Skin impedance detection device and method

Abstract

The application discloses a skin impedance detection device and method, which is used for detecting the impedance of the skin of a user and recommending different electric stimulation current intensities according to the skin impedance. The device comprises an excitation voltage division module, a voltage acquisition module, an external load module and a signal conditioning module. The excitation voltage division module is connected with the external load module to generate a first voltage node and a second voltage node, and the external load module is used for being in contact with the skin to generate an external load voltage. The voltage acquisition module comprises a first voltage sampling module and a second voltage sampling module. The first voltage sampling module is electrically connected with the excitation voltage division module, and is used for acquiring the node voltage of the first voltage node. The input end of the signal conditioning module is electrically connected with the second voltage node, and the output end of the signal conditioning module is electrically connected with the second voltage sampling module. The second voltage sampling module is used for acquiring the node voltage of the second voltage node after conditioning.

Description

Technical Field

[0001] This application relates to the field of detection technology, and in particular to a skin impedance detection device and method. Background Technology

[0002] With the continuous development of electrical stimulation technology, electrical stimulation products are increasingly widely used in daily life and medical rehabilitation, including various types of products such as electrical stimulation massagers and electrical stimulation rehabilitation training devices, which are used to relieve muscle fatigue and assist in the recovery of limb function in different scenarios.

[0003] Skin impedance is influenced by a variety of factors, and there are significant differences in skin impedance among different people, different body parts, and different environments. During the use of electrical stimulation products, the magnitude of skin impedance directly affects the current conduction efficiency, thereby affecting the electrical stimulation effect and safety. If the skin impedance is too high, the electrical stimulation effect will be poor, and the expected massage or rehabilitation effect cannot be achieved. If the skin impedance is too low, it may cause irritation and stinging sensation to the skin, and may even pose safety hazards.

[0004] However, most electrical stimulation products on the market currently use fixed current settings or manual adjustment by the user. Users are forced to blindly try different current levels based on their subjective feelings to test the appropriate intensity, which is inconvenient and affects the user experience and the effectiveness of the stimulation. Furthermore, users may experience poor stimulation, skin discomfort, or even safety risks in extreme cases due to a mismatch between the current intensity and skin impedance. Summary of the Invention

[0005] This application discloses a skin impedance detection device and method for detecting the impedance of a user's skin and recommending different electrical stimulation current intensities based on the skin impedance.

[0006] In a first aspect, this application provides a skin impedance detection device, comprising:

[0007] The system includes an excitation voltage divider module, a voltage acquisition module, an external load module, and a signal conditioning module. The excitation voltage divider module is connected to the external load module to generate a first voltage node and a second voltage node. The external load module is used to contact the skin to generate an external load voltage. The voltage acquisition module includes a first voltage sampling module and a second voltage sampling module. The first voltage sampling module is electrically connected to the excitation voltage divider module and is used to acquire the node voltage of the first voltage node. The input terminal of the signal conditioning module is electrically connected to the second voltage node, and the signal conditioning module is used to buffer and amplify the node voltage of the second node. The output of the signal conditioning module is electrically connected to the second voltage sampling module, which is used to collect the node voltage of the second voltage node after conditioning.

[0008] Optionally, the excitation voltage divider module includes a sampling resistor R1 and a sampling resistor R9; One end of the sampling resistor R1 is connected to the power supply, and the other end of the sampling resistor R1 is electrically connected to one end of the external load module. One end of the sampling resistor R9 is electrically connected to the other end of the external load module, the other end of the sampling resistor R9 is grounded, and the connection node between the sampling resistor R1 and the sampling resistor R9 is the first voltage node.

[0009] Optionally, the signal conditioning module includes an operational amplifier, resistors R2, R6, R8, and R10; The non-inverting input of the operational amplifier is connected to the second voltage node through the resistor R10, and the inverting input of the operational amplifier is connected to one end of the resistor R2 and one end of the resistor R6, respectively. The other end of resistor R6 is grounded, and the other end of resistor R2 is connected to the output of the operational amplifier; The output of the operational amplifier is also connected to one end of resistor R8, and the other end of resistor R8 is connected to the second voltage sampling module.

[0010] Optionally, the skin impedance detection device further includes a clamping module; The clamping module is electrically connected to the second voltage node and is used to clamp and protect the node voltage of the second voltage node.

[0011] Optionally, the clamping module includes a Zener diode DZ1 and a diode D1; One end of the Zener diode DZ1 is electrically connected to the second voltage node, and the other end of the Zener diode DZ1 is electrically connected to the cathode of the diode D1, while the anode of the diode D1 is grounded.

[0012] Secondly, this application discloses a skin impedance detection method, applied to the first aspect and any optional device of the first aspect, comprising: Obtain the first node voltage and the second node voltage, and calculate the skin impedance value based on the first node voltage and the second node voltage; Based on the skin impedance value, confirm the strength of the corresponding impedance range; The recommended current intensity is calculated based on the skin impedance value and the impedance range strength.

[0013] Optionally, determining the corresponding impedance range strength based on the skin impedance value includes: If the skin impedance value is less than the upper threshold of the preset range, then the skin impedance value corresponds to a low impedance state. If the skin impedance value is within the preset range, then the skin impedance value corresponds to a medium impedance state; If the skin impedance value is greater than the lower threshold of the preset range, then the skin impedance value corresponds to a high impedance state.

[0014] Optionally, the step of calculating the recommended current intensity based on the skin impedance value and the impedance range strength includes: When the skin is determined to be in the low impedance state, the skin impedance value is input into the Sigmoid curve fitting model to calculate the recommended current intensity. When the skin is determined to be in the medium impedance state, the skin impedance value is input into a linear interpolation model to calculate the recommended current intensity. When the skin is determined to be in the high impedance state, the skin impedance value is input into a preset linear compensation model to calculate the recommended current intensity.

[0015] Optionally, the recommended current intensity is calculated by inputting the skin impedance value into a preset linear compensation model, including: Calculate the recommended current intensity using the following formula 1: I=min(9,Isafe)×(1+0.0002×(Zskin 6000); Where I represents the recommended current intensity, Zskin represents the skin impedance value, and Isafe represents the preset safe current value of the electrical stimulation device.

[0016] Optionally, after calculating the recommended current intensity based on the skin impedance value and the impedance range strength, the method further includes: The voltage of the first node and the voltage of the second node are continuously acquired in real time, and the second skin impedance value is recalculated. The second skin impedance value is compared with the skin impedance value. If the comparison result exceeds a preset threshold, the impedance range strength is reconfirmed and the recommended current intensity is recalculated based on the new impedance range strength and the second skin impedance value.

[0017] As can be seen from the above technical solutions, this application has the following advantages: The signal conditioning module buffers and amplifies the signal at the second voltage node, which not only solves the problem of signal distortion caused by shunting of subsequent circuits under high-impedance skin conditions, but also adapts the signal to the input characteristics of the sampling module through impedance matching and amplitude adjustment, avoiding sampling errors caused by excessively low signal amplitude or impedance mismatch, thus significantly improving the accuracy and stability of skin impedance detection.

[0018] An external load module generates an external load voltage by attaching electrodes to the user's skin, enabling the skin impedance detection device to directly detect the skin. A first voltage sampling module and a second voltage sampling module are configured to collect the voltages at the first and second voltage nodes, respectively. By combining the voltage data from these two nodes, the relationship between skin impedance and the voltages of various parts of the circuit can be accurately analyzed, improving the accuracy and reliability of the detection results. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 A circuit diagram of the skin impedance detection device provided in this application; Figure 2 A schematic flowchart of the skin impedance detection method provided in this application; Figure 3 A flowchart illustrating the method for confirming impedance interval strength provided in this application; Figure 4 A flowchart illustrating the method for calculating the recommended current intensity provided in this application; Figure 5 This is a flowchart illustrating the method for resetting the recommended current intensity provided in this application. Detailed Implementation

[0021] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0022] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0023] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0024] As used in this application specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if detected [the described condition or event]" may be interpreted, depending on the context, as meaning "once determined," "in response to determination," "once detected [the described condition or event]," or "in response to detection [the described condition or event]."

[0025] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0026] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not an embodiment," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0027] Based on this, this application discloses a skin impedance detection device and method for detecting the impedance of a user's skin and recommending different electrical stimulation current intensities based on the skin impedance.

[0028] The technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0029] Please see Figure 1 This application provides an embodiment of a skin impedance detection device, comprising: The system includes an excitation voltage divider module, a voltage acquisition module, an external load module R5, and a signal conditioning module. The excitation voltage divider module is connected to the external load module R5 to generate the first voltage node and the second voltage node. The external load module R5 is used to contact the skin to generate the external load voltage. The voltage acquisition module includes a first voltage sampling module and a second voltage sampling module. The first voltage sampling module is electrically connected to the excitation voltage divider module and is used to acquire the node voltage of the first voltage node. The input terminal of the signal conditioning module is electrically connected to the second voltage node. The signal conditioning module is used to buffer and amplify the node voltage of the second node. The output of the signal conditioning module is electrically connected to the second voltage sampling module, which is used to collect the node voltage of the second voltage node after conditioning.

[0030] The excitation voltage divider module is connected to the external load module R5, forming a first voltage node and a second voltage node during the connection process. The external load module R5 is in contact with the user's skin through electrodes. When in contact with the skin, due to the physiological characteristics of the skin (such as humidity, stratum corneum thickness, temperature, etc.), the skin has certain resistive characteristics (i.e., impedance value). This impedance value directly affects the current distribution in the series circuit and the potential of the two voltage nodes, thereby generating an external load voltage signal carrying skin impedance information. The excitation voltage divider module, through its own voltage divider characteristics, provides a specific voltage basis for subsequent voltage acquisition.

[0031] The voltage acquisition module consists of a first voltage sampling module and a second voltage sampling module. The first voltage sampling module is directly electrically connected to the first voltage node and acquires the voltage signal of the first voltage node at a preset sampling frequency. The raw voltage signal of the second voltage node is first input to the signal conditioning module. The signal conditioning module uses a voltage follower circuit composed of operational amplifiers to buffer and transform the signal. On the one hand, it increases the input impedance to prevent the signal of the second voltage node from being shunted and distorted by subsequent circuits; on the other hand, it reduces the output impedance to enhance the driving capability of the signal. At the same time, it appropriately amplifies the signal according to the sampling requirements to make the signal amplitude match the input range of the subsequent sampling module and improve the sampling accuracy. The second voltage node signal, after being processed by the signal conditioning module, is then input to the second voltage sampling module for acquisition. Finally, based on the acquired voltages of the first and second voltage nodes and the current calculation relationship of the series circuit, the device can derive the actual value of the skin impedance.

[0032] In this embodiment, the signal conditioning module buffers and amplifies the signal at the second voltage node, which not only solves the problem of signal distortion caused by shunting of subsequent circuits under high-impedance skin conditions, but also adapts the signal to the input characteristics of the sampling module through impedance matching and amplitude adjustment, avoiding sampling errors caused by excessively low signal amplitude or impedance mismatch, thus significantly improving the accuracy and stability of skin impedance detection.

[0033] The external load module R5 is attached to the user's skin via electrodes to generate an external load voltage, enabling the skin impedance detection device to directly detect the skin. A first voltage sampling module and a second voltage sampling module are configured to collect the voltages at the first and second voltage nodes, respectively. By combining the voltage data from these two nodes, the relationship between skin impedance and the voltages of various parts of the circuit can be accurately analyzed, improving the accuracy and reliability of the detection results.

[0034] In an optional embodiment, the excitation voltage divider module includes sampling resistor R1 and sampling resistor R9; One end of the sampling resistor R1 is connected to the power supply, and the other end of the sampling resistor R1 is electrically connected to one end of the external load module R5. One end of the sampling resistor R9 is electrically connected to the other end of the external load module R5, and the other end of the sampling resistor R9 is grounded. The connection node between the sampling resistor R1 and the sampling resistor R9 is the first voltage node.

[0035] When the power is turned on, since one end of the sampling resistor R1 is connected to the power supply, the current will first flow through the sampling resistor R1. The sampling resistor R1 impedes the current to a certain extent, and according to Ohm's law, a certain voltage drop will be generated across the sampling resistor R1 at this time.

[0036] The other end of sampling resistor R1 is electrically connected to one end of external load module R5, and the other end of external load module R5 is electrically connected to one end of sampling resistor R9, while the other end of sampling resistor R9 is grounded. External load module R5 (electrode pad) is the part in contact with the skin, which has a certain resistance characteristic and can be considered equivalent to a resistor. When external load module R5 is connected to the circuit, the current flowing out of sampling resistor R1 splits into two branches: one branch flows through external load module R5, and the other branch flows through sampling resistor R9. Finally, the currents from the two branches merge and flow to ground.

[0037] The connection points between the external load module R5 and the sampling resistors R1 and R9 are designated as the first voltage node and the second voltage node. According to the voltage divider principle of a series circuit, in the series circuit consisting of sampling resistor R1, external load module R5, and sampling resistor R9 (where external load module R5 can be considered as a resistor connected in series with R1 and R9), the power supply voltage will be distributed across these three resistors. The voltage value at the first voltage node depends on the resistance values ​​of sampling resistors R1 and R9, as well as the resistance value of external load module R5.

[0038] Let the power supply voltage be Usource. According to the principle that the current is the same everywhere in a series circuit, let the current flowing through the circuit be I. Then, Usource = I. (R1+Rload+R9) (where Rload is the equivalent resistance of the external load module R5), and the voltage U1 of the first voltage node = I R9+0 (with the ground terminal as the 0 potential reference point), can also be expressed as U1=(R9 / (R1+Rload+R9)) Usource. When the external load module R5 (i.e., the skin equivalent resistance) changes, the current I flowing through the circuit will change, which will cause the voltage U1 of the first voltage node to change.

[0039] In an optional embodiment, the signal conditioning module includes an operational amplifier, resistors R2, R6, R8, and R10; The non-inverting input of the operational amplifier is connected to the second voltage node through resistor R10, and the inverting input of the operational amplifier is connected to one end of resistor R2 and one end of resistor R6, respectively. The other end of resistor R6 is grounded, and the other end of resistor R2 is connected to the output of the operational amplifier. The output of the operational amplifier is also connected to one end of resistor R8, and the other end of resistor R8 is connected to the second voltage sampling module.

[0040] The non-inverting input of the operational amplifier is connected to the second voltage node via resistor R10. Resistor R10 serves to limit current and provide isolation, preventing the large current from the second voltage node from directly impacting the operational amplifier's input. It also reduces interference from subsequent circuits, ensuring stable signal input. The operational amplifier itself has high input impedance and low output impedance. When the signal from the second voltage node is input to the non-inverting input, the high input impedance of the operational amplifier means it hardly shunts any current, thus preventing a voltage drop at the second voltage node. This provides initial buffering of the input signal, ensuring signal integrity during transmission.

[0041] The inverting input of the operational amplifier is connected to one end of resistor R2 and one end of resistor R6, with the other end of resistor R6 grounded. The other end of resistor R2 is connected to the output of the operational amplifier. This forms a typical negative feedback amplifier circuit, where resistor R2 is the feedback resistor and resistor R6 is the input resistor.

[0042] Based on the "virtual short" and "virtual open" characteristics of the operational amplifier, the relationship between the output voltage Uout and the input voltage Uin can be obtained as: Uout = (1 + R6 / R2)Uin.

[0043] Therefore, this negative feedback circuit amplifies the input signal (the voltage at the second voltage node), and the amplification factor is determined by the resistance values ​​of resistors R2 and R6. By appropriately selecting the resistance values ​​of R2 and R6, the relatively small voltage signal at the second voltage node can be amplified to a suitable range, allowing the subsequent voltage acquisition module to acquire the signal more accurately.

[0044] The other end of resistor R8 is connected to the second voltage sampling module, and the output of the operational amplifier is connected to one end of resistor R8. Resistor R8 here can play a certain role in current limiting and protection, preventing the large current output by the operational amplifier from damaging the subsequent second voltage sampling module. At the same time, it can also improve the signal transmission characteristics to a certain extent, making the output signal more stable.

[0045] In an optional embodiment, the skin impedance detection device further includes a clamping module; The clamping module is electrically connected to the second voltage node and is used to clamp and protect the node voltage of the second voltage node.

[0046] The clamping module includes a Zener diode DZ1 and a diode D1; One end of Zener diode DZ1 is electrically connected to the second voltage node, and the other end of Zener diode DZ1 is electrically connected to the cathode of diode D1. The anode of diode D1 is grounded.

[0047] During skin impedance detection, various factors, such as power fluctuations, external interference, or sudden changes in skin condition, may cause a sharp increase in the voltage at the second voltage node. When the voltage at the second voltage node exceeds the upper limit set by the clamping module, the diode associated with this upper limit clamping will conduct, causing the excess current to be shunted through the diode. This forcibly limits the voltage at the second voltage node to around Vmax, preventing damage to subsequent signal conditioning modules, voltage sampling modules, etc., due to excessive voltage, and ensuring that these modules can operate within the normal voltage range.

[0048] Specifically, when the voltage at the second voltage node rises due to certain reasons (such as power fluctuations, external interference, etc.) and exceeds the reverse breakdown voltage Vmax of the Zener diode DZ1, the Zener diode DZ1 enters the reverse breakdown state and conducts. At this time, the Zener diode DZ1 is equivalent to a voltage-stabilized component, and the voltage across its terminals remains basically around Vmax.

[0049] Excess voltage is applied to Zener diode DZ1, causing current to flow through it to the cathode of diode D1. However, since the anode of diode D1 is grounded, after Zener diode DZ1 is turned on, diode D1 remains reverse-biased (because its anode potential is 0 and its cathode potential is Vmax) and will not conduct. Thus, the current primarily forms a loop through Zener diode DZ1, clamping the voltage at the second voltage node to around Vmax, preventing further voltage increases that could damage subsequent signal conditioning and voltage sampling modules.

[0050] Similarly, when the voltage of the second voltage node drops below the lower limit Vmin set by the clamping module due to some reason (such as circuit failure, excessive signal attenuation, etc.), the diode related to the lower limit clamping will conduct. At this time, current will flow through the diode to supplement the second voltage node with a certain amount of current, so that the voltage of the second voltage node will not continue to drop, but will be clamped at around Vmin, maintaining the voltage at a relatively stable low level, and avoiding signal loss or subsequent modules being unable to recognize the signal properly due to excessively low voltage.

[0051] When the voltage at the second voltage node drops to a certain level, such that the voltage difference between the anode (ground terminal, potential 0) and cathode of diode D1 reaches the forward conduction voltage Vmin of diode D1 (generally about 0.6-0.7V for silicon diodes), diode D1 begins to conduct in the forward direction.

[0052] When diode D1 conducts, it effectively provides a low-impedance path to ground for the second voltage node. If the voltage at the second voltage node continues to drop, current will flow through diode D1 from ground to the second voltage node (from a potential perspective, current flows from a high potential to a low potential), thus supplementing the current and preventing the voltage at the second voltage node from dropping further. For example, if the voltage at the second voltage node drops to near 0V for some reason but has not yet reached the forward conduction voltage of diode D1, once the voltage drops slightly enough to meet the conduction condition, diode D1 will conduct, stabilizing the voltage at a value slightly above 0V and close to the diode's forward conduction voltage. This ensures that the voltage at the second voltage node does not drop too low, preventing subsequent modules from malfunctioning.

[0053] The method described in this application is applied to a skin impedance detection device. Please refer to [link / reference]. Figure 2This application provides an embodiment of a skin impedance detection method, comprising: 101. Obtain the first node voltage and the second node voltage, and calculate the skin impedance value based on the first node voltage and the second node voltage; First, the skin impedance detection device is activated. One end of the sampling resistor R1 in the excitation voltage divider module is connected to the power supply VDD, and the other end of the sampling resistor R1 is electrically connected to one end of the external load module. The other end of the external load module R5 is electrically connected to one end of the sampling resistor R9, and the other end of the sampling resistor R9 is grounded, forming a complete series excitation circuit. The power supply VDD outputs a constant DC excitation signal, causing a stable current I to flow through this series circuit. The current I flowing through this circuit satisfies: ; In the skin impedance detection device, two electrode nodes are set up to contact the skin, designated as the first node and the second node. The voltage of the first node is the potential of the connection node between the sampling resistor R1 and the external load module, and the voltage of the second node is the potential of the connection node between the external load module and the sampling resistor R9. The voltages of the first node Ua1 and the second node Ua2 are as follows: ; ; A voltage acquisition module is connected to two node circuits to measure the voltage difference between the first and second nodes. To ensure the reliability of the measurement results, multiple measurements may be performed and the average value taken to reduce the impact of random errors.

[0054] After acquiring the voltages of the first and second nodes, the skin impedance value is calculated based on the voltage divider principle of a series circuit and Ohm's law. Specifically, according to Ohm's law Z=IU (impedance Z is similar to resistance R in a DC circuit), given the current I passing through the skin and the measured voltage ΔU between the first and second nodes, the skin impedance value Z can be calculated. First, the voltage difference ΔU across the external load module (i.e., the skin's equivalent impedance Zskin) is calculated. ΔU is equal to the difference between the voltages of the first and second nodes. ; Then, by combining Ohm's law to derive the skin impedance value Zskin, the accurate calculation of the skin impedance value is completed: .

[0055] 102. Based on the skin impedance value, determine the corresponding impedance range strength; Based on the physiological characteristics of human skin impedance and the actual needs of electrical stimulation therapy, three differentiated impedance ranges are pre-defined. The division of each range is based on skin hydration, stratum corneum state, and conductivity, with clear range thresholds to achieve precise classification. For example, the ranges are divided as follows: the low impedance range is a skin impedance value Zskin < 2kΩ, corresponding to a state of high skin hydration, thin stratum corneum, and good conductivity; the medium impedance range is 2kΩ ≤ Zskin ≤ 6kΩ, corresponding to a state where the stratum corneum forms a complete barrier, is not excessively keratinized or dry, and has moderate conductivity; the high impedance range is Zskin > 6kΩ, corresponding to a state of strong skin insulation, thick or dry stratum corneum, and poor conductivity.

[0056] The skin impedance value Zskin calculated in step 101 is compared one by one with the three preset impedance interval thresholds mentioned above, and the impedance interval strength corresponding to the skin impedance value is determined based on the comparison results.

[0057] The method for confirming the impedance range strength is described in detail in subsequent embodiments, and will not be repeated here.

[0058] 103. The recommended current intensity is calculated based on the skin impedance value and the impedance range strength.

[0059] Based on the different impedance ranges identified in step 102, and combined with the specific values ​​of skin impedance, a differentiated quantitative calculation model is adopted to calculate the corresponding recommended current intensity, taking into account the efficacy, safety, and user comfort of electrical stimulation.

[0060] If the strength in the corresponding low impedance range is confirmed, a Sigmoid curve fitting calculation model is used. If the strength in the corresponding medium impedance range is confirmed, a linear interpolation calculation model is used. If the strength in the corresponding high impedance range is confirmed, a constant current compensation calculation model is used.

[0061] By substituting the skin impedance value Zskin obtained in step 101 into the calculation model of the corresponding intervals mentioned above, the recommended current intensity that is suitable for the current skin condition can be accurately calculated, thus completing the matching of skin impedance detection and electrical stimulation current intensity.

[0062] The method for calculating the recommended current intensity is described in detail in subsequent embodiments, and will not be repeated here.

[0063] Please see Figure 3 This application provides an embodiment of a method for confirming the strength of an impedance interval, comprising: 201. If the skin impedance value is less than the upper threshold of the preset range, the skin impedance value corresponds to a low impedance state. 202. If the skin impedance value is within the preset range, the skin impedance value corresponds to the medium impedance state; 203. If the skin impedance value is greater than the lower threshold of the preset range, the skin impedance value corresponds to a high impedance state.

[0064] First, thresholds for dividing skin impedance ranges were preset. Combining human skin physiological characteristics, electrical stimulation treatment needs, and clinical trial data, the upper threshold for dividing low and medium impedance was determined to be 2kΩ, and the lower threshold for dividing medium and high impedance was determined to be 6kΩ. 2kΩ is the critical reference value for skin hydration and stratum corneum thickness, corresponding to a clear dividing point for skin conductivity. 6kΩ corresponds to the critical value where skin insulation begins to significantly increase. Based on clinical data, when skin impedance exceeds 6kΩ, current penetration efficiency will decrease significantly, and a compensation mechanism is needed to increase the current intensity to ensure treatment effectiveness.

[0065] The calculated skin impedance value Zskin is compared with a 2kΩ threshold. If Zskin < 2kΩ, meaning the skin impedance value is less than the upper threshold of the preset range, the skin impedance value is determined to be in a low impedance state. In this state, the skin has high hydration, a thin stratum corneum, and no obvious dryness or keratin buildup on the skin surface. It also exhibits good conductivity, allowing current to easily penetrate the skin surface and act on deeper tissues. Therefore, during electrical stimulation, the current intensity must be controlled to avoid excessive current and skin stinging caused by good conductivity.

[0066] The calculated skin impedance value Zskin is compared with the two threshold intervals mentioned above. If Zskin is detected to be between 2kΩ and 6kΩ (inclusive), meaning the skin impedance value is within the threshold interval, then the skin impedance value is determined to be in a medium impedance state. In this state, the stratum corneum has formed a complete barrier, without excessive keratinization, dryness, or overhydration. The conductivity is at a moderate level, and the skin impedance and current penetration efficiency show an approximately linear negative correlation, making it one of the optimal states for electrical stimulation therapy.

[0067] The calculated skin impedance value Zskin is compared with a 6kΩ threshold. If Zskin > 6kΩ, meaning the skin impedance value is greater than the lower threshold of the preset range, the skin impedance value is determined to be in a high impedance state. In this state, the skin has strong insulation, often corresponding to thick stratum corneum, dry skin, and severe keratin buildup. Its conductivity is poor, making it difficult for current to penetrate the skin surface to reach the expected stimulation depth. In this case, a specific current compensation mechanism is needed to increase the current intensity within a safe range to ensure that the therapeutic effect of electrical stimulation is not diminished.

[0068] It should be noted that the threshold values ​​(2kΩ, 6kΩ) of the preset interval in this embodiment can be finely adjusted according to the actual application scenario, device type and target population, but the core division logic remains unchanged, achieving accurate classification of skin impedance status, and the judgment process does not require manual intervention and can be automatically completed by the skin impedance detection device, ensuring judgment efficiency and accuracy.

[0069] In addition, during the determination process, the device will verify the skin impedance value in real time. If abnormal fluctuations in the impedance value are detected (such as momentarily exceeding the threshold range), multiple sampling and verification will be performed to avoid determination errors caused by factors such as poor skin contact and environmental interference. This ensures that the confirmation of the impedance range strength is true and reliable, providing an accurate range basis for the calculation of the recommended current intensity in the subsequent step 103.

[0070] Please see Figure 4 This application provides an embodiment of a method for calculating recommended current intensity, comprising: 301. When the skin is determined to be in a low impedance state, the skin impedance value is input into the Sigmoid curve fitting model to calculate the recommended current intensity. First, confirm the determination result of step 201 above. When the skin impedance value Zskin < 2kΩ, that is, when the skin is determined to be in a low impedance state, start the preset Sigmoid curve fitting model. The design of this model is based on the skin physiological characteristics and electrode polarization effect in a low impedance state. The purpose is to avoid the exponential increase in pain caused by linearly increasing the current, while ensuring that the current intensity can reach the basic stimulation threshold, taking into account both safety and basic efficacy.

[0071] The core logic of this Sigmoid curve fitting model is logarithmic compression, which adapts to the characteristics of good skin conductivity and easy current penetration under low impedance conditions. The specific expression of the model is as follows: ; Where I is the recommended current intensity (unit: mA), and Zskin is the skin impedance value calculated in step 101 (unit: Ω).

[0072] The skin impedance value is accurately substituted into the above model, and the corresponding recommended current intensity is calculated through curve fitting. At the same time, to further ensure safety, the upper limit of the current intensity is set to 3mA. That is, no matter what the model calculation result is, the final output recommended current intensity will not exceed 3mA, so as to avoid discomfort such as skin stinging and burning caused by excessive skin conductivity and excessive current, and to ensure the safety and comfort of electrical stimulation under low impedance.

[0073] 302. When the skin is determined to be in a medium impedance state, the skin impedance value is input into the linear interpolation model to calculate the recommended current intensity; Confirming the determination result of step 202 above, when the skin impedance value is 2kΩ≤Zskin≤6kΩ, that is, when the skin is determined to be in a medium impedance state, the preset linear interpolation model is activated. The design of this model is based on the conductivity characteristics of the skin in a medium impedance state. At this time, the stratum corneum of the skin is intact, and the skin impedance and the current penetration efficiency are approximately linearly negatively correlated. That is, for every 1kΩ increase in impedance, the current that effectively penetrates the skin decreases by about 40%~50%. Therefore, it is necessary to increase the current intensity through linear interpolation to maintain a stable stimulation dose.

[0074] The core logic of this linear interpolation model is to linearly adjust the current intensity based on changes in skin impedance to ensure stable current penetration efficiency. The specific expression of the model is as follows: ; Where I is the recommended current intensity (unit: mA), and Zskin is the skin impedance value calculated in step 101 (unit: Ω).

[0075] After substituting the skin impedance value into the model, the corresponding recommended current intensity is calculated through linear interpolation. The output range of the model is adapted to the skin characteristics under medium impedance conditions. This ensures that the current intensity exceeds the motion threshold to achieve the expected electrostimulation treatment or health care effect, while avoiding the attenuation of efficacy or skin discomfort due to excessively high or low current, thus achieving stable control of the stimulation dose.

[0076] 303. When the skin is determined to be in a high impedance state, the skin impedance value is input into the preset linear compensation model to calculate the recommended current intensity.

[0077] Confirming the determination result of step 203 above, when the skin impedance value Zskin > 6kΩ, that is, when the skin is determined to be in a high impedance state, the preset linear compensation model is activated. The design of this model is based on the insulation characteristics of the skin under high impedance state and the clinical safety standard (GB / T13870.1). The core purpose is to increase the current intensity through linear compensation to ensure that the current can penetrate the skin to reach the expected stimulation depth, while strictly controlling the upper limit of the current to avoid safety hazards.

[0078] The core logic of this linear compensation model is constant current compensation, which means that as the skin impedance increases, the current intensity is increased synchronously to maintain the current density per unit area of ​​the skin surface above the treatment threshold. The specific expression of the model is as follows: ; Where I is the recommended current intensity (unit: mA), Zskin is the skin impedance value calculated in step 101 (unit: Ω), Isafe is the preset safe current value of the electrical stimulation device, and min(9,Isafe) is used to clamp the upper limit of the current intensity to within 9mA (refer to GB / T13870.1 standard, short-term contact current exceeding 10mA has the risk of causing fibrillation).

[0079] After substituting the skin impedance value into the model, the corresponding recommended current intensity is obtained through linear compensation calculation. The slope of 0.0002 in the model is the active boost compensation coefficient, which can achieve a smooth boost when the impedance increases, ensuring that the therapeutic effect of electrical stimulation does not decrease, while strictly adhering to the safety limits, thus balancing efficacy and safety.

[0080] It should be noted that the three preset calculation models (Sigmoid curve fitting model, linear interpolation model, and linear compensation model) in this embodiment are all designed based on the physiological characteristics of human skin, clinical trial data, and safety standards. The model parameters can be fine-tuned according to the actual application scenario, device type (such as massage device, rehabilitation training device), and target population (such as adults and the elderly), but the core adaptation logic remains unchanged, that is, "different impedance states match different calculation models" to ensure the accuracy and adaptability of the recommended current intensity.

[0081] In addition, during the model calculation process, the device performs a secondary verification of the input skin impedance value to confirm that it is consistent with the determined impedance state, avoiding calculation deviations caused by abnormal fluctuations in impedance value or range determination errors. At the same time, the device performs range verification on the calculated recommended current intensity to ensure that it is within the device's preset safety range, further improving the reliability and safety of the recommended current intensity and providing an accurate and safe basis for the current output of the electrostimulation device.

[0082] In this embodiment, by substituting the skin impedance value Zskin obtained in step 101 into the calculation model of the corresponding steps described above, the recommended current intensity that is suitable for the current skin condition can be accurately calculated. This completes the matching of skin impedance detection and electrical stimulation current intensity, achieving adaptive adjustment of current intensity without manual intervention by the user, thus solving the problem of blind adjustment of current levels in existing electrical stimulation devices.

[0083] Please see Figure 5 This application provides an embodiment of a method for resetting the recommended current intensity, comprising: 401. Continuously acquire the voltage of the first node and the voltage of the second node in real time, and recalculate the second skin impedance value; After calculating and outputting the recommended current intensity, the skin impedance detection device does not stop working but enters continuous monitoring mode, continuously acquiring the first node voltage and the second node voltage in real time according to the preset sampling frequency. The acquisition method is consistent with step 101 to ensure the continuity of the acquisition logic and the consistency of the data. After acquiring the real-time first node voltage and the second node voltage, the calculation logic of step 101 is used to recalculate the real-time skin impedance value, which is defined as the second skin impedance value Zskin'.

[0084] 402. Compare the second skin impedance value with the skin impedance value. If the comparison result exceeds the preset threshold, reconfirm the impedance range strength and recalculate the recommended current intensity based on the new impedance range strength and the second skin impedance value.

[0085] A preset threshold for judging changes in skin impedance (i.e., the comparison threshold) is set based on the physiological characteristics of the skin and the therapeutic needs of electrical stimulation, combined with clinical trial data, and is preset to ±500Ω (which can be finely adjusted according to the type of equipment and the target population).

[0086] The second skin impedance value Zskin' calculated in step 401 is compared with the initial skin impedance value Zskin calculated in step 101, and the absolute difference between the two, |Zskin'-Zskin|, is calculated. If the absolute difference does not exceed the preset ±500Ω threshold, it indicates that the skin impedance state has not changed significantly, the current recommended current intensity is still suitable for the real-time skin state, and no reset is required. The device continues to maintain the current current intensity output and continues to perform the real-time monitoring and calculation in step 401.

[0087] If the absolute difference exceeds the preset ±500Ω threshold, it indicates that the skin impedance has changed significantly (such as the user's skin sweating causing a decrease in impedance, the skin dryness causing an increase in impedance, the slight displacement of the electrode contact position causing a sudden change in impedance, etc.). The current recommended current intensity can no longer adapt to the real-time skin condition. At this time, the reset process is initiated, the device automatically switches to output a new recommended current intensity, completes the reset of the recommended current intensity, and updates Zskin' to the new initial skin impedance value. The continuous monitoring in step 401 continues to be executed, forming a closed loop of dynamic adaptation.

[0088] In this embodiment, by continuously and in real-time acquiring the dual-node voltage and recalculating the second skin impedance value, dynamic monitoring of the skin impedance state is achieved, timely capturing real-time changes in skin impedance, and providing accurate data support for subsequent reset determination. By presetting a reasonable impedance change comparison threshold, accurate determination of skin impedance changes is achieved. When the comparison result exceeds the threshold, dynamic reset of the current intensity is initiated to ensure that the current intensity always adapts to the real-time skin state, avoiding efficacy attenuation or safety hazards caused by impedance changes. At the same time, the reset process is completed automatically without manual intervention by the user, improving the intelligence level and ease of use of the device. Furthermore, the initial impedance value is updated after the reset, forming a dynamic adaptation closed loop, further improving the adaptation accuracy.

[0089] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0090] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces, or indirect coupling or communication connection between apparatuses or units, and may be electrical, mechanical, or other forms.

[0091] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0092] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0093] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

Claims

1. A skin impedance detection device, characterized in that, include: The system includes an excitation voltage divider module, a voltage acquisition module, an external load module, and a signal conditioning module. The excitation voltage divider module is connected to the external load module to generate a first voltage node and a second voltage node. The external load module is used to contact the skin to generate a skin impedance value. The voltage acquisition module includes a first voltage sampling module and a second voltage sampling module. The first voltage sampling module is electrically connected to the excitation voltage divider module and is used to acquire the node voltage of the first voltage node. The input terminal of the signal conditioning module is electrically connected to the second voltage node, and the signal conditioning module is used to buffer and amplify the node voltage of the second voltage node. The output terminal of the signal conditioning module is electrically connected to the second voltage sampling module, which is used to collect the node voltage of the second voltage node after conditioning. The excitation voltage divider module includes sampling resistor R1 and sampling resistor R9; One end of the sampling resistor R1 is connected to the power supply, and the other end of the sampling resistor R1 is electrically connected to one end of the external load module. One end of the sampling resistor R9 is electrically connected to the other end of the external load module, the other end of the sampling resistor R9 is grounded, and the connection node between the sampling resistor R1 and the external load module is the first voltage node; The signal conditioning module includes an operational amplifier, resistors R2, R6, R8, and R10; The non-inverting input of the operational amplifier is connected to the second voltage node through the resistor R10, and the inverting input of the operational amplifier is connected to one end of the resistor R2 and one end of the resistor R6, respectively. The other end of resistor R6 is grounded, and the other end of resistor R2 is connected to the output of the operational amplifier; The output terminal of the operational amplifier is also connected to one end of resistor R8, and the other end of resistor R8 is connected to the second voltage sampling module. The skin impedance detection device also includes a clamping module; The clamping module is electrically connected to the second voltage node and is used to clamp and protect the node voltage of the second voltage node.

2. The skin impedance detection device according to claim 1, characterized in that, The clamping module includes a Zener diode DZ1 and a diode D1; One end of the Zener diode DZ1 is electrically connected to the second voltage node, and the other end of the Zener diode DZ1 is electrically connected to the cathode of the diode D1, while the anode of the diode D1 is grounded.

3. A method for detecting skin impedance, characterized in that, The skin impedance detection device according to any one of claims 1-2 comprises: Obtain the first node voltage and the second node voltage, and calculate the skin impedance value based on the first node voltage and the second node voltage; Based on the skin impedance value, confirm the strength of the corresponding impedance range; The recommended current intensity is calculated based on the skin impedance value and the impedance range strength.

4. The skin impedance detection method according to claim 3, characterized in that, The step of determining the corresponding impedance range strength based on the skin impedance value includes: If the skin impedance value is less than the upper threshold of the preset range, then the skin impedance value corresponds to a low impedance state. If the skin impedance value is within the preset range, then the skin impedance value corresponds to a medium impedance state; If the skin impedance value is greater than the lower threshold of the preset range, then the skin impedance value corresponds to a high impedance state.

5. The skin impedance detection method according to claim 4, characterized in that, The step of calculating the recommended current intensity based on the skin impedance value and the impedance range strength includes: When the skin is determined to be in the low impedance state, the skin impedance value is input into the Sigmoid curve fitting model to calculate the recommended current intensity. When the skin is determined to be in the medium impedance state, the skin impedance value is input into a linear interpolation model to calculate the recommended current intensity. When the skin is determined to be in the high impedance state, the skin impedance value is input into a preset linear compensation model to calculate the recommended current intensity.

6. The skin impedance detection method according to claim 5, characterized in that, The recommended current intensity is calculated by inputting the skin impedance value into a preset linear compensation model, including: Calculate the recommended current intensity using the following formula: I=min(9,Isafe)×(1+0.0002×(Zskin 6000)),Zskin>6kΩ; Where I represents the recommended current intensity, Zskin represents the skin impedance value, and Isafe represents the preset safe current value of the electrical stimulation device.

7. The skin impedance detection method according to any one of claims 3 to 6, characterized in that, After calculating the recommended current intensity based on the skin impedance value and the impedance range strength, the process further includes: The voltage of the first node and the voltage of the second node are continuously acquired in real time, and the second skin impedance value is recalculated. The second skin impedance value is compared with the skin impedance value. If the comparison result exceeds a preset threshold, the impedance range strength is reconfirmed and the recommended current intensity is recalculated based on the new impedance range strength and the second skin impedance value.

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