CN1745857A - An implantable electrical nerve impulse stimulation system - Google Patents

Abstract

The invention relates to the field of implantable medical instruments, and is characterized in that it consists of a pulse generator implanted in the human body, wire electrodes, an external programmable remote sensing program controller, a handheld computer PDA, and a control magnet. The pulse generator uses an external magnet, a program controller and a PDA to non-contactly control the working state and adjust pulse parameters. It achieves arbitrary waveform electrical pulse stimulation with precise and flexible adjustment of pulse amplitude, frequency, pulse width and other parameters to the target area through electrodes. , which is helpful to find the optimal electrical stimulation treatment parameters. The software of the internal controller can also be updated through PDA and programmable controller, so that the product software can be updated without surgery, which improves the reliability, maintainability and service life of the implanted pulse generator. The invention can be used for electrical stimulation treatment of neurological diseases such as Parkinson's disease, epilepsy, pain, torsion and spasm.

Description

An implantable electrical nerve impulse stimulation system

technical field

The invention relates to an implanted nerve electrical pulse stimulation system for treating nervous system diseases through electrical pulse stimulation to targets, and belongs to the technical field of implantable medical instruments.

Background technique

For certain types of neurological diseases, such as Parkinson's disease, epilepsy, intractable pain, torsion spasm, spastic torticollis, chorea, idiopathic vertigo, clinically commonly used drug therapy and surgical treatment, but side effects and complications Symptoms are important disadvantages. Electrical stimulation therapy performs chronic electrical pulse stimulation on the corresponding targets of different diseases, such as stimulating the subthalamic nucleus and globus pallidus for Parkinson's disease, stimulating the vagus nerve for epilepsy, and playing a therapeutic effect on the cause. It is a reversible neuromodulation Treatment is an ideal treatment method.

Chinese invention patent "multi-channel implantable neurostimulator" (application number 86103049), uses an external transmitter to send digitally encoded signals and energy through the skin to the implanted receiver/stimulator, and the stimulator decodes the bit stream, A charge or current waveform is sent to electrodes implanted in the auditory nerve or cochlea. The stimulator must be controlled by an external transmitter to work simultaneously, and the circuit structure and algorithm determine that the stimulator can only be used in the auditory nerve repair system. Chinese Invention Patent (Application No. 01810456.8) "Implantable and Programmable Electrical Stimulator for Stimulating Organs and Tissues of Organisms", which spreads biosensors all over the surface of the shell, and changes in breathing and cardiovascular caused by diseases are recorded by sensors, According to a certain algorithm, a current pulse is formed on the wire electrode. The stimulator is based on the physiological signals of breathing and cardiovascular, and changes the functional activities of tissues and organs through electrical stimulation, which is not suitable for nerve stimulation.

Implantable electric pulse stimulation systems currently in clinical use are mainly produced by American companies such as Medtronic and Cyberonics, and the technical solutions are not disclosed. The disadvantage is that the pulse parameters (including pulse amplitude, pulse width, and period) can only be roughly adjusted, divided into several to dozens of levels; the pulse parameter error is large, reaching ±25% or even higher; after the pulse generator is implanted in the body, the soft The hardware cannot be changed. Once there is any failure due to external reasons, or the software needs to be upgraded, it must be taken out and replaced by surgery, which not only increases the pain of the patient, but also increases the economic burden.

Contents of the invention

In view of the deficiencies in the prior art, the purpose of the present invention is to provide an implantable nerve electrical pulse stimulation system for patients with neurological diseases, which can be used to stimulate the brain or nerves, effectively control and treat diseases, and the system can be used to treat Nervous system disease.

The present invention is characterized in that: the system includes electrodes implanted in the corresponding parts of the human body, a pulse generator implanted in the human body and the shell is made of pure titanium, a handheld computer located outside the body, and a program controller, wherein:

The pulse generator contains a microprocessor, internal and external two-way communication components, current pulse stimulation components and a power supply, of which:

A microprocessor, which integrates a large-capacity FLASH memory used as a program memory inside the microprocessor, and supports self-programming operations;

a program-controlled oscillator, the control signal input of which is connected to the corresponding output of the microprocessor;

a transmitting coil, the transmitting signal input end of the coil is connected with the corresponding output end of the program-controlled oscillator;

a detector, the data signal output of the detector is connected to the corresponding input of the microprocessor;

an amplifier, the signal output of the amplifier is connected to the signal input of the detector;

a receiving coil, the receiving signal output end of which is connected to the signal input end of the amplifier;

The programmable oscillator, transmitting coil, wave detector, amplifier and receiving coil jointly constitute a two-way communication component between the pulse generator and the external program controller;

Programmable voltage source, the voltage source is composed of a DC-DC converter, powered by the pulse generator power supply, the control signal input end of the output voltage is connected with the corresponding output end of the microprocessor, under the control of the microprocessor, The output voltage of the program-controlled voltage source is multi-level adjustable;

A program-controlled current source, the power signal input terminal of the current source is connected to the power output terminal of the program-controlled voltage source;

A DA converter, the digital signal input end of the converter is connected with the corresponding output end of the microprocessor, and the analog power output end of the converter is connected with the output current control signal input end of the programmable current source;

A current feedback circuit, the detection signal input end of the circuit is connected to the current output end of the program-controlled current source, and the feedback signal output end of the current feedback circuit is connected to the corresponding input end of the microprocessor;

The above program-controlled voltage source, program-controlled current source, DA converter and current feedback circuit constitute a current pulse stimulation component;

Pulse generator power supply;

Program controller, including power supply circuit, signal transmitting circuit and signal receiving circuit, in which:

The power circuit is composed of a battery and a voltage converter connected in series;

The signal transmitting circuit is formed by serially connecting a transmitting converter, an oscillator, a transmitting signal power amplifier circuit and a transmitting coil, and the receiving coil in the pulse generator receives the transmitting signal sent by the signal transmitting circuit in the program controller;

The signal receiving circuit is sequentially connected in series by a receiving converter, a receiving detector, a receiving signal amplifier circuit and a receiving coil, and the transmitting coil in the pulse generator sends a signal to the signal receiving circuit in the program controller;

The handheld computer communicates bidirectionally with the programmer through its serial port, so as to carry out information and state telemetry, program control of operating parameters and update of the microprocessor program to the pulse generator.

The electrodes are connected with the current pulse stimulation signal output end of the pulse generator through wires.

Compared with the prior art, the present invention has the following beneficial effects: (1) using the DA converter, not only the pulse amplitude parameters, pulse width, cycle and other time parameters are controlled accurately and flexibly, but also realizes the arbitrary waveform generation function, which can output Conventional rectangular stimulation pulses can also output complex waveform stimulation pulses; (2) Using large-capacity Flash as a program memory, the software of the implanted pulse generator can be updated through PDA and program controller, which can realize based on the latest scientific research and clinical achievements, Update the stimulation method, so that the relevant algorithm and stimulation mode can be updated without surgery, so as to realize the replacement of the product, reduce the patient's surgical pain and economic burden; Possibility of solution; (3) there are tens of millions of patients with nervous system diseases such as Parkinson's and epilepsy in the whole country, and the present invention has extremely high economic and social benefits.

Description of drawings

Fig. 1 is a system block diagram of the present invention.

Fig. 2 is a functional block diagram of the implanted pulse generator of the present invention.

Fig. 3 is a schematic diagram of the electrical stimulation pulse waveform of the present invention.

Fig. 4 is a functional block diagram of the in vitro programmer of the present invention.

Detailed ways

In order to achieve the above object, the technical solution of the present invention is realized by the following solution: an implantable electrical nerve pulse stimulation system, comprising a pulse generator and electrodes implanted in the human body, the pulse generator includes a microprocessor and a digital-analog A converter, the digital-to-analog converter converts the digital signal output by the microprocessor into an analog signal, so as to output stimulation electrical pulses with adjustable parameters to the electrodes.

The shell of the pulse generator of the present invention can be made of biocompatible pure titanium, stamped and formed, and sealed by laser welding.

Further, the pulse generator may include a programmable current source, and the output current value of the programmable current source is controlled by the analog signal, so as to provide the electrodes with adjustable stimulating electric pulses.

Further, the pulse generator may include a programmable voltage source to supply power to the programmable current source.

Furthermore, the pulse generator may include a current feedback circuit, and the microprocessor adjusts the output voltage of the programmable voltage source to take into account both the accuracy of the output current of the programmable current source and the power consumption of the pulse generator.

Further, the pulse generator may include a charge balancing circuit for providing reverse current compensation to the stimulated nerve.

In addition, the system of the present invention has two working modes: automatic stimulation mode and magnet stimulation mode, and the two working modes can be realized by opening and closing the reed switch inside the pulse generator. When there is no external magnetic field, the reed switch is released to normally emit electric pulses, which is the automatic stimulation mode; when there is an external magnetic field, the reed switch is closed to stop emitting electric pulses, and this is the magnet stimulation mode. The switching of the above modes can be realized by controlling the on-off of the program-controlled current source, the external magnetic field can be applied by the control magnet, and the reed switch is preferably a single-pole double-throw type.

Further, the system of the present invention may include a palmtop computer PDA, which establishes radio frequency two-way communication with the radio frequency communication circuit of the pulse generator, and is used for remotely measuring the information and working status of the pulse generator, and setting the pulse generator pulse parameters. The telemetered pulse generator information includes serial number, battery level, electrode impedance. The pulse parameters include pulse waveform, pulse width, frequency, pulse transmission time and pulse pause time.

In addition, the PDA can establish radio frequency two-way communication with the pulse generator through a program controller, and the program controller is a communication interface device between the PDA and the pulse generator, which includes a transmitting circuit and a receiving circuit. The transmitting circuit includes a converter, an oscillator, a power amplifier and a transmitting coil. After the output signal of the PDA is level-converted by the converter, it is modulated by the oscillator and driven by the power amplifier after power amplification. the transmitting coil. The receiving circuit includes a receiving coil, an amplifier, a detector and a converter. The receiving coil receives a signal, which is amplified by the amplifier, demodulated by the detector and converted by the converter, and then output to the PDAs.

Further, the radio frequency communication circuit includes a transmitting circuit and a receiving circuit. The transmitting circuit is composed of an oscillator and a transmitting coil. The TTL level signal output by the microprocessor controls the working state of the oscillator. By switching between two working states of the oscillator, oscillation and vibration stop, a binary signal is obtained. The amplitude keying modulates the electromagnetic wave signal, and the electromagnetic wave is emitted by the transmitting coil. The receiving circuit is composed of a receiving coil, an amplifier and a wave detector. The receiving coil receives modulated electromagnetic waves, and the obtained weak electric signal is amplified by the amplifier, and then demodulated by the wave detector into a TTL level signal, which is output to the microprocessor.

In addition, the microprocessor of the present invention integrates a large-capacity FLASH memory as a program memory. The microprocessor can obtain new program files through radio frequency communication with the PDA, and then erase and write the FLASH again. , to achieve an in vitro update of the microprocessor software.

The preferred implementation of the implantable nerve electrical pulse stimulation system of the present invention will be described in detail below in conjunction with the accompanying drawings.

As shown in Figure 1, the implantable electrical nerve pulse stimulation system of the present invention is made of a pulse generator 1, a wire 2 and an electrode 3 implanted in the human body, and a program controller 4, a PDA 5 and a magnet 6 positioned outside the human body. . The pulse generator 1 generates stimulating electric pulses, which are transmitted to the electrodes 3 through the wires 2 to stimulate the target. Lead wire 2 requires good biocompatibility, softness and smoothness, and is generally made of metal wire coated with silicone rubber. The metal can be cobalt-based alloy, platinum-iridium alloy or stainless steel. The electrode 3 requires good biocompatibility and high stability, and can be made of platinum or a platinum-iridium alloy material. The program controller 4 serves as the communication interface between the pulse generator 1 and the PDA5, establishes wireless communication between the two, remotely measures the information and working status of the pulse generator, and sets the pulse parameters. The magnet 6 is used to control the pull-in of the reed switch of the pulse generator 1, so that the pulse generator switches to the magnet stimulation mode.

As shown in Figure 2, the implantable pulse generator of the present invention consists of a power supply 10, a microprocessor 11, a crystal oscillator 12, a program-controlled voltage source 13, a DA converter 14, a program-controlled current source 15, a current feedback circuit 16, a charge balance A circuit 17, a reed switch 18, a programmable oscillator 19, a transmitting coil 20, a receiving coil 21, an amplifier 22, and a wave detector 23 constitute.

The power supply 10 is generally made of a lithium battery and a voltage regulator. If the battery used has a gentle discharge curve and an output voltage of about 3V, the battery can be used to directly supply power to the circuit of the pulse generator without the voltage regulator.

Microprocessor 11 selects highly integrated low-power single-chip microcomputer for use, has multiple power-saving modes, integrates FLASH, RAM, timer, serial communication port, etc., DA converter 14 can be a separate device, but preferably integrated in the micro inside the processor 11 to simplify circuit design, improve system reliability and reduce power consumption.

The crystal oscillator 12 can be a 32.768kHz low-frequency watch crystal oscillator to reduce the power consumption of the implanted stimulator.

The microprocessor 11 controls the programmable voltage source 13, the DA converter 14, the programmable current source 15, the current feedback current 16, and the charge balance circuit 17 to form a current pulse stimulation circuit. The core of the programmable voltage source 13 is a DC-DC converter powered by a lithium battery. The IO port of the microprocessor controls the output voltage of the voltage source to 16 levels, the lowest is the lithium battery voltage, and the highest is 12V. The output voltage should be as low as possible , to reduce power consumption. The programmable current source 15 is powered by the programmable voltage source 13 , and the DA converter 14 converts the digital signal output by the microprocessor 11 into an analog voltage to control the output current value of the programmable current source 15 . When the digital signal output by the microprocessor 11 changes, the output current of the current source 15 changes accordingly. The current feedback circuit 16 detects the current output by the program-controlled current source 15. When the actual current value does not reach the set current value, it indicates that the electrode impedance is too large, resulting in insufficient output voltage of the program-controlled voltage source 13. The microprocessor 11 is set through the IO port. Increase the output voltage of the programmable voltage source 13 to realize the precise current waveform output of the programmable current source 15, adapting to the differences in nerve tissue impedance of different patients and the increase in electrode impedance during the use of the implantable nerve electrical pulse stimulation system. Since the resolution of the DA converter can generally be as high as 12 bits, combined with the 16-level output of the programmable voltage source, the current value output by the current source 15 can be adjusted in thousands of levels, which can realize precise and flexible control of the pulse amplitude. The output change of the DA converter 14 is controlled by the timer inside the microprocessor, the time resolution is high, and the precise and flexible control of time parameters such as pulse width and cycle can be realized. In this way, the single-chip microcomputer controls the output value of the DA according to the pulse parameters (including pulse amplitude, pulse width, cycle, etc.) set by the PDA, and provides constant current electric pulse stimulation to the target nerve. After the stimulation pulse, the charge balance circuit 17 provides reverse current compensation for the stimulated nerve, ensuring that the total charge of the compensation is equal to the total charge of the stimulation pulse to achieve electrical neutrality, so that the charge of the stimulated nerve is balanced to avoid damage . Figure 3 is a typical stimulation pulse waveform with automatic charge balance compensation during the interpulse intervals.

The reed switch 18 is a single-pole double-throw type. When there is no external magnetic field, the reed switch 18 is released to connect the programmable current source 15, and the stimulator can normally emit current pulses. When applying an external magnetic field with a magnet, the reed switch 18 is attracted, the programmable current source 15 is disconnected, the pulse generator no longer emits current pulses, and the microprocessor 11 detects the action of the reed switch 18 at the same time. Under control, the pulse generator will switch to magnet stimulation mode after the magnet is removed.

The program-controlled oscillator 19, transmitting coil 20, receiving coil 21, amplifier 22, and detector 23 constitute a two-way communication module between the implanted pulse generator and the in vitro instrument, and transmit binary data information by 2ASK modulation. When sending data, the data flow output by the serial port of the microprocessor 11 controls the programmable oscillator 19 to switch between the two states of oscillation and stop to realize 2ASK modulation and coding, and transmit electromagnetic waves through the transmitting coil 20, which are received and processed by the external program controller. When receiving data, the receiving coil 21 receives the 2ASK modulated and coded signal from the external program controller. Because the signal is weak, the amplifier 22 amplifies the signal, and the detector 23 demodulates it. The serial port of the microprocessor 11 receives and processes the communication data.

The microprocessor 11 integrates a large-capacity FLASH memory as a program memory, and supports self-programming operations, that is, it can perform erasure and writing operations on the Flash while executing programs in the Flash. Usually, the length of the software written into the microprocessor is 2-3k bytes, while the FLASH memory may have a capacity of up to 60k bytes. Through multiple erasing and writing of FLASH, online update of microprocessor software can be realized. The implementation process is as follows: the developer modifies and recompiles the program implanted in the pulse generator on the computer, copies the execution code file to the PDA, the PDA communicates with the microprocessor through the program controller, and sends the code file byte by byte, and the microprocessor After receiving the data, write the data in the redundant space of FLASH one by one, modify the entry variable of the main program of the pulse generation after completion, point to the starting address of the new program, and then make the microprocessor enter the stimulation mode again, that is, start to execute the updated program.

As shown in Figure 4, the program controller 4 mainly includes three parts: a power supply circuit, a signal transmitting circuit and a signal receiving circuit. The composition and working principle of each part are described as follows:

The power supply circuit is composed of a battery 41 and a voltage converter 42. The battery 41 can be a 9V alkaline battery, and the voltage converter 42 is a group of DC-DC converters to generate the 15V, 10V and -10V three-way power required by the program controller 4. .

The signal transmitting circuit is composed of a converter 43 , an oscillator 44 , a power amplifier 45 and a transmitting coil 46 . The signal voltage that PDA serial port sends is RS232 level, is converted into TTL level by converter 43, controls oscillator 44 to oscillate or stops, carries out 2ASK modulation coding, drives transmitting coil 46 through power amplifier 45 (power MOSFET can be used). A capacitor can be connected in parallel to both ends of the transmitting coil 46 to generate resonance and improve the transmitting capability of the transmitting coil 46 .

The signal receiving circuit is composed of a receiving coil 47 , an amplifier 48 , a detector 49 and a converter 50 . The receiving coil 47 receives the 2ASK signal emitted by the implanted pulse generator. Because the signal is weak, it is first amplified by the amplifier 48, and then detected by the detector 49. During the detection, it first passes through the comparator to obtain a modulated signal of TTL level, and then The original signal of TTL level is obtained through a low-pass filter, then converted to RS232 level by the converter 50, and input to the serial port of the PDA.

The functional characteristics of the system described in the specific embodiment of the present invention are briefly described as follows:

1. Using the DA converter, not only the pulse amplitude parameters, pulse width, cycle and other time parameters are controlled accurately and flexibly, but also realizes the arbitrary waveform generation function, which can output both conventional rectangular stimulation pulses and complex waveform stimulation pulses.

2. The microprocessor embedded in the pulse generator integrates a large-capacity FLASH memory as a program memory. The microcontroller can obtain new program files through wireless communication with the PDA and the program controller, and then re-erase the FLASH In addition and write, realize the in vitro update of the microprocessor software.

3. The PDA controls the program controller, communicates with the implanted pulse generator in the patient's body through radio frequency, reads the information and working status of the pulse generator, and sets the pulse parameters of the automatic stimulation mode and the magnet stimulation mode.

4. The default working state of the pulse generator is the automatic stimulation mode, which sends stimulation pulses to the electrodes regularly according to the set pulse parameters to control the onset of the disease.

5. If you need to implement electrical stimulation immediately, just brush the patient's chest with a magnet, and the pulse generator immediately starts the magnet stimulation mode, and sends stimulation pulses to the electrodes according to the set pulse parameters of the magnet stimulation mode.

6. If you need to turn off the implanted pulse generator, you only need to use the PDA to control the programmer, and set the pulse amplitude of the automatic stimulation mode to zero. If the pulse amplitude of the automatic stimulation mode is set to zero, but the pulse amplitude of the magnet stimulation mode is not zero, the manual control of electrical stimulation is realized, that is, the pulse generator emits the stimulation pulse of the set parameters only when the magnet is brushed against the patient's chest .

The above-mentioned method is only a preferred embodiment of the present invention. For those of ordinary skill in the art, on the basis that the present invention discloses the use of DA converters to output stimulation electric pulses with adjustable parameters to the electrodes, it is easy to imagine that the It is applicable to various implantable nerve electrical pulse stimulation systems, and is not limited to the system structure described in the specific embodiments of the present invention, so the above-described methods are only preferred and not limiting.

Claims (3)

1. An implantable electrical nerve pulse stimulation system, characterized in that the system contains electrodes implanted into the corresponding parts of the human body, implanted into the human body and a pulse generator made of pure titanium for the shell, a handheld computer outside the body, a program-controlled device, of which: The pulse generator contains a microprocessor, internal and external two-way communication components, current pulse stimulation components and a power supply, of which: A microprocessor, which integrates a large-capacity FLASH memory used as a program memory inside the microprocessor, and supports self-programming operations; a program-controlled oscillator, the control signal input of which is connected to the corresponding output of the microprocessor; a transmitting coil, the transmitting signal input end of the coil is connected with the corresponding output end of the program-controlled oscillator; A detector, the data signal output of the detector is connected to the corresponding input of the microprocessor: an amplifier, the signal output of the amplifier is connected to the signal input of the detector; a receiving coil, the receiving signal output end of which is connected to the signal input end of the amplifier; The program-controlled oscillator, transmitting coil, detector, amplifier and receiving coil jointly constitute a two-way communication component between the pulse generator and the external program controller: Programmable voltage source, the voltage source is composed of a DC-DC converter, powered by the pulse generator power supply, the control signal input end of the output voltage is connected with the corresponding output end of the microprocessor, under the control of the microprocessor, The output voltage of the program-controlled voltage source is multi-level adjustable; A program-controlled current source, the power signal input terminal of the current source is connected to the power output terminal of the program-controlled voltage source; A DA converter, the digital signal input end of the converter is connected with the corresponding output end of the microprocessor, and the analog power output end of the converter is connected with the output current control signal input end of the programmable current source; A current feedback circuit, the detection signal input end of the circuit is connected to the current output end of the program-controlled current source, and the feedback signal output end of the current feedback circuit is connected to the corresponding input end of the microprocessor; The above program-controlled voltage source, program-controlled current source, DA converter and current feedback circuit constitute a current pulse stimulation component; Pulse generator power supply; Program controller, including power supply circuit, signal transmitting circuit and signal receiving circuit, in which: The power circuit is composed of a battery and a voltage converter connected in series; The signal transmitting circuit is formed by serially connecting a transmitting converter, an oscillator, a transmitting signal power amplifier circuit and a transmitting coil, and the receiving coil in the pulse generator receives the transmitting signal sent by the signal transmitting circuit in the program controller; The signal receiving circuit is sequentially connected in series by a receiving converter, a receiving detector, a receiving signal amplifier circuit and a receiving coil, and the transmitting coil in the pulse generator sends a signal to the signal receiving circuit in the program controller; The handheld computer communicates bidirectionally with the programmer through its serial port, so as to carry out information and state telemetry, program control of operating parameters and update of the microprocessor program to the pulse generator. The electrodes are connected with the current pulse stimulation signal output end of the pulse generator through wires. 2. A kind of implantable electrical nerve pulse stimulation system according to claim 1, characterized in that: in the pulse generator, there is a charge balance circuit between the programmable current source and the electrodes, so as to provide The stimulated nerve provides reverse current compensation to achieve charge balance of the stimulated nerve. 3. A kind of implantable electrical nerve pulse stimulation system according to claim 1, characterized in that: in the pulse generator, there is a reed switch, and a magnet is arranged outside the body, and the reed switch is connected with The input terminal of the detection signal of the microprocessor is connected with the input terminal of the power signal of the programmable current source. When the magnet acts on the skin on the chest of a person, the reed switch pulls in and the programmed current source is disconnected. The pulse generator Electric pulses are no longer emitted, and at the same time, under program control, the pulse generator switches to magnet stimulation mode after the magnet is removed, while the reed switch is released, the programmed current source is connected, and the pulse generator emits electric pulses.

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