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

Abstract

The invention belongs to the technical field of biochemical sensing, and particularly provides a non-contact real-time detection system for liquid concentration detection and substance identification, which is used for overcoming the defects that Raman spectroscopy is interfered by fluorescence and is influenced by strong absorption of water molecules, and photoacoustic spectroscopy is long in wavelength scanning time, limited in detection distance and the like. 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, exciting and generating ultrasonic waves for a detected sample, and the laser ultrasonic detection system is used for detecting ultrasonic signals in the detected sample; the CCD focusing control system is used for monitoring the focusing state of the pumping light beam and the detection light beam in real time and ensuring the pumping efficiency and the detection sensitivity; the detection module is used for accommodating a detected sample; and finally, carrying out integral summation on time domain data acquired by the system, and detecting the liquid concentration through integral intensity calibration. Collected time domain data are converted into frequency spectrum data, and then substance types can be identified by using a machine learning method.

Description

Technical Field

[0001] The invention belongs to the technical field of biochemical sensing, 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 assays 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] At present, spectral analysis techniques such as Raman spectroscopy and photoacoustic spectroscopy are widely used to characterize the types of liquid substances. Raman spectroscopy relies on the Raman shift generated by the interaction between light and molecules in the sample, which can directly reflect the type of substance. In terms of chemical composition characterization and substance identification, Raman spectroscopy can provide high-resolution information, so it is widely used in drug testing, environmental monitoring, food safety and other fields. However, this method has the problems of weak signal and low detection efficiency, and is also easily affected by fluorescence interference and strong absorption of water molecules. Therefore, the application of this method is limited in water-based samples or complex environments. Photoacoustic spectroscopy uses the principles of optical excitation and acoustic detection. After the substance absorbs short pulses of light in different bands, it undergoes thermoelastic expansion and generates ultrasonic waves, thereby realizing the identification of substances. This method has a wide range of applications in the qualitative and quantitative analysis of liquid substances, especially in environmental monitoring, water quality analysis and chemical reaction kinetics research. However, this method requires wavelength scanning analysis of the sample, which takes a long time. At the same time, since acoustic wave detection needs to be carried out at a close distance, these limit its application in large-scale industrial environments. Summary of the invention

[0004] The purpose of the present invention is to provide a non-contact real-time detection system for liquid concentration detection and substance identification in order to solve the problem of liquid detection in biochemical sensing, medical treatment and industrial preparation processes, so as to overcome the shortcomings of Raman spectroscopy such as fluorescence interference, strong absorption of water molecules, 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] A non-contact real-time detection system for liquid concentration detection and material identification comprises: a laser pumping system, a laser ultrasonic detection system, a CCD focusing control system and a detection module, wherein 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; and the CCD focusing control system is used to detect in real time and control the pumping light and the detection light to focus on the surface of the sample to be tested.

[0007] Further, the non-contact real-time detection system for liquid concentration detection and substance identification specifically includes: 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;

[0008] The Q-switched laser, the reflector, 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 pump light, which passes through the reflector, the aperture and the adjustable spatial light attenuation sheet in sequence and then reaches the dichroic mirror and is combined with the detection light. After being combined, the pump light passes through the objective lens and is vertically irradiated on the surface of the sample to be tested. The sample to be tested generates ultrasonic waves after absorbing the pump light energy.

[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 a 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 tested. The detection light is modulated by ultrasonic waves and 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. Meanwhile, the second beam splitter is arranged between the aperture and the adjustable spatial light attenuation plate, and the photodetector detects the pump light through the second beam splitter and outputs a trigger signal to the oscilloscope.

[0010] The computer, CCD, attenuation sheet and objective lens form a CCD focusing control system. The CCD and objective lens form a microscope. The computer monitors and controls the light spot focusing in real time. The attenuation sheet is used to adjust the brightness of the light spot entering the CCD.

[0011] The syringe, the microfluidic channel and the 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.

[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 detection light.

[0013] Furthermore, the pump light and the detection 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, and 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, and the liquid concentration is judged according to 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 form a training sample. The training set and the test set are obtained through multiple measurements, and the material identification model is obtained by training in combination with the 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, and 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 performance 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, and has a wider range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0021] Figure 2 This is a working flow chart of the non-contact real-time detection system applicable to liquid concentration detection and substance identification of the present invention;

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

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

[0024] in, Figure 1 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 attenuation plate, 8 is a first beam splitter, 9 is a reflector, 10 is an aperture, 11 is a second beam splitter, 12 is an adjustable spatial light attenuation plate, 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 solution and beneficial effects of the present invention more clearly understood, the present invention is further described in detail below in conjunction with 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. The system can realize concentration detection of the measured liquid and substance type identification.

[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 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;

[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 form a laser pumping system. The Q-switched laser 3 emits a laser (green light) with a wavelength of 532nm as pumping light. The pumping light adjusts the optical path through the reflector 9, and the aperture 10 controls the light spot size. The laser energy is then controlled through the adjustable spatial light attenuation plate 12, and then reaches the dichroic mirror 13 and merges with the detection light. Finally, the light spot is vertically irradiated on the surface of the sample to be measured through the objective lens 14. Based on the photoacoustic effect, the sample to be measured generates ultrasonic waves after absorbing the pumping light energy.

[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 form 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 vertically irradiate the light spot on the surface of the sample to be tested. The detection light is modulated by the ultrasonic wave and 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, and the oscilloscope 1 starts to record the data after receiving the trigger signal;

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

[0031] The syringe 15 , the microfluidic channel 16 and the capillary 17 form 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 platform.

[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 is 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, and the above RhB calibration solutions with different concentrations are respectively introduced into the capillary as the tested samples, the RhB solution is pumped by a laser pumping system, the ultrasonic signal generated by the RhB solution is detected by a laser ultrasonic detection system, and the spot size is dynamically adjusted by a CCD focusing control system to control the pumping efficiency and the detection sensitivity; the collected time domain signal is integrated and summed to obtain the time domain signal integral intensity, and the concentration calibration curve of the RhB solution is plotted with the concentration of the RhB solution as the horizontal coordinate and the time domain signal integral intensity as the vertical coordinate, 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, and 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 used as input feature after dimension reduction. The input feature and the prior material type label constitute a training sample, and the training set and test set are obtained through multiple measurements. The material type is identified by combining the machine learning method. The identification results are shown in Figure 4 As shown, the horizontal axis is the predicted material type, and the vertical axis is the actual material type. It can be seen from the figure that the accuracy of material type recognition can reach more than 98%.

[0038] The above description is only a specific implementation mode of the present invention. Any feature disclosed in this specification, unless otherwise stated, can be replaced by other alternative features that are equivalent or have similar purposes; all the disclosed features, or all the 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 the 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 in real time and control the pumping light and the detection light to focus on the surface of the sample to be tested.

2. The non-contact real-time detection system for liquid concentration detection and substance identification according to claim 1 is characterized in that: The non-contact real-time detection system for liquid concentration detection and material 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 sheet, the dichroic mirror and the objective lens form a laser pumping system. The Q-switched laser emits pump light, which passes through the reflector, the aperture and the adjustable spatial light attenuation sheet in sequence and then reaches the dichroic mirror and is combined with the detection light. After being combined, the pump light passes through the objective lens and is vertically irradiated on the surface of the sample to be tested. The sample to be tested generates ultrasonic waves after absorbing the pump light energy. 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 a 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 tested. The detection light is modulated by ultrasonic waves and 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. Meanwhile, the second beam splitter is arranged between the aperture and the adjustable spatial light attenuation plate, and the photodetector detects the pump light through the second beam splitter and outputs a trigger signal to the oscilloscope. The computer, CCD, attenuation sheet and objective lens form a CCD focusing control system. The CCD and objective lens form a microscope. The computer monitors and controls the light spot focusing in real time. The attenuation sheet is used to adjust the brightness of the light spot entering the CCD. The syringe, the microfluidic channel and the 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.

3. The non-contact real-time detection system for liquid concentration detection and substance identification according to claim 2 is 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 detection light.

4. The non-contact real-time detection system for liquid concentration detection and substance identification according to claim 2 is characterized in that: The pump light and the probe light reach the dichroic mirror simultaneously.

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 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 abscissa and the signal integral intensity as the ordinate; 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, and the liquid concentration is judged according to the signal integral intensity and concentration calibration curve.

6. 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 material identification, the calibration solution is detected by the non-contact real-time detection system, and the collected detection signal is Fourier transformed to obtain spectrum characteristics. The spectrum 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. 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 spectrum characteristics. The spectrum characteristics are input into the material identification model, and the material identification model outputs a material type identification result.

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