Skin impedance detection device and skin impedance detection method

Abstract

This invention relates to a skin impedance detection device and method, comprising a detection probe, a mechanical drive unit, a force-sensing closed-loop feedback module, a near-ultraviolet array excitation module, a multi-frequency impedance acquisition module, and a data processing unit. This application can induce physiological stress in the skin through 365nm near-ultraviolet pre-irradiation, utilize a stepper motor in conjunction with a force sensor to achieve a constant 1.5N downward pressure on the electrodes, and employs a four-electrode independent drive and a group-by-group contact mode to eliminate electric field coupling interference. Impedance data is acquired through multi-frequency constant current excitation, and based on a nonlinear closed-loop algorithm using logarithmic, exponential, and square operations, the data is converted into the Skin Barrier Index (SBI) and the Inflammatory Skin Index (ILI), significantly improving detection repeatability and clinical discriminability.

Description

Technical Field

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

[0002] Skin impedance can reflect the integrity of the epidermal barrier, dermal microcirculation, tissue inflammation and edema, and has important reference value in auxiliary assessment in dermatology.

[0003] Existing skin impedance detection devices typically have the following shortcomings: 1. Static impedance testing alone cannot reflect the dynamic response of the skin under external stimuli, and is insufficient in distinguishing between sensitive skin, inflamed skin, and skin with a damaged barrier. 2. The electrode arrangement is mostly linear, and the pressing pressure is unstable, resulting in poor detection repeatability; 3. The multi-frequency impedance parameters are numerous and lack a closed computing system bound to the hardware structure, resulting in poor clinical readability; 4. The lack of integration of optical excitation and impedance detection makes it impossible to obtain stable skin photoresponse characteristics; 5. Simultaneous contact of multiple electrodes with the skin can easily generate electric field coupling and lateral interference, affecting detection accuracy; 6. Existing composite indices mostly use simple weighting operations, with a single algorithm form and weak technical creativity and differentiation.

[0004] Therefore, to improve the scientific rigor and accuracy of skin condition assessment, there is an urgent need to develop an integrated detection device that combines specific wavelength light excitation, high-precision closed-loop constant force control, and an independent electrode driving mechanism. By introducing a scientific pre-irradiation sequence to induce a stable stress response in the skin, and combining this with a nonlinear closed-loop calculation method strongly integrated with the hardware system, multi-frequency impedance information can be fused into an intuitive clinical reference indicator. This would solve the core problems of low detection accuracy, poor repeatability, and insufficient clinical discrimination in existing technologies. Summary of the Invention

[0005] The purpose of this invention is to provide a skin impedance detection device and a skin impedance detection method to improve the scientificity and accuracy of skin condition assessment.

[0006] To achieve the above objectives, this invention proposes a skin impedance detection device, comprising a detection probe assembly, a mechanical drive power assembly (1), a force sensing closed-loop feedback module, a near-ultraviolet array excitation module, a multi-frequency impedance acquisition module, and a central data processing unit; the detection probe assembly is provided with a stainless steel light shield (3), and an LED-PCB (5) is installed on the top of the stainless steel light shield (3); the mechanical drive power assembly (1) consists of 4 independent drive branches, each drive branch including a stepper motor (1-3), a stepper motor (1-2), and a precision lead screw as an output shaft (1-1), the output shaft (1-1) meshing with the internal thread pair inside the connecting rod (8); the force sensing closed-loop feedback module is connected in series between the connecting rod (8) and the stainless steel electrode (6); the central data processing unit controls the number of drive steps of the stepper motor (1-3) through a PID algorithm based on the pressure signal fed back by the force sensing closed-loop feedback module, so that the stainless steel electrode (6) contacts the skin with constant pressure.

[0007] Furthermore, the near-ultraviolet array excitation module includes 21 UVA-LED arrays (4) distributed on the LED-PCB (5), the emission wavelength of the UVA-LED arrays (4) being 365nm; the inner wall of the stainless steel light-shielding tube (3) is provided with a black matte anodized coating that absorbs scattered light.

[0008] Furthermore, the mechanical drive power assembly (1) is mounted on an aluminum alloy base plate (2), and the aluminum alloy base plate (2) has four D-shaped guide holes; the connecting rod (8) has a D-shaped rod body (8-1) that matches the D-shaped guide holes, and the D-shaped guide holes apply circumferential constraints to the connecting rod (8) to convert the rotational motion of the output shaft (1-1) into the linear displacement of the connecting rod (8).

[0009] Furthermore, the force sensing closed-loop feedback module includes a decoupled three-layer force sensor (7), which consists of an A connecting plate (7-2), a B connecting plate (7-4), and an elastic compressible ring (7-3) sandwiched between the two; the A connecting plate (7-2) is fixedly connected to the linkage rod (8), and the B connecting plate (7-4) serves as the mounting base for the stainless steel electrode (6); the B connecting plate (7-4) is made of polyoxymethylene insulating material.

[0010] Furthermore, there are four stainless steel electrodes (6) arranged in a square. Each stainless steel electrode (6) has a round contact end (6-1) and an M3 screw (6-2) located on the back. The stainless steel electrodes (6) are independently locked to the end of the force sensing closed-loop feedback module by the M3 screw (6-2).

[0011] Furthermore, the central data processing unit is pre-set with group-by-group contact control logic, which controls the mechanical drive power component (1) to perform cyclic operation according to the combination of 6 groups of two-electrode paths formed by four electrodes during the impedance acquisition stage; when one group of paths is detected, the corresponding two stepper motors (1-3) drive the corresponding two stainless steel electrodes (6) to extend and contact the skin, while the other two stainless steel electrodes (6) remain in the retracted position.

[0012] A method for detecting skin impedance includes the following steps: S1: Calculate the layered impedance characteristic quantity based on the average impedance values ​​at five frequencies (10Hz, 100Hz, 1kHz, 10kHz, and 100kHz) obtained by the multi-frequency impedance acquisition module: Skin impedance characteristics: Ze = (Z 10 + 2 × Z 100 ) ÷ 3; Transition layer impedance characteristics: Zt = (Z 1k + Z 10k ) ÷ 2; Dermal impedance characteristics: Zd = Z 100k ; S2: Calculate the frequency gradient characteristic G that reflects the heterogeneity of skin electrophysiology. The formula is: G = (Ze - Zd) ÷ Ze; The phase characteristic P, which reflects the deviation of the tissue dielectric loss, is calculated using the following formula: P = (φ0 - φ) ÷ φ0, where φ0 is a pre-set reference phase angle constant of 45°. S3: Calculates and outputs the Skin Barrier Index (SBI) using a non-linear fusion formula. The formula for calculating the Skin Barrier Index (SBI) is: SBI = K1 × ln(Ze + 1) + K2 × Zt + K3 × (G × G); Where K1=0.18, K2=0.32, K3=42; this index balances the range by logarithmically compressing Ze and amplifies the nonlinear electrical response caused by weak damage to the skin barrier by using the square term of the frequency gradient G. S4: Calculate the skin inflammation response index ILI: ILI = exp( (Ze ÷ Zd - 1) × K4 ) × (φ0 -φ) × (φ0 - φ) × K.

[0013] Compared with the prior art, the advantages of the present invention are: This invention overcomes the shortcomings of traditional skin impedance detection, such as low accuracy, large interference, and unclear clinical significance of parameters, by constructing a detection device with near-ultraviolet excitation, precise constant force control, and independent electrode driving mechanism, and combining it with a nonlinear algorithm that deeply couples hardware characteristics.

[0014] This invention introduces two indices, SBI and ILI, which are intuitive and easy to use in clinical practice. This invention does not lead to automatic diagnosis of diseases, but only provides objective, quantitative, and highly repeatable biophysical reference indicators, providing a reliable engineering technology for auxiliary assessment, efficacy monitoring, and skin research in clinical dermatology. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall structure of the skin impedance detection device in an embodiment of the present invention; Figure 2 This is a schematic diagram of the force sensor in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of the electrode and the linkage in an embodiment of the present invention; Figure 4 This is a schematic diagram of the LED-PCB structure in an embodiment of the present invention; Figure 5 This is an embodiment of the present invention. Figure 1 A-direction view; Figure 6 This is an embodiment of the present invention. Figure 1 View from direction B; Figure 7 The graphs show the five characteristic frequencies of the multi-frequency constant current detection in this embodiment of the invention. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be further described below.

[0017] This invention proposes a skin impedance detection device and a skin impedance detection method, with reference to... Figures 1-6 The skin impedance testing device includes the following structure: Mechanical drive power assembly 1 includes a stepper motor 1-3, a reduction gearbox 1-2, and an output shaft 1-1 (M4 lead screw). Under the control of the MCU, the mechanical drive power assembly 1 rotates the M4 lead screw on the output shaft 1-1, causing the connecting rod 8 to achieve vertical displacement. There are four sets of mechanical drive power assemblies 1 in the device. With the cooperation of the MCU and force sensor 7, they ultimately control the vertical displacement of the four electrodes 6 respectively, so as to keep the force pressed against the skin of the subject constant.

[0018] Output shaft 1-1: This is the rotary output end of the mechanical drive power component 1. It is an M4 lead screw. This lead screw engages with the threaded hole in the connecting rod 8 to realize the vertical movement of the connecting rod 8.

[0019] Reduction gearbox 1-2: The reduction gear set in the mechanical drive power assembly 1, the main shaft is the motor shaft, and the driven shaft is the output shaft 1-1, which is the M4 screw.

[0020] Stepper motor: The power source in the mechanical drive power component 1 is a small stepper motor 1-3, whose rotation speed and step size are controlled by the MCU.

[0021] The base plate 2 is made of aluminum alloy. Four mechanical drive power components 1 are installed on one side of the base plate 2, and a light shielding tube 3 is installed on the other side. There are also four "D" shaped holes on the base plate 2. Four "D" shaped connecting rods 8 pass through these four "D" shaped holes respectively. The reason for the "D" shaped holes is to prevent the connecting rods 8 from being rotated along with the lead screw output shaft 1-1, so as to ensure that they only have vertical displacement.

[0022] Light-shielding cylinder 3: It serves both to shield light and to provide structural support. The outer 50 mm circular stainless steel cylinder of the probe section has a matte black surface treatment to prevent the diffusion of near-ultraviolet light from the inside and to block external light interference. It serves both to block light and to provide support when electrode 6 is subjected to force.

[0023] Near-ultraviolet LED4: It is a 365nm UVA-LED light source. 21 LEDs are evenly mounted on LED-PCB5. The brightness of the LEDs is controlled by constant current.

[0024] LED-PCB5: such as Figure 5 and Figure 6 As shown, 21 UVA-LEDs are mounted on one side of PCB5, and the other end is connected to the leads of 4 force sensors 7, the leads of 4 electrodes 6, power lines, and communication lines with the main MCU. The non-LED side of the circuit board also houses the constant current control circuit for the slave MCU and the LEDs. The slave MCU communicates with the main MCU via I2C.

[0025] Electrode holes 5-1: The four 6.2mm diameter circular through holes on the LED-PCB5 are the through holes for the four electrodes 6.

[0026] Electrode 6: A medical stainless steel electrode 6 in direct contact with the subject's skin, 6mm in diameter. One end in contact with the skin is rounded, and the other end is connected to the B-connector 7-4 of the force sensor 7 via an M3 lead screw on electrode 6. There are four electrodes 6 arranged in a square, with each electrode 6 located at the top of the square, which has a side length of 30mm. During operation, impedance is measured once between every two electrodes 6, for a total of six measurements. During measurement, only the pair of electrodes 6 used for signal acquisition is in contact with the skin with a pressure of 1.5N; the other two electrodes 6 are not in contact with the skin.

[0027] Patient contact end 6-1: The patient contact end 6-1 on electrode 6 has a round head.

[0028] M3 Screw 6-2: The screw on electrode 6 that is assembled with the M3 screw hole 7-1 on the force sensor B connecting plate 7-4.

[0029] Electrode lead 6-3: The electrical signal lead of electrode 6 is connected to LED-PCB5.

[0030] Force Sensor 7: The device contains four force sensors, each consisting of a connecting plate A 7-2, a connecting plate B 7-4, and a central elastic compressible ring 7-3, connected in series between the connecting rod 8 and the electrode 6, all via threaded connections. This sensor is an analog output force sensor 7 with temperature compensation and signal processing functions, an effective range of 0-3N, an overpressure bearing capacity of 30N, and an operating voltage of DC 5V. The entire force transmission channel is powered by a mechanical drive power assembly 1, which generates the force source. This force is transmitted through the output shaft 1-1, connecting rod 8, force sensor 7, and electrode 6 in series, ultimately pressing against the user's skin area being tested.

[0031] M3 screw hole 7-1 on the connecting plate A: connects to M3 screw 8-4 of the connecting rod 8 to realize the transmission of force.

[0032] A connecting plate 7-2: Part of the force sensor 7, with a diameter of 10mm, a height of 6mm, and an M3 screw hole 7-1 in the middle.

[0033] Elastic compressible ring 7-3: This compression ring has a diameter of 8mm and a height of 3mm. Under the action of force, it will produce elastic deformation along the central axis, and it is located between connecting plate A 7-2 and connecting plate B 7-4. This elastic compressible ring 7-3 buffers the force pressing on the user's skin in the entire force transmission channel.

[0034] B connecting plate 7-4: Part of the force sensor 7, it is made of POM (polyoxymethylene) non-metallic material, with a diameter of 10mm and a height of 8mm. It has an M3 screw hole 7-5 in the middle. The reason for choosing non-metallic material is to keep the electrode 6 insulated from other metals and charged bodies.

[0035] M3 screw hole 7-5 on the B connecting plate: connects to M3 screw 6-2 of electrode 6 to realize force transmission.

[0036] The force sensor 7 has three output leads 7-6: positive power supply, negative power supply, and analog output, which are connected to LED-PCB5.

[0037] Linkage rod 8: There are 4 of them in the equipment. They are D-shaped cylinders made of metal with a diameter of 10mm. One end is an M4 threaded hole, and the other end is an M3 screw. The D-shaped connecting rod passes through the corresponding D-shaped hole on the bottom liner 2.

[0038] Linkage rod body 8-1.

[0039] M4 threaded hole 8-2: connected to the output shaft 1-1 of the mechanical drive power component 1. The rotation of the output shaft 1-1 drives this connecting rod 8 to move vertically.

[0040] Plane 8-3: The plane 8-3 section on the connecting rod is made to have a "D-shaped" anti-rotation form. The "D-shaped" connecting rod passes through the "D-shaped" hole on the corresponding bottom plate 2 to prevent rotation.

[0041] M3 screw 8-4 is assembled and connected to M3 screw hole 7-1 on force sensor A connecting plate 7-2.

[0042] Based on the above structure: four electrodes, each 6 mm in diameter, are arranged in a square at the four vertices, with a 30 mm spacing between adjacent electrodes. The four electrodes can form six pairs of electrically connected combinations. A force sensor and a motor-driven constant force module are used; the device employs an automatic motor-driven pressing method. A high-precision force sensor is connected in series above each electrode to collect the contact pressure between the electrode and the skin in real time. The system forms a closed-loop control through force sensor feedback, automatically adjusting the motor's pressing stroke to ensure that the contact pressure of each electrode is accurately and stably maintained at 1.5 N at the moment of detection, eliminating system errors caused by pressure fluctuations.

[0043] Independent electrode driving and group-by-group contact detection mechanism: The four electrodes adopt an independent driving, group contact, and group-by-group detection mode, rather than contacting the skin simultaneously.

[0044] When testing a set of electrical pathways, only two electrodes in that set are extended by the motor and contact the skin, while the other electrodes remain suspended. After the test of this set is completed, the electrodes are retracted and the next set of tests is performed.

[0045] This method completely avoids electric field coupling, edge interference, and skin micro-deformation errors caused by simultaneous contact of multiple electrodes.

[0046] 365nm near-ultraviolet excitation module A 365nm UVA-LED light source is evenly distributed on the top of the probe. Average illuminance: 0.6-0.7 mW / cm² 2 , The detection procedure is as follows: after continuous irradiation for 25 seconds, the illumination is kept constant, and then impedance data is collected. The impedance data collection involves four electrodes.

[0047] Multi-frequency constant current detection: Five characteristic frequencies were used: The impedance detection signal source is a 45µA constant current unidirectional rectified sine wave, with a maximum open-circuit voltage peak of 5V. (The values ​​are 10 Hz, 100 Hz, 1 kHz, 10 kHz, and 100 kHz.) Figure 7 As shown.

[0048] This invention also relates to a skin impedance detection method, using the skin impedance detection device described above, with the specific detection steps and calculation method as follows: Symbol definition Z 10 Average impedance at 10Hz; Z 100 Average impedance at 100Hz; Z 1k : Average impedance at 1kHz; Z 10k : Average impedance at 10kHz; Z 100k : 100kHz average impedance; φ: average phase angle; φ0: reference phase angle, empirical constant 45°; Ze: epidermal impedance characteristic; Zt: transition layer impedance characteristic; Zd: dermal impedance characteristic; G: frequency gradient characteristic; P: phase characteristic; SBI: skin barrier comprehensive index; ILI: skin inflammation response index; ln: natural logarithm; exp: natural exponent.

[0049] (iv) System empirical constants K1 = 0.18; K2 = 0.32; K3 = 42; K4 = 0.25; K5 = 6.8; φ0 = 45° All the above constants were obtained by fitting a large amount of measured data from this system.

[0050] Testing process Place the probe over the skin area to be tested; Turn on the 365nm ultraviolet LED at 0.6-0.7 mW / cm². 2 Continuous irradiation for 25 seconds; Keep the lighting constant and start the motor drive module; According to the 6 sets of power-on combinations, extend the electrodes one by one → stabilize the force sensor at 1.5N → collect the impedance → retract the electrodes; The arithmetic mean of the six sets of electrode pathway data was calculated. Calculate SBI and ILI using the closed nonlinear algorithm of this system; Two comprehensive parameters are output for clinical reference.

[0051] Calculation method (closed nonlinear system, applicable only to this invention) Step 1: Calculate the layered impedance characteristics Skin impedance characteristics: Ze = (Z 10 + 2 × Z 100 ) ÷ 3 Transition layer impedance characteristics: Zt = (Z 1k + Z 10k ) ÷ 2 Dermal impedance characteristics: Zd = Z 100k Step 2: Calculate intermediate features Frequency gradient characteristics: G = (Ze - Zd) ÷ Ze Phase characteristics: P = (φ0 - φ) ÷ φ0 Step 3: Calculate the Skin Barrier Index (SBI) (non-linear: logarithmic + squared). SBI = K1 × ln(Ze + 1) + K2 × Zt + K3 × (G × G) Step 4: Calculate the skin inflammation response index ILI (non-linear: exponential + squared). ILI = exp( (Ze ÷ Zd - 1) × K4 ) × (φ0 - φ) × (φ0 - φ) × K5 Specific implementation calculation example (1) Input data (measured after 25 seconds of ultraviolet irradiation) Z 10 = 180 Z 100 = 160 Z 1k = 115 Z 10k = 109 Z 100k = 60 φ = 28° (2) Calculate the hierarchical features Ze = (180 + 2×160) ÷ 3 = 166.67 Zt = (115 + 109) ÷ 2 = 112 Zd = 60 (3) Calculate intermediate quantities G = (166.67 - 60) ÷ 166.67 = 0.640 P = (45 - 28) ÷ 45 = 0.378 (4) Calculate SBI ln(Ze + 1) = ln(167.67) ≈ 5.126 SBI = 0.18×5.126 + 0.32×112 + 42×(0.640×0.640) SBI = 0.923 + 35.84 + 42×0.4096 SBI = 0.923 + 35.84 + 17.203 SBI = 53.966 (5) Calculate ILI Ze÷Zd-1 = 166.67÷60-1 ≈ 2.778-1 = 1.778 exp(1.778×0.25) = exp(0.4445) ≈ 1.559 (45-28) 2 = 17 2 = 289 ILI = 1.559 × 289 × 6.8 ILI = 1.559 × 1965.2 ILI = 3063.75 (6) Output results Skin Barrier Index (SBI) = 53.97 Skin inflammation index (ILI) = 3063.75 This device does not provide disease diagnosis; it only outputs the aforementioned objective parameters.

[0052] The technical effects of the present invention will be further illustrated below through specific embodiments: The Skin Barrier Index (SBI) and the Inflammatory Skin Index (ILI) proposed in this invention are quantitative parameters obtained after 25 seconds of weak ultraviolet irradiation at 365nm. They objectively reflect the differences in impedance characteristics under different physiological and pathological skin conditions and have a stable correlation with the degree of skin barrier damage, inflammatory activity, tissue edema, and stress response characteristics. The hardware and algorithms involved in this patent are still in the early stages of development. During this stage, 192 clinical samples were tested. These cases were patients diagnosed by clinicians, and the results are as follows: 30 cases of healthy skin Because the stratum corneum structure is intact, the epidermal resistance is high, and there is no obvious inflammation or edema, it presents as follows: SBI is high (60-92), ILI is low (10-1050).

[0053] 26 cases of atopic dermatitis (acute phase) The epidermal barrier is severely damaged, accompanied by significant epidermal edema, dermal congestion, and inflammatory infiltration, manifesting as: SBI was significantly low (20–40), and ILI was significantly high (2500–4500).

[0054] 28 cases of atopic dermatitis (chronic phase / lichenification) Thickened stratum corneum with disordered structure, persistently impaired barrier function, and relatively mild inflammation, manifested as: SBI is low (27-52), ILI is moderately high (1510-2730).

[0055] 32 cases of acute eczema / exudative eczema Epidermal intercellular edema and significant tissue fluid exudation were observed, along with a markedly increased cell membrane permeability, manifesting as: SBI was significantly low (15–35), while ILI was extremely high (2910–5000).

[0056] 22 cases of seborrheic dermatitis Abnormal sebaceous gland secretion, mild epidermal inflammation with barrier damage, manifests as: SBI is low to moderate (40-60), ILI is moderate (1200-2200).

[0057] 18 cases of contact dermatitis (allergic / irritant). Characterized by acute epidermal inflammation, edema, and erythema, it manifests as follows: SBI was moderately low (35-55), while ILI was significantly high (2200-3500).

[0058] 8 cases of psoriasis (plastic psoriasis vulgaris) Abnormal epidermal keratinization and rapid proliferation, accompanied by dermal vasodilation and inflammatory infiltration, manifest as: SBI is low (25-45), ILI is high (2090-3200).

[0059] 28 cases of simple dryness, senile dryness, and asteatotic eczema The main characteristics are decreased stratum corneum moisture content and weakened barrier function, without obvious inflammation and edema, manifested as: A low SBI (35-55) and a low or normal ILI (30-1200) can clearly distinguish it from inflammatory skin diseases.

[0060] The Skin Barrier Index (SBI) and Skin Inflammatory Response Index (ILI) described in this invention are currently in the early stages of research and development. Therefore, this patent can clearly establish the corresponding relationship between the parameters and the above 8 different skin conditions, but it cannot yet provide strict diagnostic thresholds for these 8 skin conditions, nor can it provide parameters and related thresholds for other skin diseases. This needs to be further established and determined through big data statistics and machine learning analysis methods after the technology of this patent is applied on a large scale and after the collection of objective data from multiple centers and large samples is completed, in order to ensure the universality, accuracy and clinical applicability of the thresholds.

[0061] The above are merely preferred embodiments of the present invention and do not constitute any limitation on the present invention. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and content disclosed in the present invention without departing from the scope of the present invention shall be deemed to have remained within the protection scope of the present invention.

Claims

1. A skin impedance detecting apparatus characterized by comprising: The system includes a detection probe assembly, a mechanical drive power assembly (1), a force sensing closed-loop feedback module, a near-ultraviolet array excitation module, a multi-frequency impedance acquisition module, and a central data processing unit. The detection probe assembly is equipped with a stainless steel light shield (3), and an LED-PCB (5) is installed on the top of the stainless steel light shield (3). The mechanical drive power assembly (1) consists of four independent drive branches, each of which includes a stepper motor (1-3), a stepper motor (1-2), and a precision lead screw as an output shaft (1-1). The output shaft (1-1) meshes with the internal thread pair inside the connecting rod (8). The force sensing closed-loop feedback module is connected in series between the connecting rod (8) and the stainless steel electrode (6). The central data processing unit controls the number of drive steps of the stepper motor (1-3) through a PID algorithm based on the pressure signal fed back by the force sensing closed-loop feedback module, so that the stainless steel electrode (6) contacts the skin with constant pressure.

2. The skin impedance detection device according to claim 1, characterized in that, The near-ultraviolet array excitation module includes 21 UVA-LED arrays (4) distributed on the LED-PCB (5). The emission wavelength of the UVA-LED arrays (4) is 365nm. The inner wall of the stainless steel light shield (3) is provided with a black matte anodized coating that absorbs scattered light.

3. The skin impedance detection device according to claim 1, characterized in that, The mechanical drive power assembly (1) is mounted on an aluminum alloy base plate (2), and the aluminum alloy base plate (2) has four D-shaped guide holes. The connecting rod (8) has a D-shaped rod body (8-1) that matches the D-shaped guide holes. The D-shaped guide holes apply circumferential constraints to the connecting rod (8) to convert the rotational motion of the output shaft (1-1) into the linear displacement of the connecting rod (8).

4. The skin impedance detection device according to claim 1, characterized in that, The force sensing closed-loop feedback module includes a decoupled three-layer force sensor (7), which consists of an A connecting plate (7-2), a B connecting plate (7-4), and an elastic compressible ring (7-3) sandwiched between the two. The A connecting plate (7-2) is fixedly connected to the linkage rod (8), and the B connecting plate (7-4) serves as the mounting base for the stainless steel electrode (6). The B connecting plate (7-4) is made of polyoxymethylene insulating material.

5. The skin impedance detection device according to claim 1, characterized in that, There are four stainless steel electrodes (6) arranged in a square. Each stainless steel electrode (6) has a round contact end (6-1) and an M3 screw (6-2) located on the back. The stainless steel electrodes (6) are independently locked to the end of the force sensing closed-loop feedback module by the M3 screw (6-2).

6. The skin impedance detection device according to claim 1, characterized in that, The central data processing unit is pre-set with a group-by-group contact control logic, which controls the mechanical drive power component (1) to perform cyclic operation according to the six groups of two-electrode paths formed by the four electrodes during the impedance acquisition stage; when one group of paths is detected, the corresponding two stepper motors (1-3) drive the corresponding two stainless steel electrodes (6) to extend and contact the skin, while the other two stainless steel electrodes (6) remain in the retracted position.

7. A method for detecting skin impedance, using the skin impedance detection device as described in any one of claims 1-6, characterized in that, Includes the following steps: S1: Calculate the layered impedance characteristic quantity based on the average impedance values ​​at five frequencies (10Hz, 100Hz, 1kHz, 10kHz, and 100kHz) obtained by the multi-frequency impedance acquisition module: Epidermal impedance characteristic: Ze = (Z 10 + 2 × Z 100 ) ÷ 3; transition layer impedance feature: Zt = (Z 1k + Z 10k ) ÷ 2; Dermal impedance characteristics: Zd = Z 100k ; S2: Calculate the frequency gradient characteristic G that reflects changes in skin electrophysiological heterogeneity. The formula is: G = (Ze - Zd) ÷ Ze; The phase characteristic P, which reflects the deviation of the tissue dielectric loss, is calculated using the following formula: P = (φ0 - φ) ÷ φ0, where φ0 is a pre-set reference phase angle constant of 45°. S3: Calculates and outputs the Skin Barrier Index (SBI) using a non-linear fusion formula. The formula for calculating the Skin Barrier Index (SBI) is: SBI = K1 × ln(Ze + 1) + K2 × Zt + K3 × (G × G); Where K1=0.18, K2=0.32, K3=42; this index balances the range by logarithmically compressing Ze and amplifies the nonlinear electrical response caused by weak damage to the skin barrier by using the square term of the frequency gradient G. S4: Calculate the skin inflammation response index ILI: ILI = exp( (Ze ÷ Zd - 1) × K4 ) × (φ0 - φ)× (φ0 - φ) × K.

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