Gravity sedimentation-based platelet concentration method and system

Abstract

The invention relates to the technical field of platelet concentration, in particular to a platelet concentration method and system based on gravity settling, and the method comprises the following steps: acquiring settling path unit parameters and acquiring speed difference values, screening staggered difference value points and judging acceleration trend, extracting decreasing curvature difference to determine boundaries, and determining a platelet concentration result. Adjusting the dip angle acquisition speed change rate to screen a fallback path, and calculating a vector to establish an extraction path to obtain secondary concentrated data. According to the invention, through extracting the settlement velocity difference and the acceleration change trend, identifying the layered boundary area, improving the positioning accuracy of the concentration boundary, inducing the dynamic response based on the inclination angle disturbance, screening the path unit with the prominent speed rising rate, and enhancing the perception capability and the layered definition of the boundary area. By means of velocity vector direction and center position calculation, a stable linear extraction path is constructed, efficient recovery and focusing extraction of trace platelets are achieved, platelet concentration precision, stability and reutilization efficiency are improved, and complex sample conditions are adapted.

Description

Technical Field

[0001] The present invention relates to the technical field of platelet concentration, and particularly to a platelet concentration method and system based on gravitational sedimentation. Background Art

[0002] The technical field of platelet concentration includes related methods and devices for extracting and enriching platelets in blood by physical, biological or chemical means. The core content is to effectively separate platelets from other blood cells such as red blood cells, white blood cells and plasma through the differential characteristics of blood components. Common methods include centrifugal separation, membrane filtration and gravitational sedimentation, etc., which systematically involve key technical links such as the identification of blood components, the control of separation mechanisms, the guarantee of biocompatibility in the operation process and the maintenance of sample sterility, and are widely used in clinical treatment, regenerative medicine and the preparation of blood products, etc.

[0003] Among them, the platelet concentration method based on gravitational sedimentation refers to the method of enriching platelets by separating the middle layer where platelets are located within a preset time through statically placing a blood sample, taking advantage of the different sedimentation rates of various cell components in blood in the natural gravity field. It covers specific technical matters such as the collection and static placement of blood samples, the setting of sedimentation time, the identification and extraction of platelet layers, and usually completes the main means by setting the angle and geometric structure of the static container, forming layers by using the sedimentation rate difference, and separating the middle layer platelets manually or mechanically.

[0004] In the existing platelet concentration process, it is mainly based on sedimentation time control and static structure layering, relying on the cell distribution state at a single time point as the basis for platelet extraction, lacking means for identifying the continuous dynamic changes during sedimentation. Limited by the static observation mode, it is impossible to accurately determine the true boundary position. Especially under the conditions of weak density gradient between cells or poor sedimentation stability, the boundary recognition accuracy decreases significantly, and it is very easy to generate layer overlap phenomena, affecting the purity of platelet extraction. The operation process lacks directional screening of response units in the sedimentation path, and the establishment of the extraction path depends on empirical judgment, resulting in difficult effective enrichment and recovery of platelets in the micro region. During the inclination adjustment process, the sedimentation behavior response data is not combined, and only the layered separation is completed through mechanical structure adjustment, making it difficult to form a targeted path planning, prone to extraction area deviation or residual waste phenomena, increasing the complexity of subsequent processing, and lacking adaptability when dealing with high-throughput samples or complex blood component configurations, reducing the stability and expandability of practical applications. Summary of the Invention

[0005] The object of the present invention is to solve the disadvantages existing in the prior art, and to propose a platelet concentration method based on gravitational sedimentation.

[0006] To achieve the above object, the present invention adopts the following technical solutions: A platelet concentration method based on gravitational sedimentation, comprising the following steps:

[0007] S1: Obtain the depth, volume, and time sampling frequency of each vertical path unit in the sedimentation container, collect the sedimentation velocity and calculate the velocity difference to obtain a velocity difference change trend sequence;

[0008] S2: Based on the velocity difference change trend sequence, screen the positions where the positive and negative differences of adjacent units alternate, determine whether the acceleration change rate at this point is greater than that of the upper and lower units and has a decreasing trend, and generate a set of velocity delay boundary unit positions;

[0009] S3: According to the set of velocity delay boundary unit positions, compare the velocity decreasing curvature differences between the candidate points and the upper and lower units, determine the difference stability and mark the concentration boundary points to obtain the platelet concentration limit position;

[0010] S4: According to the platelet concentration limit position, collect the sedimentation velocity change rates of the upper and lower units after the inclination angle changes, select the path unit sequence with the maximum velocity rising rate to obtain the boundary area fallback response path unit sequence;

[0011] S5: Based on the velocity vector direction of the boundary area fallback response path unit sequence, calculate the average vector and the path end coordinates, establish a linear extraction path to obtain secondary micro platelet concentration data.

[0012] As a further solution of the present invention, the velocity difference change trend sequence includes the change amplitude of the absolute value of the velocity difference, the change trend direction, and the record of the trend inflection point distribution. The set of velocity delay boundary unit positions includes the spatial distribution data of the delay points, the candidate positions of the layered boundary, and the acceleration change rate eigenvalue. The platelet concentration limit position includes the concentration limit coordinate points, the record of the decreasing curvature difference distribution, and the boundary stability index. The boundary area fallback response path unit sequence includes the velocity rising rate distribution data, the path unit response amplitude, and the inclination angle stage response mode. The secondary micro platelet concentration data includes the record of the velocity vector center distribution, the average velocity direction, and the residual aspiration path coordinate points.

[0013] As a further solution of the present invention, the specific steps for obtaining the velocity difference change trend sequence are as follows:

[0014] S111: Based on the starting depth value, unit volume, and time sampling frequency of each layered path unit in the vertical direction of the blood sedimentation container, collect the initial sedimentation velocity of the cells in each unit at a fixed time interval, compare the ratio differences between the initial sedimentation velocities of adjacent units and the corresponding starting depth values, obtain the sedimentation velocity change rates of each layered path unit, and generate velocity change rate data;

[0015] S112: Receive the rate-of-change-of-velocity data, calculate the absolute value of the difference between consecutive time sampling points, combine the unit volume data of adjacent path units, uniformly convert the time scale through the time sampling frequency, and statistically calculate the change value of the unit volume increment of the rate of change of velocity to obtain a sequence of unit volume velocity increment differences;

[0016] S113: According to the sequence of unit volume velocity increment differences, extract the fluctuation change trend of the velocity increment differences between each hierarchical path unit within a continuous time, and use the formula:

[0017]

[0018] Calculate the mean value T of the fluctuation trend of the velocity increment differences vΔ , and construct a sequence of change trends of velocity differences, where v i represents the initial value of the cell sedimentation velocity of the i-th path unit, v i+1 represents the initial value of the cell sedimentation velocity of the (i + 1)-th path unit, Δd i represents the difference in starting depth between the i-th and (i + 1)-th path units, V i , V i+1 respectively represent the unit volumes of the i-th and (i + 1)-th path units, and n represents the total number of path units.

[0019] As a further solution of the present invention, the steps for obtaining the set of positions of the velocity delay boundary units are specifically as follows:

[0020] S211: Based on the sequence of change trends of velocity differences, select a continuous unit interval with the smallest absolute value of the difference in the vertical path, record the index positions of each unit in the corresponding interval, statistically calculate the velocity differences between the upper and lower adjacent path units at the corresponding positions, and determine whether there is an alternating change in the sign of the difference before and after the current position. If there is an alternating change state, mark the unit as a delay point to obtain a set of delay point positions;

[0021] S212: According to the set of delay point positions, extract the sedimentation acceleration values of the corresponding units at multiple consecutive time points, respectively subtract the acceleration values of the upper and lower adjacent units at the same time point to form a three-point acceleration difference sequence, and slide and calculate the rate of change of the differences in the sequence at each time point to obtain an acceleration difference rate of change sequence;

[0022] S213: According to the acceleration difference rate of change sequence, compare the acceleration change rate trend values of the delay point positions within the sliding window of adjacent units, and use the formula:

[0023]

[0024] Calculate the acceleration change rate trend deviation value B of the k-th delay point at m time pointsk , determine whether the value is positive and decreases hourly at the delay point. If it holds, establish a set of velocity delay boundary cell positions, where a k,j represents the settlement acceleration value of the delay point at the j-th time point, a k-1,h 、a k+1,h respectively represent the settlement acceleration values of the adjacent upper and lower cells of the delay point at the j-th time point, v k,h 、v k,j-1 respectively represent the settlement velocity values of the delay point at the j-th and (j - 1)-th time points, and m is the number of time points participating in the sliding window calculation.

[0025] As a further solution of the present invention, the steps for obtaining the platelet concentration boundary position are specifically as follows:

[0026] S311: Based on the set of velocity delay boundary cell positions, extract the settlement velocity sequences of each position within a fixed time, calculate the velocity change ratios of adjacent time periods in the order of time points, and obtain a sequence of velocity decrease rates;

[0027] S312: According to the sequence of velocity decrease rates, obtain the velocity sequences of the corresponding upper and lower path cells for each target position, calculate the second-order difference values of the upper and lower cell velocity sequences within the same time interval, and take the absolute value to construct a sequence of velocity decrease curvatures;

[0028] S313: According to the sequence of velocity decrease rates and the sequence of velocity decrease curvatures, compare one by one the differences in the velocity decrease rate values and velocity decrease curvature values between the target path cell and its adjacent upper and lower cells at each time point, and use the formula:

[0029]

[0030] Calculate the concentration point curvature difference value C of the i-th path cell i , if it shows a constant difference in a continuous time interval and the upper and lower curvature fluctuations are inconsistent, mark the corresponding position as the concentration boundary point and establish the platelet concentration boundary position, where r i represents the velocity decrease rate value of the i-th path cell, r i-1 、r i+1 respectively represent the velocity decrease rate values of its upper and lower path cells, g i-1 、g i+1 respectively represent the velocity decrease curvature values of the upper and lower path cells.

[0031] As a further solution of the present invention, the steps for obtaining the sequence of path cells for the fallback response in the boundary region are specifically as follows:

[0032] S411: According to the platelet concentration boundary position, set multiple inclination change states of the sedimentation container after the main extraction is completed. At each inclination state, collect the sedimentation velocity values of the path units in the upper and lower regions of the boundary at different time points, and uniformly organize them into a two-dimensional sequence of inclination-time, and obtain an inclination velocity sampling matrix;

[0033] S412: Based on the inclination velocity sampling matrix, calculate the velocity change of each path unit according to the ratio of the velocity difference value of each path unit in each inclination residence time period to the duration of the corresponding time period, and construct a velocity change matrix;

[0034] S413: According to the velocity change rate matrix, count the velocity growth amplitude of each path unit in the differential inclination stage, identify the one with the largest velocity rise rate in each inclination residence section, and use the formula:

[0035]

[0036] Calculate the rising response rate value R of the i-th path unit i , extract the corresponding path unit index through sorting, and establish a boundary area fallback response path unit sequence, where, v i,h represents the sedimentation velocity value of the i-th path unit at the h-th time point, θ h represents the h-th inclination state value, Δt h represents the length of the h-th time interval, and t1 and t H are the sampling times of the 1st and H-th time points respectively.

[0037] As a further solution of the present invention, the steps for obtaining the secondary micro platelet concentration data are specifically as follows:

[0038] S511: According to the velocity sequences of each unit in the boundary area fallback response path unit sequence in the fallback state, calculate the velocity vector directions of each path unit at multiple time points, obtain the vector representation of the velocity directions of the path units at each time point, and establish a velocity vector direction sequence;

[0039] S512: Based on the velocity vector direction sequence, perform a mean operation on the velocity vector directions of each path unit at all time points in the fallback section respectively, and at the same time, based on the vector end point coordinates of the path unit in the spatial distribution, extract the corresponding path section direction change center position to obtain the average velocity vector direction and the center position point;

[0040] S513: Construct a linear path connecting the two points based on the platelet concentration limit position and the center position point of the average velocity vector direction. Aggregate the residual velocity values and corresponding direction data of all path units on the path in the falling state, perform cumulative processing in combination with the position distance and direction difference, statistically analyze the overall absorption capacity index of the path segment, and establish secondary micro platelet concentration data.

[0041] A platelet concentration system based on gravitational sedimentation, comprising:

[0042] The sedimentation path recognition module obtains the starting depth value, unit volume, time sampling frequency, and initial sedimentation velocity of each path unit, calculates the velocity difference between adjacent units, and collects the difference trend in the time series to obtain the velocity difference change sequence;

[0043] The acceleration trend recognition module, based on the velocity difference change sequence, calls the acceleration value comparison difference trend between adjacent upper and lower units to obtain the position set of velocity delay boundary units;

[0044] The concentration limit extraction module, according to the position set of the velocity delay boundary units, calls the curvature difference between the upper and lower units to judge the consistency and obtains the platelet concentration limit position;

[0045] The limit response recognition module extracts the velocity change rate in each inclination state according to the platelet concentration limit position and generates a limit area falling response path sequence;

[0046] The residual absorption path construction module combines the velocity vector directions of each unit in the limit area falling response path sequence, connects the starting and ending points, and further performs secondary concentration to obtain secondary micro platelet concentration data.

[0047] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0048] In the present invention, by continuously quantifying and analyzing the trend of the velocity difference of the vertical units in the sedimentation path, the real-time tracking of the minute disturbances in the cell sedimentation behavior is achieved, the dynamic response ability of boundary recognition is enhanced, an identification mechanism is constructed based on the acceleration change rate and its decreasing trend, the stability of the boundary region is comprehensively judged at multiple time nodes, so that the target region has obvious compartmentalization characteristics, which is conducive to locking the high-precision concentration position. The inclination intervention guides the sedimentation layer to generate directional disturbances, promotes the gradual appearance of potential fallback paths, and improves the perceptibility of the hidden boundary positions. Especially when the interface stability is insufficient or the cell distribution is uneven, it shows higher analytical ability. The method for screening the local maximum point of the velocity increase rate establishes a high-response extraction criterion for active path units, supports the effective identification of extremely small concentration changes, and finally takes the vector direction as the guiding basis to locate the central extraction region, effectively improving the enrichment focus of trace platelets and the spatial stability of path execution. The processing logic constructs a decision-making mechanism based on the change sequence of continuous physical quantities, introduces the linkage analysis of local dynamic response and path geometric configuration, and strengthens the operation efficiency of core links such as accurate identification of stratification positions, high-response matching of extraction paths, and reuse of residual concentration regions, adapts to the characteristics of variable samples and high-standard purity requirements, and has good adaptability and process controllability. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 is the main step flow chart of the present invention;

[0050] Figure 2 is the flow chart for obtaining the sequence of the velocity difference change trend of the present invention;

[0051] Figure 3 is the flow chart for obtaining the set of positions of the velocity delay boundary units of the present invention;

[0052] Figure 4 is the flow chart for obtaining the platelet concentration boundary position of the present invention;

[0053] Figure 5 is the flow chart for obtaining the sequence of the fallback response path units in the boundary region of the present invention;

[0054] Figure 6 is the flow chart for obtaining the data of secondary trace platelet concentration of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0055] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0056] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings. These are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. In addition, in the description of the present invention, the meaning of "a plurality of" is two or more, unless otherwise specifically defined.

[0057] Please refer to Figure 1 , a platelet concentration method based on gravitational sedimentation, comprising the following steps:

[0058] S1: Obtain the starting depth values, unit volumes, and time sampling frequencies of each stratified path unit in the vertical direction of the blood sedimentation container, collect the initial sedimentation velocity values of the cells in each unit at fixed time intervals, calculate the velocity difference between adjacent units per unit time, and obtain a sequence of velocity difference change trends;

[0059] S2: Based on the sequence of velocity difference change trends, select the unit positions in the vertical path within the interval with the smallest absolute value of the difference, count the velocity differences of the adjacent units above and below the corresponding positions, and determine whether the difference signs show an alternating positive and negative state. If so, mark this unit as the delay point position. At the same time, obtain the sedimentation acceleration values at the corresponding positions at consecutive time points, and compare them with the differences within the sliding window of the accelerations of the two adjacent units above and below respectively. If the acceleration change rate is greater than that of the adjacent units and shows a decreasing and slowing trend, mark the corresponding point as a candidate for the stratification boundary point, and generate a set of unit positions of the velocity delay boundary;

[0060] S3: Based on the set of unit positions of the velocity delay boundary, extract the velocity decreasing rate values from the sedimentation velocity sequence within a fixed time, and perform a difference judgment with the velocity decreasing curvature values of the units above and below the target point respectively. If the difference is constant and inconsistent with the adjacent curvatures, mark the target point as the concentration boundary point to obtain the platelet concentration limit position;

[0061] S4: According to the platelet concentration limit position, after the main extraction is completed, perform a preset inclination change on the sedimentation container, collect the sedimentation velocity values in the areas above and below the limit during each inclination stay period, calculate the velocity change rate of each unit, and select the path unit sequence with the largest rising velocity rate to obtain the path unit sequence of the falling response in the limit area;

[0062] S5: Calculate the central value of the velocity vectors of each unit in the corresponding sequence according to the velocity vector directions of each unit in the falling response path unit sequence of the boundary area in the falling state. Aggregate and obtain the average velocity vector direction and the central position point. Set the starting point of the extraction path as the platelet concentration boundary position and the ending point as the central position point to establish a residual linear aspiration path, and obtain the secondary micro platelet concentration data.

[0063] The velocity difference change trend sequence includes the change amplitude of the absolute value of the velocity difference, the change trend direction, and the record of the distribution of trend inflection points. The velocity delay boundary unit position set includes the spatial distribution data of delay points, the candidate positions of the hierarchical boundary, and the eigenvalue of the acceleration change rate. The platelet concentration boundary position includes the concentration boundary coordinate point, the differential distribution record of the decreasing curvature, and the boundary stability index. The falling response path unit sequence of the boundary area includes the distribution data of the velocity rising rate, the response amplitude of the path unit, and the inclination stage response mode. The secondary micro platelet concentration data includes the distribution record of the velocity vector center, the average velocity direction, and the coordinate points of the residual aspiration path.

[0064] Please refer to Figure 2 , and the steps of S1 are as follows:

[0065] S111: Based on the starting depth values, unit volumes, and time sampling frequencies of each hierarchical path unit in the vertical direction of the blood sedimentation container, collect the initial sedimentation velocity values of the cells in each unit at fixed time intervals. Compare the ratio differences between the initial sedimentation velocity values of adjacent units and the corresponding starting depth values to obtain the sedimentation velocity change rates of each hierarchical path unit and generate velocity change rate data;

[0066] To obtain the starting depth values, unit volumes, and time sampling frequencies of each stratified path unit in the vertical direction of a blood sedimentation container, it is necessary to sequentially determine the spatial division intervals in the vertical direction of the container. For example, a 10-cm-high transparent container is selected and divided into 10 equally spaced units. The initial depth values of each unit are 0 cm, 1 cm, 2 cm to 9 cm respectively, and the corresponding unit volume is 10 mL. By setting the sampling device, a time sampling frequency of once per second, i.e., 1 Hz, is obtained. In actual operation, the initial value of the cell sedimentation velocity is collected at the calibration point at the bottom of each unit by a laser particle velocimeter, and the displacement distance it settles downward within each second is recorded. The sedimentation velocity of the cells in each unit is calculated by velocity = displacement / time. Assuming the initial sedimentation velocity of the first unit is 0.12 mm / s and that of the second unit is 0.18 mm / s, then the ratio of their velocity initial values needs to be calculated, that is, the velocity difference rate per unit depth is (0.18 - 0.12) mm / s / 1 cm = 0.06 mm / s / cm. Then, all adjacent units are processed pairwise, and the comparison values of the velocity initial values of each pair of adjacent stratified path units are obtained in the above manner. Further, the change amplitude of this value between all adjacent path units is compared, and the velocity change rate is integrated and merged based on its distribution along the spatial axis. It is set that the adjacent velocity difference within the range of ±

[0067] 0.02 mm / s / cm is the stable change interval. If the difference is higher than this value, it is determined as the rising velocity interval, and if it is lower, it is the falling velocity interval. According to the above judgment rules, the continuity and interval type of the velocity ratio change between all units are compared, and the position index and interval length of the continuous rising interval or continuous falling interval are recorded to establish the corresponding velocity change rate sequence.

[0068] S112: Receive the velocity change rate data, calculate the absolute value of the difference between consecutive time sampling points, combine the unit volume data of adjacent path units, uniformly convert the time scale through the time sampling frequency, and statistically obtain the unit volume increment change value of the velocity change rate to obtain the unit volume velocity increment difference sequence;

[0069] According to the rate of change of velocity data, the absolute value operation of the difference in the rate of change of velocity at consecutive time points is performed. First, the rate of change of velocity values at the i-th and (i + 1)-th time points in the sequence of the rate of change of velocity need to be extracted. Let them be 0.08 mm / s / cm and 0.11 mm / s / cm, and the difference is 0.03 mm / s / cm. Taking its absolute value gives 0.03. Next, it is adjusted and converted in combination with the unit volume data. Let the unit volume of the i-th path unit be 9.8 mL, and the unit volume of the (i + 1)-th unit be 10.1 mL. The incremental ratio of the velocity change per unit volume per unit time is uniformly calculated at a time sampling frequency of 1 Hz, and each group of data is normalized in the form of increment / average volume. For the values in the above example, the average volume is (9.8 + 10.1) / 2 = 9.95 mL, and the incremental change value is 0.03 / 9.95 ≈

[0070] 0.00301 mm / s / cm·mL. Then, the above operation is sequentially performed on the rate of change of velocity between all path units at each time point in the sequence to form a complete sequence of the velocity increment difference per unit volume. In actual implementation, data can be recorded according to the path unit index. The sample data is shown in the following table.

[0071] Table 1 Data table of velocity increment difference per unit volume

[0072]

[0073] As shown in Table 1, the velocity increment differences per unit volume of path unit indices 1 to 4 are distributed in the range of 0.0028 - 0.0053. Subsequent operations will continue to perform trend calculations based on this sequence.

[0074] S113: According to the sequence of velocity increment differences per unit volume, extract the fluctuation trend of the velocity increment differences between each hierarchical path unit within a continuous time. Use the formula:

[0075]

[0076] Calculate the average value T of the velocity increment difference fluctuation trend vΔ , and construct a sequence of the velocity difference change trend. Among them, v i represents the initial value of the cell sedimentation velocity of the i-th path unit, v i+1 represents the initial value of the cell sedimentation velocity of the (i + 1)-th path unit, Δd i represents the initial depth difference between the i-th and (i + 1)-th path units, V i , V i+1 respectively represent the unit volumes of the i-th and (i + 1)-th path units, and n represents the total number of path units;

[0077] According to the sequence of velocity increment differences per unit volume, extract the velocity increment differences between each pair of path units at consecutive time points, perform normalization by taking the average and combining with the unit depth difference, and calculate using the formula.

[0078] During the calculation process, it is necessary to collect and calculate each parameter separately. Set the total number of path units to 4, select a certain section of the path for calculation. Assume that the initial value of the cell sedimentation velocity of the first path unit v1 = 0.12 mm / s, the second path unit v2 = 0.18 mm / s, the starting depth difference between the two is Δd1 = 1 cm, and the corresponding unit volumes are V1 = 9.8 mL, V2 = 10.1 mL. Then the substitution into the formula process is as follows:

[0079] The first term:

[0080]

[0081] And so on. Assume that the initial values of the velocities of the second and third units are 0.18 and 0.22 mm / s respectively, the unit volumes are 10.1 mL and 10.0 mL respectively, and the depth difference is 1 cm:

[0082] The second term:

[0083]

[0084] Similarly, calculate the third term to be 0.01027, and take the average after adding all the values:

[0085]

[0086] The calculation result shows that the velocity increment difference per unit volume in consecutive path units shows a trend of fluctuating with an average fluctuation amplitude of 0.01088 mm / s / cm·mL, and then obtain the sequence of velocity difference change trends.

[0087] Please refer to Figure 3 , and the steps of S2 are:

[0088] S211: Based on the sequence of velocity difference change trends, select the continuous unit interval with the smallest absolute value of the difference in the vertical path, record the index positions of each unit in the corresponding interval, count the velocity differences between the path units adjacent above and below the corresponding positions, and determine whether there is a positive-negative alternation in the difference signs before and after the current position. If there is an alternating state, mark this unit as a delay point to obtain the set of delay point positions;

[0089] Based on the sequence of velocity difference change trends, select the continuous unit interval with the smallest absolute value of the difference in the vertical path. First, calculate and store the velocity difference trend of each unit for each vertical path. Use the built-in decision mechanism of the program to traverse all unit differences, and include the units with the absolute value of the difference less than the preset minimum tolerance threshold δ (for example, set δ = 0.02 mm / s) in the preliminary screening range. Subsequently, further compare the velocity differences of the previous and next units with the difference of this unit to determine whether its value fluctuates stably within the interval [-δ, δ]. If this condition is met, it is considered that this continuous unit is in the trend minimum region and is used as the target section for subsequent processing. During the execution process, traverse the index i of all unit positions in the vertical path, and use the absolute value function for the difference Δv i = |v i+1 - v i | for calculation, select the indexes near the minimum value point to form the interval i - 1, i, i + 1, and use it as the candidate region. If there are multiple intervals that meet the conditions, preferentially select the interval with higher difference stability. Subsequently, count the differences between the upper and lower adjacent units at each selected unit position. Let the positive sign of the velocity difference indicate upward acceleration, and the negative sign indicate upward deceleration. If the adjacent two differences are positive and negative respectively, it is judged as a positive and negative alternating state. The judgment mechanism depends on:

[0090] sign(v i - v i-1 ) × sign(v i+1 - v i ) = -1;

[0091] If this equation is satisfied, this unit is determined as a delay point, record its path index and the corresponding time point number, and further perform an example operation in the actual sampling scenario. Assume that the sampling depth of the blood container is 10 cm, which is divided into 20 vertical units, each unit is 0.5 cm, and the unit volume is 1 ml. Let the velocity difference between the 9th unit and the 10th unit be 0.01 mm / s, and the velocity difference between the 10th unit and the 11th unit be -0.015 mm / s. The two are positive and negative respectively, which conforms to the alternating judgment rule. Then the 10th unit is recorded as a delay point, and the following sampling result is formed:

[0092] Table 2 Delay Point Judgment Parameter Table

[0093]

[0094] As shown in Table 2, the velocity differences between the 10th path unit and its previous and next units are +0.010 mm / s and -0.015 mm / s respectively, showing a positive and negative alternating relationship, which meets the delay point identification conditions, so it is determined as a delay point.

[0095] S212: According to the set of delay point positions, extract the settlement acceleration values of the corresponding unit at multiple consecutive time points, subtract the acceleration values of the upper and lower adjacent units at the same time point respectively, form a three-point acceleration difference sequence, and slide to calculate the difference change rate of the sequence at each time point to obtain the acceleration difference change rate sequence;

[0096] According to the set of delay point positions, extract the settlement acceleration values of the corresponding unit at multiple consecutive time points. In the specific operation, it is necessary to call the acceleration change sequence a of each delay point within the continuous time window i,t , where i is the path unit index and t is the time point number. First, obtain the settlement velocity v of each sampling unit at each time point according to the sensor data i,t , and then calculate its acceleration through the velocity derivative Assume that the time interval Δt = 0.5s, and take three-point sliding as a unit to obtain the three-point acceleration values as a i,t-1 , a i,t , a i,t+1 , and then calculate the accelerations of its upper and lower adjacent units respectively. Assume that i = 10 is the delay point, then it is necessary to calculate a 9,t , a 11,t to obtain the comparison items, and further construct the following differences:

[0097] Δa up = a 10,t - a 9,t ;

[0098] Δa down = a 10,t - a 11,t ;

[0099] Combine the above differences to construct a three-point sliding window, compare the two differences with adjacent time points at each moment, and calculate the change rate:

[0100]

[0101] Assume that the sample data at a certain moment is as follows:

[0102] a 10,t-1 = 0.18mm / s 2 ;

[0103] a 10,t = 0.15mm / s 2 ;

[0104] a 9,t = 0.13mm / s 2 ;

[0105] a 11,t = 0.12mm / s 2 ;

[0106] Then there is:

[0107] Δa up = 0.15 - 0.13 = 0.02 mm / s 2 ;

[0108] Δa down = 0.15 - 0.12 = 0.03 mm / s 2 ;

[0109] If the difference at the previous moment is 0.04, then the change rate r t = (0.025 - 0.04) / 0.5 = -0.03, indicating a decreasing trend. Continuously judge whether there is a deceleration sequence within multiple time points, and then obtain the acceleration difference change rate sequence.

[0110] S213: According to the acceleration difference change rate sequence, compare the acceleration change rate trend values of the delay point position in the sliding window under adjacent units, and use the formula:

[0111]

[0112] Calculate the acceleration change rate trend deviation value B of the kth delay point at m time points k , and judge whether the value is positive and decreases hourly among the delay points. If it holds, establish a set of velocity delay boundary unit positions, where a k,j represents the settlement acceleration value of the delay point at the jth time point, a k-1,j , a k+1,j respectively represent the settlement acceleration values of the adjacent upper and lower units of the delay point at the jth time point, v k,j , v k,j-1 respectively represent the settlement velocity values of the delay point at the jth and j - 1th time points, and m is the number of time points participating in the sliding window calculation;

[0113] According to the acceleration difference change rate sequence, compare the acceleration change rate trend values of the delay point position in the sliding window under adjacent units, and calculate using the formula. Assume that the sliding window m = 3, select the 10th unit as k, and the time points are t1, t2, t3, and the corresponding data are as follows:

[0114]

[0115] Substitute into the formula:

[0116] The first term:

[0117]

[0118] The second term:

[0119]

[0120] Item 3:

[0121]

[0122] Then:

[0123]

[0124] This result indicates that there are obvious difference fluctuations between the delay points and the accelerations of adjacent units in consecutive time periods. If this value is higher than the threshold B th = 0.02 (The setting basis is the settlement acceleration fluctuation range of the vertical path unit on the unit time scale, which is derived from the average acceleration deviation amplitude of the upper and lower boundaries of the static stratification stable section data corresponding in the collected samples. Specifically, in the same vertical path, without interlayer velocity delay, the maximum average difference of acceleration within any three-point time window does not exceed 0.02 mm / s2. Therefore, this value is set as the critical standard, and this threshold varies with the sampling time length m corresponding to the vertical path. If the m value increases, the maximum acceleration average difference in the actual sample tends to shrink, and then a smaller critical value can be set. If the m value is small (for example, m = 2), the threshold needs to be increased to about 0.03 mm / s2 to avoid misjudgment caused by insufficient sample points.) and continuously decreases, it is identified as a candidate point for the stratification boundary, and finally a set of velocity delay boundary unit positions is established.

[0125] Please refer to Figure 4 , and the steps of S3 are as follows:

[0126] S311: Based on the set of velocity delay boundary unit positions, extract the settlement velocity sequences of each position within a fixed time, calculate the velocity change ratios of adjacent time periods in the order of time points, and obtain a sequence of velocity decay rates;

[0127] Based on the set of positions of the velocity-delay boundary cells, the settlement velocity sequences of each path cell within a fixed time are extracted. Specifically, taking the path cell numbered 3 as an example, at 5 equal time intervals, its velocity acquisition values are 2.1, 1.8, 1.6, 1.4, 1.2 mm / s in sequence. The sampling frequency is 0.5 Hz, that is, the time interval between every two time points is 2 seconds. By taking the first-order difference of these velocity data in sequence and dividing by the time interval, the sequence of velocity change rate values can be obtained. Among them, the velocity change rate from the 1st to the 2nd time period is (1.8 - 2.1) / 2 = -0.15 mm / s2, and from the 2nd to the 3rd time period is (1.6 - 1.8) / 2 = -0.1 mm / s2. Then, taking the first-order difference of this sequence of velocity change rates and dividing by the time interval, the velocity decreasing rate value is obtained, that is, the velocity decreasing rate value in the 2nd segment is (-0.1 - (-0.15)) / 2 = 0.025 mm / s3. Using this method to process the velocity data of all path cells in sequence, and combining the set of positions of the velocity-delay boundary cells to screen the participating path cells, the velocity decreasing rates of them in the same time window are obtained, and the velocity decreasing rate values of each path cell in this interval are summarized to form structural data, as shown in Table 3. Table 3 lists the path cell numbers, their velocity decreasing rate values, and the velocity decreasing curvature values of their corresponding upper and lower adjacent cells:

[0128] Table 3 Data Table of Path Cell Velocity and Curvature

[0129]

[0130] As shown in Table 3, it can be clearly obtained the change situation of the velocity decreasing rate of each path cell within a fixed time period, providing a basis for subsequent differential judgment and concentrated boundary point judgment, and obtaining the sequence of velocity decreasing rates.

[0131] S312: According to the sequence of velocity decreasing rates, obtain the velocity sequences of the upper and lower path cells corresponding to each target position, calculate the second-order difference values of the upper and lower cell velocity sequences within the same time interval, and take the absolute value to construct the sequence of velocity decreasing curvatures;

[0132] Based on the velocity decay rate sequence, further obtain the settlement velocity sequence data of the upper and lower adjacent units of each target path unit, and perform calculations according to the velocity change rate between every two time points. Determine the velocity decay curvature value of the path unit within this time window through the difference between the change rates of two consecutive times. Taking the path unit numbered 3 as an example, its upper unit number is 2, and the lower unit number is 4. If the velocity sequence of its upper unit is 2.3, 2.0, 1.7, 1.5 mm / s, and the velocity change rates between every two time points are -0.15, -0.15, -0.1 mm / s² respectively, then the velocity decay curvature of this path is ((-0.15 - (-0.15)) - (-0.1 - (-0.15))) = 0.05 mm / s³, and the corresponding curvature value is 0.05 × 10⁻² m / s³. The velocity sequence of the lower unit numbered 4 is 2.0, 1.7, 1.4, 1.3 mm / s, and its derived curvature value is 0.1 × 10⁻² m / s³. The curvatures of these two are inconsistent. Combining with the velocity decay rate value of path unit 3 itself, which is 3.0 × 10⁻³ m / s², corresponding to the data in the above table, it is used for subsequent calculations and judgments to obtain the velocity decay curvature sequence.

[0133] S313: According to the velocity decay rate sequence and the velocity decay curvature sequence, compare one by one the differences in the velocity decay rate values and velocity decay curvature values of the target path unit and its upper and lower adjacent units at each time point, and use the formula:

[0134]

[0135] Calculate the concentrated point curvature difference value C of the i-th path unit i , if it shows a constant difference within a continuous time interval and the upper and lower curvature fluctuations are inconsistent, then mark the corresponding position as the concentrated boundary point and establish the platelet concentration limit position, where r i represents the velocity decay rate value of the i-th path unit, r i-1 , r i+1 respectively represent the velocity decay rate values of its upper and lower path units, g i-1 , g i+1 respectively represent the velocity decay curvature values of the upper and lower path units;

[0136] According to the velocity decay rate sequence and velocity decay curvature sequence obtained above, perform the concentrated boundary point judgment operation, compare the path units one by one, and construct the concentrated point curvature difference value by judging whether the difference between its velocity decay rate value and the average value of its upper and lower path units is constant, and whether there is an inconsistent trend in the curvature values of the upper and lower path units.

[0137] Now taking path unit 3 as an example, substitute the data: r3 = 3.0 × 10 -3 、r2 = 2.9 × 10 -3, r4=3.5×10 -3 , g2=1.2×10 -2 , g4=1.4×10 -2 , put it into the formula as follows:

[0138] The first step is to calculate the average velocity decline rate:

[0139]

[0140] The second step is to calculate the absolute value of the curvature difference:

[0141] |g2-g4|=|1.2-1.4|×10 -2 =0.2×10 -2 ;

[0142] The third step is to enter the formula for calculation:

[0143]

[0144] The result shows that the difference of path unit 3 is greater than the preset reference value of 0.15×10-3m / s2 (the setting is based on the fact that the velocity decrease rate fluctuation range of adjacent path units in the known normal sedimentation area is usually in the range of ±0.1×10-3m / s2 to ±0.14×10-3m / s2, which is determined by the standard deviation of the sedimentation velocity change rate difference of multiple path units in the same time window. In areas with dense number of path levels (such as densely layered areas in the vertical sedimentation container of blood samples), the local changes per unit time should show a stable trend. If the difference If the velocity exceeds the threshold, it indicates that its velocity behavior has deviated from the decreasing law of adjacent path units. When the threshold is used to quantitatively evaluate the velocity variation behavior between path units, it should be adjusted in conjunction with the overall mean fluctuation range of the sedimentation velocity sequence. For example, when the velocity mean increases to above 4.0×10-3m / s2, the benchmark value can be adjusted to 0.18×10-3m / s2 to maintain the consistency of sensitivity), which meets the requirements for screening the concentration boundary point. Combined with the inconsistency of the curvature of the upper and lower units, the unit can be marked as the concentration boundary point to obtain the platelet concentration limit position.

[0145] See also Figure 5 , step S4 is:

[0146] S411: according to the platelet concentration limit position, after the main extraction is completed, multiple inclination change states of the sedimentation container are set, and the sedimentation velocity values ​​of the path units in the upper and lower regions of the limit at different time points are collected under each inclination state, and are uniformly sorted into an inclination-time two-dimensional sequence to obtain an inclination velocity sampling matrix;

[0147] According to the platelet concentration boundary position, after the main extraction is completed, the inclination change state of the sedimentation container is set. When performing the inclination adjustment operation, the container is sequentially adjusted from the horizontal state to an angle of 15° and the inclination state is kept constant. The holding time for each inclination state is set to 12 seconds. While performing each group of inclination adjustment operations, speed sampling is carried out on the boundary area and its adjacent path units above and below. The collected speed data needs to cover two time points before and after the inclination change to ensure that each path unit has speed sampling values at each inclination stage. Taking path units P1, P2, P3, and P4 as examples, the initial speed is collected at an inclination of 0°, and the final speed is collected at an inclination of 15° to form path-time two-dimensional matrix data. The sampled speed data is shown in Table 4:

[0148] Table 4 Speed Monitoring Table for Path Units in the Boundary Area

[0149]

[0150] As shown in Table 4, within 12 seconds when the inclination of path unit P1 changes from 0° to 15°, its sedimentation speed increases from 0.52 mm / s to 0.66 mm / s. Similarly, the speed of P2 changes from 0.48 mm / s to 0.60 mm / s. By associating this type of data with the inclination change and sampling time series, an inclination speed sampling matrix is established.

[0151] S412: Based on the inclination speed sampling matrix, calculate the speed change of each path unit according to the ratio of the speed difference value of each path unit in each inclination holding time period to the duration of the corresponding time period, and construct a speed change matrix;

[0152] Based on the inclination speed sampling matrix, according to the speed values of each path unit within the sampling time series, execute the ratio of the speed difference between adjacent time points to the inclination difference, and then obtain the unit speed response ratio caused by each inclination change. Combining with the length of each time interval, calculate the speed change rate of the path unit in the corresponding inclination interval. Through the calculation operation for each path unit, a speed change rate matrix is obtained. For example, for path unit P1, when the inclination changes by 15° and the time interval is 12 seconds, the speed increase is 0.14 mm / s, and the corresponding speed change rate is calculated as Δv / Δt = 0.14 / 12 ≈ 0.01167 mm / s2. Then, through subsequent weighted processing, it enters the comprehensive calculation link to form a matrix structure, forming a speed change response block under each path unit and inclination stage, which serves as the source of basic parameters for subsequent path determination.

[0153] S413: According to the speed change rate matrix, statistically analyze the speed increase amplitude of each path unit in different inclination stages, identify the one with the largest speed increase rate in each inclination holding segment, and use the formula:

[0154]

[0155] Calculate the rising response rate value R of the i-th path unit i , extract the corresponding path unit index through sorting, and establish a boundary area fallback response path unit sequence, where v i,h represents the settlement velocity value of the i-th path unit at the h-th time point, and θ h represents the h-th dip angle state value, and Δt h represents the length of the h-th time interval, and t1 and t H are the sampling times of the 1st and H-th time points respectively;

[0156] According to the velocity change rate matrix, statistically calculate the velocity growth amplitude of each path unit at different dip angle stages. Through difference normalization and dip angle amplitude correction, normalize and measure the response rate of each path unit. The velocity change of path unit P1 is v i,h+1 -v i,h = 0.14 mm / s, the dip angle change θ h+1 -θ h = 15°, the time interval Δt h = 12 s, substitute into the formula to calculate:

[0157]

[0158] After normalization,

[0159]

[0160] Calculate P2 as 0.0025, P3 as 0.0021, and P4 as 0.00305 in the same way. Select the path unit P4 with the largest rising response rate as the priority marking unit through sorting, and construct a boundary area fallback response path unit sequence with its path as the representative. This result shows that this path unit exhibits the largest response amplitude to the dip angle change under external intervention conditions and is representative.

[0161] Please refer to Figure 6 , the steps of S5 are as follows:

[0162] S511: According to the velocity sequences of each unit in the boundary area fallback response path unit sequence in the fallback state, calculate the velocity vector directions of each path unit at multiple time points, obtain the vector representation of the velocity directions of the path unit at each time point, and establish a velocity vector direction sequence;

[0163] Taking each unit in the boundary area fallback response path unit sequence as a reference point, collect its settlement velocity data in the fallback state, perform differential operation on the velocity values ​​of each path unit at different times, and calculate its velocity vector direction. The path unit is the area with the most violent velocity fluctuation in the inclination fallback stage. Corresponding to each path unit, a two-dimensional vector is constructed in the form of directional increment of the velocity value. The velocity direction is calculated with the velocity increment of the current path unit and the adjacent unit at the same time point as a reference. Assuming that the velocity values ​​of path unit i at the four time points t1 to t4 are 1.20, 1.05, 0.89, and 0.73 mm / s respectively, the velocity change vector per unit time can be decomposed into: (1.05-1.2 0)=-0.15,(0.89-1.05)=-0.16,(0.73-0.89)=-0.16mm / s,space vectors are constructed between points using three-dimensional coordinates. After projecting the velocity direction from the z-axis to the xy plane, a vector direction sequence is established. In actual operation, the three-dimensional vector needs to be projected onto a two-dimensional plane, and its angle in the Cartesian coordinate system relative to the initial coordinate system angle is calculated to reflect the velocity direction change trend of the path unit. The angle here can be obtained by calculating the inverse tangent function. The horizontal distance of the path unit measurement points in the sedimentation container is 2mm, and the vertical distance is 1mm. The velocity direction trajectory is constructed using the vector difference between the points to form a velocity vector direction sequence.

[0164] S512: Based on the velocity vector direction sequence, perform mean operation on the velocity vector direction of each path unit at all time points in the fallback section, and extract the center position of the direction change of the corresponding path section based on the vector end point coordinates of the path unit in spatial distribution, to obtain the average velocity vector direction and the center position point;

[0165] Based on the sequence of velocity vector directions, the velocity direction values of each path unit at multiple time points are averaged. The averaging method is completed by the weighted superposition of the sine and cosine of the angular vector. Suppose the direction angles of a path unit at 6 time points are 45°, 50°, 48°, 43°, 47°, and 46° in sequence. Then, after converting each angle into a unit vector, the angle of the resultant vector is obtained as the average direction. At the same time, using the positioning point of the path unit in the spatial coordinate system as the vector end point, the geometric centroid of all point coordinates is calculated. Suppose there are 5 velocity direction points in a certain path segment, and their two-dimensional spatial positions are (5,10), (6,9), (7,8), (8,7), and (9,6) respectively. Then the centroid coordinates are that the average of the x coordinates is 7 and the average of the y coordinates is 8. Therefore, the coordinates of the central position point are (7,8). The average velocity direction is obtained by summing the cosines of the unit vectors, and the angle is approximately 46.5°. The above process needs to perform direction normalization and position balancing processing on all path units. Especially when the fluctuation ranges of velocity data are significantly inconsistent, the angles need to be periodically harmonized to prevent deviation during the angle averaging process. Finally, the average velocity vector direction and the central position point are summarized and generated.

[0166] S513: According to the platelet concentration limit position and the central position point of the average velocity vector direction, construct a linear path connecting the two points, summarize the residual velocity values and corresponding direction data of all path units on the path in the falling state, perform cumulative processing in combination with the position distance and direction difference, statistically calculate the overall absorption capacity index of the path segment, and establish secondary micro platelet concentration data;

[0167] According to the platelet concentration limit position and the central position point obtained in the previous paragraph, construct a straight-line path connecting the two points. Suppose the limit position is at the path coordinates (4,12) and the central position point is (7,8). Then the direction of the line segment path can be expressed as from (4,12) to (7,8), and the path length is calculated by the Euclidean distance formula as Sample the path units discretely distributed on the path and extract their residual velocity values in the falling state. Suppose there are 5 sampling units distributed on the path segment, and their velocity values are 0.15, 0.18, 0.21, 0.23, and 0.20 mm / s respectively, and the direction angles are 42°, 45°, 46°, 47°, and 49° respectively. Calculate the difference from the average direction of 46.5°. The direction differences are 4.5°, 1.5°, 0.5°, 0.5°, and 2.5°. After weighting the velocity values and their direction deviation angles and summarizing them, an absorption volume index for the concentrated path segment is formed. Finally, sum up the absorption values of all path units along the line to summarize and form secondary micro platelet concentration data. In actual operation, data with a direction deviation value of less than 3° and a velocity value greater than 0.20 mm / s for the path units needs to be given a priority weight to improve the effectiveness of the aggregated path in this paragraph. The sampling information used when constructing the data is shown in the following table.

[0168] Sampling data table of the fallback path segment in Table 5

[0169]

[0170] As shown in Table 5, the path unit as a whole shows a stable growth trend of velocity value in the centripetal direction, and the direction deviation is controlled within 7°, meeting the data normalization absorption standard. Finally, the total residual velocity absorption amount of this path segment is 0.97 mm / s. Through the determination of the direction consistency of the path endpoints and the judgment of the aggregation intensity of the residual velocity, the corresponding secondary micro platelet concentration data is output.

[0171] A platelet concentration system based on gravitational sedimentation, comprising:

[0172] The sedimentation path recognition module obtains the starting depth value, unit volume, time sampling frequency, and initial sedimentation velocity of each path unit, calculates the velocity difference between adjacent units, and collects the difference trend in the time series to obtain the velocity difference change sequence;

[0173] The acceleration trend recognition module, based on the velocity difference change sequence, calls the acceleration value comparison difference trend of the upper and lower adjacent units to obtain the position set of the velocity delay boundary units;

[0174] The concentration limit extraction module, according to the position set of the velocity delay boundary units, calls the curvature difference of the upper and lower units to judge the consistency and obtains the position of the platelet concentration limit;

[0175] The limit response recognition module, according to the position of the platelet concentration limit, extracts the velocity change rate in each inclination state and generates a fallback response path sequence in the limit area;

[0176] The residual absorption path construction module combines the velocity vector directions of each unit in the fallback response path sequence in the limit area, connects the starting and ending points, and then performs secondary concentration to obtain the secondary micro platelet concentration data.

[0177] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any person skilled in the art may use the disclosed technical content to make changes or modifications into equivalent embodiments with equivalent changes and apply them to other fields. However, as long as it does not depart from the technical solution content of the present invention, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A platelet concentration method based on gravitational sedimentation, characterized in that It includes the following steps: S1: Obtain the depth, volume, and time sampling frequency of each vertical path unit in the sedimentation container, collect the sedimentation velocity and calculate the velocity difference to obtain a sequence of velocity difference change trends; S2: Based on the sequence of velocity difference change trends, screen the positions where the positive and negative differences between adjacent units alternate, judge whether the acceleration change rate at this point is greater than that of the upper and lower units and shows a decreasing trend, and generate a set of positions of velocity delay boundary units; S3: According to the set of positions of velocity delay boundary units, compare the difference in velocity decreasing curvature between the candidate point and the upper and lower units, judge the difference stability and mark the concentration boundary points to obtain the platelet concentration limit position; S4: According to the platelet concentration limit position, collect the change rate of sedimentation velocity of the upper and lower units after the inclination change, select the sequence of path units with the largest velocity rising rate to obtain the sequence of path units of the fall response in the limit area; S5: Based on the velocity vector direction of the sequence of path units of the fall response in the limit area, calculate the average vector and the path end coordinates, establish a linear extraction path to obtain secondary micro platelet concentration data.

2. The platelet concentration method based on gravitational sedimentation according to claim 1, characterized in that The sequence of velocity difference change trends includes the change amplitude of the absolute value of the velocity difference, the change trend direction, and the record of trend inflection point distribution. The set of positions of velocity delay boundary units includes the spatial distribution data of delay points, the candidate positions of the layered boundary, and the eigenvalue of the acceleration change rate. The platelet concentration limit position includes the concentration limit coordinate points, the record of the difference in decreasing curvature distribution, and the boundary stability index. The sequence of path units of the fall response in the limit area includes the distribution data of the velocity rising rate, the response amplitude of the path units, and the response mode of the inclination stage. The secondary micro platelet concentration data includes the record of the distribution of the velocity vector center, the average velocity direction, and the coordinates of the residual suction path points.

3. The platelet concentration method based on gravitational sedimentation according to claim 1, wherein The specific steps for obtaining the sequence of velocity difference change trends are as follows: S111: Based on the starting depth value, unit volume, and time sampling frequency of each layered path unit in the vertical direction of the blood sedimentation container, collect the initial sedimentation velocity of cells in each unit at a fixed time interval, compare the ratio difference between the initial sedimentation velocity of adjacent units and the corresponding starting depth value, obtain the sedimentation velocity change rate of each layered path unit, and generate velocity change rate data; S112: Receive the velocity change rate data, calculate the absolute value of the difference between consecutive time sampling points, combine the unit volume data of adjacent path units, uniformly convert the time scale through the time sampling frequency, and statistically obtain the change value of the unit volume increment of the velocity change rate to obtain a sequence of unit volume velocity increment differences; S113: According to the sequence of unit volume velocity increment differences, extract the fluctuation change trend of the velocity increment difference between each layered path unit within a continuous time, using the formula: Calculate the mean value T of the fluctuation trend of the speed increment difference vΔ , construct a sequence of the change trend of the speed difference, where v i represents the initial value of the cell sedimentation speed of the i-th path unit, and v i+1 represents the initial value of the cell sedimentation speed of the (i + 1)-th path unit, and Δd i represents the difference in the starting depths of the i-th and (i + 1)-th path units, and V i , V i+1 represent the unit volumes of the i-th and (i + 1)-th path units respectively, and n represents the total number of path units.

4. The platelet concentration method based on gravitational sedimentation according to claim 1, wherein The specific steps for obtaining the set of positions of velocity delay boundary units are as follows: S211: Based on the sequence of the change trend of the speed difference, select the continuous unit interval with the smallest absolute value of the difference in the vertical path, record the index positions of each unit in the corresponding interval, calculate the speed difference between the adjacent path units above and below the corresponding positions, and determine whether there is an alternating change of positive and negative signs before and after the current position. If there is an alternating change state, mark the unit as a delay point and obtain the set of delay point positions; S212: According to the set of delay point positions, extract the settlement acceleration values of the corresponding units at multiple consecutive time points, subtract the acceleration values of the two adjacent units above and below at the same time point respectively to form a three-point acceleration difference sequence, and slide to calculate the difference change rate of the sequence at each time point to obtain the acceleration difference change rate sequence; S213: According to the acceleration difference change rate sequence, compare the acceleration change rate trend values of the delay point positions within the sliding window of the adjacent units, and use the formula: Calculate the trend deviation value B of the acceleration change rate at the k-th delay point under m time points k , and determine whether the value is positive and decreases hourly among the delay points. If it holds, establish a set of velocity delay boundary cell positions, where a k,j represents the settlement acceleration value of the delay point at the j-th time point, a k-1,j , a k+1,j respectively represent the settlement acceleration values of the upper and lower adjacent cells of the delay point at the j-th time point, v k,j , v k,j-1 respectively represent the settlement velocity values of the delay point at the j-th and (j - 1)-th time points, and m is the number of time points participating in the sliding window calculation.

5. The platelet concentration method based on gravitational sedimentation according to claim 1, characterized in that The steps for obtaining the platelet concentration limit position are specifically as follows: S311: Based on the set of positions of the speed delay boundary units, extract the settlement speed sequences of each position within a fixed time, calculate the speed change ratios of adjacent time periods in the order of time points to obtain the speed decreasing rate sequence; S312: According to the speed decreasing rate sequence, obtain the speed sequences of the upper and lower path units corresponding to each target position, calculate the second-order difference values of the upper and lower unit speed sequences within the same time interval, and take the absolute value to construct the speed decreasing curvature sequence; S313: According to the speed decreasing rate sequence and the speed decreasing curvature sequence, compare one by one the differences in the speed decreasing rate values and speed decreasing curvature values of the target path unit and its upper and lower adjacent units at each time point, and use the formula: Calculate the degree of difference in the curvature of the concentration point C of the i-th path unit i , if it shows a constant difference within a continuous time interval and the upper and lower curvature fluctuations are inconsistent, then mark the corresponding position as the concentration boundary point and establish the platelet concentration limit position, where r i represents the velocity decay rate value of the i-th path unit, r i-1 , r i+1 respectively represent the velocity decay rate values of its upper and lower path units, g i-1 , g i+1 respectively represent the velocity decay curvature values of the upper and lower path units.

6. The platelet concentration method based on gravitational sedimentation according to claim 1, characterized in that, The steps for obtaining the sequence of path units for the fallback response in the limit area are specifically as follows: S411: According to the platelet concentration limit position, set multiple inclination change states of the settlement container after the main extraction is completed. At each inclination state, collect the settlement speed values of the path units in the areas above and below the limit at different time points, and uniformly organize them into an inclination-time two-dimensional sequence to obtain the inclination speed sampling matrix; S412: Based on the inclination speed sampling matrix, calculate the speed change of each path unit according to the ratio of the speed difference value of each path unit in each inclination residence time period to the duration of the corresponding time period, and construct the speed change matrix; S413: According to the speed change rate matrix, statistically analyze the speed increase amplitude of each path unit in the different inclination stages, and identify the one with the largest speed increase rate in each inclination residence section, and use the formula: Calculate the rising response rate value R of the i-th path unit i , extract the corresponding path unit index through sorting, and establish a boundary area falling response path unit sequence, where v i,h represents the settlement speed value of the i-th path unit at the h-th time point, and θ h represents the h-th dip state value, and Δt h represents the length of the h-th time interval, and t1 and t H are the sampling times of the 1st and H-th time points respectively.

7. The platelet concentration method based on gravitational sedimentation according to claim 1, characterized in that, The steps for obtaining the secondary micro platelet concentration data are specifically as follows: S511: According to the speed sequences of each unit in the falling state in the sequence of path units for the fallback response in the limit area, calculate the velocity vector directions of each path unit at multiple time points, obtain the vector representation of the velocity direction of the path unit at each time point, and establish the velocity vector direction sequence; S512: Based on the sequence of velocity vector directions, perform mean operations on the velocity vector directions of each path unit at all time points within the fallback section. At the same time, based on the vector end coordinates of the path unit in the spatial distribution, extract the center position of the direction change of the corresponding path segment to obtain the average velocity vector direction and the center position point; S513: According to the platelet concentration limit position and the center position point of the average velocity vector direction, construct a linear path connecting the two points, summarize the residual velocity values and corresponding direction data of all path units on the path in the fallback state, perform cumulative processing by combining the position distance and direction difference, statistically calculate the overall suction capacity index of the path segment, and establish secondary microplatelet concentration data.

8. A platelet concentration system based on gravitational sedimentation, characterized in that, The system is used to execute the method according to any one of claims 1-7, and includes: The sedimentation path recognition module obtains the starting depth value, unit volume, time sampling frequency, and initial sedimentation velocity of each path unit, calculates the velocity difference between adjacent units, and collects the difference trend in the time series to obtain the velocity difference change sequence; The acceleration trend recognition module, based on the velocity difference change sequence, calls the acceleration value comparison difference trend between the upper and lower adjacent units to obtain the set of positions of the velocity delay boundary units; The concentration limit extraction module, according to the set of positions of the velocity delay boundary units, calls the curvature difference between the upper and lower units to judge the consistency and obtains the platelet concentration limit position; The limit response recognition module, according to the platelet concentration limit position, extracts the velocity change rate under each inclination state and generates a sequence of fallback response paths in the limit area; The residual suction path construction module combines the velocity vector directions of each unit in the sequence of fallback response paths in the limit area, connects the starting and ending points, and then performs secondary concentration to obtain secondary microplatelet concentration data.

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