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

Abstract

The application discloses an implantable spinal cord nerve signal acquisition electrode array based on a ZnO thin film transistor. The flexible circuit board of the signal acquisition electrode array comprises a ZnO layer, each electrode module is arranged on the flexible circuit board, each first lead wire is arranged at intervals along the length direction of the flexible circuit board and is electrically connected with each adjacent electrode module, each second lead wire is arranged at intervals along the width direction of the flexible circuit board and is electrically connected with each adjacent electrode module, each first lead wire sequentially transmits a pulse signal and then sequentially turns on each adjacent electrode module, and each second lead wire outputs the acquired nerve and muscle electric signals of the spinal cord. The electrode array can maximize the circumferential distribution of the electrodes distributed around the spinal cord and minimize the crosstalk pollution, effectively reducing the noise. The design of the array electrode can not only acquire the spinal cord signals at a high density but also realize in-situ amplification of the signals, reducing the noise interference on the weak signals in the transmission process.

Description

TECHNICAL FIELD

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

[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 the peripheral system. Spinal cord injury can lead to serious consequences including paralysis and autonomic dysfunction. The quality of life of patients with spinal cord injury is poor, and pain, walking and various basic functions need to be solved. Traditional spinal cord stimulation devices are mainly designed for the treatment of chronic pain, rather than directly restoring 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 the spinal cord region, thereby causing paralysis, cardiovascular and gastrointestinal dysfunction.

[0003] Whether it is from the damaged upstream spinal cord nerve signal acquisition or at the downstream spinal cord nerve to apply the electric stimulation signal, a suitable electrode is needed as an interface device. Because the signal of the damaged upstream spinal cord nerve is relatively weak, and multiple nerve lines are gathered together, it is a big problem to collect and analyze such signals.

[0004] The electrode implanted in the human body needs to face the bad biological environment caused by inflammation after implantation, that is, the electrode must be able to resist corrosion, delamination, swelling, dissolution and mechanical strain under continuous electrical stimulation. The traditional metal substrate cannot meet the safety requirements of the implantable electrode. And the existing implantable electrode design, 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; for example, the spiral electrode and the skin electrode cannot meet the need of tightly wrapping the spinal cord. SUMMARY

[0005] In order to solve the problems in the background art, the application provides an implantable spinal cord nerve signal acquisition electrode array based on a ZnO thin film transistor. The design of the ZnO thin film transistor in the application makes the electrode array can completely wrap the whole spinal cord, so that the circumferential distribution of the electrodes distributed around the spinal cord is maximized while the crosstalk pollution is minimized.

[0006] The technical scheme adopted by the application is:

[0007] I. An implantable spinal cord nerve signal acquisition electrode array based on a ZnO thin film transistor:

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

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

[0010] The signal acquisition electrode array comprises a plurality of first conductive wires and a plurality of second conductive wires, each first conductive wire is arranged in each electrode module along the length direction of the flexible circuit board and is electrically connected with each electrode module adjacent to itself, each second conductive wire is arranged in each electrode module along the width direction of the flexible circuit board and is electrically connected with each electrode module adjacent to itself, each first conductive wire sequentially transmits a pulse signal and sequentially turns on the adjacent row of electrode modules, and each second conductive wire acquires the neuroelectric signal of the spinal cord and transmits the neuroelectric signal to an external signal processing device.

[0011] The flexible circuit board adopts a top gate structure in which an active layer covers the inside, and the flexible circuit board comprises a glass substrate, a source-drain electrode layer, an active layer, a gate oxide layer and a gate electrode layer which are sequentially stacked, the active layer is a zinc oxide (ZnO) layer, and an aluminum oxide protective layer is deposited between the active layer and the gate oxide layer.

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

[0013] The third TFT C is a depletion mode TFT with the gate electrode and the source electrode short-circuited, the gate-source voltage of the third TFT C is constant at 0V, the current almost does not change after the third TFT C is turned on, and the third TFT C can be regarded as a constant current source load. Therefore, when the gate voltage of the third TFT C fails to reach the opening voltage, the reverse resistance is large, and at this time, the third TFT C can be regarded as a large resistance.

[0014] Each adjacent three electrode modules form a three-electrode structure, and the neuroelectric signal of the spinal cord is acquired in a double-differential manner, so that the noise can be effectively reduced, and the neuroelectric signal of a to-be-measured part is acquired or an electric stimulation signal is applied to a to-be-stimulated part.

[0015] The flexible circuit board is also equipped with positioning anchors at both ends. After the flexible circuit board wraps around the spinal cord, the positioning anchors are aligned to confirm the position and fix it in place. In a specific implementation, two hollowed-out positioning anchors can be set along the width direction of the flexible circuit board.

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

[0017] During signal acquisition, the aforementioned acquisition electrode array first sequentially inputs pulse signals to each first wire at time intervals. The conduction of the second thin-film transistor (TFT B) is determined by the input signal. When the pulse signal of the nth first wire is SCAN... n Upon arrival, the second thin-film transistor TFT B of an electrode module connected to the nth first wire is turned on, when the pulse signal SCAN of the (n+1)th first wire is activated. n+1 Upon arrival, the previously turned-on second thin-film transistor TFT B turns off, and the second thin-film transistor TFT B of an electrode module connected to the (n+1)th first wire turns on. The neuromuscular 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 neuromuscular signal of the spinal cord is less than a preset threshold voltage, the signal output by the second wire is only a pulse signal. When the voltage of the neuromuscular 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 resulting from the superposition of the pulse signal and the neuromuscular signal of the spinal cord.

[0018] The beneficial effects of this invention are:

[0019] The implantable spinal cord nerve signal high-efficiency acquisition electrode array of the present invention can adapt to the complex human environment after implantation and will not cause harm to the human body; the electrodes are made of transparent materials, allowing for monitoring of the spinal cord at any time; they can completely adhere to the surface of the spinal cord without causing direct damage to the spinal cord, while being more sensitive to nerve signals; the size of the electrodes can be adjusted according to the specific spinal cord condition and attachment position of the experimental subject, and is applicable to all vertebrates.

[0020] Compared with existing technologies, this invention, based on flexible integrated circuit technology, creatively proposes a flexible circuit array electrode scheme that maximizes the circumferential distribution of electrodes around the spinal cord while minimizing crosstalk contamination, effectively reducing noise. The array electrode design enables high-density acquisition of spinal cord signals and on-site signal amplification, reducing noise interference to weak signals during transmission. Attached Figure Description

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

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

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

[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 Implementation

[0025] The present invention will be 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 transistors of the present invention includes a flexible circuit board 3 containing a zinc oxide (ZnO) layer, several electrode modules 2, and several 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 spaced apart along the length of the flexible circuit board 3 within each electrode module 2 and electrically connected to its adjacent electrode modules 2. Each second wire 5 is spaced apart along the width of the flexible circuit board 3 within each electrode module 2 and electrically connected to its adjacent electrode modules 2. Each first wire 4 transmits pulse signals sequentially and then sequentially connects to an adjacent row of electrode modules 2. Each second wire 5 acquires neuromuscular signals from the spinal cord and transmits them 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 and fix the position. In specific implementation, two perforated positioning anchors 1 can be set along the width of the flexible circuit board 3.

[0027] The flexible circuit board 3 adopts a top gate structure with the active layer covered inside, and 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 a layer of aluminum oxide protective layer is deposited between the active layer and the gate oxide layer. The flexible circuit board adopts a top gate structure with the active layer covered inside to avoid the influence of moisture on its conductivity. For transparency, the glass substrate is made of Corning glass and is pretreated in acetone and isopropyl alcohol. In the construction structure, the first layer is set as the source-drain electrode layer, which selects transparent indium tin oxide (ITO) as the electrode material and precisely controls the thickness of the required film by controlling the length of the sputtering process. The design of the second layer mainly includes two key components: first, a 20-nanometer zinc oxide (ZnO) layer is precisely 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 liquid, an 8-12-nanometer aluminum oxide layer 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, which adopts 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 selects 100-120-nanometer transparent indium tin oxide as the material. This not only ensures the conductivity of the electrode, but also facilitates observation and detection of the lower structure due to its transparent property. Such design not only meets the electrical performance requirements, but also takes into account the visualization and practicality of the structure, providing strong technical support and guarantee for the preparation of high-performance and high-reliability ZnO-TFT (Thin Film Transistor) thin film transistor devices with high on-off 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. One row of electrode modules 2 is arranged between every two adjacent first conductive lines 4, one column of electrode modules 2 is arranged between every two adjacent second conductive lines 5, and one electrode module 2 is arranged in the gap between every two adjacent first conductive lines 4 and second conductive lines 5 as an array unit. Figure 2As shown, 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 with the electrode 21 and works as a source follower, the drain of the first thin film transistor TFT A 22 and the gate of the second thin film transistor TFT B 23 and one first wire 4 adjacent to the electrode module 2 are electrically connected, the source of the first thin film transistor TFT A 22 and the source of the second thin film transistor TFT B 23 and the drain of the third thin film transistor TFT C 24 are electrically connected, the drain of the second thin film transistor TFT B 23 is electrically connected with one second wire 5 adjacent to the electrode module 2, the source and the gate of the third thin film transistor TFT C 24 are short-circuited and electrically connected with another first wire 4 adjacent to the electrode module 2. The third thin film transistor TFT C 24 is a depletion mode TFT with the gate and the source short-circuited, the gate-source voltage is constant at 0V, the current is almost constant after being turned on, and it can be regarded as a constant current source load. Therefore, when the gate voltage of the third thin film transistor TFT C 24 fails to reach the opening voltage, the reverse resistance is large, and at this time it can be regarded as a large resistance. Each adjacent three electrode modules 2 form a three-electrode structure, and the nerve and muscle electric signals of the spinal cord are collected in a double-difference mode, which can effectively reduce the noise and be used for collecting nerve electric signals of a to-be-measured part or applying an electric stimulation signal to a to-be-stimulated part.

[0029] The array scheme of the electrode module 2 of the present application 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 adopts 128 electrode contacts arranged in the form of 8 rows and 16 columns, and a rectangular space with a size of 180x200μm is arranged in the gap between every two adjacent first wires 4 and second wires 5 and one electrode module 2 is arranged in the rectangular space.

[0030] The signal collection method of the implantable spinal cord nerve signal collection electrode array of the present application is as follows:

[0031] In the signal collection of the collection electrode array, firstly, a pulse signal is input to each first wire 4 in turn and at intervals, whether the second thin film transistor TFT B 23 is turned on or not is determined by the input signal, when the pulse signal SCAN n of the nth first wire 4 arrives, the second thin film transistor TFT B 23 of one electrode module 2 connected with the nth first wire 4 is turned on, when the pulse signal SCAN n+1When arriving, the last turned-on second thin film transistor TFT B23 is turned off, the second thin film transistor TFT B23 of an electrode module 2 connected with the n+1th first lead wire 4 is turned on, and the nerve and muscle electric signal of the spinal cord is output to the external signal processing device through a second lead wire 5 connected with the drain electrode of the second thin film transistor TFT B23; when the voltage of the nerve and muscle electric signal of the spinal cord is less than the preset threshold voltage, the signal output by the second lead wire 5 is only a pulse signal, and when the voltage of the nerve and muscle electric signal of the spinal cord is greater than or equal to the preset threshold voltage, the signal output by the second lead wire 5 is a pulse signal and a signal obtained by superimposing the nerve and muscle electric signal of the spinal cord.

[0032] The application directly collects signals from damaged upstream spinal nerves for AI training, decodes instructions, stimulates downstream spinal nerves after signal decoding and amplification, completes the transmission of instructions from the brain to the end, and realizes corresponding movement or control functions. The specific operation is as follows: the sequential activation of bilateral motor evoked potentials MEP (motor evoked potential) is triggered through the hindlimb motor cortex, somatosensory evoked potentials SSEP (Somatosensory evoked potential) are triggered through the sciatic nerve, acute electrophysiology is performed, and nerve signals around the spinal cord are recorded by the device. Then, the threshold method based on the mean value of the peak amplitude is used to extract the characteristics of the collected signals, and a machine learning algorithm is used to classify the evoked potential source. After the instructions are decoded and amplified, the nerve signals recorded around the spinal cord are used as triggers to produce targeted spinal cord electrical stimulation, thereby functionally bypassing the site of acute spinal cord injury. This way is clear in direction and clean in signal, avoiding the uncertainty of collecting signals from brain electricity.

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

[0034] As shown in Figure 3 As shown in the figure, the acquisition result of a single electrode module 2 in the implantable spinal nerve signal high-efficiency acquisition electrode array based on a ZnO thin film transistor is displayed, and the simulation experiment is carried out on the Cadence Virtuoso software of the Red Hat system. It can be seen that the single electrode module 2 in the array successfully acquires the nerve and muscle electric signal when the pulse signal arrives, and returns to the off state after the pulse signal ends.

[0035] Based on the flexible integrated circuit technology of the present application, the design of the flexible circuit array electrode scheme of the present application can maximize the circumferential distribution of the electrodes distributed around the spinal cord while minimizing the cross-talk pollution. The design of the array electrode can both collect the spinal cord signals at high density and realize on-site signal amplification, reducing the noise interference suffered by the weak signals in the transmission process.

Claims

1. An implantable spinal cord nerve signal acquisition electrode array based on ZnO thin-film transistors, characterized in that: Including flexible circuit boards containing zinc oxide (ZnO) layers (3); It includes several electrode modules (2), and each electrode module (2) is arranged in an array on one side of the flexible circuit board (3); It includes several first wires (4) and second wires (5). Each first wire (4) is arranged at intervals in each electrode module (2) 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 at intervals in each electrode module (2) 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 pulse signals in sequence and then sequentially connects to an adjacent row of electrode modules (2). Each second wire (5) collects the neuromuscular signals of the spinal cord and transmits them to an external signal processing device. The electrode module (2) includes 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), the gate of the second thin-film transistor TFT B (23), and a first wire (4) adjacent to the electrode module (2) are electrically connected. The source of the first thin-film transistor TFT A (22), the source of the second thin-film transistor TFT B (23), and the drain of the third thin-film transistor TFT C (24) are electrically connected. 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).

2. The implantable spinal cord nerve signal acquisition electrode array based on ZnO thin-film transistors according to claim 1, characterized in that: The flexible circuit board (3) adopts a top gate structure with the active layer 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 is a zinc oxide (ZnO) layer. An aluminum oxide protective layer is also 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 transistors according to claim 2, characterized in that: Each of the electrode modules (2) is 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.

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

5. The implantable spinal cord nerve signal acquisition electrode array based on ZnO thin-film transistors according to claim 1, characterized in that: The flexible circuit board (3) is also provided with positioning anchors (1) at both ends. 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 for the implantable spinal cord nerve signal acquisition electrode array according to any one of claims 1-5, characterized in that, include: During signal acquisition, the aforementioned acquisition electrode array first sequentially inputs pulse signals to each first wire (4) at time intervals. When the pulse signal of the nth first wire (4) is SCAN... n Upon arrival, the second thin-film transistor TFT B (23) of an electrode module (2) connected to the nth first wire (4) is turned on, when the pulse signal SCAN of the (n+1)th first wire (4) is activated. n+1 Upon arrival, the previously 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+1)th first wire (4) is turned on. The neuromuscular 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 neuromuscular 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. When the voltage of the neuromuscular signal of the spinal cord is greater than or equal to the preset threshold voltage, the signal output by the second wire (5) is the signal after the pulse signal and the neuromuscular signal of the spinal cord are superimposed.

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