Stimulation current error measuring device for implantable nerve stimulator
By using a multi-channel current source and a hysteresis comparator to directly monitor the stimulation current error in an implantable neurostimulator, the problems of measurement accuracy and power consumption in the prior art are solved, achieving low-power, high-efficiency current error monitoring, and improving treatment efficacy and safety.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BEIJING LEADING INNOVATION MEDICAL VALLEY CO LTD
- Filing Date
- 2026-02-26
- Publication Date
- 2026-05-01
AI Technical Summary
Existing methods for measuring the stimulation current of implantable neurostimulators cannot simultaneously meet the requirements of measurement accuracy, simplification, and low power consumption, resulting in large measurement errors and high power consumption, which affects the treatment effect and safety.
By adding multiple identical stimulation current sources and setting multiple sets of resistors with different fixed errors, a hysteresis comparator is used to compare the actual stimulation voltage with the fixed error stimulation voltage, directly monitoring the relative error range of the stimulation current, thus eliminating the need for an analog-to-digital converter and subsequent calculation steps.
It achieves low-power, simple and efficient stimulation current error monitoring, reduces chip power consumption, extends usage time, and improves the effectiveness and safety of treatment.
Smart Images
Figure CN121955487A_ABST
Abstract
Description
Stimulation current error measurement device for implantable neurostimulators Technical Field
[0001] This invention relates to the field of performance testing technology for implantable neurostimulator systems, and more specifically to a device for measuring the stimulation current error of implantable neurostimulators. Background Technology
[0002] Implantable neurostimulation systems, comprising an external programmer and an implantable neurostimulator, have been widely used in the medical field, providing effective solutions for the treatment of diseases such as chronic pain. The external programmer and the implantable neurostimulator achieve bidirectional interaction through antenna radio frequency coupling: on one hand, the external programmer transmits energy to the implantable neurostimulator to ensure its stable operation, while simultaneously sending key stimulation parameters such as stimulation frequency and amplitude; on the other hand, the implantable neurostimulator transmits electrical signals to the spinal cord through implanted electrodes based on the received parameters, and provides real-time feedback of its own operating status data to the external programmer, enabling regulation of the stimulation current and ensuring therapeutic efficacy and clinical safety. Therefore, the measurement of the stimulation current must simultaneously meet the requirements of high efficiency and accuracy, providing reliable data support for timely parameter adjustments.
[0003] In existing stimulation current measurement technology, the stimulation current is mainly converted into an acquireable voltage signal by sampling resistor. This voltage signal is then acquired and transmitted to the next stage analog-to-digital converter (ADC). The ADC converts the signal to obtain the corresponding digital code value, which is then transmitted wirelessly to an external programmer. Finally, the actual stimulation current value is obtained through external data processing.
[0004] However, existing methods for measuring stimulation current still have many technical shortcomings that urgently need to be addressed in practical clinical applications. These shortcomings manifest in the following ways: First, measurement accuracy is easily affected by various factors, leading to deviations in the measurement results. In implantable scenarios, the inherent characteristics of the chip manufacturing process, circuit noise, fluctuations in the body's ambient temperature, dynamic changes in the impedance of the implanted electrodes, and interference from biological neural electrical signals and external electromagnetic interference all affect the stimulation current, resulting in a relative error between the measurement result obtained from the ADC conversion and the target stimulation current. Furthermore, the measured stimulation current value cannot directly quantify this relative error, requiring additional subsequent processing, significantly increasing the complexity of the measurement process and data processing costs. Second, power consumption and heat dissipation are significant issues. During the chip's release of the stimulation current, the stimulation current operates in multiple modes, and the switching between these modes causes dynamic changes in the voltage domain corresponding to the stimulation current, further exacerbating the deviation between the stimulation current and the target value. To compensate for this deficiency, multiple acquisition and conversion operations are required through the ADC to improve the accuracy of the measurement results. However, multiple acquisition and conversion operations will significantly increase the system power consumption and generate more heat dissipation. Since implantable neurostimulators need to be implanted in the body for a long time, excessive power consumption will shorten their battery life. Frequent device replacement will increase patient suffering and medical costs, and the accumulation of excess heat may damage the surrounding normal tissues, bringing additional clinical safety risks.
[0005] In summary, existing methods for measuring the stimulation current of implantable neurostimulators cannot simultaneously meet the requirements of measurement accuracy, simplification, and low power consumption. They cannot fully meet the clinical application needs for efficient and accurate measurement of stimulation current, thus hindering further improvements in the therapeutic efficacy and safety of implantable neurostimulator systems. Therefore, there is an urgent need to propose a stimulation current measurement scheme that can overcome the above-mentioned technical deficiencies.
[0006] The above description of the background technology is only for the purpose of facilitating a deeper understanding of the technical solution of the present invention (the technical means used, the technical problems solved, and the technical effects produced, etc.), and should not be regarded as an admission or in any form an implication that the information constitutes prior art known to those skilled in the art. Summary of the Invention
[0007] This invention aims to provide a device for measuring the stimulation current error of implantable neurostimulators. It obtains different fixed-error stimulation voltages by adding multiple identical stimulation current sources and setting multiple sets of resistors with different fixed errors. These fixed-error stimulation voltages with different gradients are connected to a multiplexer. A hysteresis comparator compares the actual stimulation voltage with the different fixed-error stimulation voltages. The relative error range of the actual stimulation current can be determined by the high and low level output of the hysteresis comparator, enabling rapid real-time monitoring of the stimulation current and quantifying the error range of the stimulation current.
[0008] According to an embodiment of the present invention, a stimulation current error measurement device for an implantable neurostimulator is provided, comprising: an actual stimulation voltage generation module configured to generate sampled values of the actual stimulation voltage of the stimulation electrode; a stimulation error voltage generation module configured to generate a plurality of preset stimulation error voltage thresholds; a stimulation voltage error comparison module electrically connected to the stimulation voltage error generation module and the actual stimulation voltage generation module, the stimulation voltage error comparison module being configured to receive the sampled values of the actual stimulation voltage and the plurality of preset stimulation error voltage thresholds, compare the actual stimulation voltage with one or more of the plurality of preset stimulation error voltage thresholds, and generate a comparison result; and a control module electrically connected to the stimulation voltage error comparison module, the control module being configured to determine the relative error of the actual stimulation current based on the comparison result.
[0009] Preferably, the actual stimulation voltage generation module includes a variable stimulation current source circuit and an H-bridge module, with the variable stimulation current source circuit electrically connected to the H-bridge module; the H-bridge module includes multiple switches and a power supply voltage HVDD, is electrically connected to the stimulation electrode, and outputs the actual stimulation current of the stimulation electrode; the variable stimulation current source circuit includes a digital-to-analog converter (DAC), a first operational amplifier (A1), and a power transistor (MN). B and resistance R B It also outputs the sampled value of the actual stimulation voltage of the stimulation electrode.
[0010] Preferably, the input terminal of the digital-to-analog converter (DAC) receives an external digital signal; the output terminal of the DAC is electrically connected to the positive input terminal of the first operational amplifier A1; the output terminal of the first operational amplifier A1 is connected to the power transistor MN. B The gate electrical connection; power transistor MN B The drain of the power transistor MN is electrically connected to the output of the H-bridge module; B The source of is electrically connected to the negative input terminal of the first operational amplifier A1; resistor R B The first terminal is connected to the power transistor MN B Source electrical connection; resistor R B The second end is grounded.
[0011] Preferably, the stimulation error voltage generation module includes a reference current source circuit, a power supply voltage VDDA, and a multi-channel current source circuit; the reference current source circuit and the multi-channel current source circuit are electrically connected to the power supply voltage VDDA; the reference current source circuit includes a second operational amplifier A2 and a reference power transistor MN. C and reference resistor R C And generate a reference current I ref ;Multi-channel current source circuit generates and references current I ref The same current is used, and multiple preset stimulation error voltage thresholds are output.
[0012] Preferably, the positive input terminal of the second operational amplifier A2 is electrically connected to the output terminal of the digital-to-analog converter (DAC); the output terminal of the second operational amplifier A2 is connected to the reference power transistor MN. C Gate electrical connection; reference power transistor MN C The drain of the reference power transistor MN is electrically connected to the power supply voltage VDDA. C The source of the amplifier is electrically connected to the negative input terminal of the second operational amplifier A2; the reference resistor R C The first terminal is connected to the reference power transistor MN C The source electrical connection; the reference resistor R C The second end is grounded.
[0013] Preferably, the multi-current source circuit may include multiple switches S0 to S10. n-1 Multiple power transistors MN0 to MN n-1 and multiple resistors R C0 To R C(n-1) The sources of the power transistors in each current source circuit are electrically connected together; the drains of the power transistors in each current source circuit are electrically connected to the first terminal of their respective switches; the second terminal of the switches in each current source circuit is electrically connected to the power supply voltage VDDA; the sources of the power transistors in each current source circuit are electrically connected to the first terminal of their respective resistors; the second terminal of the resistors in each current source circuit is grounded.
[0014] Preferably, the plurality of resistors R C0 To R C(n-1) Set to the reference resistor R C It has the following relationship: R Ck = (1 ± x%) × R C Where k is an integer between 0 and n-1, n is the number of branches in the multi-current source circuit, and x% represents the deviation coefficient for multiple resistors R C0 To R C(n-1) x% is set to a step-by-step progression, with x% ranging from 1% to 10%.
[0015] Preferably, the stimulation voltage error comparison module includes a multiplexer MUX and a comparator A. The output terminal of the stimulation error voltage generation module is electrically connected to multiple input terminals of the multiplexer MUX, respectively. The output terminal of the multiplexer MUX is electrically connected to the negative input terminal of the comparator A. The output terminal of the actual stimulation voltage generation module is electrically connected to the positive input terminal of the comparator A. The output terminal of the comparator A is electrically connected to the control module.
[0016] Preferably, the control module is configured to: determine that the error of the actual stimulation current exceeds the corresponding deviation coefficient when the comparison result of the comparator is high; and determine that the error of the actual stimulation current is within the corresponding deviation coefficient when the comparison result of the comparator is low.
[0017] The present invention adopts the above technical solution, which has the following beneficial effects: 1. Power consumption optimization: By directly comparing the preset stimulation error voltage threshold with the actual stimulation voltage through the hysteresis comparator, the analog-to-digital converter and subsequent calculation links are eliminated, which greatly reduces the chip power consumption, extends the chip usage time, and reduces chip heat dissipation; during the non-measurement stage, the newly added multiple current paths can be turned off by the switch, without additional current consumption, further reducing power consumption.
[0018] 2. High efficiency and simple circuit: The actual stimulation current error can be measured by relying on multi-branch current mirrors, multiplexers and hysteresis comparators. The circuit structure is simple, efficient and has strong versatility.
[0019] 3. Precise monitoring and control: The relative error of the stimulation current can be monitored in real time during the chip-based electrical stimulation process. Based on the monitoring results, the stimulation current can be externally adjusted, effectively improving the effectiveness and safety of the implantable neurostimulator. Attached Figure Description
[0020] The exemplary embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. For clarity, the same components in different drawings are shown with the same reference numerals. It should be noted that the drawings are for illustrative purposes only and are not necessarily drawn to scale. In these drawings: FIG1 is a circuit diagram of a current measurement method according to the prior art.
[0021] Figure 2 is a block diagram of a stimulation current error measurement device for an implantable neurostimulator according to an embodiment of the present invention.
[0022] Figure 3 is a circuit diagram of the actual stimulation voltage generation module of the stimulation current error measurement device for an implantable neurostimulator according to an embodiment of the present invention.
[0023] Figure 4 is a circuit diagram of the stimulation error voltage generation module of the stimulation current error measurement device for an implantable neurostimulator according to an embodiment of the present invention.
[0024] Figure 5 is a circuit diagram of the stimulation voltage error comparison module of the stimulation current error measurement device for an implantable neurostimulator according to an embodiment of the present invention. Detailed Implementation
[0025] The following is a detailed description of the embodiments of the present invention. These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments.
[0026] In the following, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0027] Figure 1 is a circuit diagram of a current measurement method according to the prior art. As shown in Figure 1, it consists of a digital-to-analog converter (DAC), an operational amplifier A0, and a power transistor MN. A and sampling resistor R A Together they form a variable current source circuit.
[0028] The DAC receives an external digital signal V. in [N-1:0] (N is the number of bits in the DAC) and is controlled by it, serving as the control reference for the current source. Operational amplifier A0 forms a negative feedback loop to ensure that power transistor MN... A Source voltage V A Track the output voltage of the DAC ("virtual short" characteristic). Power transistor MN A The gate voltage V is controlled by the output of operational amplifier A0. A Acting on resistor R A According to Ohm's law, a corresponding current is generated, thereby achieving precise control of the output current through the DAC input code value.
[0029] The current measurement process is as follows: through the sampling resistor R A Voltage V across the terminals A The sampled voltage V A The signal is transmitted to an analog-to-digital converter (ADC); the ADC processes the input voltage signal and outputs a digital code value V. out [M-1:0] (M is the number of bits in the ADC), and the current value can be derived from this digital code value through subsequent calculations.
[0030] Figure 2 is a block diagram of a stimulation current error measurement device for an implantable neurostimulator according to an embodiment of the present invention. Referring to Figure 2, the stimulation current error measurement device for an implantable neurostimulator according to an embodiment of the present invention may include: an actual stimulation voltage generation module 100, a stimulation error voltage generation module 200, a stimulation voltage error comparison module 300, and a control module 400. The actual stimulation voltage generation module 100 may be electrically connected to the stimulation voltage error comparison module 300, the stimulation error voltage generation module 200 may be electrically connected to the stimulation voltage error comparison module 300, and the stimulation voltage error comparison module 300 may also be electrically connected to the control module 400.
[0031] The actual stimulation voltage generation module 100 can be configured to generate a sampled value of the actual stimulation voltage of the stimulation electrode; the stimulation error voltage generation module 200 can be configured to generate multiple preset stimulation error voltage thresholds; the stimulation voltage error comparison module 300 can be configured to receive the sampled value of the actual stimulation voltage and multiple preset stimulation error voltage thresholds, compare the sampled value of the actual stimulation voltage with one or more of the multiple preset stimulation error voltage thresholds, and generate a comparison result; the control module 400 can be configured to determine the relative error of the actual stimulation current based on the comparison result.
[0032] The following describes in detail the various modules of the stimulation current error measurement device for an implantable neurostimulator according to an embodiment of the present invention.
[0033] Figure 3 is a circuit diagram of the actual stimulation voltage generation module of the stimulation current error measurement device for an implantable neurostimulator according to an embodiment of the present invention. As shown in Figure 3, the actual stimulation voltage generation module of the stimulation current error measurement device for an implantable neurostimulator may include a variable stimulation current source circuit and an H-bridge module. The variable stimulation current source circuit may be electrically connected to the H-bridge module, and the H-bridge module may be electrically connected to the stimulation electrode.
[0034] The H-bridge module can output the actual stimulation current I of the stimulation electrode. real The H-bridge module may include a switch S H0 To S H3 By controlling four switches S H0 To S H3 The on / off state of the resistor is used to switch the output polarity of the stimulation current, enabling bidirectional stimulation current from electrode 1 to electrode 2 or from electrode 2 to electrode 1. Resistor R H0 and resistance R H1 and capacitor C H0This is the equivalent circuit representation of the electrode model, used to simulate the capacitive and resistive characteristics of biological tissue. Excitation is applied to the biological tissue via the electrodes, and the response current is detected. The power supply voltage HVDD is powered by a battery or external wireless radio frequency, providing independent voltages for the H-bridge module and the stimulation electrodes, while avoiding power interference with other modules of the device.
[0035] The variable stimulation current source circuit may include a digital-to-analog converter (DAC), an operational amplifier (A1), and a power transistor (MN). B and resistance R B It outputs the actual stimulation voltage of the stimulation electrode. The digital-to-analog converter (DAC) can receive external digital signals V. in [N-1:0] (N is the number of bits in the DAC) and is controlled by it, serving as the control reference for the current source. Specifically, the output of the digital-to-analog converter (DAC) can be electrically connected to the positive input of operational amplifier A1, and the output of operational amplifier A1 can be connected to the power transistor MN. B The gate electrical connection of the power transistor MN B The drain of the transistor can be electrically connected to the output of the H-bridge module, and the power transistor MN... B The source of the resistor can be electrically connected to the negative input terminal of operational amplifier A1, and the resistor R B The first terminal can be connected to the power transistor MN B The source is electrically connected, and the resistor R is... B The second terminal can be grounded. In this example, the power transistor MN B This is an N-channel enhancement-mode MOSFET; it is just one example, but it could also be a PMOS transistor, etc.
[0036] In practical applications, attenuation / interference of RF power supply and transient noise from switching in the H-bridge module can cause HVDD voltage fluctuations, which in turn affect the actual stimulation current I. real If the value deviates from the target value, this fluctuation will be reflected synchronously in the sampled value V of the actual stimulation voltage. B Therefore, it is necessary to sample the actual stimulation voltage V. B Multiple data acquisitions and conversions, along with data processing (such as mean filtering) to offset random fluctuations, are necessary to obtain more accurate actual stimulation current values.
[0037] According to an embodiment of the present invention, the stimulation current error measurement device for an implantable neurostimulator does not perform analog-to-digital converter conversion after acquiring the voltage value of the stimulation current. Instead, it adds multiple identical stimulation current sources and sets multiple sets of resistors with different fixed errors by changing the resistance values, thereby obtaining corresponding different fixed error stimulation voltages. Then, these fixed error stimulation voltages with different gradients are connected to a multiplexer, and the actual stimulation voltage is compared with the different fixed error stimulation voltages in a comparator. The relative error range of the actual stimulation current can be obtained through the high and low level results output by the comparator, thereby realizing rapid real-time monitoring of the stimulation current and quantifying the error range of the stimulation current. This avoids excessive current consumption during the measurement of the stimulation current, reduces the power consumption of the chip, and allows for real-time dynamic adjustment of the stimulation current based on the comparator output results.
[0038] Figure 4 is a circuit diagram of the stimulation error voltage generation module of the stimulation current error measurement device for an implantable neurostimulator according to an embodiment of the present invention. The stimulation error voltage generation module of the stimulation current error measurement device for an implantable neurostimulator may include a reference current source circuit, a multi-channel current source circuit, and a power supply voltage VDDA.
[0039] As shown in Figure 4, the reference current source circuit may include a second operational amplifier A2 and a reference power transistor MN. C and reference resistor R C The reference current source circuit reuses the reference voltage V output from the digital-to-analog converter (DAC) of the front-end actual stimulus voltage generation module. ref This is used as input to drive the second operational amplifier A2. The output of the digital-to-analog converter (DAC) can be electrically connected to the positive input of the second operational amplifier A2, and the output of the second operational amplifier A2 can be connected to the reference power transistor MN. C The gate electrical connection of the reference power transistor MN C The drain of the reference power transistor MN can be electrically connected to the power supply voltage VDDA. C The source of the resistor can be electrically connected to the negative input terminal of operational amplifier A1. Reference resistor R C The first terminal can be connected to the reference power transistor MN C The source electrical connection, reference resistor R C The second end can be grounded.
[0040] A multi-current source circuit may include multiple switches (first switch S0, second switch S1, ..., n-1th switch S...). n-1 Multiple power transistors (first power transistor MN0, second power transistor MN1, ..., n-1th power transistor MN) n-1 ) and multiple resistors (first resistor R) C0 First resistor RC1 ..., First resistor R C(n-1) That is, the first current source circuit may include a first switch S0, a first power transistor MN0, and a first resistor R. C0 The second current source circuit may include a second switch S1, a second power transistor MN1, and a second resistor R. C1 ... The sources of the power transistors in each current source circuit can be electrically connected together. The drains of the power transistors in each current source circuit can be electrically connected to the first terminal of the switch in that current source circuit. The second terminal of the switch in each current source circuit is electrically connected to the power supply voltage VDDA. The sources of the power transistors in each current source circuit can be electrically connected to the first terminal of the resistor in that current source circuit. The second terminal of the resistor in each current source circuit is grounded.
[0041] Reference power transistor MN C and power transistors in multiple current sources (first power transistor MN0, second power transistor MN1, ..., n-1th power transistor MN) n-1 () can be an N-channel enhancement-mode MOSFET, which is just an example; they can also be PMOS transistors, etc.
[0042] To avoid interference from power fluctuations on current accuracy, the power supply VDDA uses a low-voltage constant voltage source generated by a low-dropout linear regulator (LDO) inside the implanted neurostimulator.
[0043] The second operational amplifier A2 uses a negative feedback mechanism to ensure that the resistor R C The voltage across the terminals is equal to V ref This generates a reference current. .
[0044] The circuit employs a multi-channel current mirror replication architecture, with the reference power transistor MN... C With multiple power transistors MN0 to MN connected in parallel n-1 It forms a mirror structure that can replicate the reference current I. ref It outputs multiple identical and highly consistent replica currents. To meet the basic requirements of multi-threshold configuration, the number of branches n must satisfy n≥2. Its upper limit is limited by chip area and power consumption budget, and is usually implemented in the range of 8 to 16 branches, but this invention is not limited to this.
[0045] To generate differentiated fixed error threshold voltage V E0 To V E(n-1) Each branch is equipped with a differentiated resistor R. C0 To R C(n-1) Multiple resistors R C0 To R C(n-1) It can be set to be the same as the reference resistor R C It has the following relationship: R Ck= (1 ± x%)R C .
[0046] Where k is an integer between 0 and n-1, and x% represents the deviation coefficient, for multiple resistors R C0 To R C(n-1) x% is set to a step-by-step progression, with x% ranging from 1% to 10%.
[0047] According to an embodiment of the present invention, multiple resistors R C0 To R C(n-1) The resistance values are (1 ± a%)R C (1 ± b%)R C (1 ± c%)R C (1 ± d%)R C ..., where the deviation coefficients a%, b%, c%, d%, etc. can be set to progressively increase from 1% to 10% in a stepwise manner, but the present invention is not limited thereto. The deviation coefficients a%, b%, c%, d%, etc. can maintain a reasonable interval between each other (e.g., arithmetic or geometric distribution) to ensure that each threshold voltage has clear distinguishability and meets the requirements for error grading.
[0048] By setting different resistance values, different fixed error threshold voltages V can be obtained. E0 To V E(n-1) Accordingly, according to (0≤k≤n-1) The error threshold voltage V was obtained. E0 To V E(n-1) , where V E0 < V E1 < V E2 < …… < V E(n-1) Each threshold voltage V Ek Corresponding to a known relative error value E k Threshold voltage V Ek With relative error value E k Direct association, that is: according to , , It can be deduced that: Among them, x% is one of the deviation coefficients a%, b%, c%, etc.
[0049] In other words, to achieve an error threshold of E0 = 1%, the corresponding resistance deviation coefficient a% = 1%, i.e., R C0 = (1+1%)×R CTo achieve an error threshold of E1 = 2%, the corresponding resistance deviation coefficient b% = 2%, i.e., R C1 = (1+2%)×R C To achieve an error threshold of E2 = 3%, the corresponding resistance deviation coefficient c% = 3%, i.e., R C2 = (1+3%)×R C .
[0050] Considering the low power consumption requirement of implantable chips, a low-voltage constant voltage source generated by a low-dropout linear regulator (LDO) within the implantable neurostimulator is used to power the device, supplying a preset reference current I. ref With the actual stimulation current I real Reduced proportionally by a factor of m, that is And set resistor R B With resistance R A Increase proportionally by a factor of m, that is This way, without changing V A ( ) and V B ( Under the condition of ), by increasing the resistance value, the power transistors MN0 to MN0 can be reduced. n-1 The current is reduced to decrease power consumption. According to an embodiment of the present invention, the value of m needs to be determined according to the chip's requirements, because increasing the value of m will decrease the current, which saves power consumption, but the resistance value will increase, which will lead to an increase in area. Therefore, a trade-off needs to be made between area and power consumption. m can be set to a positive integer greater than or equal to 2, preferably m is 4.
[0051] During the measurement process, only switches S0 to S2 can be switched. n-1 One of them is turned on, and the error threshold voltage of only one channel is measured at a time. This can be achieved by switching S0 to S... n-1 It controls the on and off of multiple current source circuits, thereby flexibly selecting the required error threshold. It can also further reduce dynamic power consumption by activating only the currently needed branch and shutting off the current output of the other branches, thereby further reducing ineffective power consumption based on scaling the static current.
[0052] Figure 5 is a schematic diagram of the stimulation voltage error comparison module of the stimulation current error measurement device for an implantable neurostimulator according to an embodiment of the present invention. Referring to Figure 5, the stimulation voltage error comparison module includes a multiplexer MUX and a comparator A.
[0053] The output of the stimulus error voltage generation module is connected to the multiple inputs a0, a1, ..., a of the multiplexer MUX. n-1 The electrical connections are respectively set to the fixed error threshold voltage V.E0 I to V E(n-1) are input to the input terminals of the multiplexer MUX, and the multiplexer is controlled by the control signal CTL generated by the control module to select multiple paths. Accordingly, each path of the multiplexer can be switched according to requirements, and the error threshold voltage Y corresponding to the currently selected path is output.
[0054] The output terminal of the multiplexer MUX is electrically connected to the negative input terminal of the comparator A. The output terminal of the actual stimulation voltage generation module is electrically connected to the positive input terminal of the comparator A. That is, the comparator A can receive two inputs, that is, the positive input terminal receives the sampled value V of the actual stimulation voltage B , and the negative input terminal receives the error threshold voltage Y output by the multiplexer, and the actual stimulation voltage and the stimulation error voltage are compared in the comparator A.
[0055] According to the embodiments of the present invention, the comparator A can be a hysteresis comparator. During the process of dynamically adjusting the error threshold, the introduction of the hysteresis characteristic can effectively suppress the output jitter of the comparator caused by signal noise, which enables the control module to stably lock the error range and will not repeatedly switch the threshold due to small voltage fluctuations, improving the reliability of the entire error detection closed-loop. The hysteresis comparator can achieve noise immunity without an additional filter circuit, which reduces the complexity and power consumption of the peripheral circuit and meets the design requirements of implantable chips for low power consumption and small area.
[0056] The hysteresis comparator compares these two voltages and outputs a digital level signal V COMP . When V B >Y, V COMP is at a high level, indicating that the error of the actual stimulation current exceeds the current threshold; when V B <Y, V COMP is at a low level, indicating that the error of the actual stimulation current is within the current threshold range.
[0057] The output terminal of the hysteresis comparator can be electrically connected to the control module, and the output signal V COMP of the hysteresis comparator can be fed back to the control module to dynamically adjust the input selection of the multiplexer. When the error exceeds the threshold (V COMP is at a high level), the control module can select a larger error threshold voltage (for example, switch from V E0 to V E1 , ……), expanding the allowable error range until V COMP flips to a low level. When the error is within the threshold (V COMP is at a low level), the control module can select a smaller error threshold voltage (such as switching from V E1 to V E0 , ……), narrowing the allowable error range until V COMPFlip to high level.
[0058] According to an embodiment of the present invention, the relative error range of the actual stimulation current can be locked when the output of the comparator flips. Assuming V E1 The output is high (actual error > 2%), at V E2 The output is low (actual error <3%). This determines the relative error range of the actual stimulation current to be 2% to 3%. Through this closed-loop adjustment mechanism, the precise relative error range of the actual stimulation current can be locked, thus completing the quantitative assessment of the stimulation current accuracy.
[0059] According to an embodiment of the present invention, a stimulation current error measurement device for an implantable neurostimulator can compare a preset stimulation error voltage threshold V using a hysteresis comparator. E(n-1) The sampled value V of the actual stimulation voltage B Without the need for an analog-to-digital converter (ADC) and subsequent calculations, the output logic level V of the hysteresis comparator is directly obtained. comp The high and low levels are used to determine the relative error of the actual stimulation current, which greatly reduces power consumption, extends the chip's service life, and reduces the chip's heat dissipation.
[0060] This invention achieves direct analog quantity comparison, direct logic level output, and direct error state judgment through a hysteresis comparator, eliminating the high-power module of the analog-to-digital converter (ADC), thus simplifying power consumption at its source. At the same time, the hysteresis comparator itself is a low-power analog device, and its operating power consumption is much lower than that of the ADC, ultimately achieving a significant reduction in chip power consumption. This, in turn, reduces the chip's heat dissipation (power consumption and heat dissipation are positively correlated; the lower the power consumption, the less heat the circuit generates during operation), and effectively extends the chip's service life due to reduced power consumption.
[0061] The various embodiments of the present invention are not an exhaustive list of all possible combinations, but are intended to describe representative aspects of the invention, and the contents described in the various embodiments can be applied independently or in two or more combinations.
[0062] The description of the exemplary embodiments presented above is merely illustrative of the technical solutions of the present invention and is not intended to be exhaustive, nor is it intended to limit the invention to the precise forms described. Obviously, those skilled in the art can make many changes and variations based on the above teachings. The exemplary embodiments were chosen and described to explain the specific principles of the invention and its practical application, thereby enabling others skilled in the art to understand, implement, and utilize the various exemplary embodiments of the invention and their various alternatives and modifications. The scope of protection of the present invention is intended to be defined by the appended claims and their equivalents.
Claims
1. A device for measuring the stimulation current error of an implantable neurostimulator, comprising: actual... The system includes a stimulation voltage generation module configured to generate sampled values of the actual stimulation voltage of the stimulation electrode; a stimulation error voltage generation module configured to generate multiple preset stimulation error voltage thresholds; a stimulation voltage error comparison module electrically connected to both the stimulation voltage error generation module and the actual stimulation voltage generation module, wherein the stimulation voltage error comparison module is configured to receive sampled values of the actual stimulation voltage and multiple preset stimulation error voltage thresholds, compare the sampled values of the actual stimulation voltage with one or more of the multiple preset stimulation error voltage thresholds, and generate a comparison result; and a control module electrically connected to the stimulation voltage error comparison module, wherein the control module is configured to determine the relative error of the actual stimulation current based on the comparison result.
2. The stimulation current error measuring device for an implantable neurostimulator according to claim 1, wherein, The actual stimulation voltage generation module includes a variable stimulation current source circuit and an H-bridge module. The variable stimulation current source circuit is electrically connected to the H-bridge module. The H-bridge module includes multiple switches and a power supply voltage HVDD. The H-bridge module is electrically connected to the stimulation electrode and outputs the actual stimulation current of the stimulation electrode. The variable stimulation current source circuit includes a digital-to-analog converter (DAC), a first operational amplifier (A1), and a power transistor (MN). B and resistance R B It also outputs the sampled value of the actual stimulation voltage of the stimulation electrode.
3. The stimulation current error measuring device for an implantable neurostimulator according to claim 2, wherein, The input terminal of the digital-to-analog converter (DAC) receives external digital signals; the output terminal of the DAC is electrically connected to the positive input terminal of the first operational amplifier A1; the output terminal of the first operational amplifier A1 is connected to the power transistor MN. B The gate electrical connection; power transistor MN B The drain of the power transistor MN is electrically connected to the output of the H-bridge module; B The source of is electrically connected to the negative input terminal of the first operational amplifier A1; resistor R B The first terminal is connected to the power transistor MN B Source electrical connection; resistor R B The second terminal is grounded.
4. The stimulation current error measuring device for an implantable neurostimulator according to claim 3, wherein, The stimulation error voltage generation module includes a reference current source circuit, a power supply voltage VDDA, and a multi-channel current source circuit; the reference current source circuit and the multi-channel current source circuit are electrically connected to the power supply voltage VDDA; the reference current source circuit includes a second operational amplifier A2 and a reference power transistor MN. C and reference resistor R C And generate a reference current I ref ; Multi-channel current source circuit generates and reference current I ref The same current is used, and multiple preset stimulation error voltage thresholds are output.
5. The stimulation current error measuring device for an implantable neurostimulator according to claim 4, wherein, The positive input terminal of the second operational amplifier A2 is electrically connected to the output terminal of the digital-to-analog converter (DAC); the output terminal of the second operational amplifier A2 is connected to the reference power transistor MN. C The gate electrical connection; the reference power transistor MN C The drain of the reference power transistor MN is electrically connected to the power supply voltage VDDA. C The source of the amplifier is electrically connected to the negative input terminal of the second operational amplifier A2; the reference resistor R C The first terminal is connected to the reference power transistor MN C The source electrical connection; the reference resistor R C The second terminal is grounded.
6. The stimulation current error measuring device for an implantable neurostimulator according to claim 4, wherein, The multi-current source circuit may include multiple switches S0 to S10. n-1 Multiple power transistors MN0 to MN n-1 and multiple resistors R C0 To R C(n-1) The sources of the power transistors in each current source circuit are electrically connected together; the drains of the power transistors in each current source circuit are electrically connected to the first terminal of their respective switches; the second terminal of the switches in each current source circuit is electrically connected to the power supply voltage VDDA; the sources of the power transistors in each current source circuit are electrically connected to the first terminal of their respective resistors; the second terminal of the resistors in each current source circuit is grounded.
7. The stimulation current error measuring device for an implantable neurostimulator according to claim 6, wherein, The plurality of resistors R C0 To R C(n-1) Set to the reference resistor R C It has the following relationship: R Ck = (1 ± x%) × R C Where k is an integer between 0 and n-1, n is the number of branches in the multi-current source circuit, and x% represents the deviation coefficient for multiple resistors R C0 To R C(n-1) x% is set to a step-by-step progression, with x% ranging from 1% to 10%.
8. The stimulation current error measuring device for an implantable neurostimulator according to claim 7, wherein, The stimulation voltage error comparison module includes a multiplexer MUX and a comparator A. The output of the stimulation error voltage generation module is electrically connected to multiple inputs of the multiplexer MUX. The output of the multiplexer MUX is electrically connected to the negative input of the comparator A. The output of the actual stimulation voltage generation module is electrically connected to the positive input of the comparator A. The output of the comparator A is electrically connected to the control module.
9. The stimulation current error measuring device for an implantable neurostimulator according to claim 8, wherein, The control module is configured to: when the comparison result of the comparator is high, determine that the error of the actual stimulation current exceeds the corresponding deviation coefficient; when the comparison result of the comparator is low, determine that the error of the actual stimulation current is within the corresponding deviation coefficient.