CN206792806U - A kind of low frequency transcutaneous stimulation instrument of multi-channel multi-parameter bipolarity constant current - Google Patents

Abstract

The utility model discloses a multi-channel multi-parameter bipolar constant current low-frequency percutaneous stimulator, which mainly includes a single chip microcomputer, a touch screen display module, a power management module, a boost module, a constant current module, a bipolar control circuit, a DA conversion circuit; the constant current module includes a negative feedback regulation circuit; the touch screen display module, bipolar control circuit, and DA conversion circuit are respectively connected to the single-chip microcomputer; The polarity control circuit is connected with the constant current module and the boost module respectively. The stimulator uses multiple channels to work independently without interfering with each other, including independent boosting and independent generation of electrical stimulation with different parameters and different waveform combinations; bipolar symmetrical electrical stimulation is used to avoid the extreme effects of unipolar electrical stimulation on the human body surface. Transformation phenomenon; the generated controlled multiple simple waves and combined waves and two kinds of dense and dense square-pointed waves of different frequencies are converted into electrical stimulation, which can simulate acupuncture, thumping, massage, cupping, massage and other different effects in a more realistic way. stimulating effect.

Description

A multi-channel multi-parameter bipolar constant current low-frequency percutaneous stimulator

technical field

The utility model relates to a multi-channel multi-parameter bipolar constant current low-frequency percutaneous stimulator, which can excite neuromuscular tissue and calm nerves by applying bipolar constant current stimulation with various wave combinations to the human body. The physiological meaning and therapeutic effect of pain.

Background technique

From the perspective of meridian theory of traditional Chinese medicine, when some organs or parts of the body are abnormal, the normal bioelectricity will also be abnormal, which will cause various discomforts or pains in the human body, and the external electrical stimulation pulse can be converted into bioelectricity. affect tissues and organs. Low-frequency pulse electrotherapy is a method of applying pulse current with a frequency below 1000Hz to treat diseases. It is characterized by a strong stimulating effect on sensory and motor nerves, no obvious electrolysis phenomenon, significant stimulating effect but no thermal effect. As a kind of physical factor, the physiological and therapeutic effects of low-frequency current on the human body are mainly as follows: 1. Analgesic effect; 2. Exciting neuromuscular tissue; 3. Promote local blood circulation; 4. Enhance blood and lymph circulation; 5. . Change the permeability of biological membranes, blood vessels, skin, mucous membranes and other tissues. In view of the fact that low-frequency current has various physiological and therapeutic effects on the human body, especially the effects of analgesia, excitatory neuromuscular tissue and promotion of local blood circulation, a multifunctional, miniaturized, family-type, portable, and non-toxic side effect Low frequency percutaneous therapeutic apparatus is very necessary. The low-frequency percutaneous therapeutic instrument can not only provide new treatment methods and approaches for the treatment of some diseases, but also save patients from surgical trauma and reduce or avoid the toxic and side effects of drugs. All kinds of percutaneous therapeutic devices currently on the market have shortcomings such as single waveform, non-constant current, unipolarity, and limited parameters. All-in-one low-frequency percutaneous therapeutic device.

Utility model content

The purpose of the utility model is to overcome the deficiencies of the existing transdermal stimulators, and provide a multi-channel, multi-parameter, bipolar, constant-current, low-frequency transdermal stimulator with rich waveforms, complete parameters, good stimulation effects, and portability. It can be used in clinical Chinese medicine, and the target can be hemiplegia or total hemiplegia patients, and the weak low-frequency pulse current is applied to the relevant parts of the human body through electrodes.

In order to achieve the above object, the specific technical scheme adopted by the utility model is as follows: the transcutaneous stimulator mainly includes a single-chip microcomputer, a touch screen display module, a power management module, a boost module, a constant current module, a bipolar control circuit, and a DA conversion circuit The constant current module includes a negative feedback regulation circuit; the touch screen display module, the bipolar control circuit, and the DA conversion circuit are connected to the single-chip microcomputer respectively, and the power management module is connected to the boost module, the single-chip microcomputer, and the touch screen display module respectively, and the bipolar The control circuit is connected to the constant current module and the boost module respectively;

The boost module is realized by boost chip MCP1651;

The bipolar control circuit has a unipolar input and a bipolar output, and is used to reverse the polarity of the even cycle time interval of the unipolar voltage signal output by the single chip microcomputer.

In the transcutaneous stimulator of the present invention, the single-chip microcomputer is the main controller of the system, which controls the normal operation of the touch screen display, the DA conversion module and the bipolar control module. The touch screen display module is the control interface of the entire system, mainly including: selecting parameters and channels, selecting waveform combinations, starting, pausing, modifying parameters and stopping work, etc., and displays the current working status of the system in real time on the LCD screen. The power management module can mainly include battery power supply, AC to DC, battery power detection and charging; when the power management module detects that there is a mains power supply, it can automatically cut off the battery power supply and charge it.

The role of the booster module in the present invention is critical, because if an instantaneous peak current of 20mA is to be applied to the skin, assuming that the impedance of the affected skin is 5k, then the required instantaneous peak voltage according to Ohm's law is at least 100V. The constant current module ensures that all waveforms are output in the form of constant current, avoiding differences caused by different materials of electroacupuncture or electrode stickers, different human bodies or different impedances of different parts of the human body. The definition of constant current here means that the charge flowing through the load within a unit time t is the same.

The bipolar control circuit ensures that all waveforms are bipolar symmetrical waveforms, avoiding the polarization phenomenon generated by unipolar electric stimulation on the surface of the human body. The combination type of bipolar waveforms can be set by parameters. The DA conversion circuit is the key to generate various waveforms. For example, to generate a combined wave of sine wave+triangular wave, it is necessary to use DAC to collect and store the values required to form the relevant waveform, and then use the above-mentioned bipolar control circuit to convert Combined wave output can be realized by TLC5615 chip.

Compared with the prior art, the beneficial effect of the utility model is that the generated controlled multiple simple waves and combined waves and two kinds of dense square-shaped waves with different frequencies are converted into electric stimulation, which can more realistically simulate Acupuncture, hammering, massage, cupping, massage and other different stimulating effects.

Description of drawings

Fig. 1 is a structural schematic block diagram of the utility model;

Fig. 2 is the working flow chart that the utility model produces electrical stimulation;

Fig. 3 is the step-up circuit diagram of an example of the utility model;

Fig. 4 is the bipolar control circuit diagram of an example of the utility model;

Fig. 5 is a DAC module circuit diagram and a constant current circuit diagram of an example of the utility model;

Fig. 6 is a schematic diagram of various simple waves and various combined waves generated by the utility model.

detailed description

As an implementation of the present invention, the multi-channel multi-parameter bipolar constant current low-frequency stimulator shown in Figure 1 includes a single-chip microcomputer, a 7-inch liquid crystal touch screen display module, a power management module, a boost module, a constant current module, Bipolar control circuit, DA conversion circuit.

Among them, the 7-inch LCD touch screen display module, the power management module, the bipolar control circuit, and the DA conversion module are respectively connected with the single-chip microcomputer. The LCD touch screen display module is also the system control interface. All required parameters, such as pulse width, frequency, current amplitude, duration, waveform selection, and channel selection are all completed by the LCD touch screen and send commands to the main control microcontroller. Then the main control single-chip microcomputer responds to the command, outputs the required electrical stimulation and displays it on the LCD touch screen display module.

The single-chip microcomputer is the control core of the whole system. In this example, the STM32F103 series single-chip microcomputer with rich on-chip resources and peripheral I/O ports and fast running speed is selected. Due to the problem of accuracy, this example does not use the AD and DA that comes with the microcontroller, but uses a separate DA chip.

The power management module provides power for each module unit, and the power supply mode can be commercial power or battery, and the battery power supply is convenient for carrying the instrument and responding to sudden power failure. The power management module also monitors the power supply mode in real time. When the mains power is supplied, the battery will automatically stop supplying power and switch to charging mode. When the mains is withdrawn, it will automatically switch to battery power. This process is controlled by the single chip microcomputer. The single-chip microcomputer also controls the liquid crystal touch screen display module, the DA conversion circuit and the bipolar control circuit at the same time. The DA conversion circuit is responsible for sending the analog data required to form the waveform to the microcontroller in the form of an array and saving it; in general, the voltage or current signal output by the microcontroller is unipolar, that is, the amplitude is positive voltage greater than 0 Or positive current signal, therefore, in order to output the current stimulation to the load is bipolar, use the bipolar control circuit; at the same time, the boost circuit ensures that the instantaneous peak value of the output current stimulation meets the requirements, and it is controlled by a special boost chip Complete; the constant current circuit ensures that the output current is constant, that is, the amount of charge output to the load per unit time is constant, and does not change with the voltage across the load and the impedance of the load.

Figure 2 shows the specific workflow of the instrument, which can be operated in the following ways:

(1) Select the stimulated part and the stimulating lead. The stimulated part is selected by medical staff with professional background; there are two main types of stimulating leads, one is acupuncture needles, and the other is electrode paste. The former is to stimulate deeply below the epidermis of the skin, while the latter is to apply stimulation on the surface of the skin, and the stimulation lead mode is selected according to the different stimulation effects required.

(2) Power on the instrument.

(3) Select the parameters, waveform and output channel on the control panel (LCD screen). Among them, it is recommended to choose a low intensity at the beginning of the stimulation intensity, so as not to cause unnecessary harm and discomfort to the user; the waveform selection is determined according to different treatment requirements, because the stimulation effects produced by different waveforms are obviously different; the output channel You can choose a single channel or choose multiple channels to work at the same time.

(4) Connect the instrument to the stimulating leads. The utility model adopts alligator clips to connect the output channel and the stimulating lead.

(5) Press the "Start" button, and the instrument starts to work until the preset continuous stimulation time is completed. Of course, during the stimulation process, the stimulation parameters can also be paused and changed according to the actual situation.

Figure 3 is an implementation of the boost circuit. The traditional boost method adopts a transformer-coupled structure, and its disadvantages are complex circuits and high-frequency output distortion. This instrument uses a boost chip MCP1651 from Microchip Company to design the boost circuit. The MCP1651 is a 750kHz gated oscillator boost controller in an 8-pin MSOP package. It can work in a wide input voltage range (2.0V to 5.5V), the output voltage can reach more than 100V, and can provide 5W of power for the load, while the quiescent current at no-load is only 120uA, suitable for a variety of battery-powered portable device. Depending on the input voltage, the duty cycle of the MCP1651 is limited to 56% or 80%. When the input voltage is between 2.7V and 3.8V, the duty cycle is 80%; when the input voltage is between 3.8V and 5.5V, the duty cycle is 56%.

The specific circuit is shown in Figure 3. The working principle of the circuit is that during the boost operation, the external gate drive (EXT) pin outputs pulses at a gate oscillation frequency of 750kHz to control the on and off of the external N-channel MOSFET. When the MOSFET is turned on, the Schottky diode D12 is reverse-biased, the power supply forms a loop to the MOSFET through the inductor L1, and the input voltage is added to the boost inductor and converted into magnetic energy storage; when the MOSFET is turned off, the Schottky diode D12 is positive Direction bias, the magnetic energy in the inductor cannot be transformed into electrical energy because it cannot change suddenly. This voltage provides energy for the load together with the input power supply, and charges the output capacitor C4. It takes several pulses to provide enough energy to increase the output voltage. Complete boost function. The output voltage is fed back to the FB pin through external divider resistors (R6, R5), and then compared with the internal reference voltage of 1.22V. When the divided voltage feedback is lower than the 1.22V reference voltage, the internal oscillator works, and the EXT pin outputs pulses to control the on and off of the external N-channel MOSFET to transmit energy from the power supply to the load. This will cause the output voltage to rise until the feedback voltage exceeds the threshold voltage of 1.22V and the internal oscillator stops.

Figure 4 is an implementation of the bipolar control circuit. The pulses and pulse trains output by the low-frequency percutaneous stimulation therapy device should be positive and negative fully symmetrical bipolar stimulation signals, while the waveform generated by the single-chip microcomputer control circuit is unipolar. In order to realize the transition from unipolar waveform to bipolar waveform, a bipolar control circuit with unipolar input and bipolar output is designed here to control the even cycle of the unipolar voltage signal output by the STM32 control circuit The signal output of reverse polarity is obtained in the time interval, so as to obtain the effect of bipolar stimulation on the load. Therefore, using the general-purpose I/O port of STM32 to generate pulses with opposite polarities, and cooperating with the power switch tube to control the conversion of the polarity of the output signal, is equivalent to the function of a switch.

As shown in Figure 4, the circuit is mainly composed of peripheral components such as a power switch tube, a photocoupler, and an open-collector NOT gate. The working principle of the circuit is as follows: the power switch tubes Q21, Q22, Q23, and Q24 act as current reversing switches, Q21 and Q23 are used as a group, and Q22 and Q24 are used as another group. The bases of Q21, Q22, Q23, and Q24 are connected to the emitter of the optocoupler, and a set of pulse signals (PORT21, PORT22) with opposite polarities generated by STM32 drive and control Q21, Q22, Q23, and Q24 between saturation and cut-off states. switch between. When port21 is low level and port22 is high level, Q22 and Q23 are saturated and turned on, Q21 and Q24 are in the cut-off state, and the current flowing through the load RL2 is Q22→RL2→Q23->A; when port21 is high level , when porrt22 is low level, Q21 and Q24 are saturated and turned on, Q22 and Q23 are in cut-off state, and the current flowing through the load RL2 is Q21→RL2→Q24->A; by switching the level state of port21 and port22 to achieve single Direction and bidirectional pulse conversion, so that even if the circuit is powered by a single power supply, the output of bipolar signals can also be achieved.

Fig. 5 is the circuit diagram of the DAC module and the control circuit diagram of the constant current source. The constant current source circuit is composed of operational amplifier MCP6001, transistor Q25, sampling resistor R15(2) and stimulating electrode (ie load resistor RL2). MCP6001 is a 1MHz low-power operational amplifier produced by Microchip using advanced CMOS technology. The operating voltage is 1.8V-5.5V and the quiescent current is 100uA. It can meet the small signal input situation and has the advantages of low power consumption and fast operation speed. The operational amplifier MCP6001, Q25 and the sampling resistor R15(2) form a voltage series negative feedback circuit. According to the virtual short and virtual break characteristics of the amplifier, it can be known that the voltage of the non-inverting and inverting input terminals of the amplifier is the same, V ₊ = V _- = V _daout , that is The voltage across the resistor R15(2) is V _daout , and the currents flowing through RL2 and R15(2) are both equal to I _R15(2) .

When the external power supply voltage is high enough, the transistor Q25 will work in an amplified state (I _c ≈ I _e ). The magnitude of the output current of the load resistor _RL is determined by the ratio of the input voltage V _daout to the sampling resistor R15(2), regardless of the size of the load resistor, so that a voltage-controlled constant current output is realized.

The DAC chip shown in Figure 5 is TLC5615. The DIN, SCLK, and CS pins of TLC5615 are respectively connected to the general I/O port of the STM32 chip. Through the control of STM32, the timing in line with the normal operation of TLC5615 is generated, so as to control the normal operation of the external D/A conversion chip. The analog voltage output terminal OUT of the D/A chip is connected to the positive input terminal of the operational amplifier in the output circuit of the voltage-controlled constant current source to control the output current of the constant current source.

Fig. 6 is all waveform types that the utility model produces, for actual selection. The stimuli for different waveforms obtained through human experiments are as follows. Due to the fact that different human bodies may not have the same stimuli for the same kind of stimulation, and the differences in the descriptions of the subjects, the results may not be accurate enough and are for reference only.

The stimulation experience of the square wave is: regular tingling, and the greater the amplitude and the higher the frequency, the stronger the pain; the larger the wave width, the longer the pain lasts; Fibers are "lifted up" or "pulled down".

The stimulation experience of sine wave is: a regular tearing feeling, and the larger the amplitude, the higher the frequency, the stronger the feeling; the larger the wave width, the longer the feeling lasts; "Sense shifts left and right or up and down.

The stimulation feeling of the sawtooth wave is: a regular sense of oppression, as if there is a heavy object pressing on the leg, and the greater the amplitude, the higher the frequency, the stronger the oppressive feeling; the larger the wave width, the longer the feeling lasts; with There is a knocking feeling.

The stimulation feeling of white noise wave is: compared with other waveforms, it feels more gentle and relaxed, without obvious pain and discomfort.

The stimulation experience of square wave + sine wave is: roughly the superposition of the two waveforms. Of course, if the positions (positive and negative) of the two waveforms are different, the sensations are roughly interchanged.

The stimulation experience of square wave + sawtooth wave is: roughly the superimposition of the two waveforms. Of course, if the positions (positive and negative) of the two waveforms are different, the sensations are roughly interchanged.

The stimulation feeling of sine wave + sawtooth wave: it is roughly the superposition of the two waveforms. Of course, if the positions (positive and negative) of the two waveforms are different, the feeling is roughly interchanged.

The stimulator in this example has three channels, which are named "Channel 1", "Channel 2" and "Channel 3". 1Hz to 100Hz, the step size is 1Hz below 10Hz, and the step size is 10Hz above 10Hz; 3) The current size is 0.5mA to 50mA, the step size is 0.5mA below 10mA, and the step size is 2mA above 10mA; 4) The duration is 1min to 60min, the step size is 5min, There is a reminder for the countdown.

Multiple channels work independently without interfering with each other, including independent boosting and independent generation of electrical stimulation with different parameters and different waveform combinations. When multiple channels work at the same time, different channels may require different output stimulation currents, and if multiple channels share a boost circuit, voltage instability may occur, so each channel is equipped with an independent boost circuit.

The frequency of the waveform does not exceed 1000Hz, because when the frequency is less than 1000Hz, the effect of the current on the human cell tissue is mainly based on the stimulating effect (that is, mainly based on dielectric properties, showing a capacitive effect). The absolute refractory period of nerve fibers in mammals is about 1ms, so it can only generate 1000 excitations per second at most, and when the stimulation frequency is greater than 1kHz, there is almost no stimulation effect. At this time, the ability of the human body to withstand the current gradually increases with the frequency, and its main effect is the thermal effect.

The waveform combinations include square wave, sine wave, sawtooth wave, square wave + sine wave, square wave + sawtooth wave, sine wave + sawtooth wave, white noise, and dense square wave. Among them, the dense square wave is divided into two groups, one group is 2Hz (sparse): 10Hz (dense), and the other group is 2Hz (sparse): 100Hz (dense). This design allows simultaneous application of the required stimulation type, stimulation intensity and stimulation time to different parts of the patient according to actual needs.

Claims (4)

1. a kind of low frequency transcutaneous stimulation instrument of multi-channel multi-parameter bipolarity constant current, it is characterised in that the percutaneous stimulator mainly wraps Include single-chip microcomputer, touch screen display module, power management module, boost module, constant flow module, Bipolar control circuit, DA conversion electricity Road；Wherein constant flow module includes negative-feedback regu- lation circuit；Touch screen display module, Bipolar control circuit, DA change-over circuits difference It is connected with single-chip microcomputer, power management module is connected with boost module, single-chip microcomputer, touch screen display module respectively, Bipolar control electricity Road is connected respectively with constant flow module, boost module.

2. the low frequency transcutaneous stimulation instrument of multi-channel multi-parameter bipolarity constant current according to claim 1, it is characterised in that described Boost module using boost chip MCP1651 realize.

3. the low frequency transcutaneous stimulation instrument of multi-channel multi-parameter bipolarity constant current according to claim 1, it is characterised in that described Bipolar control circuit for unipolarity input double-polarity control, for the even for the electrode signal for exporting single-chip microcomputer Periodic intervals carry out the signal output of reversed polarity.

4. the low frequency transcutaneous stimulation instrument of multi-channel multi-parameter bipolarity constant current according to claim 1, it is characterised in that the thorn Sharp instrument shares three passages.