A high-sensitivity, wide dynamic range single-particle optical sensor

Abstract

This invention relates to the field of photoelectric detection and particle analysis technology, specifically a high-sensitivity, wide dynamic range single-particle optical sensor. It includes a fluid cell, a light source, an extinction detection unit, a scattering detection unit, and a signal synthesis unit. The fluid cell forms a detection channel for particles carried by the fluid to pass through, and the light source emits a detection beam into the detection channel. The extinction detection unit is positioned in the transmission optical path to acquire the extinction signal, and the scattering detection unit is positioned in the scattering optical path to acquire the scattering signal. The signal synthesis unit sums or weighted sums the extinction and scattering signals to generate a single composite signal, and outputs particle size information and / or counting information based on the composite signal. The composite signal is dominated by the scattering signal in the small particle size range, the extinction signal in the large particle size range, and achieves a smooth transition in the transition range.

Description

Technical Field

[0001] This invention relates to the field of photoelectric detection and particle analysis technology, specifically a high-sensitivity, wide dynamic range single-particle optical sensor. Background Technology

[0002] Single-particle optical sensors are widely used for particle size measurement and counting in liquids or gases. Their basic principle is typically based on the transmission extinction effect and / or scattering effect produced by a particle passing through the detection area on an incident light beam. Extinction detection exhibits better linear response characteristics for larger particles, while scattering detection has higher sensitivity in the small particle size range. Therefore, existing technologies have proposed combining extinction and scattering signals to broaden the measurable particle size range of the sensor to some extent. For example, US Patent 5,835,211 discloses a single-particle optical sensing scheme that combines light scattering and photoresistance signals to form a single composite signal, balancing detection sensitivity in the small particle size range with dynamic range in the larger particle size range.

[0003] However, in practical applications, the aforementioned existing technical solutions still have many technical defects, which limit their stable application under conditions of high sensitivity and wide dynamic range.

[0004] First, in existing single-particle optical sensors, extinction and scattering signals typically correspond to different physical mechanisms, and their signal amplitudes are highly sensitive to particle refractive index, particle size, and optical system parameters. Scattering signals, in particular, exhibit a significant dependence on the refractive index of the particle material; samples with different refractive indices will produce significantly different scattering response intensities under the same particle size conditions. Current technologies commonly employ fixed gain or uniform correction via software algorithms at the back end to process scattering signals. However, such methods struggle to compensate for amplitude shifts caused by refractive index differences in a timely and effective manner, easily leading to inconsistencies in signal scale within small particle sizes. This, in turn, affects the continuity and consistency of extinction and scattering signals during recombination or splicing processes.

[0005] Secondly, in order to balance the detection sensitivity for small particles with the upper limit of detection for large particles, existing technologies often enhance weak signals by increasing the front-end amplification factor or increasing the power of the light source. However, while this method improves the sensitivity for small particles, it easily causes the signal amplitude under large particle conditions to rapidly approach or exceed the linear operating range of the circuit, thereby causing signal saturation, clipping, or severe nonlinear distortion. Especially when using a fixed supply voltage and fixed signal link parameters, existing technologies often struggle to simultaneously meet the requirements of detecting weak signals and preventing clipping of strong signals across the entire particle size range, resulting in limited dynamic range.

[0006] Furthermore, in the structural design of existing single-particle optical sensors, the cross-sectional dimensions of the fluid cell detection channel are typically selected based on experience or simple geometric passage conditions, ensuring that only particles with the largest target diameter can pass through the detection channel without clogging. This experience-based dimensional selection method fails to take into account factors such as optical detection performance, circuit dynamic range, and sample optical characteristics. This can easily lead to problems such as an excessively large detection channel size reducing extinction detection sensitivity, or an excessively small detection channel size causing signal saturation, abnormal occlusion, or even clogging under large particle size conditions, thus affecting measurement stability and reliability.

[0007] Furthermore, existing technologies often employ simple weighting, splicing, or threshold switching strategies when combining extinction and scattering signals into a single detection signal. Because these strategies fail to adequately constrain the matching relationship between the two signals in terms of amplitude scale, linear range, and dynamic range during structural design and signal conditioning, they are prone to producing signal discontinuities, particle size distribution breakpoints, or systematic biases within the particle size transition range, thereby reducing the reliability of the measurement results. Summary of the Invention

[0008] The purpose of this invention is to provide a high-sensitivity, wide-dynamic-range single-particle optical sensor to solve the technical problems mentioned in the background art.

[0009] Based on the above ideas, the present invention provides the following technical solution:

[0010] A high-sensitivity, wide dynamic range single-particle optical sensor, comprising:

[0011] A fluid pool that forms a detection channel through which the fluid carrying particles passes;

[0012] A light source is configured to emit a detection beam toward the detection channel;

[0013] An extinction detection unit is disposed on the transmission optical path of the detection beam and is used to acquire the extinction signal generated when the particles pass through the detection beam;

[0014] A scattering detection unit is disposed on a scattering light path different from the transmitted light path, and is used to acquire the scattering signal generated when the particle passes through the detection beam.

[0015] The signal synthesis unit is electrically connected to the extinction detection unit and the scattering detection unit, and is used to sum or weighted sum the extinction signal and the scattering signal to generate a single composite signal, and output particle size information and / or counting information based on the single composite signal;

[0016] The single composite signal is mainly contributed by the scattering signal in the smaller particle size range, mainly contributed by the extinction signal in the larger particle size range, and in the transitional particle size range between the two, it is contributed by both the scattering signal and the extinction signal to achieve a smooth transition.

[0017] By simultaneously acquiring extinction and scattering signals within the same sensor and combining them into a single composite signal, the scattering signal dominates the small particle size range to ensure the detection lower limit and sensitivity, while the extinction signal dominates the large particle size range to ensure the upper limit and linear range. At the same time, a continuous and smooth transition is achieved in the transition particle size range. This allows for both high sensitivity and wide dynamic range without relying on hard switching / splitting, reducing the risk of discontinuities, jumps, or systematic deviations in particle size distribution at the intersection zone, and improving the stability and consistency of counting and particle size output.

[0018] Preferably, a scattering signal conditioning unit is provided between the scattering detection unit and the signal synthesis unit. The scattering signal conditioning unit includes a variable gain amplifier, which is used to scale the gain of the scattering signal before it is input into the signal synthesis unit, so as to compensate for the differences in scattering response caused by samples with different refractive indices.

[0019] A scattering signal conditioning unit with variable gain is set between scattering detection and signal synthesis. The amplitude of the scattering signal can be pre-conditioned before signal synthesis, so that the scattering channel can perform amplitude matching for the scattering response differences of samples with different refractive indices. This reduces the signal scale drift and threshold drift in small particle size segments caused by refractive index changes, improves the comparability and repeatability between different samples, and provides a unified amplitude basis for the smooth transition of subsequent composite signals.

[0020] Preferably, the scattering signal conditioning unit further includes a refractive index parameter setting unit and a gain control unit; the refractive index parameter setting unit is used to output a setting signal corresponding to the sample refractive index level, and the gain control unit controls the gain coefficient of the variable gain amplifier according to the setting signal, so that the gain coefficient is an attenuation coefficient less than 1 and / or an amplification coefficient greater than 1.

[0021] By introducing a refractive index parameter setting unit and a gain control unit, the sample refractive index difference is mapped to the scattering signal gain coefficient in a selectable range, thereby achieving controllable attenuation or amplification of the scattering signal. This avoids relying on backend software algorithms or repeated parameter adjustments based on human experience, allowing refractive index compensation to be completed in real time on the hardware side. This reduces computational latency and processing complexity, improves the robustness of field applications, and enhances reproducibility under different batches and environmental conditions.

[0022] Preferably, the signal synthesis unit and / or the scattering signal conditioning unit includes an operational amplifier circuit, the operational amplifier circuit being supplied with a voltage of 15V, to increase the output dynamic range of the single composite signal and reduce the risk of saturation clipping.

[0023] Increasing the supply voltage of the operational amplifiers in the signal synthesis unit and / or scattering signal conditioning unit to 15V can significantly expand the available output swing of the signal link, improve the dynamic margin of a single composite signal in large-particle-size and strong-signal scenarios, reduce misjudgment and counting errors of the upper-end particle size caused by clipping, saturation and nonlinear compression, thereby improving the effective dynamic range and measurement reliability of the large-particle-size segment.

[0024] Preferably, the light source is a laser, the emission wavelength of which is in the range of 770nm to 820nm, and the output power is 100mW.

[0025] By limiting the laser wavelength to 770nm–820nm and the output power to 100mW, the light source output becomes more stable and has a higher light energy reserve. This is beneficial for improving the signal-to-noise ratio of the scattered / extinction signal, lowering the detection limit, and improving the detectability of low-concentration, small-diameter particles. At the same time, the higher power, while ensuring detection sensitivity, provides a basis for maintaining a usable amplitude of the composite signal over a wide particle size range, thereby enhancing the overall dynamic range and stability.

[0026] Preferably, a narrowband filter is provided on the scattering optical path and / or the transmission optical path, the center wavelength of the narrowband filter being located near and matched with the emission wavelength of the laser, so as to suppress non-target band background light from entering the scattering detection unit and / or the extinction detection unit; and the detection channel of the fluid pool has a minimum cross-sectional size, the minimum cross-sectional size being used to define the maximum particle size range that can pass through the detection channel.

[0027] By setting narrowband filters that match the laser wavelength in the scattering and / or transmission optical paths, ambient light, stray light, and background radiation from non-target wavelengths can be effectively suppressed from entering the detector, reducing baseline drift and noise levels, improving signal stability and signal-to-noise ratio, thereby enhancing weak signal recognition capabilities and improving measurement reliability in the low-particle-size range. At the same time, by setting the minimum cross-sectional size of the detection channel to limit the maximum passable particle size range, the risk of blockage, abnormal occlusion, and signal distortion caused by oversized particles or agglomerates can be reduced, providing a structural basis and safety boundary for the effective measurement of the upper limit particle size.

[0028] Preferably, the steps for determining the minimum cross-sectional dimension of the detection channel in the fluid pool include:

[0029] S1. Obtain the target particle size range of the sample to be tested, and at least determine the maximum target particle size of the particles to be tested.

[0030] S2. Based on the calibration results of the extinction detection unit and the scattering detection unit, determine the particle size range in which the extinction signal dominates and the particle size range in which the scattering signal dominates in a single composite signal within different particle size ranges.

[0031] S3. Based on the maximum target particle size and the particle size range where the extinction signal dominates, determine the basic passage conditions that the detection channel must meet structurally for particles to pass through smoothly.

[0032] S4. Before the scattered signal enters the signal synthesis unit, a refractive index compensation parameter for the scattered signal is introduced to compensate for the difference between samples with different refractive indices. This refractive index compensation parameter is used as a constraint condition when solving for the minimum cross-sectional size, so that the scattered signals corresponding to samples with different refractive indices are within the effective amplitude range that can be synthesized when they enter the signal synthesis unit.

[0033] S5. Introduce voltage constraint parameters related to the power supply capability and output dynamic range of the signal synthesis unit and signal conditioning circuit, and use the voltage constraint parameters as constraints when solving for the minimum cross-sectional size, so as to avoid saturation or clipping of a single composite signal under the maximum target particle size condition.

[0034] S6. Under the constraints formed by steps S4 and S5, calculate and determine the minimum cross-sectional size of the detection channel so that when particles with the largest target particle size pass through the detection channel, both the extinction signal and the single composite signal meet the requirements for stable and effective detection.

[0035] By decomposing the process of determining the minimum cross-sectional size of the detection channel into obtaining the target particle size range, determining the extinction / scattering dominance region, establishing the passage conditions, introducing refractive index compensation constraints, introducing voltage dynamic range constraints, and finally solving them together, the structural size design can be transformed from empirical selection into a systematic solution process driven by the physical constraints of the signal. This allows the channel size to simultaneously meet multiple requirements such as maximum particle size passability, composite signal synthesis capability, and dynamic range without clipping. Thus, while keeping the structural size as small as possible, detection performance is guaranteed, reducing the dilemma of sensitivity decrease due to excessively large channel size and blockage / clipping / distortion due to excessively small channel size.

[0036] Preferably, step S4 specifically includes:

[0037] The refractive index of the particulate material and the refractive index of the fluid medium are obtained, and the refractive index difference parameter is determined based on their relative relationship.

[0038] The effect of refractive index difference on the intensity of scattered signal is evaluated by combining the emission wavelength of the detection light source and the reference particle size conditions.

[0039] Based on the aforementioned impact results, the required refractive index compensation for the scattered signal is determined, and the amplitude of the scattered signal is conditioned by hardware to ensure that the refractive index-compensated scattered signal has a consistent or equivalent amplitude scale under different refractive index sample conditions, thereby serving as a constraint basis for subsequently solving the minimum cross-sectional size of the detection channel.

[0040] By acquiring the refractive indices of particles and media and evaluating their impact on the intensity of scattered signals, the required refractive index compensation for the scattered signals is further determined and implemented using hardware amplitude conditioning. This enables samples with different refractive indices to obtain a consistent or equivalent amplitude scale on the scattering channel side, reducing the risk of measurement deviations in small particle size segments and discontinuities in the composite signal transition region caused by differences in the optical properties of the samples from the source. This compensation amount serves as a constraint for subsequently solving the minimum cross-sectional size of the channel, and can incorporate refractive index differences into the structural design closed loop, improving the applicability and stability of the design results for multiple types of samples.

[0041] Preferably, step S5 specifically includes:

[0042] A single composite signal amplitude model is established under the condition of maximum target particle size, formed by the combined action of the extinction signal and the scattering signal after refractive index compensation.

[0043] By combining the power supply voltage capability, output swing limit, and allowable input range of the subsequent signal processing circuit of the signal synthesis unit and its signal conditioning circuit, the dynamic margin of a single composite signal under the maximum target particle size condition is determined.

[0044] The dynamic margin is used as a constraint in the process of solving the minimum cross-sectional size of the detection channel to ensure that the single composite signal is still within the linear working range under the condition of the maximum target particle size.

[0045] By establishing a composite signal amplitude model under the maximum target particle size condition, and combining it with power supply capacity, output swing limit, and allowable input range of subsequent stages to determine the dynamic margin, and then using the dynamic margin as a constraint condition for solving the channel size, the saturation clipping and nonlinear distortion of the composite signal under large particle size conditions can be prevented during the structural design stage, thereby improving the measurement accuracy in the large particle size range and enhancing the linearity across the entire range. At the same time, this dynamic margin constraint and the refractive index compensation constraint work together to enable the channel size design to simultaneously take into account the dual uncertainties of sample differences and circuit dynamic range, thereby improving the robustness of the system.

[0046] Preferably, the minimum cross-sectional dimension of the detection channel in step S6 includes the width and height dimensions of the detection channel cross-section, wherein the width and height dimensions correspond to the minimum geometric dimensions in two mutually perpendicular directions of the detection channel cross-section, respectively.

[0047] The minimum cross-sectional size is determined as follows: under the premise that the particles with the largest target particle size can pass smoothly in the detection channel without obstruction or abnormal posture deviation, and in combination with the linear operation requirements of the extinction signal and the dynamic range constraints of the single composite signal, the width and height dimensions of the detection channel cross-section are solved together to obtain the combination of detection channel cross-sectional dimensions that meets the detection performance requirements and minimizes the structural size.

[0048] By explicitly breaking down the minimum cross-sectional dimension into the width and height dimensions of the detection channel cross-section, and combining the linear operation requirements of the extinction signal with the dynamic range constraints of the composite signal under the premise of ensuring the smooth passage of the maximum particle size and the tolerance of attitude deviation, the channel geometry design can be upgraded from single-dimensional control to two-dimensional coupled optimization. This allows for a more precise balance between the channel cross-sectional dimensions and detection performance, resulting in a size combination that meets the detection performance requirements while minimizing the structural dimensions. This approach helps reduce sample consumption, fluid disturbance, and the probability of blockage, while maintaining the linear reliability of extinction measurement and the stable output of the composite signal, achieving the system goal of high sensitivity and wide dynamic range.

[0049] The technical solution of the present invention may include the following beneficial effects:

[0050] By simultaneously acquiring extinction and scattering signals in the same sensor and synthesizing the two signals at the front end, the scattering signal dominates the small particle size range to ensure the detection lower limit and sensitivity, while the extinction signal dominates the large particle size range to ensure the upper limit and linear range. At the same time, the two signals contribute to the transition of particle size range to achieve a continuous and smooth transition. This avoids the discontinuity, jumps or systematic deviations in particle size distribution caused by the "hard switching / splitting" at the cross-particle size of traditional solutions, which significantly improves the consistency and stability of the full-range particle size output and counting results.

[0051] By introducing a variable gain amplifier into the scattering channel and combining it with refractive index parameter setting and gain control, hardware-side amplitude compensation and scale uniformity are achieved for samples with different refractive indices, reducing signal drift and threshold drift in small particle size segments caused by differences in sample optical properties. At the same time, by increasing the power supply voltage of the signal link to expand the available swing, and by limiting the laser wavelength and power, and configuring narrowband filters that match the light source in the scattering optical path and / or transmission optical path to suppress background light and stray light, the signal-to-noise ratio is improved, baseline drift is reduced, and the risk of saturation clipping in large particle size strong signal scenarios is reduced, so that the composite signal can maintain a detectable and linear output window over a wide particle size range.

[0052] Furthermore, the minimum cross-sectional dimension of the fluid cell detection channel is upgraded from empirical selection to a constrained joint solution process: based on determining the target particle size range and the extinction / scattering dominance range, refractive index compensation constraints and power supply / dynamic range constraints are introduced into the dimension solution, and the minimum cross-sectional dimension is refined into the width and height in mutually perpendicular directions for joint optimization. This ensures that the channel size satisfies both the requirement for the maximum particle size to pass smoothly and the attitude deviation tolerance, as well as the requirements for linear operation of the extinction signal and the dynamic margin requirement of the composite signal. Thus, while minimizing the structural size, it balances the control of blockage risk, the reduction of sample consumption, and the stability of detection performance, achieving a synergistic improvement in high sensitivity and wide dynamic range.

[0053] By employing a 15V operational amplifier circuit, the output swing of the composite signal is increased, reducing the risk of saturation clipping under large particle size conditions, thereby extending the upper limit of large particle size measurements. The customer's notes indicate a comparison: 9V corresponds to a maximum particle size of approximately 400 μm, while 15V can reach approximately 800 μm.

[0054] By setting 256, 512, or 1024 channel bins for particle size, the bin width near the main peak can be reduced, improving the resolvability and stability of the main peak statistics. USP materials explicitly state that a higher channel configuration is more conducive to meeting the bin width constraints related to s_observed when evaluating resolution.

[0055] By adding a scattering detection module around the detection area, or by using a scattering light collection structure that folds / reflects / converges, the utilization rate of circumferential scattered light can be improved, and the difference between the forward and reverse directions of liquid flow through the sensor can be reduced. Attached Figure Description

[0056] Figure 1 This is a component relationship diagram of a high-sensitivity, wide dynamic range single-particle optical sensor according to the present invention.

[0057] Figure 2 This is a flowchart illustrating the process of determining the minimum cross-sectional size of the detection channel for a high-sensitivity, wide dynamic range single-particle optical sensor according to the present invention.

[0058] Figure 3 This is the first method of the scattering detection unit in Example 1;

[0059] Figure 4 This is the second method of the scattering detection unit in Example 1;

[0060] Figure 5 This is the third method of the scattering detection unit in Example 1;

[0061] Figure 6 This is a schematic diagram comparing the particle size response distribution results of Example 1 with those of the traditional single photoresist response method;

[0062] Figure 7 This is a schematic diagram showing the results of particle size measurement and counting verification using standard particle samples in Example 1;

[0063] Figure 8 This is a schematic diagram showing the results of electronic calculations verified using 0.8 μm standard particle samples in this embodiment;

[0064] Figure 9 This is a schematic diagram showing the results of electronic calculations verified using 2.0 μm standard particle samples in this embodiment;

[0065] Figure 10 This is a schematic diagram showing the results of electronic calculations verified using a 5.0 μm standard particle sample in this embodiment. Detailed Implementation

[0066] Example 1

[0067] like Figure 1 and 2 A high-sensitivity, wide dynamic range single-particle optical sensor, comprising:

[0068] A fluid pool that forms a detection channel through which the fluid carrying particles passes;

[0069] A light source is configured to emit a detection beam toward the detection channel;

[0070] An extinction detection unit is disposed on the transmission optical path of the detection beam and is used to acquire the extinction signal generated when the particles pass through the detection beam;

[0071] A scattering detection unit is disposed on a scattering light path different from the transmitted light path, and is used to acquire the scattering signal generated when the particle passes through the detection beam.

[0072] In this embodiment, as shown Figure 3-5 :

[0073] The scattering detection unit typically includes multiple scattering detection modules arranged circumferentially along the detection area, and / or includes a scattering light-collecting component for refracting, reflecting, or converging the circumferentially scattered light from the detection area, and the combination includes the following methods:

[0074] The first method:

[0075] Multiple scattering detection modules are symmetrically arranged around the detection area of ​​the fluid pool in the upward, downward, left, and right directions;

[0076] The second method:

[0077] The obstruction signal on the transmitted light path is refracted by the reflector and received by the corresponding detector. The scattered light around the detection area is converged by two sets of lenses and received by the scattering detector.

[0078] The third method:

[0079] The light-scattering and collecting component is a concave reflector with a central through-hole. The circumferentially scattered light is focused by the concave reflector and then received by the scattering detector. The blocking signal in the transmitted light path passes through the central through-hole and is received by the rear detector.

[0080] The signal synthesis unit is electrically connected to the extinction detection unit and the scattering detection unit, and is used to sum or weighted sum the extinction signal and the scattering signal to generate a single composite signal, and output particle size information and / or counting information based on the single composite signal;

[0081] The single composite signal is mainly contributed by the scattering signal in the smaller particle size range, mainly contributed by the extinction signal in the larger particle size range, and in the transitional particle size range between the two, it is contributed by both the scattering signal and the extinction signal to achieve a smooth transition.

[0082] In this embodiment, the extinction detection unit and the scattering detection unit acquire the extinction signal and the scattering signal generated when particles pass through the detection channel, respectively. The signal synthesis unit then sums or performs a weighted summation of the two signals to generate a single composite signal. By constructing this composite signal, the sensor can primarily utilize the scattering signal to enhance the response capability of small particles in the smaller particle size range, while primarily utilizing the extinction signal to maintain a good linear response and upper limit of the measurement range in the larger particle size range, thereby achieving stable detection within a wider dynamic response range.

[0083] Compared to traditional single-particle sensors based solely on photoresistivity, this embodiment introduces scattering signals into composite detection, which improves the response capability for particles in the submicron particle size range. Through system design and signal matching, the sensor's theoretical detection capability can be further lowered to the particle size response level of approximately 0.1 μm. However, in practical applications, considering background particles, solution cleanliness, environmental noise, calibration stability, and the requirements for false positive control in the application scenario, this embodiment preferably sets the actual effective detection lower limit to 0.4 μm and the upper limit to 400 μm, thus forming a wide dynamic response range of 0.4–400 μm.

[0084] In other words, this embodiment does not simply pursue the theoretical lower limit, but rather optimizes and limits the actual working range while ensuring detection stability, repeatability, and engineering usability. Through the aforementioned composite detection mechanism, the detection sensitivity for small-diameter particles and the range coverage capability for large-diameter particles can be balanced, overcoming the problem of traditional single-photoresistance sensors having a narrow dynamic response range and difficulty in simultaneously meeting the detection requirements of both large and small particles. For traditional photoresistance sensors, their dynamic response range is usually limited by a single detection mechanism, and the practically usable range is often concentrated in a narrow area, making it difficult to achieve stable detection of submicron and hundreds of micrometer particles simultaneously in the same system. This embodiment, however, significantly broadens the system's practically usable particle size response range by combining extinction and scattering signals.

[0085] In one embodiment, the detection channel of the fluid pool is used to allow the fluid carrying particles to pass through the detection beam in a single-particle manner. The detection beam output by the light source is collimated and then passes through the detection channel. The extinction detection unit on the transmission light path outputs an extinction signal characterizing the change in transmitted light intensity, and the scattering detection unit on the scattering light path outputs a scattering signal characterizing the change in scattered light intensity. The two signals enter the signal synthesis unit to form a single composite signal. To enable those skilled in the art to reproduce the results, it is preferable to sample the extinction signal and the scattering signal synchronously using the same acquisition link. For each trigger event, a time window containing an event pre-window and an event post-window (e.g., a pre-window of 1 to 5 milliseconds and a post-window of 5 to 20 milliseconds) is extracted. Within the event pre-window, the baseline is estimated using the median or robust mean and then subtracted. Subsequently, the peak amplitude, pulse area, and pulse width of the two pulses are calculated as characteristic quantities. The composite signal can be constructed in peak form or area form. Preferably, the peak value is used for the main particle size estimation, and the area is used for consistency verification. When abnormal patterns such as sampling saturation, clipping, or bimodalization occur, it is preferable to mark the event as abnormal and perform degradation processing to avoid contamination of particle size estimation and counting by abnormal events.

[0086] Specifically, a scattering signal conditioning unit is provided between the scattering detection unit and the signal synthesis unit. The scattering signal conditioning unit includes a variable gain amplifier, which is used to scale the gain of the scattering signal before it is input into the signal synthesis unit, so as to compensate for the differences in scattering response caused by samples with different refractive indices.

[0087] In one embodiment, a scattering signal conditioning unit is provided between the scattering detection unit and the signal synthesis unit. The scattering signal conditioning unit includes a variable gain amplifier for amplitude scaling of the scattering signal before it enters the signal synthesis unit. The variable gain amplifier can be a graded programmable gain amplifier or a continuously adjustable gain amplifier, with a gain range of 0.25 to 8 times, preferably 0.5 to 4 times. To improve repeatability, graded gain is preferably used, and the gain setting is locked before each batch of sample measurements, so that the scattering signal, after gain scaling, is within a preset effective scattering amplitude range, thereby reducing the impact of differences in scattering response caused by samples with different refractive indices on the consistency of the composite signal scale.

[0088] Specifically, the scattering signal conditioning unit further includes a refractive index parameter setting unit and a gain control unit; the refractive index parameter setting unit is used to output a setting signal corresponding to the sample refractive index level, and the gain control unit controls the gain coefficient of the variable gain amplifier according to the setting signal, so that the gain coefficient is an attenuation coefficient less than 1 and / or an amplification coefficient greater than 1.

[0089] In one embodiment, the scattering signal conditioning unit further includes a refractive index parameter setting unit and a gain control unit. The refractive index parameter setting unit outputs a setting signal corresponding to the sample refractive index level. The setting signal can be generated by a DIP switch, knob, or touch input and represented by a level number. After receiving the setting signal, the gain control unit controls the gain coefficient of the variable gain amplifier according to a pre-established "refractive index level - gain coefficient" mapping table, making the gain coefficient an attenuation coefficient less than 1 and / or an amplification coefficient greater than 1. To ensure feasibility, the mapping table can be obtained through calibration: under the same light source wavelength and reference particle size conditions, at least 5,000 single-particle events are collected for the reference refractive index sample and the target refractive index sample, respectively. The mean or quantile of the scattering peak values ​​is statistically analyzed, and the ratio of the reference scattering statistics to the target scattering statistics is used as a candidate value for the gain coefficient. This value is then quantized to the level achievable by the variable gain amplifier. After quantization, the compensated scattering peak value should fall within a preset effective scattering amplitude range (e.g., the 5th to 95th percentile range of the reference sample scattering peak value). Otherwise, it is preferable to select an adjacent level or adjust the boundary of the effective amplitude range to maintain a consistent scale.

[0090] Specifically, the signal synthesis unit and / or the scattering signal conditioning unit includes an operational amplifier circuit, the operational amplifier circuit being supplied with a voltage of 15V, in order to increase the output dynamic range of the single composite signal and reduce the risk of saturation clipping.

[0091] In this embodiment, the signal synthesis unit and / or the scattering signal conditioning unit include operational amplifier circuits. To effectively characterize a wide dynamic range of particle size response within a limited output voltage range, this embodiment performs a compression mapping process on the response relationship between a single composite signal and particle size. Specifically, within the effective voltage-controlled output range, by compressing and transforming the particle size response relationship, the original large-order-of-magnitude variation between the optical response and voltage output is converted into an output relationship more suitable for hierarchical representation and fine division. Based on this processing method, 1024 approximately equivalent and practically usable channels can be formed, achieving a channel resolution on the order of approximately 0.01 μm near approximately 0.5 μm. This improves the uniformity of response to a single signal source input while ensuring circuit simulation stability and controllable hardware noise.

[0092] Furthermore, by increasing the supply voltage of the operational amplifier circuit from 10V to 15V, the output dynamic range of the single composite signal is further expanded, increasing the upper limit of the system particle size response from approximately 400μm to approximately 800μm. Therefore, this embodiment not only maintains high resolution in the small particle size range but also maintains a wide range coverage in the large particle size range, thereby achieving stable detection over a wider dynamic range.

[0093] In this embodiment, to achieve effective characterization of a wide particle size range within a limited voltage output range, the single composite signal output by the signal synthesis unit is preferably quantized within the effective output range of 0–10V, while the operational amplifier circuit can be powered by 0–15V to provide sufficient dynamic margin for the effective output range. The underlying quantization hardware uses two 12-bit ADCs to physically divide the 0–10V effective output range, thereby forming over 8000 equally divided channels. Considering that directly using all equally divided channels for particle size representation would result in overly dense division in the large particle size range, and such overly fine division has relatively limited practical application significance, this embodiment further performs logarithmic remapping and merging processing on the equally divided channels, maintaining a higher density of channels near the small particle size end and relatively widening the channel division near the large particle size end. Based on the above remapping and merging processing, the system ultimately forms 1024 practically usable channels for output characterization of the particle size range. Therefore, this embodiment does not simply reduce the number of channels, but rather optimizes the distribution of the actually available channels non-uniformly while retaining the high quantization capability of the underlying layer. This allows for higher resolution in the small particle size range, while maintaining sufficient dynamic expression capability in the large particle size range. For example, finer particle size range segmentation accuracy can be obtained around 0.5 μm, thus achieving a balance between high resolution and wide dynamic range while keeping hardware noise, stability, and detection accuracy under control.

[0094] like Figure 6 As shown, the particle size response distribution curve obtained in actual testing of this embodiment exhibits a more concentrated peak shape, specifically sharper peaks and narrower peak widths. This indicates that this embodiment has higher resolution and better signal concentration within the same particle size range. In contrast, the distribution curve obtained under the traditional single photoresist response method has a lower and wider peak shape, indicating weaker particle size discrimination ability and a more dispersed response distribution. In other words, this embodiment, by combining the extinction signal and the scattering signal and combining them with compression mapping processing, demonstrates a significantly better peak shape resolution effect than the traditional scheme in actual test results, thus being more conducive to the identification and stable characterization of minute particle size differences.

[0095] In one embodiment, the signal synthesis unit and / or scattering signal conditioning unit includes an operational amplifier circuit with a supply voltage of 15V. To ensure that the output dynamic range is quantifiable and reproducible, the operational amplifier circuit is preferably calibrated for swing: with a signal source injecting progressively increasing inputs under a 15V supply, the maximum linear output amplitude before the output enters a significant nonlinearity or clipping is measured, and the ratio of the maximum linear output amplitude to the supply voltage is used as the swing coefficient; during online operation, when the composite signal exhibits a clipping pattern where consecutive sampling points reach full scale and the top is flat, it is preferably marked as a clipping event and downgraded, for example, by replacing the composite signal peak value with the area of ​​the extinction signal pulse for particle size estimation of the event, while simultaneously lowering the confidence level of the event so that it can be excluded from statistics or separately counted as an anomaly.

[0096] Specifically, the light source is a laser, the emission wavelength of which is in the range of 770nm to 820nm, and the output power is 100mW.

[0097] In this embodiment, the light source is preferably a laser, and the emission wavelength of the laser can be selected according to the optical absorption characteristics of the sample to be tested. For some colored liquid samples, especially blue liquids or liquid systems that exhibit significant absorption in a specific wavelength band, if the detection wavelength commonly used in traditional light scattering or light obscuration methods is employed, the detection light may experience strong absorption in the sample, leading to a decrease in effective transmitted light intensity, a reduction in signal-to-noise ratio, and further affecting the detection limit and detection stability of small particles.

[0098] Therefore, in this embodiment, to reduce the influence of the liquid under test on the absorption of the detection light and to improve the detection sensitivity under colored sample conditions, the laser wavelength can be adaptively configured according to the sample color characteristics and absorption spectrum characteristics. Specifically, when testing blue liquid samples, a detection light source with relatively weak absorption bands can be selected, such as 450nm blue light or 560nm green light, to improve the propagation conditions of the detection light in the liquid under test and alleviate the problem of increased detection limit caused by sample absorption.

[0099] Furthermore, since this embodiment uses a multimode LD as an optional light source, different colored samples can be detected by switching multimode LD modules with different output wavelengths in different application scenarios. Through this method, this embodiment not only improves the particle detection capability in colored liquid samples but also expands the sensor's applicability to different liquid systems.

[0100] In one embodiment, the light source is a laser with an emission wavelength in the range of 770nm to 820nm and an output power of 100mW. To ensure the implementability and consistency of the light source parameters, it is preferable to use a power meter or a monitoring photodiode to calibrate the output power and record the calibration fields (including power, operating current, and temperature). During online operation, the drive current can be optionally fine-tuned in a closed loop according to the temperature to maintain the power within ±5% of the set value. The laser wavelength can be recorded by the device's nominal value or by sampling a spectrometer for matching and verification with the center wavelength of the filter.

[0101] Specifically, a narrowband filter is provided on the scattering optical path and / or the transmission optical path. The center wavelength of the narrowband filter is located near and matched with the emission wavelength of the laser to suppress non-target band background light from entering the scattering detection unit and / or the extinction detection unit. Furthermore, the detection channel of the fluid pool has a minimum cross-sectional size, which is used to define the maximum particle size range that can pass through the detection channel.

[0102] In one embodiment, a narrowband filter is provided on the scattering optical path and / or the transmission optical path. The center wavelength of the filter is located near and matched to the emission wavelength of the laser to suppress background light of non-target wavelength bands from entering the scattering detection unit and / or the extinction detection unit. The filter can be optionally installed at the incident end of the scattering detection unit, the incident end of the extinction detection unit, or both simultaneously. The bandwidth of the filter can be selected from 5nm to 30nm, preferably 10nm to 20nm, to achieve a balance between transmittance and background suppression. In this embodiment, the detection channel has a minimum cross-sectional dimension to define the maximum passable particle size range. The minimum cross-sectional dimension is composed of two minimum geometric dimensions in mutually perpendicular directions, corresponding to the width and height dimensions of the channel cross-section, respectively. The width and height dimensions can be determined by the nominal values ​​and tolerances of the machining drawings and can be obtained by microscopic measurement for subsequent calculation and verification of the minimum cross-sectional dimension.

[0103] Specifically, the steps for determining the minimum cross-sectional dimension of the detection channel in the fluid pool include:

[0104] S1. Obtain the target particle size range of the sample to be tested, and at least determine the maximum target particle size of the particles to be tested.

[0105] S2. Based on the calibration results of the extinction detection unit and the scattering detection unit, determine the particle size range in which the extinction signal dominates and the particle size range in which the scattering signal dominates in a single composite signal within different particle size ranges.

[0106] S3. Based on the maximum target particle size and the particle size range where the extinction signal dominates, determine the basic passage conditions that the detection channel must meet structurally for particles to pass through smoothly.

[0107] S4. Before the scattered signal enters the signal synthesis unit, a refractive index compensation parameter for the scattered signal is introduced to compensate for the difference between samples with different refractive indices. This refractive index compensation parameter is used as a constraint condition when solving for the minimum cross-sectional size, so that the scattered signals corresponding to samples with different refractive indices are within the effective amplitude range that can be synthesized when they enter the signal synthesis unit.

[0108] S5. Introduce voltage constraint parameters related to the power supply capability and output dynamic range of the signal synthesis unit and signal conditioning circuit, and use the voltage constraint parameters as constraints when solving for the minimum cross-sectional size, so as to avoid saturation or clipping of a single composite signal under the maximum target particle size condition.

[0109] S6. Under the constraints formed by steps S4 and S5, calculate and determine the minimum cross-sectional size of the detection channel so that when particles with the largest target particle size pass through the detection channel, both the extinction signal and the single composite signal meet the requirements for stable and effective detection.

[0110] In one implementation, the solution for the minimum cross-sectional dimension is performed according to steps S1 to S6, forming a feasible calculation process: In step S1, the target particle size range of the sample to be detected is input, and at least the maximum target particle size is determined. The input can come from detection requirements or standard specifications. If only the range is given without specifying the maximum target particle size, the upper limit is taken as the maximum target particle size. In step S2, the extinction-dominant region and scattering-dominant region in the composite signal are determined based on the calibration results of the extinction detection unit and the scattering detection unit. The calibration is preferably performed using multi-size standard particles covering the scattering-dominant region, the transition region, and the extinction-dominant region. For each particle size point, no less than 5,000 events are collected, and the scattering peak, extinction peak, and composite peak are calculated. Then, the dominant region is determined by the contribution ratio of the scattering peak to the composite peak and the contribution ratio of the extinction peak to the composite peak. The contribution ratio threshold can be selected as 0.7 to 0.9. In step S3, the basic passage conditions of the channel structure are determined based on the maximum target particle size. Preferably, both the width and height dimensions of the channel are larger than the maximum target particle size, with a margin set. The margin can be selected as 5% to 30% of the maximum target particle size or a fixed value of 1 μm to 10 μm, preferably the larger of the two to cover processing tolerances and attitude deviations. In step S4, a refractive index compensation parameter for the scattered signal is introduced as a constraint to ensure that the scattered signals of samples with different refractive indices fall within the effective amplitude range that can be synthesized when entering the signal synthesis unit. In step S5, a voltage constraint parameter related to the power supply capability and output dynamic range is introduced as a constraint to ensure that the composite signal does not saturate or clip under the maximum target particle size condition. In step S6, under the premise of simultaneously satisfying the constraints of steps S4 and S5, the width and height dimensions of the channel are jointly solved to output the minimum cross-sectional dimension combination that meets the requirements of stable and effective detection and has the smallest possible structural size. Feasibility / infeasibility flags and constraints that lead to infeasibility (such as clipping risk or the scattering amplitude not falling into the effective range) are also output.

[0111] Specifically, step S4 includes:

[0112] The refractive index of the particles and the refractive index of the medium are obtained, and the refractive index ratio is determined; the laser wavelength is obtained, and the size parameter is determined; a scattering efficiency factor is calculated based on the refractive index ratio and the size parameter; using the scattering efficiency factor corresponding to the reference refractive index ratio as a benchmark, a refractive index compensation parameter is calculated so that the scattering signal after refractive index compensation is consistent with the reference scattering amplitude or falls within the preset scattering amplitude range; wherein, the functional relationship formed by the refractive index compensation parameter is:

[0113]

[0114] in, The refractive index ratio, For reference refractive index ratio, Reference particle size Dr The size parameter at wavelength λ, Qsca(⋅) is the scattering efficiency factor.

[0115] In one implementation, step S4 is specifically implemented as follows: inputting the refractive index of the particulate material and the refractive index of the fluid medium and determining the refractive index ratio; inputting the emission wavelength of the detection light source and selecting reference particle size conditions; evaluating the influence of refractive index differences on the intensity of the scattered signal and determining the refractive index compensation amount of the scattered signal accordingly, so that the compensated scattered signal has a consistent or equivalent amplitude scale under different refractive index sample conditions. To reflect the mechanism and ensure feasibility, the refractive index compensation amount can be determined in two equivalent ways: one is the physical model method, which calculates the scattering efficiency factor corresponding to the reference refractive index ratio and the scattering efficiency factor corresponding to the target refractive index ratio under the reference particle size and wavelength conditions, and takes the ratio of the two as the refractive index compensation amount; the other is the empirical calibration method, which collects the scattering peak statistics (preferably the mean or median) of the reference refractive index sample and the target refractive index sample while keeping the wavelength and reference particle size unchanged, and takes the ratio of the reference scattering statistics to the target scattering statistics as the refractive index compensation amount, and then maps the refractive index compensation amount to the gain setting value of the variable gain amplifier. To facilitate reproduction, a set of example values ​​are given: Under the conditions of a wavelength of 800 nm and a reference particle size of 1.0 μm, the average peak value of the reference sample scattering is 0.80 V and the effective amplitude range is 0.65 V to 0.95 V, while the average peak value of the target sample scattering is 0.55 V. Therefore, the refractive index compensation is 0.80 / 0.55, which is approximately equal to 1.45. If a stepped gain is used, a gain of 1.41 can be selected as an approximation. After compensation, the average peak value of the target sample scattering is approximately 0.78 V and falls within the effective amplitude range, thus meeting the constraint requirement that the scattered signal is within the synthesizable effective amplitude range before entering the synthesis. If a continuous gain is used, it is directly set to approximately 1.45 times, and the compensation of the scattering peak value falling within the effective amplitude range is also verified.

[0116] Specifically, step S5 includes:

[0117] A composite signal peak model is established under the condition of maximum target particle size. This model includes at least an extinction term and a scattering term after refractive index compensation in step S4. The maximum allowable linear output swing of the signal link and the full-scale limit of the subsequent stage are obtained, and a dynamic margin is determined accordingly. This dynamic margin is not less than a preset threshold to avoid saturation clipping. The functional relationship formed by the dynamic margin is as follows:

[0118]

[0119] and

[0120]

[0121] Among them, V sV is the supply voltage, α is the swing coefficient, and V FS To limit the full scale of the subsequent stage, D max Where kLE and kLS represent the maximum target particle size, and A represents the electro-optical conversion coefficient. beam To detect the equivalent beam area of ​​the beam at the detection channel, σ ext (D) and σ sca (D) represents the extinction section and the scattering section, respectively.

[0122] In one implementation, step S5 is specifically implemented as follows: establishing a composite signal amplitude model formed by the combined action of the extinction signal and the scattering signal after refractive index compensation under the maximum target particle size condition, and determining the dynamic margin of the composite signal by combining the power supply voltage capability, output swing limit and the allowable input range of the subsequent stage, and using the dynamic margin as a constraint condition for solving the channel size, so as to ensure that the composite signal is still in the linear working range under the maximum target particle size condition. To ensure the reproducibility of how the weights / coefficients are derived, this implementation method obtains the electro-optical conversion coefficients and swing coefficients in the composite signal amplitude model through calibration: First, multi-size standard particles are used to collect data on the corresponding peak or area of ​​the extinction channel pulses and the actual particle size. Monotonic constraint regression fitting is used to obtain the mapping of "extinction characteristics - particle size / extinction cross section", and the electro-optical conversion coefficient of the extinction channel is determined by the scale coefficient of the mapping. Second, multi-size standard particles are used to collect the peak or area of ​​the scattering channel pulses and fit the mapping of "scattering characteristics - particle size / scattering cross section", thereby determining the electro-optical conversion coefficient of the scattering channel. Third, the operational amplifier swing is calibrated under a 15V power supply, and the ratio of the maximum linear output amplitude to the power supply voltage is obtained as the swing coefficient. During online calculation, the maximum allowable linear output swing is first obtained from the supply voltage and swing coefficient. Then, the more stringent one of the following is taken as the upper limit of the allowable peak value, and the composite signal peak prediction value corresponding to the maximum target particle size is calculated by the amplitude model. Finally, the dynamic margin is obtained by subtracting the composite peak prediction value from the upper limit of the allowable peak value. The dynamic margin is required to be no less than the threshold (which can be selected as 5% to 20% of the full scale, preferably 10%). Here is a set of example calculations: with a supply voltage of 15V and a measured maximum linear output amplitude of 12V, the swing coefficient is 0.8; with a full-scale output of 10V for the subsequent stage, the allowable peak value is 10V; the maximum target particle size contributes approximately 7.0V to the extinction term and approximately 1.5V to the scattering term after refractive index compensation, so the predicted composite peak value is 8.5V, and the dynamic margin is 1.5V (15% of the full scale), which meets the threshold requirement; if the size of a certain channel causes the predicted composite peak value to be close to 9.6V, then the dynamic margin is only 0.4V (4%), which does not meet the threshold. The candidate channel size should be removed or the gain / compensation parameters of the preceding stage should be adjusted to make it meet the constraints again.

[0123] Specifically, step S6 includes the following more specific steps:

[0124] Under the premise of satisfying the particle passage constraint, a feasible region set is constructed, which includes geometric passage constraints, linear working area constraints of the extinction line, and dynamic range constraints. The optimal value of the minimum cross-sectional size of the detection channel is then obtained within this feasible region set. The functional relationship between the feasible region set and the final optimization is as follows:

[0125]

[0126] Furthermore, the optimal value satisfies:

[0127]

[0128] Where a and b are the minimum cross-sectional dimensions of the detection channel, i.e., the width and height dimensions, δa and δb are geometric margin parameters, w is the equivalent beam width or a beam parameter related to the beam area, η is the extinction linear working area threshold, and H min This is the dynamic margin threshold.

[0129] In one implementation, the minimum cross-sectional dimension of the detection channel in step S6 includes the width dimension and the height dimension, which correspond to the minimum geometric dimensions in two mutually perpendicular directions of the channel cross-section, respectively. In terms of determination, the geometric constraints are first determined using the maximum target particle size and margin, ensuring that both the width and height dimensions are not less than the maximum target particle size plus double the margin. Then, the linear operation requirement for the extinction light and the dynamic range constraint requirement for the composite signal are introduced to form a feasible domain set. The linear operation requirement for the extinction light can be achieved by a calibrated linear region threshold; that is, under the condition of the maximum target particle size, the peak value and area of ​​the extinction signal should fall within the linear operating range. If they exceed this range, it is considered that there is a risk of occlusion saturation or strong nonlinearity, and the candidate size is eliminated. The dynamic range constraint requirement for the composite signal uses a calculated dynamic margin and requires it to be no less than the threshold. From the candidate size set that satisfies the above constraints, the size combination with the smallest product of the width and height dimensions is selected as the optimal value, and the optimal value is output as the design value of the minimum cross-sectional dimension of the fluid pool detection channel. To facilitate engineering implementation, an offline mesh enumeration solution can be used: first, enumerate the width and height dimensions with a coarser step size and filter the feasible region, and then refine the search near the boundary of the feasible region with a finer step size to obtain the minimum product solution; alternatively, an online selection method can be used: pre-process multi-specification channel modules and select the module with the smallest cross-section that meets the constraints based on refractive index compensation constraints and dynamic margin constraints before operation.

[0130] In this embodiment, the minimum cross-sectional dimension of the detection channel in the fluid pool is solved jointly according to steps S1 to S6. First, based on the actual application requirements of the sample to be tested, the effective particle size response range of the system is set to 0.4–400 μm, and a dynamic response margin of approximately 800 μm is reserved for the larger particle size end after the circuit power supply capability is improved. Subsequently, based on the calibration results of the extinction detection unit and the scattering detection unit, the dominant mechanism of the single composite signal in different particle size ranges is determined, and the refractive index compensation constraint and voltage dynamic range constraint are simultaneously introduced into the detection channel size solution process, so that when the largest target particle size passes through the detection channel, both the extinction signal and the single composite signal remain stable and effective without significant saturation or clipping.

[0131] Specifically, in step S6, the width dimension *a* and height dimension *b* of the detection channel cross-section are used as joint solution variables. First, offline mesh enumeration is performed on candidate size combinations with a coarser step size. Then, a refined search is conducted near the boundary of the feasible region satisfying the constraints formed in steps S4 and S5, with the minimum cross-sectional area *a*×*b* being the preferred target. For smaller candidate size combinations, although the cross-sectional area is smaller, problems such as insufficient particle passage tolerance, extinction response deviating from the linear working region, and insufficient dynamic margin of the composite signal are more likely to occur under the maximum target particle size condition. For larger candidate size combinations, although the detection requirements can be met, it leads to an increase in the channel cross-sectional area, which is not conducive to structural compactness and high-sensitivity detection. Therefore, considering the smooth passage of particles, the linear working requirements of the extinction light, the dynamic range constraints of the composite signal, and the stability of subsequent high-resolution output, the preferred cross-sectional size of the detection channel is finally determined to be 400×1000 μm.

[0132] In this embodiment, the fluid pool further employs a sandwich layered structure, with an opaque intermediate layer of 1000 μm thickness placed between oppositely arranged transparent layers. By matching the aforementioned preferred detection channel size with the sandwich light-shielding structure and adjusting the physical spot size of the incident laser, the dynamic response range can be expanded while suppressing stray background, improving the stability of the single composite signal across the entire range. Customer verification shows that under this structural condition, the system can not only maintain an effective response range of 0.4–400 μm, but also further increase the upper limit of the particle size response to approximately 800 μm under a 15V power supply.

[0133] Furthermore, in this embodiment, to achieve high-resolution test results, the single composite signal is characterized using a compression mapping method within the effective output voltage range, preferably forming 1024 practically usable channels. Customer test results show that if an overly coarse binning method is used, such as a 64-channel configuration, the particle size span of a single bin near the main peak is too large, making it difficult to meet the bin width requirements for high-resolution evaluation. However, with at least 256 channels, preferably 1024 channels, the particle size interval near the main peak is finer, which is more conducive to obtaining a concentrated, sharp, and narrow peak width response distribution, thereby improving particle size discrimination and resolution. This point is consistent with the requirements of USP <1788.1> regarding the relationship between bin width and resolution prerequisites.

[0134] Therefore, this embodiment does not simply select the channel size empirically. Instead, under the premise that the refractive index compensation constraint in step S4 and the dynamic range constraint in step S5 are both met, the detection channel width and height dimensions are optimized in two dimensions through two-dimensional coupling in step S6. Then, the candidate dimensions are verified by combining the prototype calibration and high-resolution test results, and finally 400×1000 μm is selected as the preferred size combination that meets the requirements of high sensitivity, wide dynamic range and high resolution. This preferred size avoids the insufficient throughput and clipping risk under small cross-section conditions, and avoids the decrease in sensitivity and resolution degradation caused by excessively large cross-sections, thus achieving a balance between detection performance and structural size.

[0135] To verify the detection performance of this embodiment, the system was tested using standard particle samples with nominal particle sizes of 0.8 μm, 2.0 μm, and 5.0 μm, according to the method in GB / T 29024.3-2012. The test results are as follows: Figure 7 As shown in the figure, the table section presents the measured concentration, acceptable concentration range, measured average particle size, and acceptable average particle size range for each standard particle size sample. All results are marked as "PASS," indicating that the concentration and average particle size measurements obtained under the corresponding test conditions in this embodiment fall within the preset acceptable range. The particle size distribution plot at the bottom of the figure shows independent and distinguishable response peaks around approximately 0.8 μm, 2.0 μm, and 5.0 μm, demonstrating that this embodiment can effectively distinguish particles of different sizes and has good particle size characterization ability and counting stability.

[0136] The performance of this embodiment was verified using standard particle samples. The results showed that the concentration measurement results and the average particle size measurement results at each particle size point fell within the corresponding acceptable range, and particles of different sizes formed clear and distinguishable peaks in the distribution diagram. This result can be used to demonstrate that this embodiment has good performance in terms of particle size measurement accuracy and counting result consistency, and can serve as the experimental basis for further standardized verification according to GB / T 29024.3-2012.

[0137] The test method according to USP 1788.1 is then used as follows:

[0138] Specifically, standard particle samples with nominal particle sizes of 0.8 μm, 2.0 μm, and 5.0 μm were selected, and electronic calculations were performed based on continuous particle size intervals near the main peak. Following the description of electronic methods in USP <1788.1>, the selected bins were continuous particle size intervals near the main peak. The lower and upper limits of these continuous particle size intervals, along with their corresponding count values, were recorded to determine bin width conditions, coverage interval conditions, and resolution conditions, respectively.

[0139] like Figure 8 As shown, a 0.8 μm standard particle sample was used as the test object. Figure 8 (a) shows the input data for seven consecutive particle size ranges near the main peak. Figure 8 (b) shows the calculation results obtained based on the input data. The results show that the bin width determination result is PASS, the coverage interval determination result is PASS, the resolution determination result is PASS, and the Overall result is PASS, indicating that this embodiment meets the corresponding electronic method calculation requirements under the 0.8 μm particle size point condition.

[0140] like Figure 9 As shown, a 2.0 μm standard particle sample was used as the test object. Figure 9 (a) shows the input data for seven consecutive particle size ranges near the main peak. Figure 9 (b) shows the calculation results obtained based on the input data. The results show that the bin width determination result is PASS, the coverage interval determination result is PASS, the resolution determination result is PASS, and the Overall result is PASS, indicating that this embodiment meets the corresponding electronic method calculation requirements under the 2.0 μm particle size point condition.

[0141] like Figure 10 As shown, a 5.0 μm standard particle sample was used as the test object. Figure 10 (a) shows the input data for seven consecutive particle size ranges near the main peak. Figure 10(b) shows the calculation results obtained based on the input data. The results show that the bin width determination result is PASS, the coverage interval determination result is PASS, the resolution determination result is PASS, and the overall result is PASS, indicating that this embodiment meets the corresponding electronic method calculation requirements under the 5.0 μm particle size point condition.

[0142] Depend on Figures 8 to 10 It can be seen that, under the conditions of three standard particle size points of 0.8 μm, 2.0 μm, and 5.0 μm, this embodiment, when performing electronic calculations based on continuous particle size interval data near the main peak, can simultaneously meet the bin width constraint, coverage interval constraint, and resolution judgment requirements, thus obtaining a passing result. Combined with the aforementioned particle size measurement and counting verification results of standard particle samples, it can be demonstrated that this embodiment has a stable, effective, and resolvable detection capability in the range of 0.8 μm to 5.0 μm.

[0143] In this embodiment, to balance the detection sensitivity for small-diameter particles with the throughput capacity for large-diameter particles, the cross-sectional size of the fluid cell detection channel is not fixed to a single value, but can be adjusted within a certain range according to actual detection needs. Specifically, the detection channel can achieve higher response sensitivity for microparticles with a smaller cross-section, and can also obtain a wider dynamic response range and a higher upper limit for large-diameter particles with a larger cross-section. Preferably, the size of the detection channel can be adjusted within the range of 5 μm × 400 μm to 60 μm × 400 μm to adapt to different requirements for particle size detection lower limit and dynamic range in different application scenarios.

[0144] The reason is that the width and height of the detection channel together determine the cross-sectional area of ​​the fluid pool. When the cross-sectional area decreases, the change in photoresistance caused by particles passing through the detection beam is more significant, and the scattered signal is also more easily enhanced. This helps improve the system's response to small-diameter particles and lower the lower limit of particle size detection; however, at the same time, the upper limit of the size of large-diameter particles that can pass through the detection channel will decrease accordingly. Conversely, when the cross-sectional area increases, although the response to tiny particles weakens somewhat, it can improve the passage capacity of large-diameter particles and widen the system's dynamic response range.

[0145] Therefore, in this embodiment, the effective working ranges of the extinction response path and the scattering response path in a single composite signal can be synergistically adjusted by regulating the width and height of the detection channel, thereby achieving optimized configuration of the system's dynamic response range and the lower limit of particle size detection. In other words, changes in the size of the detection channel not only affect the physical throughput of particles but also directly influence the response strength of the photoresistance method and the scattering method in different particle size ranges, thus determining the detection range and resolution of this embodiment under different application conditions.

Claims

1. A high-sensitivity, wide dynamic range single-particle optical sensor, characterized in that, include: A fluid pool that forms a detection channel through which the fluid carrying particles passes; A light source is configured to emit a detection beam toward the detection channel; An extinction detection unit is disposed on the transmission optical path of the detection beam and is used to acquire the extinction signal generated when the particles pass through the detection beam; A scattering detection unit is disposed on a scattering light path different from the transmitted light path, and is used to acquire the scattering signal generated when the particle passes through the detection beam. The signal synthesis unit is electrically connected to the extinction detection unit and the scattering detection unit, and is used to sum or weighted sum the extinction signal and the scattering signal to generate a single composite signal, and output particle size information and / or counting information based on the single composite signal; The single composite signal is mainly contributed by the scattering signal in the smaller particle size range, mainly contributed by the extinction signal in the larger particle size range, and in the transitional particle size range between the two, it is contributed by both the scattering signal and the extinction signal to achieve a smooth transition.

2. The high-sensitivity, wide dynamic range single-particle optical sensor according to claim 1, characterized in that, A scattering signal conditioning unit is provided between the scattering detection unit and the signal synthesis unit. The scattering signal conditioning unit includes a variable gain amplifier, which is used to scale the gain of the scattering signal before it is input into the signal synthesis unit, so as to compensate for the differences in scattering response caused by samples with different refractive indices.

3. A high-sensitivity, wide dynamic range single-particle optical sensor according to claim 2, characterized in that, The scattering signal conditioning unit further includes a refractive index parameter setting unit and a gain control unit; the refractive index parameter setting unit is used to output a setting signal corresponding to the sample refractive index level, and the gain control unit controls the gain coefficient of the variable gain amplifier according to the setting signal, so that the gain coefficient is an attenuation coefficient less than 1 and / or an amplification coefficient greater than 1.

4. A high-sensitivity, wide dynamic range single-particle optical sensor according to claim 3, characterized in that, The signal synthesis unit and / or the scattering signal conditioning unit include an operational amplifier circuit, the operational amplifier circuit being supplied with a voltage of 15V, to increase the output dynamic range of the single composite signal and reduce the risk of saturation clipping.

5. A high-sensitivity, wide dynamic range single-particle optical sensor according to claim 4, characterized in that, The light source is a laser, the emission wavelength of which is in the range of 770nm to 820nm, and the output power is 100mW.

6. A high-sensitivity, wide dynamic range single-particle optical sensor according to claim 5, characterized in that, A narrowband filter is provided on the scattering optical path and / or the transmission optical path. The center wavelength of the narrowband filter is located near and matched with the emission wavelength of the laser to suppress non-target band background light from entering the scattering detection unit and / or the extinction detection unit. Furthermore, the detection channel of the fluid pool has a minimum cross-sectional size, which is used to define the maximum particle size range that can pass through the detection channel. The fluid pool includes a transparent layer disposed opposite to the transparent layer and an opaque intermediate layer located between the two, the opaque intermediate layer forming the detection channel, and the thickness of the opaque intermediate layer being 1000 μm.

7. A high-sensitivity, wide dynamic range single-particle optical sensor according to claim 6, characterized in that, The steps for determining the minimum cross-sectional dimension of the detection channel in the fluid pool include: S1. Obtain the target particle size range of the sample to be tested, and at least determine the maximum target particle size of the particles to be tested. S2. Based on the calibration results of the extinction detection unit and the scattering detection unit, determine the particle size range in which the extinction signal dominates and the particle size range in which the scattering signal dominates in a single composite signal within different particle size ranges. S3. Based on the maximum target particle size and the particle size range where the extinction signal dominates, determine the basic passage conditions that the detection channel must meet structurally for particles to pass through smoothly. S4. Before the scattered signal enters the signal synthesis unit, a refractive index compensation parameter for the scattered signal is introduced to compensate for the difference between samples with different refractive indices. This refractive index compensation parameter is used as a constraint condition when solving for the minimum cross-sectional size, so that the scattered signals corresponding to samples with different refractive indices are within the effective amplitude range that can be synthesized when they enter the signal synthesis unit. S5. Introduce voltage constraint parameters related to the power supply capability and output dynamic range of the signal synthesis unit and signal conditioning circuit, and use the voltage constraint parameters as constraints when solving for the minimum cross-sectional size, so as to avoid saturation or clipping of a single composite signal under the maximum target particle size condition. S6. Under the constraints formed by steps S4 and S5, calculate and determine the minimum cross-sectional size of the detection channel so that when particles with the largest target particle size pass through the detection channel, both the extinction signal and the single composite signal meet the requirements for stable and effective detection.

8. A high-sensitivity, wide dynamic range single-particle optical sensor according to claim 7, characterized in that: Step S4 specifically includes: The refractive index of the particulate material and the refractive index of the fluid medium are obtained, and the refractive index difference parameter is determined based on their relative relationship. The effect of refractive index difference on the intensity of scattered signal is evaluated by combining the emission wavelength of the detection light source and the reference particle size conditions. Based on the aforementioned impact results, the required refractive index compensation for the scattered signal is determined, and the amplitude of the scattered signal is conditioned by hardware to ensure that the refractive index-compensated scattered signal has a consistent or equivalent amplitude scale under different refractive index sample conditions, thereby serving as a constraint basis for subsequently solving the minimum cross-sectional size of the detection channel.

9. A high-sensitivity, wide dynamic range single-particle optical sensor according to claim 8, characterized in that: Step S5 specifically includes: A single composite signal amplitude model is established under the condition of maximum target particle size, formed by the combined action of the extinction signal and the scattering signal after refractive index compensation. By combining the power supply voltage capability, output swing limit, and allowable input range of the subsequent signal processing circuit of the signal synthesis unit and its signal conditioning circuit, the dynamic margin of a single composite signal under the maximum target particle size condition is determined. The dynamic margin is used as a constraint in the process of solving the minimum cross-sectional size of the detection channel to ensure that the single composite signal is still within the linear working range under the condition of the maximum target particle size.

10. A high-sensitivity, wide dynamic range single-particle optical sensor according to claim 9, characterized in that: The minimum cross-sectional dimension of the detection channel in step S6 includes the width and height dimensions of the detection channel cross-section, wherein the width and height dimensions correspond to the minimum geometric dimensions of the detection channel cross-section in two mutually perpendicular directions, respectively. The minimum cross-sectional size is determined as follows: under the premise that the particles with the largest target particle size can pass smoothly in the detection channel without obstruction or abnormal posture deviation, and in combination with the linear operation requirements of the extinction signal and the dynamic range constraints of the single composite signal, the width and height dimensions of the detection channel cross-section are solved together to obtain the combination of detection channel cross-sectional dimensions that meets the detection performance requirements and minimizes the structural size.

Images