A stimulation generation protection circuit for transcranial electrical stimulation

Abstract

The embodiment of the application provides a stimulation generation protection circuit for transcranial electrical stimulation, which comprises an ESD protection circuit, a current switching detection circuit, a disengagement detection circuit and a constant current source type stimulation generation circuit. By integrating the anti-static module, the damage of static electricity to the circuit can be effectively inhibited, and the normal work of the internal elements is ensured. The output value identification unit is designed, which can monitor the output signal in real time and accurately judge whether it exceeds the set value, so as to take protective measures in time. The load detection module is constructed, which can accurately perceive the connection and working state of the load. In this way, multiple protections are realized for the circuit, the reliability, safety and adaptability of the circuit in a complex working environment are improved, and a strong guarantee is provided for the stable operation of related electronic equipment.

Description

Technical Field

[0001] This invention relates to the field of medical electronics technology, and in particular to a stimulation generation protection circuit for transcranial electrical stimulation. Background Technology

[0002] In the medical field, traditional therapies such as drug therapy, surgical intervention, and physical rehabilitation training have significant limitations: drug therapy is prone to causing systemic side effects and has limited effectiveness in non-organic lesions such as nerve function repair; surgical intervention is highly invasive, has a long recovery period, and is difficult to precisely control deep tissues; physical rehabilitation relies on the patient's active cooperation, resulting in low efficiency in functional recovery. Electrical stimulation therapy, by applying external current or electric fields directly to nerves, muscles, or tissues, has become an important supplement to non-drug and non-surgical treatments due to its advantages such as non-invasiveness or minimally invasiveness, targeted regulation, fewer side effects, applicability to refractory diseases, and immediate adjustability. However, traditional transcranial electrical stimulation (such as tDCS and tACS) suffers from insufficient penetration depth, low spatial resolution, and difficulty in deep regulation, making it difficult to act on deep nuclei such as the thalamus and basal ganglia, thus limiting its effectiveness for diseases involving deep brain regions. Transcranial temporal stimulation (tTIS) emerged in this context. It applies two high-frequency alternating currents to the scalp, using the frequency difference to create a low-frequency interference electric field deep within the brain, thereby achieving targeted modulation of deep nerves. Compared with traditional transcranial electrical stimulation, it has advantages such as precise modulation of deep brain regions, high spatial resolution, higher safety, expanded applicability, and non-invasive deep brain replacement. It can be used for diseases related to deep brain regions such as Parkinson's disease and depression, and it does not require surgical implantation of electrodes, making it more acceptable to patients. In tTIS, constant current sources offer significant advantages over constant voltage sources as stimulation outputs: Due to individual differences and dynamic changes in scalp and skull impedance, constant current sources maintain a constant output current, ensuring stable stimulation parameters and preventing abnormal interference electric fields caused by impedance fluctuations, thus guaranteeing consistent results. They can precisely control the current amplitude ratio and frequency difference between the two channels, ensuring that the deep interference electric field accurately meets the needs of the target brain region. By presetting a maximum current limit, constant current sources avoid sudden current increases due to load impedance mutations, improving safety. Furthermore, they can adapt to the differences in head impedance among different patients without frequent adjustments, offering greater individual adaptability. This provides stable, precise, and safe current output for tTIS, serving as a key technological support for achieving targeted modulation of deep brain regions.

[0003] In the field of electronic circuit technology, especially in circuit applications involving mid-frequency stimulation, the technical bottlenecks of existing protection circuits are becoming increasingly prominent. On the one hand, traditional circuit electrostatic discharge (ESD) protection designs mostly use passive protection components, such as varistors. However, these solutions are prone to generating parasitic capacitance in high-frequency signal transmission scenarios, leading to signal distortion. Moreover, their ESD discharge efficiency is limited, making them unable to meet the ever-increasing industrial demands for ESD standards. Especially in fields sensitive to ESD, such as semiconductor manufacturing and medical electronics, circuit failures caused by ESD breakdown occur frequently.

[0004] On the other hand, current output control circuits generally suffer from response delay issues. Existing circuits often rely on a simple combination of comparators and reference sources to identify output overcurrent or overvoltage. However, when transient spikes occur in the output signal, the sampling rate of traditional detection circuits is difficult to match, often leading to delayed protection actions and potentially causing serious medical accidents. Meanwhile, load detection technology remains at the level of simple current sampling or impedance matching judgment, unable to monitor dynamic changes in the load in real time. Under conditions such as load short circuits, open circuits, or nonlinear switching, there is a lack of effective early warning and protection mechanisms, severely restricting the reliability and intelligence level of the stimulation circuit system.

[0005] In summary, existing stimulation circuits have significant shortcomings in terms of penetration depth, spatial resolution, safety, and deep modulation. Furthermore, their protection circuit designs suffer from deficiencies in terms of the efficiency of electrostatic discharge protection, the real-time nature of output over-value identification, and the accuracy of load detection. Therefore, an integrated and intelligent stimulation protection circuit design is urgently needed to address these challenges. Summary of the Invention

[0006] In view of the above problems, a stimulation generation protection circuit for transcranial electrical stimulation is proposed to overcome or at least partially solve the above problems, comprising: The circuit includes an ESD protection circuit, a current switching detection circuit for electrical disconnection detection, and a constant current source stimulation generation circuit, among which: The ESD protection circuit consists of an input port, resistors, diodes, capacitors, and inductors, and is used to direct electrostatic charge to the ground terminal. The current switching detection circuit includes a relay, an operational amplifier, and an ADC acquisition chip, and is used for dual-loop switching and real-time current monitoring. The detection circuit is disconnected from the input and output sides via optocouplers and connected to GPIO ports to provide feedback on the load status. A constant current source stimulation generating circuit consists of a current source, a switching switch, a power supply, and an output port; it is used to generate a controllable stimulation current.

[0007] Optionally, the ESD protection circuit includes input port STMU1, input port STMU0, resistor R39, resistor R40, diode D12, diode D13, diode D14, diode D15, capacitor C45, capacitor C46, ​​inductor L3, inductor L4, output port BOOST_OUT, and ground terminal HVSS; wherein: Left side: Input port STMU1 is connected to one end of resistor R39, the anode of diode D12 is connected to the STMU1-R39 line, the cathode of diode D12 is connected to one end of capacitor C45 and one end of inductor L3, the other end of capacitor C45 is grounded to HVSS, the other end of inductor L3 is connected to the anode of diode D13, and the cathode of diode D13 is connected to output port BOOST_OUT. At the same time, output port BOOST_OUT also serves as the connection point of the protected circuit. Right side: Input port STMU0 is connected to one end of resistor R40, the anode of diode D14 is connected to the STMU0-R40 line, the cathode of diode D14 is connected to one end of capacitor C46 and one end of inductor L4, the other end of capacitor C46 is grounded to HVSS, the other end of inductor L4 is connected to the anode of diode D15, and the cathode of diode D15 is connected to output port BOOST_OUT; the right side and the left side together form a protective structure for the protected circuit.

[0008] Optionally, the current switching detection circuit includes a relay K2, an operational amplifier U22, an ADC acquisition chip U27, and an output interface U19, wherein: Relay section K2: Current output port STMU1_1 is connected to pin 3 of relay K2, switching interface STMU1_2 is connected to pin 2 of relay K2, switching interface STMU1_3 is connected to pin 4 of relay K2, and at the same time, current output port STMU1_1 is connected to pin 5 of operational amplifier U22, and diode D31 is connected in parallel with relay K2; Operational amplifier U22 section: Pin 4 of operational amplifier U22 is connected to one end of resistor (R45), pin 3 of operational amplifier U22 is connected to ADC_5V power supply, pin 2 of operational amplifier U22 is grounded, pin 1 of operational amplifier U22 is connected to REF_2V5 reference voltage, and pin 6 of operational amplifier U22 outputs the amplified signal. ADC acquisition chip U27 section: Pin 3 of ADC acquisition chip U27 is connected to voltage signal line OUT1, pin 4 is connected to voltage signal line OUT2, pin 5 is connected to voltage signal line OUT3, and pin 6 is connected to voltage signal line OUT4, used to acquire voltage signals respectively; pins 9 and 10 of ADC acquisition chip U27 are connected to the microcontroller via I2C bus; the VDD pin of ADC acquisition chip U27 is connected to the ADC_5V power supply, and the GND pin of ADC acquisition chip U27 is grounded; The output interface U19 is used to connect electrode pads to deliver current to the patient's body.

[0009] Optionally, the current switching detection circuit is also equipped with resistors R45, R49, R59, R62, R63, R64, R65, and R67 for voltage division, current limiting, and filtering of the circuit.

[0010] Optionally, in the current switching detection circuit, relay K2 is first switched to the non-patient circuit. After the current is confirmed to be normal by the ADC acquisition chip U27, relay K2 is then switched to the patient circuit. The switching control signal JDQ_1 of relay K2 is driven by transistor Q6.

[0011] Optionally, the disconnection detection circuit includes a current input section, a core detection section, and an output section, wherein: The current input section includes input port STMU0_1 and input port STMU0_2. Input port STMU0_1 and input port STMU0_2 are connected in series with a circuit consisting of resistor R28 and diode D8, wherein resistor R28 and diode D8 are connected in parallel. The core detection section includes optocoupler U13, which is connected to the current input section through pins 1 and 2. Pin 3 of optocoupler U13 is grounded to HVSS, and pin 4 of optocoupler U13 is connected to the power supply S5V through resistor R26. The output section includes pin 4 of optocoupler U13 connected to the GPIO15 port via resistor R29, and grounded in parallel with capacitor C30.

[0012] Optionally, the GPIO15 port is used to output the detected signal to an external processor. If the external processor detects that the rate of change of the level exceeds a predetermined threshold, it will trigger a power reduction output.

[0013] Optionally, the ground terminal HVSS of the ESD protection circuit and the ground terminal DVSS of the current switching detection circuit are isolated by a ferrite bead.

[0014] Optionally, the data packets transmitted to the microcontroller via the I2C bus include timestamps to correlate the timing relationship between current anomalies and load state changes.

[0015] Optionally, if the high-level output of the disconnection detection circuit lasts for a longer than a preset time, and / or the current switching detection circuit detects that the current value exceeds the safety threshold, the stimulation output will be cut off and an audible and visual alarm will be triggered.

[0016] This invention provides a stimulation generation protection circuit for transcranial electrical stimulation (TCS), comprising an ESD protection circuit, a current switching detection circuit, a disconnection detection circuit, and a constant current source stimulation generation circuit. The ESD protection circuit consists of an input port, resistors, diodes, capacitors, and inductors, used to guide electrostatic charge to the ground terminal. The current switching detection circuit includes a relay, an operational amplifier, and an ADC acquisition chip, used for dual-loop switching and real-time current monitoring. The disconnection detection circuit isolates the input and output sides via optocouplers and connects to a GPIO port to feedback the load status. The constant current source stimulation generation circuit consists of a current source, a switching switch, a power supply, and an output port, used to generate a controllable stimulation current. This circuit integrates an anti-static module to effectively suppress electrostatic damage to the circuit and ensure the normal operation of internal components. An output value recognition unit is designed to monitor the output signal in real time, accurately determine whether it exceeds a set value, and thus take timely protective measures. A load detection module is constructed to accurately sense the connection and operating status of the load. This achieves multiple protections for the circuit, improving its reliability, safety, and adaptability in complex working environments, and providing strong support for the stable operation of related electronic equipment. Attached Figure Description

[0017] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description of the present invention will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a circuit architecture diagram of a stimulation generation protection circuit for transcranial electrical stimulation provided in an embodiment of the present invention; Figure 2 This is a circuit diagram for stimulation generation protection of transcranial electrical stimulation provided in an embodiment of the present invention; Figure 3 This is a circuit diagram of a constant current source type stimulation generation circuit provided in an embodiment of the present invention. Detailed Implementation

[0019] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0020] Reference Figures 1 to 2 This illustration shows a system architecture and circuit diagram of a stimulation generation protection circuit for transcranial electrical stimulation provided by an embodiment of the present invention. This stimulation generation protection circuit can also be used for mid-frequency stimulation. This stimulation generation protection circuit is applicable to, but not limited to, four-channel stimulation electrodes for mouse cranial nerve stimulation, and can also be applied to eight-channel, sixteen-channel, and thirty-two-channel stimulation electrodes.

[0021] Specifically, the stimulus-generating protection circuit includes the following four circuits: The circuit includes an ESD protection circuit, a current switching detection circuit, a disconnection detection circuit, and a constant current source stimulation generation circuit, among which: The ESD protection circuit consists of an input port, resistors, diodes, capacitors, and inductors, and is used to direct electrostatic charge to the ground terminal. The current switching detection circuit includes a relay, an operational amplifier, and an ADC acquisition chip, and is used for dual-loop switching and real-time current monitoring. The detection circuit is disconnected from the input and output sides via optocouplers and connected to GPIO ports to provide feedback on the load status. A constant current source stimulation generating circuit consists of a current source, a switching switch, a power supply, and an output port; it is used to generate a controllable stimulation current.

[0022] Specifically, the ESD protection circuit may include input port STMU1, input port STMU0, resistor R39, resistor R40, diode D12, diode D13, diode D14, diode D15, capacitor C45, capacitor C46, ​​inductor L3, inductor L4, output port BOOST_OUT, and ground terminal HVSS.

[0023] In embodiments of the present invention, the aforementioned related electronic components can be connected in the following manner: Left side: Input port STMU1 is connected to one end of resistor R39. The anode of diode D12 is connected to the STMU1-R39 line. The cathode of diode D12 is connected to one end of capacitor C45 and one end of inductor L3. The other end of capacitor C45 is grounded to HVSS. The other end of inductor L3 is connected to the anode of diode D13. The cathode of diode D13 is connected to output port BOOST_OUT. Output port BOOST_OUT also serves as the connection point for the protected circuit.

[0024] Right side: Input port STMU0 is connected to one end of resistor R40, the anode of diode D14 is connected to the STMU0-R40 line, the cathode of diode D14 is connected to one end of capacitor C46 and one end of inductor L4, the other end of capacitor C46 is grounded to HVSS, the other end of inductor L4 is connected to the anode of diode D15, and the cathode of diode D15 is connected to output port BOOST_OUT; the right side and the left side together form a protective structure for the protected circuit.

[0025] In this embodiment of the invention, diodes D12 to D15 constitute the electrostatic discharge (ESD) protection front end. The core characteristic of these diodes is their unidirectional conductivity. Under normal circuit operation, the voltage applied across these diodes reverse-biasss them, thus presenting a high-impedance cutoff state. This cutoff state has almost no impact on the normal signal transmission path in the circuit, ensuring that signals can pass through this region with low loss and without distortion, maintaining the core function of the circuit.

[0026] However, when a sudden and high-energy ESD event occurs, the ESD pulse typically generates a spike far exceeding the normal operating voltage within a short period. At this time, the polarity or amplitude of the voltage applied to diodes D12-D15 changes, rapidly breaking down their reverse bias and causing the diodes to enter a low-impedance conducting state. Once conducting, they provide a low-impedance release path for the transient high-voltage, high-current electrostatic charge, guiding it to the designated ground terminal HVSS. This process is short-lived, effectively releasing the ESD before it penetrates and damages circuit components, thus achieving active protection for subsequent circuits.

[0027] To further enhance overall ESD robustness and suppress high-frequency transient interference, capacitors C45 and C46, ​​as well as inductors L3 and L4, are integrated into the circuit. The main function of capacitors C45 and C46 is to absorb and buffer the high-frequency transient energy contained in ESD pulses. Based on capacitor characteristics, when an ESD-induced voltage surge occurs, the capacitor absorbs current, temporarily storing some of the charge energy in its electric field. This smooths voltage spikes, reduces the rise rate and peak value of transient voltages, and mitigates the direct impact on subsequent circuitry.

[0028] Meanwhile, inductors L3 and L4, connected in series in the signal or power path, can suppress the rate of change of transient large currents caused by ESD events based on their inductance characteristics. When the current increases sharply, the inductors generate a back electromotive force to hinder the sudden change in current, limiting the peak value and rise rate of the current.

[0029] Through the synergistic effect of capacitors and inductors, transient high voltages and large currents generated by electrostatic discharge are effectively blocked, preventing them from entering subsequent circuits and protecting sensitive components from electrostatic damage, thus improving the equipment's tolerance to electrostatic environments. This reduces the impact of electrostatic interference on circuit signal transmission, ensuring the accuracy and stability of signal transmission and avoiding signal distortion and bit errors caused by electrostatic interference. It also reduces the impact and damage of electrostatic discharge on components, extending the lifespan of electronic components in the circuit and lowering the repair and replacement costs caused by component failure.

[0030] In an embodiment of the present invention, the current switching detection circuit may include a relay K2, an operational amplifier U22, an ADC acquisition chip U27, and an output interface U19, wherein: Relay section K2: The current output port STMU1_1 is connected to pin 3 of relay K2, the switching interface STMU1_2 is connected to pin 2 of relay K2, the switching interface STMU1_3 is connected to pin 4 of relay K2, and the current output port STMU1_1 is connected to pin 5 of operational amplifier U22 to provide one of the input signals for the operational amplifier. Diode D31 is connected in parallel with relay K2 to protect the circuit and prevent the back electromotive force generated when the relay is de-energized from damaging the circuit.

[0031] Operational amplifier U22 section: Pin 4 of operational amplifier U22 is connected to one end of resistor R45, pin 3 of operational amplifier U22 is connected to the ADC_5V power supply, pin 2 of operational amplifier U22 is grounded, pin 1 of operational amplifier U22 is connected to the REF_2V5 reference voltage, and pin 6 of operational amplifier U22 outputs the amplified signal to subsequent circuits, which can provide high-precision input. The ADC acquisition chip U27 section: Pin 3 of the ADC acquisition chip U27 is connected to voltage signal line OUT1, pin 4 is connected to voltage signal line OUT2, pin 5 is connected to voltage signal line OUT3, and pin 6 is connected to voltage signal line OUT4, used for acquiring voltage signals respectively; pins 9 and 10 of the ADC acquisition chip U27 are connected to the microcontroller via the I2C bus; the VDD pin of the ADC acquisition chip U27 is connected to the ADC_5V power supply, and the GND pin is grounded. The ADDR and ALERT / RDY pins can be connected accordingly based on the chip's function. The output interface U19 is used to connect electrode pads to deliver current to the patient's body.

[0032] In the current switching detection circuit, relay K2 can be switched to the non-patient circuit first. After the ADC acquisition chip U27 confirms that the current is normal, relay K2 can be switched to the patient circuit. This can effectively avoid the initial current surge. The switching control signal JDQ_1 of relay K2 is driven by transistor Q6.

[0033] It is understandable that the current switching detection circuit constructs a real-time current monitoring system through the efficient collaboration of the operational amplifier and the ADC acquisition chip: the operational amplifier accurately amplifies the voltage signal at the output terminal STMU1_1, and the ADC acquisition chip further converts the voltage into current data to achieve dynamic monitoring, which can promptly capture abnormal conditions such as overcurrent, undercurrent and transient spikes.

[0034] In an embodiment of the present invention, to improve the level of medical safety, relay K2 adopts a dual-circuit switching mechanism, that is, when the device is started, the current is first directed to the non-patient circuit. After the ADC chip confirms that the current value is within the preset safety threshold, it automatically switches to the patient treatment circuit to avoid the risk of initial current surge.

[0035] Furthermore, the ADC acquisition chip interacts with the microcontroller via the I2C bus. This protocol has the advantages of requiring fewer pins, strong anti-interference capability, and low transmission error rate, which simplifies the complexity of system integration.

[0036] In an embodiment of the present invention, the data packets transmitted to the microcontroller via the I2C bus may include timestamps to correlate the timing relationship between current anomalies and load state changes.

[0037] For example, if the timestamp shows that the load is disconnected (GPIO15 high level) before the current drops, it is determined that the electrode has been actively removed, and only a mild alarm is triggered; if the current drops before the load disconnection signal, it is determined that the wire is broken internally, triggering an emergency stop and marking a hardware fault code.

[0038] In an embodiment of the present invention, the current switching detection circuit is further provided with resistors R45, R49, R59, R62, R63, R64, R65, and R67 for voltage division, current limiting, and filtering of the circuit.

[0039] It is understandable that the resistors set in the circuit can form a composite noise barrier with the filter capacitors, suppressing common-mode interference and ripple noise, ensuring that high current monitoring accuracy can still be maintained in a strong electromagnetic environment, and meeting the core requirements of medical safety standards for current control.

[0040] In an embodiment of the present invention, the disconnection detection circuit includes a current input section, a core detection section, and an output section, wherein: The current input section includes input ports STMU0_1 and STMU0_2. Input ports STMU0_1 and STMU0_2 are connected in series with a circuit consisting of resistor R28 and diode D8, while resistor R28 and diode D8 are connected in parallel. This connection method can be understood to provide certain protection and preprocessing for the input signal. Resistor R28 acts as a current limiter, and diode D8 can be used to prevent reverse signal flow.

[0041] The core detection section includes optocoupler U13. Optocoupler U13 is connected to the current input section via pins 1 and 2, pin 3 of optocoupler U13 is grounded (HVSS), and pin 4 of optocoupler U13 is connected to the power supply S5V via resistor R26 to provide the operating voltage for the optocoupler. It can be understood that optocoupler U13 serves the functions of electrical isolation and signal transmission, coupling the input signal to the output side via optical signal.

[0042] The output section includes pin 4 of optocoupler U13 connected to the GPIO15 port via resistor R29, and grounded in parallel with capacitor C30. Capacitor C30 acts as a filter to stabilize the output signal, while resistor R29 serves for current limiting and signal matching. The GPIO15 port can output the detected signal to external control units or processors for further judgment and processing.

[0043] For example, the GPIO15 port can output the detected signal to an external processor, and trigger a power reduction output when the external processor detects that the rate of level change exceeds a predetermined threshold.

[0044] In practical applications, when the electrode pads become partially detached due to patient movement, the GPIO15 port detects a rate of level change exceeding a predetermined threshold. The processor determines this as "progressive detachment" and then linearly reduces the stimulation power from 80mA to 25mA over three pulse cycles (exemplary). An orange warning message "Electrode contact unstable" pops up on the device screen, and the power is automatically recharged after contact is restored. This process ensures treatment continuity and avoids the risk of treatment interruption caused by traditional emergency stop procedures.

[0045] Understandably, the input drive current of optocoupler U13 changes dynamically with the load impedance, and the output conduction state corresponds to the load state: when the load is normal, the optocoupler is on, and the GPIO15 port outputs a low level; when the load is disconnected, the optocoupler is off, and the GPIO15 port outputs a high level; when the load is short-circuited, the optocoupler is saturated, the GPIO15 port outputs a low level, and the current exceeds the threshold. This enables real-time monitoring of dynamic load changes.

[0046] The disconnection detection circuit uses optocoupler U13 to achieve electrical isolation between the input and output sides, effectively blocking the influence of electrical interference and overvoltage on the output circuit and equipment, significantly improving the stability and reliability of the circuit, and is especially suitable for applications with high electrical safety requirements. At the same time, through the reasonable design of components such as resistors and diodes, the circuit can sensitively detect changes in the input signal, thereby timely and accurately determining whether a disconnection has occurred. In addition, the setting of capacitor C30 and the optimized overall circuit layout give the circuit good anti-interference ability, ensuring that it can work stably even in complex electromagnetic environments, effectively reducing the probability of false detection.

[0047] In embodiments of the present invention, when the high-level output of the disconnection detection circuit lasts for a longer than a preset time, and / or the current switching detection circuit detects that the current value exceeds the safety threshold, the stimulation output can be cut off and an audible and visual alarm can be triggered, thereby further preventing the occurrence of medical accidents.

[0048] In addition, the ground terminal HVSS of the ESD protection circuit and the ground terminal DVSS of the current switching detection circuit are isolated by a ferrite bead.

[0049] It is understandable that ferrite beads exhibit near-zero impedance to DC and low-frequency signals, ensuring potential balance between two locations and maintaining circuit reference stability; simultaneously, they exhibit high impedance to high-frequency noise, effectively blocking interference propagation into the circuit. This allows for the coordinated achievement of electrostatic energy release and signal detection accuracy on a single PCB, significantly improving the safety and reliability of medical devices in complex electromagnetic environments.

[0050] like Figure 3 As shown, this embodiment of the invention also provides a constant current source type stimulation generating circuit.

[0051] The constant current source type stimulation generating circuit can be used to generate controllable stimulation current, and can output stimulation current corresponding to a voltage of up to 45V. Its core consists of current sources U29 and U30 (built-in 8-bit DAC), switching switches SW2-SW5, power supply and output ports VDD, VSS, STMU0, and STMU1.

[0052] Specifically, U29 and U30 are core components of constant current sources with integrated DACs. The current source has a built-in 8-bit DAC that converts digital control signals into analog control quantities, thereby changing the output current of the current source. Based on the 8-bit DAC, it can achieve 255 output levels. Combined with circuit configuration, this results in 8 step values, with a base step of 33μA (33μA, 66μA, 99μA, 132μA, 165μA, 198μA, 231μA, 264μA), achieving a maximum stimulation output of 264*255=67320μA. The output waveforms include, but are not limited to, rectangular waves, triangular waves, and sine waves. Combined with multi-channel output stimulation, it can achieve transcranial time-interference stimulation, meeting the stimulation current accuracy requirements of various scenarios while also satisfying the stimulation needs of different situations. Switches SW2 and SW3 are connected in series in the branches of U29, U30 and the intermediate output node (connecting STMU1 and STMU0), respectively; switches SW4 and SW5 are connected in series in the branches of the intermediate output node and VSS (ground), respectively. VDD provides the operating voltage for the circuit, supporting the output requirements of up to 45V, while VSS serves as the ground potential reference, forming the potential reference for the current loop.

[0053] Furthermore, the built-in 8-bit DAC constant current source enables small-step (based on 33μA) and multi-level (255 levels) current adjustment, allowing for precise stimulation of cells / tissues in bioelectrical stimulation and ensuring treatment accuracy. The digitally controlled DAC adapts to various digital signal input scenarios and can flexibly respond to different treatment commands. The switching network consisting of SW2-SW5 allows for diverse configuration capabilities of the current path. It supports both conventional single-channel constant current output mode and complex circuit designs through switch combinations.

[0054] It should be noted that the stimulation generation protection circuit for transcranial electrical stimulation provided in this embodiment of the invention may include, but is not limited to, four circuit channels: ESD protection circuit, current switching detection circuit, disconnection detection circuit, and constant current source stimulation generation circuit. Those skilled in the art may add other circuit channels based on actual needs.

[0055] This invention provides a stimulation generation protection circuit for transcranial electrical stimulation (TCS), comprising an ESD protection circuit, a current switching detection circuit, a disconnection detection circuit, and a constant current source stimulation generation circuit. The ESD protection circuit consists of an input port, resistors, diodes, capacitors, and inductors, used to guide electrostatic charge to the ground terminal. The current switching detection circuit includes a relay, an operational amplifier, and an ADC acquisition chip, used for dual-loop switching and real-time current monitoring. The disconnection detection circuit isolates the input and output sides via optocouplers and connects to a GPIO port to feedback the load status. The constant current source stimulation generation circuit consists of a current source, a switching switch, a power supply, and an output port, used to generate a controllable stimulation current. This circuit integrates an anti-static module to effectively suppress electrostatic damage to the circuit and ensure the normal operation of internal components. An output value recognition unit is designed to monitor the output signal in real time, accurately determine whether it exceeds a set value, and thus take timely protective measures. A load detection module is constructed to accurately sense the connection and operating status of the load. This achieves multiple protections for the circuit, improving its reliability, safety, and adaptability in complex working environments, and providing strong support for the stable operation of related electronic equipment.

[0056] The above provides a detailed description of a stimulation generation protection circuit for transcranial electrical stimulation. Specific examples have been used to illustrate the principle and implementation of the invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the invention. Therefore, the content of this specification should not be construed as a limitation of the invention.

Claims

1. A stimulation generation protection circuit for transcranial electrical stimulation, characterized in that, include: The circuit includes an ESD protection circuit, a current switching detection circuit, a disconnection detection circuit, and a constant current source stimulation generation circuit, among which: The ESD protection circuit consists of an input port, resistors, diodes, capacitors, and inductors, and is used to guide electrostatic charge to the ground terminal. The current switching detection circuit includes a relay, an operational amplifier, and an ADC acquisition chip, used for dual-loop switching and real-time current monitoring. Among them, pins 9 and 10 of the ADC acquisition chip U27 are connected to the microcontroller via an I2C bus, and the data packets transmitted to the microcontroller via the I2C bus contain timestamps, which are used to correlate the timing relationship between current anomalies and load state changes. The disconnection detection circuit isolates the input and output sides through optocouplers and connects to the GPIO15 port to feedback the load status; The constant current source type stimulation generating circuit consists of a current source, a switching switch, a power supply, and an output port; it is used to generate a controllable stimulation current. In the current switching detection circuit, relay K2 is first switched to the non-patient circuit. After the current is confirmed to be normal by the ADC acquisition chip U27, relay K2 is then switched to the patient circuit. The switching control signal JDQ_1 of relay K2 is driven by transistor Q6. The GPIO15 port is used to output the detected signal to an external processor. When the external processor detects that the rate of change of the level exceeds a predetermined threshold, it triggers the constant current source stimulation circuit to reduce the power output.

2. The stimulation generation protection circuit for transcranial electrical stimulation according to claim 1, characterized in that, The ESD protection circuit includes input port STMU1, input port STMU0, resistor R39, resistor R40, diode D12, diode D13, diode D14, diode D15, capacitor C45, capacitor C46, ​​inductor L3, inductor L4, output port BOOST_OUT, and ground terminal HVSS; wherein: Left side: Input port STMU1 is connected to one end of resistor R39, the anode of diode D12 is connected to the STMU1-R39 line, the cathode of diode D12 is connected to one end of capacitor C45 and one end of inductor L3, the other end of capacitor C45 is connected to ground terminal HVSS, the other end of inductor L3 is connected to the anode of diode D13, and the cathode of diode D13 is connected to output port BOOST_OUT. At the same time, output port BOOST_OUT also serves as the connection point of the protected circuit. Right side: Input port STMU0 is connected to one end of resistor R40, the anode of diode D14 is connected to the STMU0-R40 line, the cathode of diode D14 is connected to one end of capacitor C46 and one end of inductor L4, the other end of capacitor C46 is connected to ground terminal HVSS, the other end of inductor L4 is connected to the anode of diode D15, and the cathode of diode D15 is connected to output port BOOST_OUT; the right side and the left side together constitute the protection structure for the protected circuit.

3. The stimulation generation protection circuit for transcranial electrical stimulation according to claim 2, characterized in that, The current switching detection circuit includes a relay K2, an operational amplifier U22, an ADC acquisition chip U27, and an output interface U19, wherein: Relay section K2: Current output port STMU1_1 is connected to pin 3 of relay K2, switching interface STMU1_2 is connected to pin 2 of relay K2, switching interface STMU1_3 is connected to pin 4 of relay K2, and at the same time, current output port STMU1_1 is connected to pin 5 of operational amplifier U22, and diode D31 is connected in parallel with relay K2; Operational amplifier U22 section: Pin 4 of operational amplifier U22 is connected to one end of resistor R45, pin 3 of operational amplifier U22 is connected to ADC_5V power supply, pin 2 of operational amplifier U22 is grounded, pin 1 of operational amplifier U22 is connected to REF_2V5 reference voltage, and pin 6 of operational amplifier U22 outputs the amplified signal. ADC acquisition chip U27 section: Pin 3 of ADC acquisition chip U27 is connected to voltage signal line OUT1, pin 4 is connected to voltage signal line OUT2, pin 5 is connected to voltage signal line OUT3, and pin 6 is connected to voltage signal line OUT4, used to acquire voltage signals respectively; the VDD pin of ADC acquisition chip U27 is connected to the ADC_5V power supply, and the GND pin of ADC acquisition chip U27 is grounded; The output interface U19 is used to connect electrode pads to deliver current to the patient's body.

4. The stimulation generation protection circuit for transcranial electrical stimulation according to claim 3, characterized in that, The current switching detection circuit is also equipped with resistors R45, R49, R59, R62, R63, R64, R65, and R67 for voltage division, current limiting, and filtering.

5. A stimulation generation protection circuit for transcranial electrical stimulation according to claim 4, characterized in that, The disconnection detection circuit includes a current input section, a core detection section, and an output section, wherein: The current input section includes input port STMU0_1 and input port STMU0_2. Input port STMU0_1 and input port STMU0_2 are connected in series with a circuit consisting of resistor R28 and diode D8, wherein resistor R28 and diode D8 are connected in parallel. The core detection part includes an optocoupler U13, which is connected to the current input part through pin 1 and pin 2. Pin 3 of the optocoupler U13 is grounded, and pin 4 of the optocoupler U13 is connected to the power supply S5V through resistor R26. The output section includes pin 4 of the optocoupler U13, which is connected to the GPIO15 port via resistor R29, and grounded in parallel with capacitor C30.

6. A stimulation generation protection circuit for transcranial electrical stimulation according to claim 5, characterized in that, The ground terminal HVSS of the ESD protection circuit is isolated from the ground terminal DVSS of the current switching detection circuit by a ferrite bead.

7. A stimulation generation protection circuit for transcranial electrical stimulation according to claim 1 or 6, characterized in that, If the high-level output of the disconnection detection circuit lasts for a longer than a preset time, and / or the current switching detection circuit detects that the current value exceeds the safety threshold, the stimulation output is cut off and an audible and visual alarm is triggered.

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