but also realize on-site signal amplification, reducing the noise interference of weak signals during transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic structural diagram of the electrode array of the present invention;

[0022] Figure 2 is a circuit diagram of the electrode module of the present invention;

[0023] Figure 3 This is a diagram of the experimental results of the electrode array of the present invention simulating the collection of electromyographic signals;

[0024] In the figure: 1. positioning anchor, 2. electrode module, 21. electrode, 22. first thin film transistor TFT A, 23. second thin film transistor TFT B, 24. third thin film transistor TFT C, 3. flexible circuit board, 4. first wire, 5. second wire. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] like Figure 1 As shown, the implantable spinal cord nerve signal acquisition electrode array based on ZnO thin film transistor of the present invention comprises a flexible circuit board 3 containing a zinc oxide ZnO layer, a plurality of electrode modules 2, and a plurality of first wires 4 and second wires 5. Each electrode module 2 is arranged in an array on one side of the flexible circuit board 3. Each first wire 4 is arranged in each electrode module 2 at intervals along the length direction of the flexible circuit board 3 and electrically connected to each electrode module 2 adjacent to itself. Each second wire 5 is arranged in each electrode module 2 at intervals along the width direction of the flexible circuit board 3 and electrically connected to each electrode module 2 adjacent to itself. Each first wire 4 transmits a pulse signal in sequence and then conducts an adjacent row of electrode modules 2 in sequence. Each second wire 5 collects the neuromyographic signal of the spinal cord and transmits it to an external signal processing device. Positioning anchors 1 are also provided at both ends of the flexible circuit board 3. When the flexible circuit board 3 surrounds the spinal cord, the positioning anchors 1 are overlapped to confirm the position and fix it. In specific implementation, two hollow positioning anchors 1 can be set in the width direction of the flexible circuit board 3.

[0027] The flexible circuit board 3 adopts a top gate structure in which the active layer is covered inside. The flexible circuit board 3 includes a glass substrate, a source-drain electrode layer, an active layer, a gate oxide layer and a gate electrode layer stacked in sequence. The active layer adopts a zinc oxide ZnO layer, and an aluminum oxide protective layer is deposited between the active layer and the gate oxide layer. The flexible circuit board adopts a top gate structure in which the active layer is covered inside to avoid the influence of moisture on its conductivity. For transparency considerations, the glass substrate uses Corning glass and is pretreated in acetone and isopropyl acetone. In the construction structure, the first layer is set as the source-drain electrode layer, which uses transparent indium tin oxide ITO as the electrode material, and the thickness of the required film is precisely controlled by controlling the duration of the sputtering process. The design of the second layer mainly includes two key components: first, a 20-nanometer zinc oxide ZnO layer is accurately deposited as the channel of the active layer by atomic layer deposition technology; then, in order to effectively protect the ZnO layer and avoid its performance degradation or damage caused by direct contact with the liquid, a layer of 8-12 nanometers of aluminum oxide is deposited on the ZnO layer as a protective layer. This design ensures the stability and durability of the structure. In the further construction of the structure, the third layer is set as the gate oxide layer, using 15-25 nanometer aluminum oxide material. Its key role is to provide electrical isolation for the gate electrode while ensuring good capacitance performance. Above this layer is the final gate electrode layer, which uses 100-120 nanometers of transparent indium tin oxide as the material, which not only ensures the conductivity of the electrode, but also facilitates the observation and detection of the underlying structure due to its transparent properties. Such a design not only meets the requirements of electrical performance, but also takes into account the visualization and practicality of the structure, and provides strong technical support and guarantee for the preparation of high-performance, high-reliability ZnO-TFT (Thin Film Transistor) thin-film transistor devices with high switching ratio, high gain and low gate leakage.

[0028] The electrode modules 2 are arranged in an array on the gate electrode layer of the flexible circuit board 3 at intervals. A row of electrode modules 2 is arranged between every two adjacent first wires 4, a column of electrode modules 2 is arranged between every two adjacent second wires 5, and an electrode module 2 is arranged in the gap between every two adjacent first wires 4 and second wires 5 as an array unit; Figure 2As shown, the electrode module 2 includes an electrode 21, a first thin film transistor TFT A22, a second thin film transistor TFT B23 and a third thin film transistor TFT C24. The gate of the first thin film transistor TFT A22 is electrically connected to the electrode 21 and works as a source follower. The drain of the first thin film transistor TFT A22 is electrically connected to the gate of the second thin film transistor TFT B23 and a first wire 4 adjacent to the electrode module 2. The source of the first thin film transistor TFT A22 is electrically connected to the source of the second thin film transistor TFT B23 and the drain of the third thin film transistor TFT C24. The drain of the second thin film transistor TFT B23 is electrically connected to a second wire 5 adjacent to the electrode module 2. The source and gate of the third thin film transistor TFT C24 are short-circuited and electrically connected to another first wire 4 adjacent to the electrode module 2. The third thin film transistor TFT C24 is a depletion type TFT with a gate and a source short-circuited. Its gate-source voltage is constant at 0V. After being turned on, the current is almost unchanged and can be regarded as a constant current source load. Therefore, when the gate terminal voltage of the third thin film transistor TFT C24 fails to reach the turn-on voltage, the reverse resistance is large, and it can be regarded as a large resistor at this time. Each three adjacent electrode modules 2 form a three-electrode structure, which collects the neuromyographic electrogram of the spinal cord in a double differential manner, can effectively reduce noise, and is used to collect the neuroelectrical signal of the part to be tested or to apply electrical stimulation signals to the part to be stimulated.

[0029] The array solution of the electrode module 2 of the present invention is improved on the basis of the classic switch model, and the connection mode of the thin film transistor is modified. In specific implementation, each electrode module 2 uses 128 electrode contacts arranged in the form of 8 rows and 16 columns, and the gap between every two adjacent first wires 4 and second wires 5 forms a rectangular space of 180×200μm and an electrode module 2 is arranged.

[0030] The signal acquisition method of the implantable spinal cord nerve signal acquisition electrode array of the present invention is specifically as follows:

[0031] When collecting signals, the collection electrode array first inputs a pulse signal to each first wire 4 at intervals. Whether the second thin film transistor TFT B23 is turned on or off is determined by the input signal. When the pulse signal SCAN of the nth first wire 4 n When the pulse signal SCAN of the n+1th first wire 4 reaches the nth first wire 4, the second thin film transistor TFT B23 of an electrode module 2 connected to the nth first wire 4 is turned on. n+1When arriving, the last turned-on second thin-film transistor TFT B23 is turned off, and the second thin-film transistor TFT B23 of an electrode module 2 connected to the n+1th first wire 4 is turned on, and the neuromyographic signal of the spinal cord is output to an external signal processing device via a second wire 5 connected to the drain of the second thin-film transistor TFT B23; when the voltage of the neuromyographic signal of the spinal cord is less than the preset threshold voltage, the signal output by the second wire 5 is only a pulse signal, and when the voltage of the neuromyographic signal of the spinal cord is greater than or equal to the preset threshold voltage, the signal output by the second wire 5 is a signal obtained by superimposing the pulse signal and the neuromyographic signal of the spinal cord.

[0032] The present invention directly collects signals from the damaged upstream spinal nerves for AI training, decodes the instructions, and after signal transcoding and amplification, stimulates the downstream spinal nerves to complete the transmission of instruction functions from the brain to the terminal, and realizes the corresponding movement or control function. The specific operation is as follows: trigger the sequential activation of bilateral motor evoked potentials MEP (motor evoked potential) through the hind limb motor cortex, and trigger the somatosensory somatosensory evoked potential SSEP (Somatosensory evoked potential) through the sciatic nerve, perform acute electrophysiology, and record the nerve signals around the spinal cord by the device. Afterwards, the threshold method based on the peak amplitude mean is used to extract the features of the collected signals, and the evoked potential sources are classified using a machine learning algorithm. After the instructions are transcoded and amplified, the nerve signals recorded around the spinal cord are used as triggers to generate targeted spinal cord electrical stimulation, thereby functionally bypassing the site of acute spinal cord injury. This method has clear directionality and clean signals, avoiding the uncertainty of collecting signals from EEG.

[0033] The specific surgical procedure of the present invention is as follows: First, a human spinal cord is reconstructed using a saline pump, which includes inserting and sealing a fluid tube in a vein and connecting it to a flow pump to maintain a controlled pressure environment for 30 minutes before implantation. Two experienced spinal surgeons perform a laminectomy at the level of thoracic vertebrae T9 to T10. Subsequently, a midline dura mater incision is performed to expose the substance. The dura mater is gently retracted using a tent suture to allow the surgeon to perform surgery in the gap, and finally the device is wrapped around the spinal cord to complete the operation.

[0034] like Figure 3 As shown, the collection results of neuroelectromyographic signals by a single electrode module 2 in an implantable spinal cord nerve signal efficient collection electrode array based on ZnO thin film transistors are demonstrated. The simulation experiment is performed on the Cadence Virtuoso software on a Red Hat system. It can be seen that the single electrode module 2 in the array successfully collects neuroelectromyographic signals when the pulse signal arrives, and returns to the closed state after the pulse signal ends.

[0035] Based on the flexible integrated circuit technology of the present invention, the design of the flexible circuit array electrode solution of the present invention can maximize the circumferential distribution of electrodes distributed around the spinal cord while minimizing crosstalk pollution. The design of the array electrode can not only collect spinal cord signals at a high density, but also amplify the signals locally, reducing the noise interference of weak signals during transmission.

Claims

1. An implantable spinal cord nerve signal acquisition electrode array based on ZnO thin film transistors, characterized in that: A flexible circuit board (3) comprising a zinc oxide ZnO layer; It comprises a plurality of electrode modules (2), wherein each electrode module (2) is arranged in an array on one side of a flexible circuit board (3); The invention comprises a plurality of first wires (4) and second wires (5), wherein each first wire (4) is arranged in each electrode module (2) at intervals along the length direction of the flexible circuit board (3) and is electrically connected to each electrode module (2) adjacent to itself, and each second wire (5) is arranged in each electrode module (2) at intervals along the width direction of the flexible circuit board (3) and is electrically connected to each electrode module (2) adjacent to itself, and each first wire (4) sequentially transmits a pulse signal and then sequentially conducts a row of adjacent electrode modules (2), and each second wire (5) collects neuromyographic electromyographic signals of the spinal cord and transmits them to an external signal processing device.

2. The implantable spinal cord nerve signal acquisition electrode array based on ZnO thin film transistor according to claim 1, characterized in that: The flexible circuit board (3) adopts a top gate structure in which an active layer is covered inside. The flexible circuit board (3) comprises a glass substrate, a source-drain electrode layer, an active layer, a gate oxide layer and a gate electrode layer stacked in sequence. The active layer adopts a zinc oxide ZnO layer, and an aluminum oxide protective layer is deposited between the active layer and the gate oxide layer.

3. The implantable spinal cord nerve signal acquisition electrode array based on ZnO thin film transistor according to claim 2, characterized in that: The electrode modules (2) are arranged in an array at intervals on the gate electrode layer of the flexible circuit board (3); a row of electrode modules (2) is arranged between every two adjacent first conductors (4); a column of electrode modules (2) is arranged between every two adjacent second conductors (5); and an electrode module (2) is arranged in the gap between every two adjacent first conductors (4) and second conductors (5) as an array unit; The electrode module (2) comprises an electrode (21), a first thin film transistor TFT A (22), a second thin film transistor TFT B (23) and a third thin film transistor TFT C (24); the gate of the first thin film transistor TFT A (22) is electrically connected to the electrode (21); the drain of the first thin film transistor TFT A (22) is electrically connected to the gate of the second thin film transistor TFT B (23) and a first wire (4) adjacent to the electrode module (2); the source of the first thin film transistor TFT A (22) is electrically connected to the source of the second thin film transistor TFT B (23) and the drain of the third thin film transistor TFT C (24); the drain of the second thin film transistor TFT B (23) is electrically connected to a second wire (5) adjacent to the electrode module (2); the source and gate of the third thin film transistor TFT C (24) are short-circuited and electrically connected to another first wire (4) adjacent to the electrode module (2).

4. The implantable spinal cord nerve signal acquisition electrode array based on ZnO thin film transistor according to claim 1, characterized in that: Each of the three adjacent electrode modules (2) forms a three-electrode structure, and collects neuromyographic signals of the spinal cord in a double differential manner.

5. The implantable spinal cord nerve signal acquisition electrode array based on ZnO thin film transistor according to claim 1, characterized in that: Positioning anchors (1) are also provided at both ends of the flexible circuit board (3). When the flexible circuit board (3) surrounds the spinal cord, the positioning anchors (1) are overlapped to confirm the position and fix it.

6. The signal acquisition method of the implantable spinal cord nerve signal acquisition electrode array according to any one of claims 1 to 5, characterized in that: include: When the acquisition electrode array acquires signals, it first inputs pulse signals to each first conductor (4) at intervals in sequence, and when the pulse signal SCAN of the nth first conductor (4) n When the nth first wire (4) is reached, the second thin film transistor TFT B (23) of an electrode module (2) connected to the nth first wire (4) is turned on, and when the pulse signal SCAN of the n+1th first wire (4) n+1 When the signal arrives, the last turned-on second thin film transistor TFT B (23) is turned off, and the second thin film transistor TFT B (23) of an electrode module (2) connected to the n+1th first wire (4) is turned on, and the neuromyographic signal of the spinal cord is output to an external signal processing device via a second wire (5) connected to the drain of the second thin film transistor TFT B (23); when the voltage of the neuromyographic signal of the spinal cord is less than a preset threshold voltage, the signal output by the second wire (5) is only a pulse signal, and when the voltage of the neuromyographic signal of the spinal cord is greater than or equal to the preset threshold voltage, the signal output by the second wire (5) is a signal obtained by superimposing the pulse signal and the neuromyographic signal of the spinal cord.

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