A method and system for controlling a multispectral therapy device

Abstract

This application discloses a control method and system for a multispectral therapy device, belonging to the field of biomedical engineering. It includes: acquiring an initial bioimpedance reference value for the area to be treated, which includes an initial resistance reference value and an initial phase angle reference value; activating the output of a multi-wavelength light source according to a preset treatment plan, wherein the multi-wavelength light source includes at least a red light source for acting on superficial tissues and a near-infrared light source for acting on deep tissues; collecting tissue complex impedance data during continuous light energy irradiation, including real-time resistance and real-time reactance values; and dynamically adjusting the output power weight of each wavelength light source based on the relative drift of the resistance component and the phase angle offset. This application helps to improve the individualization and safety of treatment.

Description

Technical Field

[0001] This application belongs to the field of biomedical engineering industry, and specifically relates to a control method and system for a multispectral therapy device. Background Technology

[0002] With the continuous advancement of photobiological modulation technology, multispectral therapy devices are increasingly widely used in rehabilitation medicine, cosmetic dermatology, and chronic pain management. By emitting light energy in specific wavelengths, multispectral therapy can act on tissues at different depths in the human body, utilizing photochemical or photothermal effects to regulate cell activity, thereby achieving therapeutic goals such as promoting tissue repair, alleviating inflammation, and improving local blood circulation.

[0003] Among these, the output control scheme of the multispectral therapy equipment is the core to ensure both effectiveness and safety in the treatment process. It primarily adjusts the output power and irradiation sequence of different wavelength light sources to adapt to varying clinical application needs. In actual operation, the controller drives each wavelength light source to emit light radiation of specific intensities according to preset parameter commands, thereby ensuring that the total energy density projected onto the target area meets the corresponding treatment specifications.

[0004] Existing technologies generally employ constant energy output modes based on predetermined schemes, making it difficult to consider individual biological differences among patients in areas such as skin moisture distribution, subcutaneous fat thickness, and melanin deposition. This results in significant uncertainty regarding the actual absorption efficiency of light radiation within tissues. Furthermore, the microcirculatory changes and fluctuations in physiological electrical properties induced by tissue heating during treatment exhibit significant dynamic characteristics. Traditional control logic lacks a closed-loop monitoring mechanism for biophysical parameters and cannot optimize the output weights of each spectrum based on the real-time drift of skin bioimpedance. In addition, due to the lack of feedback sensing capabilities regarding the state of deep tissues and superficial skin, the system often struggles to ensure effective energy coverage while avoiding the risk of local heat accumulation, easily leading to insufficient irradiation dose or local burns, severely hindering the realization of personalized precision treatment. Therefore, a multispectral therapy device control method and system are desired. Summary of the Invention

[0005] The purpose of this invention is to provide a control method and system for a multispectral therapy device, which can effectively solve the problems in the background art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for controlling a multispectral therapy device includes the following specific steps: Obtain the initial bioimpedance reference value of the area to be treated. The initial bioimpedance reference value includes the initial resistance reference value and the initial phase angle reference value. The multi-wavelength light source output is activated according to the preset treatment plan. The multi-wavelength light source includes at least a red light source for acting on the surface tissue and a near-infrared light source for acting on the deep tissue. During continuous light energy irradiation, tissue complex impedance data are collected, including real-time resistance and real-time reactance values. The relative drift of the resistance component is calculated based on the real-time resistance value and the initial resistance reference value. The real-time phase angle is calculated based on the real-time reactance value. The phase angle offset is then calculated based on the real-time phase angle and the initial phase angle reference value. The output power weights of each wavelength light source are dynamically adjusted based on the relative drift of the resistance component and the phase angle offset.

[0007] Furthermore, the acquisition of tissue complex impedance data specifically includes: Establish a synchronous acquisition timing sequence to keep the sampling start point of the bioimpedance acquisition module synchronized with the period start point of the pulse width modulation signal driving the multi-wavelength light source output; Multi-frequency excitation current is injected into the treatment area through excitation electrodes, and the response voltage signal is acquired through measuring electrodes. Synchronous demodulation processing is performed on the response voltage signal. The response voltage signal is multiplied with the in-phase reference signal and the quadrature-phase reference signal respectively. After low-pass filtering, the amplitude of the in-phase component and the amplitude of the quadrature component are obtained. Based on the amplitudes of the in-phase component, the quadrature component, the voltage quantization coefficient, and the excitation current amplitude, the real-time resistance and real-time reactance values ​​are calculated. The real-time resistance value is positively correlated with the amplitude of the in-phase component, and the real-time reactance value is positively correlated with the amplitude of the quadrature component.

[0008] Furthermore, the specific steps for establishing a synchronous acquisition time sequence are as follows: The central controller generates a synchronous clock signal through the timer module. The synchronous clock signal is used to trigger both the period start point of the pulse width modulation module and the sampling start point of the bioimpedance acquisition module, so that the impedance acquisition operation is performed at a fixed phase point of the light source driving cycle.

[0009] Furthermore, the injection of multi-frequency excitation current specifically involves: Injecting an AC excitation current with a frequency range of 1 kHz to 200 kHz into the tissue; The frequency bands of 5 kHz and below are defined as low frequency bands, used to obtain complex impedance data characterizing the impedance characteristics of deep tissues; the frequency bands of 100 kHz and above are defined as high frequency bands, used to obtain complex impedance data characterizing the impedance characteristics of epidermal tissues.

[0010] Furthermore, the dynamic adjustment of the output power weights of each wavelength light source specifically includes: Extract the high-frequency impedance change rate and the low-frequency impedance change rate from the collected tissue complex impedance data; When the impedance change rate in the high-frequency band exceeds the first preset threshold, it is determined that the energy is accumulating too fast in the epidermis, and the output power weight of the red light source is reduced. When the impedance change rate in the low-frequency band exceeds the second preset threshold, it is determined that the energy deposition of deep tissue has reached saturation, and the output power weight of the near-infrared light source is reduced.

[0011] Furthermore, obtaining the initial bioimpedance baseline value of the area to be treated specifically includes: During the static preparation period, multi-frequency excitation current is injected into the treatment area using the four-electrode method, and the induced voltage signal is collected. A multi-frequency impedance spectrum model was constructed to distinguish the difference in initial water content between the superficial and deep dermal tissues. The real and imaginary components of the complex impedance are extracted by phase-sensitive detection to obtain the initial resistance reference value and the initial phase angle reference value.

[0012] Furthermore, it also includes security threshold monitoring and protection triggering steps: Continuously monitor the relative drift of the resistance component and divide the impedance change rate into safe zone, warning zone and danger zone; When the impedance change rate enters the warning zone, the total output power of the multi-wavelength light source is limited to less than 50% of the rated power; When the impedance change rate exceeds the preset burst threshold within a preset time, the power supply to all light source drive circuits is directly cut off, and the heat dissipation components inside the treatment head are activated for forced cooling.

[0013] Furthermore, the dynamic adjustment of the output power weights of each wavelength light source specifically includes: Using the relative drift of the resistance component as the main control variable, the power correction is calculated by applying a proportional-integral-derivative control strategy. During the adjustment process, the duty cycle change step of the pulse width modulation signal is limited to the range of 0.1% to 0.5% to achieve a smooth transition of output power.

[0014] Furthermore, before activating the multi-wavelength light source output according to the preset treatment plan, the following steps are also included: Based on the patient's age, gender, and estimated cortical thickness, the initial power weights of the red light source and the near-infrared light source are calculated using a linear interpolation model. The initial power weights are then normalized to ensure that the total irradiance at the initial moment is within a preset safe ratio range.

[0015] A multispectral therapy device control system includes: The bioimpedance acquisition module is used to acquire the initial bioimpedance reference value of the area to be treated during the static preparation period, and to acquire tissue complex impedance data during continuous light energy irradiation. The initial bioimpedance reference value includes the initial resistance reference value and the initial phase angle reference value, and the tissue complex impedance data includes the real-time resistance value and the real-time reactance value. A multi-wavelength light source driving array, including a red light source for acting on superficial tissues and a near-infrared light source for acting on deep tissues, is used to activate the multi-wavelength light source output according to a preset treatment plan; The central controller is used to calculate the relative drift of the resistance component based on the real-time resistance value and the initial resistance reference value, calculate the real-time phase angle based on the real-time reactance value, calculate the phase angle offset based on the real-time phase angle and the initial phase angle reference value, and dynamically adjust the output power weight of each wavelength light source in the multi-wavelength light source drive array based on the relative drift of the resistance component and the phase angle offset.

[0016] In summary, this application includes at least one of the following beneficial technical effects: 1. This invention constructs a closed-loop control path from tissue state perception to output adjustment by acquiring the initial bioimpedance reference value of the treatment area before treatment and continuously collecting tissue complex impedance data during irradiation. Compared with open-loop control methods that rely solely on preset parameters, this method can reflect the individual tissue differences of patients to a certain extent, giving the adjustment of the light source output power weight a feedback basis related to changes in physiological state, which is conducive to achieving a more individualized treatment process.

[0017] 2. This invention injects multi-frequency excitation current into the tissue and, combined with the analysis of impedance change rates in the high-frequency and low-frequency bands, enables the system to separately sense the state changes of the epidermis and deep tissues under the influence of light energy. Based on this, the system can make differentiated output adjustments for light sources at different depths of action (such as red light sources and near-infrared light sources). This layered control method helps to form a more balanced energy distribution across different tissue depths, reducing the impact of excessively rapid energy deposition in a single layer.

[0018] 3. Based on dynamic adjustment, this invention introduces a safety threshold monitoring mechanism based on impedance change trends. By continuously assessing the degree of tissue state change, the system can take corresponding protective measures at different risk stages. For example, it can limit the total output power when the tissue response is significant, or perform operations such as turning off the light source and starting heat dissipation when abnormal changes occur. This graded response design helps to achieve a certain balance between ensuring treatment continuity and dealing with potential risks.

[0019] 4. In the data acquisition stage, this invention establishes a synchronous timing between bioimpedance acquisition and the light source drive signal, which helps reduce the interference of drive fluctuations on measurement results and improves the reliability of feedback data. In the output adjustment stage, by controlling the step change of duty cycle, the power adjustment process is made smoother, which helps reduce light source flicker or physical discomfort that may be caused by sudden output changes. These designs, to a certain extent, balance system control accuracy and user comfort. Attached Figure Description

[0020] Figure 1 This is an overall schematic diagram of the control method for multispectral therapy equipment; Figure 2 This is the core principle diagram of dynamic adjustment of output power weight of multi-wavelength light sources based on complex impedance feedback; Figure 3 It is a logical flowchart of complex impedance data acquisition, synchronous demodulation and characteristic parameter extraction. Figure 4 It is a logic diagram of output control and safety protection triggering of light sources of various wavelengths based on hierarchical feedback logic. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0022] Firstly, this embodiment discloses a control method for a multispectral therapy device. Its execution logic relies on an embedded hardware system integrating a high-performance central controller, a bioimpedance acquisition module, a multi-wavelength light source drive array, and high-precision sensors. The central controller integrates a timer unit. In this system, the control program constructs a closed-loop energy regulation scheme with a multi-dimensional feedback mechanism by real-time capture and analysis of the electrophysical parameters of biological tissues.

[0023] In the multispectral therapy device control method provided by the present invention, it is carried out according to the following implementation steps, as follows: The first step, S1, involves acquiring the initial bioimpedance baseline value of the area to be treated. Step S1 is performed during the static preparation period before the device formally enters the treatment energy output stage. Its purpose is to accurately collect the initial bioelectrophysical state of the area to be treated under conditions free from light radiation interference. By acquiring this baseline value, the system can establish static physiological background parameters for subsequent dynamic adjustment, providing a reliable comparison benchmark for closed-loop control based on impedance feedback. The specific implementation steps are as follows: Step S101: Perform static preparation and electrode contact. The central controller activates the bioimpedance acquisition module through an internal timer trigger signal. At this time, multiple sets of electrodes integrated at the end of the treatment head form a tight ohmic contact with the skin surface of the area to be treated, establishing a stable electrical interface for subsequent accurate measurements.

[0024] Step S102: Inject multi-frequency excitation current and acquire signals. The initial bioimpedance reference value is obtained by measuring using a 4-electrode method. In this measurement architecture, the four electrodes are divided into two functional units: the two outer electrodes serve as excitation electrodes and are connected to a controlled constant current source excitation circuit; the two inner electrodes serve as measurement electrodes and are connected to a differential amplifier circuit with high input impedance.

[0025] The excitation source is controlled by the central controller to inject a constant amplitude alternating current into the skin tissue. The current intensity is strictly limited to the range of 10 microamps to 500 microamps to ensure that no electric shock sensation or stimulation of the nervous system is generated. At the same time, the frequency of the excitation current is set in the range of 1 kHz to 200 kHz according to the preset control strategy.

[0026] The central controller drives a digital frequency synthesizer to continuously generate excitation signals at multiple preset characteristic frequencies, such as rapid sampling at 5kHz, 20kHz, and 100kHz, thereby executing a multi-frequency scanning mode. In this application, the frequency band of 5kHz and below is defined as the low-frequency band, used to characterize the impedance characteristics of deep tissues (such as subcutaneous fat or muscle layers); the frequency band of 100kHz and above is defined as the high-frequency band, used to characterize the impedance characteristics of epidermal tissues.

[0027] After the induced voltage signal is acquired by the measuring electrodes, the processing circuit at the front end of the system amplifies the signal initially using a differential amplifier circuit composed of a high-precision operational amplifier. Then, an 8th-order Butterworth filter is used to remove the polarization voltage DC component, 50Hz or 60Hz power frequency interference, and high-frequency environmental noise from the signal. This process ensures that the measurement accuracy error of the reference value is within the allowable range of 0.5% to 1%.

[0028] Step S103: Construct a multi-frequency impedance spectrum model. By acquiring impedance modulus and phase angles at different frequencies, the system can construct a multi-frequency impedance spectrum model of the area to be treated. This model is used to distinguish the initial water content differences between superficial dermal tissue and deep fat and muscle tissue. The principle is that different tissue components have significant characteristic differences in polarization response under electric fields of different frequencies.

[0029] For example, cell membranes exhibit high impedance characteristics under low-frequency electric fields, while extracellular fluid exhibits low impedance pathways under high-frequency electric fields. By analyzing the impedance-frequency curves, the state of tissues at different depths can be inferred.

[0030] Step S104: Extract the real and imaginary components of the complex impedance and store the reference value. In the central controller, the system extracts the real and imaginary components of the complex impedance using phase-sensitive detection or fast Fourier transform algorithms. According to the definition of complex impedance, this reference value is expressed as: Z = R + jX.

[0031] Where Z represents the complex impedance vector; R represents the resistive component, which mainly reflects the ion conduction characteristics of extracellular fluid and interstitial fluid; and X represents the reactive component, which mainly reflects the capacitive charge storage characteristics of the cell membrane. The initial complex impedance data obtained are stored in the reference parameter buffer in the high-speed random access memory as static physiological background parameters for subsequent closed-loop regulation.

[0032] In summary, step S1 constitutes the complete process for acquiring static physiological parameters. First, a stable measurement interface is established through four-electrode contact. Then, a safe excitation current is injected into the tissue using multi-frequency scanning technology, and its voltage response is acquired. The acquired signal is filtered, demodulated, and subjected to spectral analysis to ultimately quantify the tissue characteristics into the real and imaginary parts of complex impedance, which are then stored as reference values. This series of operations ensures that the system can accurately acquire the initial bioelectrophysical state of the treatment area before photoelectric intervention.

[0033] After acquiring the initial baseline values, the system possesses static physiological background parameters for dynamic feedback adjustment. Based on this, the system can then enter the treatment output phase, activating multi-wavelength light source output according to the preset treatment plan, and monitoring the dynamic changes in tissue impedance in real time during irradiation to achieve closed-loop adjustment of the output power.

[0034] The next step, S2, involves activating the multi-wavelength light source output according to the preset treatment plan. This is performed after obtaining the initial bioimpedance reference value. Step S2 involves activating the multi-wavelength light source in a safe and appropriate manner based on preset treatment parameters and individual patient characteristics, establishing an initial light energy projection field for the treatment area. Specifically, it is implemented according to the following sub-steps: Step S201: Retrieve preset treatment parameter sets; the central controller retrieves preset treatment parameter sets for specific diseases from the memory, preferably non-volatile memory. This memory uses electrically erasable programmable read-only memory or flash memory, which pre-stores treatment parameter tables corresponding to various diseases. Each set of parameters includes the initial power weights of the red light source and the near-infrared light source, the upper limit of the total irradiation intensity, the treatment duration, and the irradiation mode.

[0035] The correspondence between disease types and parameter groups is achieved through a predefined index table. The central controller generates the corresponding index value based on the disease type selected by the user on the operation interface. The complete parameter group is located and read in the memory using the index value, and the reading result is stored in the working parameter area of ​​the random access memory.

[0036] Step S202: Analyze the configuration parameters of the multi-wavelength light source; the multi-wavelength light source output includes a red light source in the wavelength range of 630 nm to 700 nm, and a near-infrared light source in the wavelength range of 800 nm to 950 nm.

[0037] These light sources consist of arrays of semiconductor light-emitting diodes or semiconductor laser diodes. Each light source is independently controlled by a corresponding driving circuit, and each driving circuit includes an independent power constant current source and a pulse width modulation signal input terminal.

[0038] The central controller parses the initial power weight configurations of the red light source and the near-infrared light source from the retrieved parameter set and stores them in two separate registers as percentages.

[0039] Step S203: Calculate the initial power weight; the initial power weight is not fixed, but is initialized at the software level based on the individual patient characteristics input into the operation interface.

[0040] The user interface receives the patient's age, gender, and estimated cortical thickness from the user. The estimated cortical thickness is obtained through clinical measurement, specifically by using a high-frequency ultrasound probe to measure the area to be treated before treatment and then inputting the value into the system.

[0041] The central controller feeds these input parameters into a preset weighting calculation model, which is pre-calibrated based on clinical trial data and sets corresponding weighting coefficients for different age ranges, genders, and cortical thickness ranges.

[0042] The weight calculation model is implemented by combining table lookup with linear interpolation: the system first divides the age into three intervals: 18 to 40 years old, 41 to 60 years old, and 61 years old and above; gender corresponds to coefficients of 1.0 and 0.95 respectively; and the cortical thickness is divided into three levels: thinner than 1 mm, 1 to 2 mm, and thicker than 2 mm.

[0043] The central controller looks up the basic weight values ​​in a preset weight coefficient table based on the input parameters, and then calculates the final weights using a linear interpolation formula. Initial power weight of red light source = basic weight value of red light × age correction coefficient × gender correction coefficient × cortical thickness correction coefficient; The initial power weight of the near-infrared light source = the basic weight value of near-infrared light × the age correction factor × the gender correction factor × the cortical thickness correction factor; Among them, the basic weight values ​​for red light and near-infrared light are preset basic weight values, and the age correction coefficient, gender correction coefficient, and cortical thickness correction coefficient are all predefined in the weight coefficient table.

[0044] After the calculation is completed, the system normalizes the sum of the red light power weight and the near-infrared light power weight to 100% to ensure that the total irradiance at the initial moment is within the preset safe ratio range.

[0045] Step S204: Generate a pulse width modulation (PWM) drive signal; the central controller configures the registers of the PWM module based on the treatment parameters in the retrieved parameter group and the calculated initial power weight. The PWM module generates a drive control signal with a corresponding duty cycle. The duty cycle is linearly related to the target output power, and its calculation formula is as follows:

[0046] in, Indicates the duty cycle of the pulse width modulation signal, expressed as a percentage; The target output power, expressed in watts, is calculated based on the initial power weight and the upper limit of total irradiance. The calculation formula is as follows: , This is the upper limit of total irradiance. This represents the initial power weight for the corresponding light source; This indicates the rated maximum power of the light source, measured in watts, and is determined by the specifications of the light source device.

[0047] The output frequency of the pulse width modulation module is set in the range of 100kHz to 500kHz, which is far beyond the range of human hearing and can avoid the generation of audible switching noise during the light source driving process.

[0048] Step S205: Drive the light source array to perform initial illumination; the drive circuit controls the constant current power source according to the pulse width modulation signal. The constant current power source adopts a closed-loop feedback control structure, which integrates a current sampling resistor and an operational amplifier. The current sampling resistor is connected in series in the load circuit to convert the output current into a voltage signal. This voltage signal and the target voltage value obtained after filtering the pulse width modulation signal are input to the two input terminals of the operational amplifier. The output terminal of the operational amplifier controls the conduction degree of the power adjustment transistor to keep the actual output current consistent with the target current, thereby ensuring the stability of the output current.

[0049] The driving circuit drives the multi-wavelength light source array to start irradiation according to the set initial power weight. The red light source and the near-infrared light source output simultaneously according to their respective driving currents, establishing an initial light energy projection field at the target tissue level.

[0050] In summary, step S2 constitutes the startup process for multi-wavelength light source output. First, preset treatment parameters for the disease are retrieved from the memory. Then, the initial power weight is calculated individually based on the patient's characteristics. Finally, the constant current source controlled by pulse width modulation drives the light source array to perform irradiation, thereby achieving individualized adaptation of the treatment plan and safe startup.

[0051] After the light source output is started in step S2, the system enters the dynamic monitoring stage. At this time, tissue complex impedance data needs to be continuously collected during the continuous irradiation of light energy in order to sense the physiological response of the tissue to light radiation in real time.

[0052] Step S3, which involves collecting tissue complex impedance data, continues during continuous light energy irradiation to achieve dynamic and synchronous monitoring of tissue state changes. Its purpose is to acquire the real-time bioelectrophysical response of tissue under light radiation, providing a dynamic data foundation for subsequent closed-loop feedback regulation. Specifically, it is implemented according to the following sub-steps: Step S301: Establish synchronous acquisition timing; Under the cycle control of the central controller, the bioimpedance acquisition module maintains a working timing synchronized with the light source output. The central controller generates a synchronous clock signal through the timer module. This clock signal is used to trigger both the cycle start point of the pulse width modulation module and the sampling start point of the bioimpedance acquisition module, ensuring that the impedance acquisition operation is performed at a fixed phase point of the light source driving cycle, thus avoiding interference from fluctuations in the light source driving current on the measurement results.

[0053] Step S302: Inject excitation current and acquire response voltage; the system adopts the same 4-electrode architecture as in step S102, injecting a constant amplitude AC excitation current into the tissue through the outer excitation electrode. The frequency of the excitation current is set within the range of 1kHz to 200kHz according to a preset control strategy. The inner measuring electrode acquires the induced voltage signal generated by the tissue response. This signal is initially amplified by a high input impedance differential amplifier circuit and then sent to the synchronous demodulation processing unit.

[0054] Step S303: Perform synchronous demodulation processing; synchronous demodulation technology is used to acquire tissue complex impedance data. The system multiplies the acquired induced voltage signal with the reference signal of the excitation current. The reference signal is generated by a digital frequency synthesizer, and its frequency is the same as the excitation current frequency. The system simultaneously generates two reference signals: the first reference signal is in phase with the excitation current, and the second reference signal lags behind by 90 degrees.

[0055] The induced voltage signal is multiplied by the two reference signals using a hardware multiplier or a multiplication instruction within a high-speed digital signal processor, separating the original induced signal into in-phase and quadrature components. The two signals after multiplication are then smoothed by a digital low-pass filter. The cutoff frequency of the digital low-pass filter is set to 10 Hz to filter out high-frequency carrier components and noise, retaining the low-frequency components that reflect tissue characteristics.

[0056] Step S304: Calculate the real resistance and imaginary reactance values; after low-pass filtering, obtain the amplitude I of the in-phase component and the amplitude Q of the quadrature component. Based on the impedance measurement principle, the real resistance R and imaginary reactance X of the complex impedance are calculated using the following formulas: , ; in, The real part of the resistance component represents the complex impedance, and its unit is ohms. It mainly reflects the ion conduction characteristics of extracellular fluid and interstitial fluid. The imaginary reactance component of complex impedance, expressed in ohms, primarily reflects the capacitive charge storage characteristics of the cell membrane. This represents the amplitude of the in-phase component obtained after synchronous demodulation, in volts. This represents the amplitude of the quadrature component obtained after synchronous demodulation, in volts. This is the voltage quantization factor for an analog-to-digital converter, measured in volts per digital value, used to convert digital values ​​into actual voltage values. The amplitude of the excitation current, measured in amperes, is determined by the actual output value of the constant current source circuit.

[0057] Step S305: Configure high-frequency sampling parameters; to capture weak impedance pulsations caused by tissue microcirculation, including cardiogenic volume fluctuations and changes in blood perfusion, the sampling frequency is set in the range of 100 Hz to 1000 Hz. This sampling frequency is much higher than the upper limit of the frequency of tissue physiological changes, which can meet the requirements of the Nyquist sampling theorem and ensure the complete acquisition of dynamic information.

[0058] Step S306: Acquire real-time complex impedance sequence data stream; using electrode pairs located at the center and periphery of the irradiation area, the system continuously monitors the amplitude ratio and time phase relationship between the current vector and voltage vector within the tissue. The electrode pair located at the center of the irradiation area mainly reflects the impedance change in the area directly affected by light radiation, while the electrode pairs located at the periphery provide reference background information to eliminate interference from environmental factors.

[0059] The impedance magnitude and phase angle acquired at each sampling moment constitute a data point. Continuous sampling forms a real-time complex impedance sequence data stream that reflects the thermodynamic state of the tissue and microcirculation fluctuations. This data stream is stored in a circular buffer for subsequent processing modules to call.

[0060] In summary, step S3 constitutes the complete process of dynamic complex impedance data acquisition. This process avoids light source driving interference through synchronous acquisition timing, extracts the real and imaginary parts of the impedance from the induced voltage using synchronous demodulation technology, and captures the dynamic changes of tissue microcirculation at a sufficiently high sampling frequency, thereby generating a continuous real-time complex impedance data stream, providing a reliable data foundation for subsequent impedance change rate calculation and feedback control.

[0061] After completing the real-time complex impedance data acquisition in step S3, the system can analyze and process the acquired data, calculate the rate of change of the real-time impedance value relative to the reference value and the phase angle shift, thereby quantifying the physiological response of the tissue to light radiation.

[0062] For step S4, the rate of change of the real-time impedance value relative to the reference value and the phase angle offset are calculated. This step is executed by the central controller and is the core calculation link of the closed-loop feedback logic. Quantitative indicators characterizing changes in the tissue's physiological state are extracted from the real-time complex impedance data stream obtained in step S3, providing a decision-making basis for subsequent power adjustment. Specifically, it is implemented according to the following sub-steps: Step S401: Calculate the relative drift of the resistance component and analyze its changing trend; the central controller reads the real-time resistance value from the circular buffer. and the initial reference resistance value stored in step S1 The relative drift of the resistance value is calculated using the following formula:

[0063] in, This indicates the relative drift of the resistance component, expressed as a percentage. This indicates the real-time resistance value at the current moment, in ohms. This indicates the initial reference resistance value, in ohms.

[0064] The central controller also performs slope analysis on the trend of resistance value changes. The system maintains a sliding window in memory, continuously storing the resistance values ​​at multiple recent sampling times. Each time a new resistance value is acquired, the change between it and the previous sampling point is calculated.

[0065] When multiple consecutive sampling points show a continuous decrease in real-time resistance value with an increasing absolute value of the decreasing slope, the system identifies this as an increase in ion mobility caused by tissue heating and an increase in effective conductive paths due to increased blood perfusion. At this point, the system will measure the impedance change rate... The main control variable for feedback regulation is output to step S5.

[0066] Step S402: Calculate the phase angle shift and determine the photobiological modulation effect; the system performs the phase angle shift calculation to assess the changes in cell membrane permeability caused by the photobiological modulation effect. The central controller obtains the real part resistance value at the current moment from the real-time complex impedance data. and imaginary part reactance value Calculate the phase angle The calculation formula is:

[0067] in, This represents the phase angle, in degrees. This represents the imaginary reactance component, expressed in ohms. This represents the real resistance component, measured in ohms. The phase angle reflects the rotation angle of the tissue in the complex plane and is a comprehensive characterization of the cell membrane capacitance and extracellular fluid conductivity.

[0068] The system will calculate the phase angle at the current moment. Compared with the initial reference phase angle stored in step S1 By comparison, the phase angle offset is obtained. If the phase angle offset exceeds a preset angle threshold and the offset direction is towards the direction of decreasing reactance, the system determines that a significant photothermal effect or photochemical reaction has occurred within the tissue. This angle threshold is pre-calibrated through clinical trials and set to 8 degrees.

[0069] This shift characterizes the dynamic migration of cell membrane capacitance properties and interstitial fluid distribution, and is used to prevent thermal injury from transforming from a subclinical state to irreversible damage. The judgment result is output as an auxiliary criterion to steps S5 and S6.

[0070] In summary, step S4 constitutes a complete process for quantifying the physiological state of tissues. This process first captures the dynamic changes in tissue conductivity by calculating the rate of change of resistance, and then uses slope analysis to quantify the trend of change, which serves as the main control variable for power regulation. Subsequently, it monitors changes in cell membrane structure by calculating phase angle shift, and uses clinically calibrated fixed thresholds as the basis for judgment, serving as an auxiliary criterion for safety monitoring.

[0071] For step S5, the output power weights of each wavelength light source are dynamically adjusted. This is executed by the central controller, which, based on the impedance change characteristics and phase angle offset obtained in step S4, applies a preset proportional-integral-derivative control strategy to correct the output power weights of each wavelength light source in real time, thereby achieving precise control of tissue photoradiation dose. Specifically, this is implemented according to the following sub-steps: Step S501: Obtain feedback control input parameters; the central controller obtains the main control variable, i.e., the relative drift of the resistance component, from the output of step S4. The system also extracts the rate of change information of high-frequency impedance and low-frequency impedance from the real-time complex impedance data stream in step S3. High-frequency impedance refers to the impedance value corresponding to frequencies above 100 kHz, and low-frequency impedance refers to the impedance value corresponding to frequencies below 5 kHz. The rate of change of impedance in these two frequency bands respectively characterizes the thermal accumulation state of the epidermis and deep tissues.

[0072] Step S502: Execute the layered feedback logic judgment; the central controller executes the layered feedback logic based on frequency band differences. The system has preset thresholds for judging thermal accumulation in the epidermis and a second preset threshold for judging thermal accumulation in deep tissues. These thresholds are pre-calibrated through clinical trials. When the impedance change rate in the high-frequency band exceeds the first preset threshold, it indicates that energy is accumulating too quickly in the epidermis. The central controller determines that it is necessary to prioritize the protection of superficial tissues and instructs to reduce the output power weight of the red light source. The reduction magnitude and the impedance change rate exhibit a preset non-linear functional relationship, specifically using an exponential decay function. The greater the impedance change rate exceeds the threshold, the greater the reduction magnitude. However, the maximum reduction in a single adjustment is limited to within 20% of the initial power weight to avoid overshoot.

[0073] When the impedance change rate in the low-frequency band exceeds the second preset threshold, it indicates that the absorption of near-infrared light in deep tissues, such as the subcutaneous fat layer or muscle layer, has reached saturation or is showing signs of overheating. The central controller determines that it is necessary to limit the energy deposition in deep tissues and instructs to reduce the output power weight of the near-infrared light source.

[0074] Step S503: Calculate the power correction and adjust the drive current; the central controller calculates the power correction for each wavelength of the light source using a proportional-integral-derivative (PID) algorithm. The PID controller uses the deviation between the impedance change rate and the target value as input, calculates the output values ​​of the proportional, integral, and derivative terms respectively, and adds the three terms to obtain the total correction. The proportional gain of the PID controller is set to 0.8, the integral time constant to 2 seconds, and the derivative time constant to 0.5 seconds; these parameters are pre-tuned through clinical trials.

[0075] For channels requiring reduced power, the central controller calculates a new target drive current value based on the correction amount and adjusts the current by regulating the duty cycle of the pulse width modulation signal. The step adjustment accuracy is controlled within 1 mA, meaning the minimum change in each adjustment is 1 mA, ensuring a smooth adjustment process.

[0076] Step S504: Perform smooth transition processing. To ensure user comfort during treatment, a smooth transition algorithm is used in the dynamic adjustment process. During each adjustment, the central controller limits the duty cycle change step of the pulse width modulation signal to within the range of 0.1% to 0.5%. The specific step value is dynamically selected based on the severity of the impedance change rate; a smaller step is used when the change rate is small, and a larger step is used when the change rate is large, but not exceeding the upper limit. This limitation prevents light source flicker caused by sudden power changes, avoids excessive visual or thermal stimulation to the human nervous system, and ensures the continuity and stability of the energy output curve.

[0077] Step S505: Update the light source output status; the central controller writes the calculated and corrected drive current parameters into the register of the pulse width modulation module, and the pulse width modulation module immediately takes effect with the new duty cycle. The drive circuit adjusts the output current of the power constant current source according to the updated pulse width modulation signal, and the red light source and near-infrared light source continue to irradiate according to the new power weight, completing this closed-loop adjustment cycle.

[0078] Step S5 constitutes the complete process of dynamic power adjustment. This process first obtains impedance change characteristics as feedback input, then identifies the target spectrum to be adjusted through hierarchical feedback logic, calculates the precise correction amount through proportional-integral-differential algorithms, and finally achieves smooth adjustment of output power through a smooth transition algorithm, thereby realizing closed-loop precise control of tissue photoradiation dose.

[0079] After completing the dynamic power adjustment in step S5, the system continues to run the data acquisition in step S3 and the feature calculation in step S4, forming a continuous closed-loop control cycle.

[0080] The multispectral therapy device control method provided by this invention further includes step S6, which is responsible for performing safety threshold monitoring and protection triggering. As the underlying safety protection mechanism of the system, it continuously assesses whether the impedance change rate reaches the preset safety limit and activates protection measures when necessary.

[0081] Step S601: Establish a biological tissue tolerance model and safety threshold zoning. During the initial configuration phase, the system pre-constructs a biological tissue tolerance model based on clinical trial data. This model defines the safety status of tissues within different impedance change rate ranges. Based on this model, the system divides the impedance change rate into three safety levels: the safe zone corresponds to an impedance change rate within 5%; the warning zone corresponds to an impedance change rate between 5% and 12%; and the danger zone corresponds to an impedance change rate exceeding 12%.

[0082] The impedance change rate is calculated based on the relative drift of the resistance component obtained in step S401, which is determined by the percentage difference between the current real-time resistance value and the initial reference resistance value.

[0083] Step S602: Implement power limiting in the warning zone; the central controller continuously monitors the dynamic changes in impedance change rate. When the system detects that the cumulative decrease in impedance within a preset time period, such as a continuous window of 10 seconds, reaches or exceeds a preset percentage threshold, it determines that the current state has entered the warning zone mode.

[0084] At this point, the system does not directly cut off the output, but instead adopts an active power reduction protection strategy to forcibly limit the total output power of the multi-wavelength light source to below 50% of the rated power. By reducing the energy injection rate, it slows down the trend of tissue heat accumulation and prevents the condition from deteriorating further.

[0085] Step S603: Perform emergency cut-off and hardware protection for the danger zone; when the system detects a violent drop in impedance change rate exceeding the preset sudden threshold within a very short time, such as 0.5 seconds, this phenomenon indicates that the local heat accumulation has reached the critical point of exceeding the standard, and there is a risk of burns.

[0086] To address this situation, the central controller does not perform a gradual power reduction operation. Instead, it directly shuts off the power supply to all light source drive circuits via the hardware control port, executing a forced power cut-off command. Simultaneously, the controller sends corresponding error codes to the user interface via the UART or SPI communication interface and triggers audible and visual alarm signals to alert operators or patients.

[0087] Step S604: Initiate forced cooling and thermal management; while cutting off the light output, the system automatically activates the integrated heat dissipation component inside the treatment head for forced cooling. The heat dissipation component can be a miniature fan or a thermoelectric cooling module, which quickly removes residual heat from the tip of the treatment head and the surface of the tissue, accelerates local heat dissipation, shortens the time the tissue is in a high-temperature state, and thus further reduces the risk of thermal damage.

[0088] Step S6 constitutes a multi-level safety protection chain for the system. From zoned monitoring based on tissue tolerance models, to active power reduction in the warning zone, and then to emergency cutoff and forced heat dissipation in the danger zone, each step is progressively enhanced, ensuring the effectiveness of energy output under normal treatment conditions and providing reliable hardware-level safety guarantees for extreme situations. Through this mechanism, step S6 complements the dynamic power adjustment of the aforementioned step S5, combining closed-loop control with safety redundancy to ensure that the entire treatment process operates within preset safety boundaries.

[0089] The multispectral therapy device control system disclosed in this application includes a bioimpedance acquisition module, a multi-wavelength light source drive array, and a central controller.

[0090] The bioimpedance acquisition module is used to obtain the initial bioimpedance reference value of the treatment area during the static preparation phase and to acquire tissue complex impedance data during continuous photoelectric irradiation. The initial bioimpedance reference value includes the initial resistance reference value and the initial phase angle reference value, while the tissue complex impedance data includes real-time resistance and real-time reactance values. This module employs a four-electrode architecture, injecting multi-frequency excitation current into the tissue through excitation electrodes and acquiring the response voltage signal through measurement electrodes. The module integrates a synchronous demodulation processing unit, which multiplies the response voltage signal with both in-phase and quadrature-phase reference signals, extracts the in-phase and quadrature-phase component amplitudes after low-pass filtering, and then calculates the real-time resistance and reactance values.

[0091] The multi-wavelength light source drive array includes a red light source for acting on superficial tissues and a near-infrared light source for acting on deep tissues, used to activate the multi-wavelength light source output according to a preset treatment plan. Each light source is composed of a semiconductor light-emitting diode or a semiconductor laser diode and is independently controlled by a corresponding drive circuit. The drive circuit integrates a power constant current source and a pulse width modulation signal input terminal, achieving precise control of the output power by adjusting the duty cycle of the pulse width modulation signal.

[0092] The central controller is electrically connected to both the bioimpedance acquisition module and the multi-wavelength light source drive array, and integrates a timer unit. On one hand, the central controller generates a synchronization clock signal through the timer module, which simultaneously triggers the start point of the pulse width modulation module's cycle and the sampling start point of the bioimpedance acquisition module. This ensures that the impedance acquisition operation is performed at a fixed phase point within the light source drive cycle, avoiding interference from drive current fluctuations on the measurement results. On the other hand, the central controller calculates the relative drift of the resistance component based on the real-time resistance value and the initial resistance reference value, calculates the real-time phase angle based on the real-time reactance value, and then calculates the phase angle offset based on the real-time phase angle and the initial phase angle reference value. Based on this, the central controller dynamically adjusts the output power weight of each wavelength light source in the multi-wavelength light source drive array using a proportional-integral-derivative control strategy, achieving closed-loop control from tissue state perception to light source output adjustment.

[0093] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be regarded as exemplary and non-limiting in all respects.

[0094] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for controlling a multispectral therapy device, characterized in that, Includes the following steps: Obtain the initial bioimpedance reference value of the area to be treated. The initial bioimpedance reference value includes the initial resistance reference value and the initial phase angle reference value. The multi-wavelength light source output is activated according to the preset treatment plan. The multi-wavelength light source includes at least a red light source for acting on the surface tissue and a near-infrared light source for acting on the deep tissue. During continuous light energy irradiation, tissue complex impedance data are collected, including real-time resistance and real-time reactance values. The relative drift of the resistance component is calculated based on the real-time resistance value and the initial resistance reference value. The real-time phase angle is calculated based on the real-time reactance value. The phase angle offset is then calculated based on the real-time phase angle and the initial phase angle reference value. The output power weights of each wavelength light source are dynamically adjusted based on the relative drift of the resistance component and the phase angle offset.

2. The control method for the multispectral therapy device according to claim 1, characterized in that, The acquisition of tissue complex impedance data specifically includes: Establish a synchronous acquisition timing sequence to keep the sampling start point of the bioimpedance acquisition module synchronized with the period start point of the pulse width modulation signal driving the multi-wavelength light source output; Multi-frequency excitation current is injected into the treatment area through excitation electrodes, and the response voltage signal is acquired through measuring electrodes. Synchronous demodulation processing is performed on the response voltage signal. The response voltage signal is multiplied with the in-phase reference signal and the quadrature-phase reference signal respectively. After low-pass filtering, the amplitude of the in-phase component and the amplitude of the quadrature component are obtained. Based on the amplitudes of the in-phase component, the quadrature component, the voltage quantization coefficient, and the excitation current amplitude, the real-time resistance and real-time reactance values ​​are calculated. The real-time resistance value is positively correlated with the amplitude of the in-phase component, and the real-time reactance value is positively correlated with the amplitude of the quadrature component.

3. The control method for the multispectral therapy device according to claim 2, characterized in that, The specific steps for establishing a synchronous acquisition timing sequence are as follows: The central controller generates a synchronous clock signal through the timer module. The synchronous clock signal is used to trigger both the period start point of the pulse width modulation module and the sampling start point of the bioimpedance acquisition module, so that the impedance acquisition operation is performed at a fixed phase point of the light source driving cycle.

4. The control method for the multispectral therapy device according to claim 2, characterized in that, The specific details of injecting multi-frequency excitation current are as follows: Injecting an AC excitation current with a frequency range of 1 kHz to 200 kHz into the tissue; The frequency bands of 5 kHz and below are defined as low frequency bands, used to obtain complex impedance data characterizing the impedance characteristics of deep tissues; the frequency bands of 100 kHz and above are defined as high frequency bands, used to obtain complex impedance data characterizing the impedance characteristics of epidermal tissues.

5. The control method for the multispectral therapy device according to claim 4, characterized in that, Dynamically adjusting the output power weights of each wavelength light source specifically includes: Extract the high-frequency impedance change rate and the low-frequency impedance change rate from the collected tissue complex impedance data; When the impedance change rate in the high-frequency band exceeds the first preset threshold, it is determined that the energy is accumulating too fast in the epidermis, and the output power weight of the red light source is reduced. When the impedance change rate in the low-frequency band exceeds the second preset threshold, it is determined that the energy deposition of deep tissue has reached saturation, and the output power weight of the near-infrared light source is reduced.

6. The control method for a multispectral therapy device according to claim 1, characterized in that, Obtaining the initial bioimpedance baseline value of the treatment area specifically includes: During the static preparation period, multi-frequency excitation current is injected into the treatment area using the four-electrode method, and the induced voltage signal is collected. A multi-frequency impedance spectrum model was constructed to distinguish the difference in initial water content between the superficial and deep dermal tissues. The real and imaginary components of the complex impedance are extracted by phase-sensitive detection to obtain the initial resistance reference value and the initial phase angle reference value.

7. The control method for a multispectral therapy device according to claim 1, characterized in that, It also includes security threshold monitoring and protection triggering steps: Continuously monitor the relative drift of the resistance component and divide the impedance change rate into safe zone, warning zone and danger zone; When the impedance change rate enters the warning zone, the total output power of the multi-wavelength light source is limited to less than 50% of the rated power; When the impedance change rate exceeds the preset burst threshold within a preset time, the power supply to all light source drive circuits is directly cut off, and the heat dissipation components inside the treatment head are activated for forced cooling.

8. The control method for the multispectral therapy device according to claim 1, characterized in that, Dynamically adjusting the output power weights of each wavelength light source specifically includes: Using the relative drift of the resistance component as the main control variable, the power correction is calculated by applying a proportional-integral-derivative control strategy. During the adjustment process, the duty cycle change step of the pulse width modulation signal is limited to the range of 0.1% to 0.5% to achieve a smooth transition of output power.

9. The control method for a multispectral therapy device according to claim 1, characterized in that, Before activating the multi-wavelength light source output according to the preset treatment plan, the following steps are also included: Based on the patient's age, gender, and estimated cortical thickness, the initial power weights of the red light source and the near-infrared light source are calculated using a linear interpolation model. The initial power weights are then normalized to ensure that the total irradiance at the initial moment is within a preset safe ratio range.

10. A multispectral therapy device control system, applied to the method described in any one of claims 1-9, characterized in that, include: The bioimpedance acquisition module is used to acquire the initial bioimpedance reference value of the area to be treated during the static preparation period, and to acquire tissue complex impedance data during continuous light energy irradiation. The initial bioimpedance reference value includes the initial resistance reference value and the initial phase angle reference value, and the tissue complex impedance data includes the real-time resistance value and the real-time reactance value. A multi-wavelength light source driving array, including a red light source for acting on superficial tissues and a near-infrared light source for acting on deep tissues, is used to activate the multi-wavelength light source output according to a preset treatment plan; The central controller is used to calculate the relative drift of the resistance component based on the real-time resistance value and the initial resistance reference value, calculate the real-time phase angle based on the real-time reactance value, calculate the phase angle offset based on the real-time phase angle and the initial phase angle reference value, and dynamically adjust the output power weight of each wavelength light source in the multi-wavelength light source drive array based on the relative drift of the resistance component and the phase angle offset.

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