A non-contact real-time detection system for liquid concentration detection and substance identification

Abstract

The present application belongs to the technical field of biochemical sensing, and specifically provides a non-contact real-time detection system for liquid concentration detection and substance identification, which is used to overcome the shortcomings of Raman spectroscopy, such as fluorescence interference, strong water molecule absorption influence, and the long wavelength scanning time and limited detection distance of photoacoustic spectroscopy. The non-contact real-time detection system comprises a laser pumping system, a laser ultrasonic detection system, a CCD focusing control system and a detection module. The laser pumping system is used for pumping the measured sample, exciting and generating ultrasonic waves, and the laser ultrasonic detection system is used for detecting the ultrasonic signal in the measured sample. The CCD focusing control system is used for real-time monitoring of the focusing state of the pumping light beam and the detection light beam, so as to ensure the pumping efficiency and the detection sensitivity. The detection module is used for accommodating the measured sample. Finally, the time-domain data collected by the system is integrated and summed, and the liquid concentration can be detected through the integral intensity calibration. After the collected time-domain data is converted into frequency spectrum data, the machine learning method can be used to identify the substance category.

Description

Technical Field

[0001] The present invention belongs to the field of biochemical sensing technology, and specifically provides a non-contact real-time detection system suitable for liquid concentration detection and substance identification. Background Art

[0002] In the field of biochemical sensing, real-time monitoring of liquid mixing processes in microfluidic chips and chemical analysis and biological determination of liquids in channels are particularly critical. Whether in water quality analysis and pollutant monitoring, or in biomolecule detection and cell analysis, the detection of liquid substance types is also an indispensable key link; therefore, detecting and identifying the types and concentrations of liquid substances is particularly important.

[0003] Currently, spectroscopic analysis techniques such as Raman spectroscopy and photoacoustic spectroscopy are widely used to characterize liquid substances. Raman spectroscopy relies on the Raman shift generated by the interaction of light with molecules in the sample, which can directly reflect the substance's identity. For chemical composition characterization and substance identification, Raman spectroscopy can provide high-resolution information, making it widely used in fields such as drug testing, environmental monitoring, and food safety. However, this method suffers from weak signals and low detection efficiency, and is also susceptible to fluorescence interference and strong absorption by water molecules. Therefore, its application is limited in water-based samples or complex environments. Photoacoustic spectroscopy utilizes the principles of optical excitation and acoustic detection. After a substance absorbs short pulses of light at different wavelengths, it undergoes thermoelastic expansion and generates ultrasonic waves, thereby enabling substance identification. This method has wide applications in the qualitative and quantitative analysis of liquid substances, particularly in environmental monitoring, water quality analysis, and chemical reaction kinetics. However, this method requires wavelength scanning of the sample, which is time-consuming. Furthermore, since acoustic detection requires close proximity, this limits its application in large-scale industrial environments. Summary of the Invention

[0004] The purpose of the present invention is to address the problem of liquid detection in biochemical sensing, medical treatment and industrial preparation processes, and to provide a non-contact real-time detection system for liquid concentration detection and substance identification, so as to overcome the shortcomings of Raman spectroscopy such as fluorescence interference and strong absorption by water molecules, as well as the long wavelength scanning time and limited detection distance of photoacoustic spectroscopy.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] The application discloses a non-contact real-time detection system for liquid concentration detection and substance identification, which comprises a laser pumping system, a laser ultrasonic detection system, a CCD focusing control system and a detection module.

[0007] Further, the non-contact real-time detection system for liquid concentration detection and substance identification specifically comprises an oscilloscope 1, a computer 2, a Q-switched laser 3, a photodetector 4, an LDV 5, a CCD 6, an attenuation sheet 7, a detection light path beam splitter 8, a mirror 9, an aperture 10, a pumping light path beam splitter 11, an adjustable spatial light attenuation sheet 12, a dichroic mirror 13, an objective lens 14, a syringe 15, a micro flow channel 16 and a capillary 17.

[0008] The Q-switched laser, the mirror, the aperture, the adjustable spatial light attenuation sheet, the dichroic mirror and the objective lens form a laser pumping system, the Q-switched laser emits pumping light, the pumping light sequentially passes through the mirror, the aperture and the adjustable spatial light attenuation sheet, reaches the dichroic mirror and is combined with detection light, and after the combination, the light is vertically irradiated on the surface of the sample to be detected by the objective lens, and the sample to be detected generates ultrasonic waves after absorbing the energy of the pumping light.

[0009] The oscilloscope, the photodetector, the LDV, the first beam splitter, the second beam splitter, the dichroic mirror and the objective lens form a laser ultrasonic detection system, the LDV emits detection light, the detection light reaches the dichroic mirror after passing through the first beam splitter and is combined with the pumping light, and after the combination, the light is vertically irradiated on the surface of the sample to be detected by the objective lens, the detection light returns to the LDV by the original path after being modulated by ultrasonic waves, the LDV demodulates the received signal and records data in real time by the oscilloscope, and outputs a detection signal; meanwhile, the second beam splitter is arranged between the aperture and the adjustable spatial light attenuation sheet, the photodetector detects the pumping light through the second beam splitter and outputs a trigger signal to the oscilloscope.

[0010] The computer, the CCD, the attenuation sheet and the objective lens form a CCD focusing control system, the CCD and the objective lens are matched to form a microscope, the light spot focusing is monitored and controlled in real time through the computer, and the attenuation sheet is used for adjusting the light spot brightness entering the CCD.

[0011] The syringe, the micro flow channel and the capillary form a detection module, the sample to be detected is injected into the capillary through the syringe and the micro flow channel.

[0012] Furthermore, the Q-switched laser emits a laser with a wavelength of 532 nm as pump light, and the LDV emits a laser with a wavelength of 632.8 nm as probe light.

[0013] Furthermore, the pump light and the probe light reach the dichroic mirror at the same time.

[0014] Furthermore, when the non-contact real-time detection system is used for liquid concentration detection, the calibration solution is detected by the non-contact real-time detection system, and the collected detection signals are integrated and summed to obtain the signal integral intensity. A concentration calibration curve is drawn with the prior concentration of the calibration solution as the horizontal coordinate and the signal integral intensity as the vertical coordinate; then the non-contact real-time detection system is used to detect the solution to be tested, and the collected detection signals are integrated and summed to obtain the signal integral intensity. The liquid concentration is judged based on the signal integral intensity and the concentration calibration curve.

[0015] Furthermore, when the non-contact real-time detection system is used for substance identification, the calibration solution is detected by the non-contact real-time detection system, and the collected detection signal is Fourier transformed to obtain spectral characteristics. The spectral characteristics are used as input data and the prior material type of the calibration solution is used as a label to constitute a training sample. A training set and a test set are obtained through multiple measurements, and a material identification model is obtained by training in combination with a machine learning method. Then, the non-contact real-time detection system is used to detect the solution to be tested, and the collected detection signal is Fourier transformed to obtain spectral characteristics. The spectral characteristics are input into the material identification model, and the material identification model outputs the material type identification result.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The present invention has a fully non-contact detection method of laser pumping and laser detection, which can prevent contamination of the measured sample during the measurement process.

[0018] 2. The present invention has real-time detection capabilities and can detect substance concentrations and distinguish substance types more quickly.

[0019] 3. The present invention has a simple structure and can be used for liquid detection in a variety of scenarios, with wider applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic structural diagram of a non-contact real-time detection system suitable for liquid concentration detection and substance identification according to the present invention;

[0021] Figure 2 This is a workflow diagram of the non-contact real-time detection system for liquid concentration detection and substance identification according to the present invention;

[0022] Figure 3 This is a calibration curve diagram of the RhB solution concentration of the non-contact real-time detection system suitable for liquid concentration detection and substance identification of the present invention;

[0023] Figure 4 A confusion matrix diagram of the substance classification results of the non-contact real-time detection system for liquid concentration detection and substance identification according to the present invention;

[0024] in, Figure 1 In the figure, 1 is an oscilloscope, 2 is a computer, 3 is a Q-switched laser, 4 is a photodetector, 5 is an LDV (laser Doppler velocimeter), 6 is a CCD, 7 is an attenuator, 8 is the first beam splitter, 9 is a reflector, 10 is an aperture, 11 is the second beam splitter, 12 is an adjustable spatial light attenuator, 13 is a dichroic mirror, 14 is an objective lens, 15 is a syringe, 16 is a microfluidic channel, and 17 is a capillary. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and beneficial effects of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be noted that the embodiments described with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be understood as limiting the present invention.

[0026] The present invention provides a non-contact real-time detection system suitable for liquid concentration detection and substance identification. The system integrates a laser pumping system, a laser ultrasonic detection system and a CCD focusing control system. Through the system, the concentration detection of the measured liquid and the identification of the substance type can be realized.

[0027] Specifically, the non-contact real-time detection system for liquid concentration detection and substance identification is as follows: Figure 1 As shown, it includes: an oscilloscope 1, a computer 2, a Q-switched laser 3, a photodetector 4, an LDV 5, a CCD 6, an attenuator 7, a detection light path beam splitter 8, a reflector 9, an aperture 10, a pump light path beam splitter 11, an adjustable spatial light attenuator 12, a dichroic mirror 13, an objective lens 14, a syringe 15, a microfluidic channel 16 and a capillary 17;

[0028] The Q-switched laser 3, the reflector 9, the aperture 10, the adjustable spatial light attenuation plate 12, the dichroic mirror 13 and the objective lens 14 constitute a laser pumping system. The Q-switched laser 3 emits a 532nm wavelength laser (green light) as pump light. The pump light adjusts the optical path through the reflector 9, and the aperture 10 controls the spot size. The pump light then passes through the adjustable spatial light attenuation plate 12 to control the laser energy. After that, it reaches the dichroic mirror 13 and merges with the probe light. Finally, the light spot passes through the objective lens 14 and is vertically irradiated onto the surface of the sample under test. Based on the photoacoustic effect, the sample under test absorbs the pump light energy and generates ultrasonic waves.

[0029] The oscilloscope 1, the photodetector 4, the LDV5, the first beam splitter 8, the second beam splitter 11, the dichroic mirror 13 and the objective lens 14 constitute a laser ultrasonic detection system. The LDV5 emits a laser (red light) with a wavelength of 632.8 nm as the detection light. The detection light adjusts the optical path through the first beam splitter 8, then reaches the dichroic mirror 13 and merges with the pump light, and finally passes through the objective lens 14 to irradiate the light spot vertically on the surface of the sample to be measured. After the detection light is modulated by the ultrasonic wave, it returns to the LDV 5 along the original path. After receiving the signal, the LDV 5 uses the optical interference technology to demodulate the vibration information generated by the ultrasonic wave to achieve accurate detection, and records the data in real time through the oscilloscope 1, and outputs the detection signal (time-frequency signal); at the same time, the second beam splitter 11 is arranged between the aperture 10 and the adjustable spatial light attenuation plate 12. The photodetector 4 detects the pump light through the second beam splitter 11 and outputs a trigger signal to the oscilloscope 1. After receiving the trigger signal, the oscilloscope 1 starts recording data;

[0030] The computer 2, CCD 6, attenuation plate 7 and objective lens 14 constitute a CCD focusing control system. The CCD 6 and objective lens 14 are combined to form a microscope. The computer 2 monitors the focusing effect of the light spot in real time. At the same time, the computer 2 controls the translation stage to adjust the distance between the sample under test and the objective lens 14 according to the monitoring results to ensure that the sample under test is located at the focus of the objective lens. The attenuation plate 7 is used to adjust the brightness of the light spot entering the CCD 6 to protect the CCD 6.

[0031] The syringe 15 , the microfluidic channel 16 and the capillary 17 constitute a detection module. The sample to be tested is injected into the capillary 17 through the syringe 15 and the microfluidic channel 16 . The capillary 17 is fixed on the displacement stage.

[0032] The following are specific embodiments:

[0033] Example 1

[0034] This embodiment uses the above-mentioned non-contact real-time detection system to measure the concentration of Rhodamine B solution (RhB). The specific process is as follows: Figure 2 As shown, a 0.1 mM Rhodamine B solution was diluted 5 times in a gradient manner to obtain RhB calibration solutions with concentrations of 20 uM, 4 uM, 0.8 uM, 0.16 uM, 32 nM, and 6.4 nM, respectively. The RhB calibration solutions of different concentrations were respectively introduced into the capillary as the test samples, and the RhB solution was pumped by a laser pumping system. The ultrasonic signal generated by the RhB solution was detected by a laser ultrasonic detection system. The spot size was dynamically adjusted using a CCD focusing control system to control the pumping efficiency and detection sensitivity. The collected time domain signals were integrated and summed to obtain the time domain signal integral intensity. The concentration calibration curve of the RhB solution was plotted with the concentration of the RhB solution as the horizontal axis and the time domain signal integral intensity as the vertical axis, as shown in FIG. Figure 3 shown.

[0035] Afterwards, a RhB solution of unknown concentration was passed into the capillary, and the corresponding time-domain signal was collected. The concentration of the RhB solution was determined based on the integrated intensity of the time-domain signal and the concentration calibration curve. The test results showed that the concentration detection limit of the Rhodamine B solution was 300nM.

[0036] Example 2

[0037] This embodiment uses the above-mentioned non-contact real-time detection system to realize the identification of the substance type of the sample being tested. The specific process is as follows: Figure 2 As shown in the figure, RhB, enzyme catalytic substrate (HRP), multi-walled carbon nanotubes (MWCNTs), magnetic beads (MB), gold nanoparticles (AuNPs), and polymer microspheres (PS) are respectively used as the samples to be tested. The laser pumping system is used to pump the samples to be tested, and the laser ultrasonic detection system is used to detect the ultrasonic signals generated by the samples to be tested. The CCD focusing control system is used to dynamically adjust the spot size to control the pumping efficiency and detection sensitivity; the collected time domain signal is converted into a frequency domain signal by Fourier transform, and then the frequency domain signal is reduced in dimension and used as the input feature. The input feature and the prior material type label constitute the training sample. The training set and test set are obtained through multiple measurements, and the material type is identified by combining the machine learning method. The identification results are shown in FIG. Figure 4 As shown, the horizontal axis is the predicted substance type and the vertical axis is the actual substance type. It can be seen from the figure that the accuracy of substance type recognition can reach more than 98%.

[0038] The above description is only a specific embodiment of the present invention. Any feature disclosed in this specification, unless otherwise stated, can be replaced by other equivalent or alternative features with similar purposes; all disclosed features, or all steps in the methods or processes, except for mutually exclusive features and / or steps, can be combined in any way.

Claims

1. A non-contact real-time detection system for liquid concentration detection and substance identification, comprising: A laser pumping system, a laser ultrasonic detection system, a CCD focusing control system, and a detection module, characterized in that the detection module is used to accommodate a sample to be tested, the laser pumping system is used to generate pumping light and irradiate the sample to be tested, and the sample to be tested generates ultrasonic waves after being excited; the laser ultrasonic detection system is used to generate detection light to detect the ultrasonic waves generated by the sample to be tested and output a detection signal; the CCD focusing control system is used to detect and control the pumping light and detection light to focus on the surface of the sample to be tested in real time; The non-contact real-time detection system for liquid concentration detection and substance identification specifically comprises: an oscilloscope (1), a computer (2), a Q-switched laser (3), a photodetector (4), an LDV (5), a CCD (6), an attenuation plate (7), a detection light path beam splitter (8), a reflector (9), an aperture (10), a pump light path beam splitter (11), an adjustable spatial light attenuation plate (12), a dichroic mirror (13), an objective lens (14), a syringe (15), a microfluidic channel (16) and a capillary (17); The Q-switched laser, the reflector, the aperture, the adjustable spatial light attenuation plate, the dichroic mirror and the objective lens constitute a laser pumping system. The Q-switched laser emits pump light, which passes through the reflector, the aperture and the adjustable spatial light attenuation plate in sequence before reaching the dichroic mirror and merging with the probe light. After merging, the pump light passes through the objective lens and is vertically irradiated onto the surface of the sample to be measured. The sample to be measured generates ultrasonic waves after absorbing the pump light energy. The oscilloscope, photodetector, LDV, first beam splitter, second beam splitter, dichroic mirror and objective lens constitute a laser ultrasonic detection system. The LDV emits detection light, which passes through the first beam splitter and reaches the dichroic mirror and is combined with the pump light. After the combination, the detection light passes through the objective lens and is vertically irradiated on the surface of the sample to be measured. The detection light is ultrasonically modulated and then returns to the LDV along the original path. The LDV demodulates the received signal, and the oscilloscope records the data in real time and outputs the detection signal. At the same time, the second beam splitter is arranged between the aperture and the adjustable spatial light attenuation plate. The photodetector detects the pump light through the second beam splitter and outputs a trigger signal to the oscilloscope. The computer, CCD, attenuation plate and objective lens form a CCD focus control system. The CCD and objective lens form a microscope, and the computer monitors and controls the focus of the light spot in real time. The attenuation plate is used to adjust the brightness of the light spot entering the CCD. The syringe, microfluidic channel and capillary tube form a detection module, and the sample to be tested is injected into the capillary tube through the syringe and the microfluidic channel.

2. The non-contact real-time detection system for liquid concentration detection and substance identification according to claim 1, characterized in that: The Q-switched laser emits a laser with a wavelength of 532 nm as pump light, and the LDV emits a laser with a wavelength of 632.8 nm as probe light.

3. The non-contact real-time detection system for liquid concentration detection and substance identification according to claim 1, characterized in that: The pump light and the probe light reach the dichroic mirror at the same time.

4. The non-contact real-time detection system for liquid concentration detection and substance identification according to claim 1, characterized in that: When the non-contact real-time detection system is used for liquid concentration detection, the calibration solution is detected by the non-contact real-time detection system, the collected detection signals are integrated and summed to obtain the signal integral intensity, and a concentration calibration curve is drawn with the prior concentration of the calibration solution as the horizontal axis and the signal integral intensity as the vertical axis; The non-contact real-time detection system is then used to detect the solution to be tested, and the collected detection signals are integrated and summed to obtain the signal integral intensity. The liquid concentration is judged based on the signal integral intensity and concentration calibration curve.

5. The non-contact real-time detection system for liquid concentration detection and substance identification according to claim 1, characterized in that: When the non-contact real-time detection system is used for substance identification, the calibration solution is detected by the non-contact real-time detection system, and the collected detection signal is Fourier transformed to obtain spectral characteristics. The spectral characteristics are used as input data and the prior material type of the calibration solution is used as a label to form a training sample. A training set and a test set are obtained through multiple measurements, and a material identification model is obtained by training in combination with a machine learning method. The non-contact real-time detection system is then used to detect the solution to be tested, and the collected detection signal is Fourier transformed to obtain spectral characteristics. The spectral characteristics are input into the material identification model, and the material identification model outputs a material type identification result.

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