A bioelectricity stimulation circuit based on digital potentiometer

Abstract

The utility model discloses a biological electricity stimulation circuit based on digital potentiometer, including PWM signal module and electric stimulation module, PWM signal module is used to produce first PWM signal and second PWM signal, and first PWM signal and second PWM signal are the PWM signal of each other time sequence phase inverse, electric stimulation module includes first digital potentiometer U8 and second digital potentiometer U9, one end of first digital potentiometer U8 is connected with first PWM signal through triode Q7, and the other end of first digital potentiometer U8 is connected with first port J1 through triode Q8, one end of second digital potentiometer U9 is connected with first port J1 through triode Q6, and the other end of second digital potentiometer U9 is connected with triode Q8 after triode Q9 and ground, and second PWM signal is connected with second port J2. Through two inverse PWM signals to control comparator, cooperate two digital potentiometers, form loop, realize positive and negative pulse formula's bidirectional current output, be favorable to simplify circuit, reduce cost.

Description

Technical Field

[0001] This utility model relates to the field of medical instrument technology, and in particular to a bioelectric stimulation circuit based on a digital potentiometer. Background Technology

[0002] Currently, most bioelectric stimulators on the market use an oscillator to generate a basic low-frequency pulse, modulate the duty cycle and pulse width via PWM output, then use a push-pull amplifier circuit built with MOSFETs to drive a transformer to boost the voltage to the therapeutic level, and finally achieve bidirectional current output through an H-bridge. This method is complex to control, costly, and the transformer has poorer consistency compared to other electronic components, making it difficult to guarantee the consistency of the output current. Utility Model Content

[0003] The purpose of this invention is to provide a bioelectric stimulation circuit based on digital potentiometers. It uses two inverse PWM signals to control a comparator, which, together with two digital potentiometers, forms a loop to achieve bidirectional current output in a positive and negative pulse manner. This simplifies the circuit and reduces costs.

[0004] To achieve this objective, the present invention adopts the following technical solution:

[0005] A bioelectric stimulation circuit based on a digital potentiometer includes a PWM signal module and an electrical stimulation module;

[0006] The PWM signal module is used to generate a first PWM signal and a second PWM signal, which are PWM signals with opposite timing sequences.

[0007] The electrical stimulation module includes a first digital potentiometer U8 and a second digital potentiometer U9;

[0008] One end of the first digital potentiometer U8 is connected to the first PWM signal via a triode Q7;

[0009] The other end of the first digital potentiometer U8 is connected to the first port J1 via a triode Q8;

[0010] One end of the second digital potentiometer U9 is connected to the first port J1 via a triode Q6;

[0011] The other end of the second digital potentiometer U9 is grounded via transistors Q9 and Q8;

[0012] The second PWM signal is connected to the second port J2.

[0013] In some implementations, the electrical stimulation module further includes a first comparator U10A and a second comparator U10B;

[0014] The first PWM signal is connected to the triode Q7 after passing through the first comparator U10A;

[0015] The second PWM signal is connected to the second port J2 after passing through the second comparator U10B.

[0016] In some implementations, pin 3 of the first comparator U10A is connected to the first PWM signal, pin 1 of the first comparator U10A is connected to diode D13 and then to pin 1 of transistor Q7, pin 3 of transistor Q7 is connected to voltage +9VS, pin 2 of transistor Q7 is connected to pin 8 of the first digital potentiometer U8, pin 1 of the first digital potentiometer U8 is connected to pin 1 of transistor Q8, pin 2 of transistor Q8 is connected to pin 1 of the first comparator U10A, and pin 3 of transistor Q8 is connected to the first port J1 via diode D10.

[0017] In some implementations, pin 4 of the first comparator U10A is connected to a voltage of -9VS, and pin 8 of the first comparator U10A is connected to a voltage of +9VS.

[0018] Pin 2 of the first comparator U10A is connected to ground after the first filter unit.

[0019] In some implementations, pin 8 of the second digital potentiometer U9 is connected to pin 2 of transistor Q6, pin 1 of transistor Q6 is connected to the first port J1, and pin 3 of transistor Q6 is connected to voltage -9VS.

[0020] Pin 1 of the second digital potentiometer U9 is connected to pin 1 of transistor Q9. Pin 3 of transistor Q9 is connected to diodes D11 and D10, and then to pin 3 of transistor Q8. Pin 2 of transistor Q8 is connected to pin 1 of the first comparator U10A.

[0021] In some implementations, pin 5 of the second comparator U10B is connected to the second PWM signal, pin 7 of the second comparator U10B is connected to the second port J2, and pin 6 of the second comparator U10B is connected to the ground after the first filter unit.

[0022] In some embodiments, the first filter element unit includes capacitors C33 and C34 connected in parallel, resistors R38 and R40 connected in series and then in parallel with capacitor C34, and capacitor C35 connected in parallel with resistor R40.

[0023] Pin 2 of the first comparator U10A and pin 6 of the second comparator U10B are both connected between resistor R38 and resistor R40.

[0024] In some implementations, resistors R29 and R31 are connected between pins 1 and 3 of transistor Q7, and capacitor C27 and resistor R27 are connected to pin 1 of transistor Q7.

[0025] Resistors R30 and R32 are connected between pins 1 and 3 of transistor Q6, and capacitor C28 and resistor R28 are connected to pin 1 of transistor Q6.

[0026] In some implementations, the frequency and pulse width of both the first PWM signal and the second PWM signal can be adjusted.

[0027] In some implementations, both the first digital potentiometer U8 and the second digital potentiometer U9 are connected to the third chip MCU via an I2C interface. The third chip MCU can adjust the nodes of the resistor arrays of the first digital potentiometer U8 and the second digital potentiometer U9, thereby adjusting the magnitude of the circuit current.

[0028] The beneficial effects of this invention are as follows: By controlling the comparator with two inverse PWM signals and cooperating with two digital potentiometers to form a loop, a bidirectional current output with positive and negative pulses can be achieved, which helps to simplify the circuit, reduce costs, and enhance the consistency of the output current. Attached Figure Description

[0029] Figure 1 This is a connection structure diagram of the bioelectric stimulation circuit of this utility model;

[0030] Figure 2 This is a circuit diagram of the electrical stimulation module and the first filter unit of this utility model;

[0031] Figure 3 This is a waveform diagram of the first PWM signal and the second PWM signal of this utility model;

[0032] Figure 4 This is a table showing the code words and corresponding parameters such as the RWB resistor for the digital potentiometer of this utility model. Detailed Implementation

[0033] The present invention will now be described in further detail with reference to the accompanying drawings.

[0034] refer to Figures 1 to 3 A bioelectric stimulation circuit based on a digital potentiometer includes a PWM signal module 100 and an electrical stimulation module 200.

[0035] The PWM signal module 100 is used to generate a first PWM signal and a second PWM signal, which are PWM signals with opposite timing sequences. The first chip MCU9 is set to generate the first PWM signal, and the second chip MCU8 is set to generate the second PWM signal. Of course, the first PWM signal and the second PWM signal can also be generated by the same chip.

[0036] The electrical stimulation module 200 includes a first digital potentiometer U8 and a second digital potentiometer U9;

[0037] One end of the first digital potentiometer U8 is connected to the first PWM signal via a triode Q7;

[0038] The other end of the first digital potentiometer U8 is connected to the first port J1 via a triode Q8;

[0039] One end of the second digital potentiometer U9 is connected to the first port J1 via a triode Q6;

[0040] The other end of the second digital potentiometer U9 is grounded via transistors Q9 and Q8;

[0041] The second PWM signal is connected to the second port J2.

[0042] Both the first port J1 and the second port J2 are connected to the corresponding electrode plates;

[0043] The first chip MCU9 and the second chip MCU8 each generate two PWM signals with opposite timings. These signals, in conjunction with two digital potentiometers (U8 and U9) and corresponding transistors, form an electrical stimulation circuit, enabling bidirectional current output in a positive and negative pulse manner. Therefore, compared to current solutions using oscillators, MOSFETs, transformers, and H-bridges, the circuit design of this application is simpler and the manufacturing cost is lower.

[0044] refer to Figure 2 The electrical stimulation module 200 also includes a first comparator U10A and a second comparator U10B;

[0045] The first PWM signal is connected to the triode Q7 after passing through the first comparator U10A; the second PWM signal is connected to the second port J2 after passing through the second comparator U10B.

[0046] Therefore, comparators have certain filtering and comparison functions, processing signals and improving the accuracy of PWM signals. For example, comparators can quickly respond to changes in PWM signals, perform level conversion and signal shaping, provide inverted signals, improve control accuracy, enhance anti-interference capabilities, and connect the inverting comparator to the chip, which simplifies circuit design.

[0047] refer to Figure 2 Pin 3 of the first comparator U10A is connected to the first PWM signal. Pin 1 of the first comparator U10A is connected to diode D13 and then to pin 1 of transistor Q7. Pin 3 of transistor Q7 is connected to voltage +9VS. Pin 2 of transistor Q7 is connected to pin 8 of the first digital potentiometer U8. Pin 1 of the first digital potentiometer U8 is connected to pin 1 of transistor Q8. Pin 2 of transistor Q8 is connected to pin 1 of the first comparator U10A. Pin 3 of transistor Q8 is connected to the first port J1 via diode D10.

[0048] Pin 4 of the first comparator U10A is connected to a voltage of -9VS, and pin 8 of the first comparator U10A is connected to a voltage of +9VS.

[0049] Pin 2 of the first comparator U10A is connected to ground after the first filter unit.

[0050] refer to Figure 2 Pin 8 of the second digital potentiometer U9 is connected to pin 2 of transistor Q6, pin 1 of transistor Q6 is connected to the first port J1, and pin 3 of transistor Q6 is connected to voltage -9VS.

[0051] Pin 1 of the second digital potentiometer U9 is connected to pin 1 of transistor Q9. Pin 3 of transistor Q9 is connected to diodes D11 and D10, and then to pin 3 of transistor Q8. Pin 2 of transistor Q8 is connected to pin 1 of the first comparator U10A.

[0052] Pin 5 of the second comparator U10B is connected to the second PWM signal, pin 7 of the second comparator U10B is connected to the second port J2, and pin 6 of the second comparator U10B is connected to the first filter unit and then grounded.

[0053] Working principle:

[0054] When the first PWM signal output by the first chip MCU9 is at a low level and the first PWM signal output by the second chip MCU8 is at a high level, pin 1 of the first comparator U10A outputs -9V and pin 7 of the second comparator U10B outputs +9V. At this time, pin 1 of transistor Q7 is at a high level, and transistor Q7 is turned on. The +9V is input through pin 8 of the first digital potentiometer U8. By controlling the digital potentiometer, the current output from pin 1 is controlled to control the current at pin 3 (collector) of transistor Q8. At this time, pin 3 (collector) of transistor Q8 is at the level of pin 7 of the second comparator U10B after passing through the human body. After passing through transistor Q8, it forms a circuit with pin 1 of the first comparator U10A.

[0055] When the first PWM signal output by the first chip MCU9 is at a high level and the first PWM signal output by the second chip MCU8 is at a low level, pin 1 of the first comparator U10 outputs +9V and pin 7 of the second comparator U10B outputs -9V. At this time, pin 1 of transistor Q6 is at a high level, and transistor Q6 is turned on. The +9V is input through pin 7 of the second digital potentiometer U9. By controlling the digital potentiometer, the output current of pin 1 is controlled to achieve the effect of controlling the current of pin 3 (collector) of transistor Q9. At this time, pin 3 (collector) of transistor Q9 is the level of pin 7 of the second comparator U10B after passing through the human body. After passing through transistor Q8, it forms a circuit with pin 1 of the first comparator U10A.

[0056] Therefore, by using two inverse PWM signals to control the comparator, and in conjunction with two digital potentiometers, a loop is formed to achieve bidirectional current output in a positive and negative pulse manner, which also helps to enhance the consistency of the output current.

[0057] refer to Figure 2 The first filter element unit 400 includes capacitors C33 and C34 connected in parallel, resistors R38 and R40 connected in series and then in parallel with capacitor C34, and capacitor C35 connected in parallel with resistor R40.

[0058] Pin 2 of the first comparator U10A and pin 6 of the second comparator U10B are both connected between resistor R38 and resistor R40.

[0059] Therefore, the first filter unit 400 filters the circuit to reduce interference.

[0060] refer to Figure 2 Resistors R29 and R31 are connected between pins 1 and 3 of transistor Q7. Resistor R29 acts as a voltage divider. Capacitor C27 and resistor R27 are connected to pin 1 of transistor Q7. Capacitor C27 acts as a filter, and resistor R27 acts as an energy absorption protection.

[0061] Resistors R30 and R32 are connected between pins 1 and 3 of transistor Q6. Resistor R30 acts as a voltage divider. Capacitor C28 and resistor R28 are connected to pin 1 of transistor Q6. Capacitor C28 acts as a filter, and resistor R28 acts as a power absorption protection.

[0062] Pin 2 of transistor Q8 is connected to resistor R34 and then to pin 1 of the first comparator U10A; pin 2 of transistor Q9 is connected to resistor R33 and then to pin 1 of the first comparator U10A.

[0063] The comparator model is TLO62CDT; the digital potentiometer model is AD5245BRJZ10-RL7; and the transistor model is MMBT3904.SOT-23.

[0064] Both the frequency and pulse width of the first PWM signal and the second PWM signal can be adjusted.

[0065] The first chip MCU9 and the second chip MCU8 can regulate the signal using their internal timer or counter modules. For example, the timer can be programmed to set its operating mode, such as timing mode or counting mode, thereby achieving precise control over the output signal frequency and pulse width. The first chip MCU9 and the second chip MCU8 are existing technologies, and they inherently possess PWM modulation protocol functionality; this is merely an application of that technology.

[0066] Both the first digital potentiometer U8 and the second digital potentiometer U9 are connected to the third chip MCU via an I2C interface. The third chip MCU can adjust the nodes of the resistor arrays of the first digital potentiometer U8 and the second digital potentiometer U9, thereby adjusting the magnitude of the circuit current.

[0067] Therefore, the digital potentiometer adjusts the nodes of its internal resistor array according to the instructions of the third-party MCU chip, causing the resistance values ​​between the input and output terminals of the digital potentiometer to differ, thereby controlling the output current and adjusting its magnitude. Adjusting the nodes of the resistor array is a function inherent to the digital potentiometer itself; the third-party MCU chip is existing technology and is merely an application here.

[0068] For example, refer to Figure 4 The third chip, the MCU, outputs instructions via the I2C interface to control the values ​​of RWA and RWB of the first digital potentiometer U8. The voltage divided by RWA is the base voltage of transistor Q8, and the base current IB = UWA / RWA, IC = βIB, i.e., IC = βUWA / RWA. RAB has 256 nodes, selected by a cursor. The 8-bit data in the RDAC latch is decoded and used for one of the 256 possibilities, achieving more precise adjustment.

[0069] Similarly, the third chip MCU outputs instructions through the I2C interface to control the values ​​of RWA and RWB of the second digital potentiometer U9.

[0070] The above description only discloses some embodiments of this utility model. For those skilled in the art, various modifications and improvements can be made without departing from the inventive concept of this utility model, and these all fall within the protection scope of this utility model.

Claims

1. A bioelectric stimulation circuit based on a digital potentiometer, characterized in that, Includes a PWM signal module and an electrical stimulation module; The PWM signal module is used to generate a first PWM signal and a second PWM signal, wherein the first PWM signal and the second PWM signal are PWM signals with opposite timing sequences. The electrical stimulation module includes a first digital potentiometer U8 and a second digital potentiometer U9; One end of the first digital potentiometer U8 is connected to the first PWM signal via a triode Q7; The other end of the first digital potentiometer U8 is connected to the first port J1 via a triode Q8; One end of the second digital potentiometer U9 is connected to the first port J1 via a triode Q6; The other end of the second digital potentiometer U9 is grounded via transistors Q9 and Q8; The second PWM signal is connected to the second port J2.

2. The bioelectric stimulation circuit based on a digital potentiometer according to claim 1, characterized in that, The electrical stimulation module also includes a first comparator U10A and a second comparator U10B; The first PWM signal is connected to the triode Q7 after passing through the first comparator U10A; The second PWM signal is connected to the second port J2 after passing through the second comparator U10B.

3. The bioelectric stimulation circuit based on a digital potentiometer according to claim 2, characterized in that, Pin 3 of the first comparator U10A is connected to the first PWM signal. Pin 1 of the first comparator U10A is connected to diode D13 and then to pin 1 of transistor Q7. Pin 3 of transistor Q7 is connected to voltage +9VS. Pin 2 of transistor Q7 is connected to pin 8 of the first digital potentiometer U8. Pin 1 of the first digital potentiometer U8 is connected to pin 1 of transistor Q8. Pin 2 of transistor Q8 is connected to pin 1 of the first comparator U10A. Pin 3 of transistor Q8 is connected to the first port J1 via diode D10.

4. The bioelectric stimulation circuit based on a digital potentiometer according to claim 3, characterized in that, Pin 4 of the first comparator U10A is connected to a voltage of -9VS, and pin 8 of the first comparator U10A is connected to a voltage of +9VS. Pin 2 of the first comparator U10A is connected to ground after the first filter unit.

5. The bioelectric stimulation circuit based on a digital potentiometer according to claim 4, characterized in that, Pin 8 of the second digital potentiometer U9 is connected to pin 2 of transistor Q6, pin 1 of transistor Q6 is connected to the first port J1, and pin 3 of transistor Q6 is connected to voltage -9VS. Pin 1 of the second digital potentiometer U9 is connected to pin 1 of transistor Q9. Pin 3 of transistor Q9 is connected to diode D11 and diode D10, and then to pin 3 of transistor Q8. Pin 2 of transistor Q8 is connected to pin 1 of the first comparator U10A.

6. The bioelectric stimulation circuit based on a digital potentiometer according to claim 5, characterized in that, Pin 5 of the second comparator U10B is connected to the second PWM signal, pin 7 of the second comparator U10B is connected to the second port J2, and pin 6 of the second comparator U10B is connected to the first filter unit and then grounded.

7. The bioelectric stimulation circuit based on a digital potentiometer according to claim 6, characterized in that, The first filter element unit includes capacitors C33 and C34 connected in parallel, resistors R38 and R40 connected in series and then in parallel with capacitor C34, and capacitor C35 connected in parallel with resistor R40. Pin 2 of the first comparator U10A and pin 6 of the second comparator U10B are both connected between resistor R38 and resistor R40.

8. The bioelectric stimulation circuit based on a digital potentiometer according to claim 5, characterized in that, Resistors R29 and R31 are connected between pins 1 and 3 of transistor Q7, and capacitor C27 and resistor R27 are connected to pin 1 of transistor Q7. Resistors R30 and R32 are connected between pins 1 and 3 of transistor Q6, and capacitor C28 and resistor R28 are connected to pin 1 of transistor Q6.

9. A bioelectric stimulation circuit based on a digital potentiometer according to any one of claims 1-8, characterized in that, Both the frequency and pulse width of the first PWM signal and the second PWM signal are adjustable.

10. A bioelectric stimulation circuit based on a digital potentiometer according to any one of claims 1-8, characterized in that, Both the first digital potentiometer U8 and the second digital potentiometer U9 are connected to the third chip MCU via an I2C interface. The third chip MCU can adjust the nodes of the resistor arrays of the first digital potentiometer U8 and the second digital potentiometer U9, thereby adjusting the magnitude of the circuit current.

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