An optical fiber optofluidic detection system and detection method for simultaneous detection of multiple ions

Abstract

The present invention provides an optical fiber optofluidic detection system and a detection method that can be used for simultaneous detection of multiple ions. A continuous wave (CW) laser generates excitation light 1-5, which passes through a beam expander system 8 composed of lenses 6-7 with focal lengths of f 1 and f 2 respectively. The beam-expanded light enters an aperture stop 9 with three small holes and then enters the front end face of a PDMS substrate 13 containing three optical fibers 10-12 respectively. After entering the end face of the optical fiber, the excitation light enters a filter system 17 composed of capillaries 14-16 containing dye solution and continuously propagates along the axial direction of the optical fiber in a total reflection manner. Its evanescent field interacts with the fluorescent probe molecules in the microfluidic channel to achieve simultaneous detection of multiple trace ions.

Description

Technical Field

[0001] The present invention belongs to the fields of optical technology and analytical chemistry, and particularly relates to an optical fiber microfluidic detection system and a detection method capable of simultaneously detecting multiple trace anions and cations under complex water environment conditions. Background Art

[0002] As is well known, even exposure to trace amounts of heavy metals, such as lead, cadmium, mercury or arsenic, can cause human diseases and even death. Therefore, on the basis of these safety thresholds, it is highly necessary to develop simple technologies to design analytical methods that can be processed within these limits. Among all analytical methods, optical detection technology has been widely used due to its advantages of high sensitivity, high efficiency and non-contact. However, traditional detection systems rely on large-volume, high-cost and high-power-consuming optical devices, making it difficult to miniaturize and integrate the system. In addition, traditional optical detection methods have a single detection parameter, can only detect one ion at a time, are time-consuming and laborious, and cannot simultaneously detect multiple ions in a complex system. Summary of the Invention

[0003] The object of the present invention is to provide an optical fiber microfluidic detection system and a detection method capable of simultaneously detecting multiple trace anions and cations under complex water environment conditions. The object of the present invention is achieved through the following steps.

[0004] The first object of the present invention is achieved as follows, including a continuous wave (CW) laser, a beam expanding system 8, a diaphragm 9, a beam filtering system 17 and a PDMS substrate 13.

[0005] The said beam expanding system 8 is composed of a first lens 6 and a second lens 7 with focal lengths of f 1 and f 2 respectively. The said f 1 < f 2. The laser generates excitation light passing through the above beam expanding system.

[0006] The said diaphragm 9 is composed of an aperture diaphragm with three small holes.

[0007] The said beam filtering system 17 is composed of three capillaries with lengths of 0.2 - 2 cm. The capillaries include a first capillary 14, a second capillary 15 and a third capillary 16.

[0008] At least three optical fiber channels are engraved on the PDMS substrate 13 (more channels can be set according to actual needs). Three bare quartz optical fibers are respectively implanted into the optical fiber channels of the PDMS substrate, and a beam filtering system (17) composed of a capillary is added to the front end of the optical fiber. The excitation light enters the front end face of the PDMS substrate 13 containing three bare quartz optical fibers after being expanded and then passing through an aperture stop with three small holes; the three bare quartz optical fibers include a first bare quartz optical fiber 10, a second bare quartz optical fiber 11, and a third bare quartz optical fiber 12;

[0009] Each of the optical fiber channels includes at least three microfluidic channels (more microfluidic channels can be set according to actual needs); each of the microfluidic channels is provided with an inlet and an outlet for the fluid. The inlets include a first fluid inlet 18, a second fluid inlet 19, and a third fluid inlet 20, and the outlets include a first fluid outlet 21, a second fluid outlet 22, and a third fluid outlet 23. The inlet and outlet of each fluid are connected to an external micropump; the refractive index of the bare quartz optical fiber is n 1; the refractive index of the water-soluble liquid cladding medium to be detected is n 3; the capillary contains a dye solution, and the refractive index of the dye solution is n 2, and the n 1> n 2 > n 3.

[0010] The second object of the present invention is achieved as follows. Step (1): A continuous wave laser generates excitation light, which passes through an expanding system composed of lenses with focal lengths of f 1 and f 2 respectively. The expanded excitation light enters the front end face of the PDMS substrate containing three bare quartz optical fibers after passing through an aperture stop with three small holes. The refractive index of the bare quartz optical fiber is n 1

[0011] Step (2): The water-soluble liquid cladding medium to be detected is respectively injected into the third microfluidic channel 27, the sixth microfluidic channel 31, and the ninth microfluidic channel 35 through a micropump. The refractive index of the water-soluble liquid cladding medium to be detected is n 3;

[0012] Step (3): After the excitation light enters the end face of the optical fiber, it enters a beam filtering system composed of a capillary containing a dye solution and then propagates continuously along the axial direction of the optical fiber in a total reflection manner. Its evanescent field interacts with the fluorescent probe molecules in the microfluidic channel to realize the simultaneous detection of multiple trace ions. The refractive index of the dye solution is n 2, and the n 1> n 2 >n 3.

[0013] 1. A beam expander system is added to the optical path, and only one excitation light can simultaneously excite multiple optical fibers;

[0014] 2. A filter system composed of a capillary is added to the optical path, which greatly reduces the background noise of the light that does not satisfy total reflection and can effectively improve the detection sensitivity. Let the total reflection angles of the optical fiber with air and fluorescent dye as the cladding be θ c1 and θ c2 , respectively. According to the Fresnel's law, we have sin θ c1 = n / n 1, sin θ c2 = n 2 / n 1. Taking the refractive index of air n as 1, the refractive index of the optical fiber n 1 = 1.458, n 3 = 1.333, n 2 is between n 1 and n 3, then θ c1 < θ c2 , that is, the light with an angle in the range of θ c1 cannot continue to propagate in the optical fiber in the form of total reflection, resulting in extremely strong refracted light in addition to the evanescent wave at the microchannel port, exciting the fluorescent dye molecules, and making the fluorescence radiation intensity strong within about L 0 length and decaying rapidly. Let the radius of the optical fiber be r , L 0 = 2 r tan θ c2 , then when the refractive index of the fluorescent dye n 2 is 1.362, L 0~2mm. For the convenience of the experiment, the length of the capillary is taken as 1 cm.

[0015] 3. On the basis of the above 1 and 2, the excitation light has a long propagation length and small attenuation along the axial direction of the optical fiber. By engraving multiple microfluidic channels along the axial direction of the optical fiber. Under the condition that the wavelength of the excitation light remains unchanged and there is only one excitation light source, the simultaneous detection of multiple trace analytes can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic diagram of the system structure described in this application;

[0017] In the figure: 1 - First CW laser, 2 - Second CW laser, 3 - Third CW laser, 4 - Fourth CW laser, 5 - Fifth CW laser, 6 - First lens; 7 - Second lens, 8 - Beam expander system, 9 - Diaphragm, 10 - First bare quartz fiber, 11 - Second bare quartz fiber, 12 - Third bare quartz fiber, 13: PDMS substrate, 14 - First capillary, 15 - Second capillary, 16 - Third capillary, 17 - Beam filtering system, 18 - First fluid inlet, 19 - Second fluid inlet, 20 - Third fluid inlet, 21 - First fluid outlet, 22 - Second fluid outlet, 23 - Third fluid outlet, 24 - First microfluidic channel group, 25 - First microfluidic channel, 26 - Second microfluidic channel, 27 - Third microfluidic channel, 28 - Second microfluidic channel group, 29 - Fourth microfluidic channel, 30 - Fifth microfluidic channel, 31 - Sixth microfluidic channel, 32: Third microfluidic channel group, 33 - Seventh microfluidic channel, 34 - Eighth microfluidic channel, 35 - Ninth microfluidic channel;

[0018] Figure 2 This is the experimental result of the fluorescence radiation intensity after the excitation light passes through the filter system composed of capillaries. The capillary (casing C) is filled with a 1 mM rhodamine 6G (Rh6G) ethanol solution. The abscissa is the fluorescence generation length in the microchannel, with the unit of centimeter (cm); the ordinate is the fluorescence radiation intensity, with the unit of arbitrary unit;

[0019] Figure 3 This is the experimental result of the first ion detection channel group 24 for detecting Pb 2+ . Among them, (a) shows the fluorescence spectrum with a 410 nm continuous wave (CW) laser as the excitation light, and channels 25 - 27 in channel group 24 are filled with blue CdSe / ZnS - PEG - NH2, related interfering ions, and the ion Pb to be detected 2+ . The abscissa is the wavelength, with the unit of nanometer; the ordinate is the laser radiation intensity, with the unit of arbitrary unit; the wavelength corresponding to the peak of the spectrum is 450 nm; (b) shows the influence of related interfering ions and the ion Pb to be detected 2+ on the fluorescence radiation intensity;

[0020] Figure 4 This is the experimental result of the first ion detection channel group 28 for detecting Hg 2+ . Among them, (a) shows the fluorescence spectrum with a 410 nm continuous wave (CW) laser as the excitation light, and channels 29 - 31 in channel group 28 are filled with green CdSe / ZnS - PEG - COOH, related interfering ions, and the ion Hg to be detected 2+Fluorescence spectrum; In the figure: The abscissa is the wavelength, with the unit of nanometer; the ordinate is the laser radiation intensity, with the unit of arbitrary unit; the wavelength corresponding to the spectral peak is 530 nm; (b) shows the relevant interfering ions and the ion Hg to be detected 2+ Effect on the fluorescence radiation intensity

[0021] Figure 5 The first ion detection channel group 32 is used to detect Fe 3+ Experimental results, (a) Using a 410 nm continuous wave (CW) laser as the excitation light, filling red light CdSe / ZnS-GSH, relevant interfering ions and the ion Fe to be detected in channels 33 - 35 of channel group 32 3+ Fluorescence spectrum; In the figure: The abscissa is the wavelength, with the unit of nanometer; the ordinate is the laser radiation intensity, with the unit of arbitrary unit; the wavelength corresponding to the spectral peak is 652 nm, (b) shows the relevant interfering ions and the ion Fe to be detected 3+ Effect on the fluorescence radiation intensity Detailed implementation mode

[0022] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but the present invention is not limited in any way. Any transformation or replacement made based on the teachings of the present invention falls within the protection scope of the present invention

[0023] An optical fiber optofluidic detection system that can be used for simultaneous detection of multiple ions, including a continuous wave (CW) laser, a beam expander system 8, a diaphragm 9, a beam filtering system 17, and a PDMS substrate 13

[0024] The described beam expander system 8 is composed of a first lens 6 and a second lens 7 with focal lengths of f 1 and f 2 respectively, and the described f 1 < f 2. The laser generates excitation light that passes through the above beam expander system

[0025] The described diaphragm 9 is composed of an aperture diaphragm with three small holes

[0026] The described beam filtering system 17 is composed of three capillaries with lengths of 0.2 - 2 cm, and the capillaries include a first capillary 14, a second capillary 15, and a third capillary 16

[0027] At least three optical fiber channels are engraved on the PDMS substrate 13 (more channels can be set according to actual needs). Three bare quartz optical fibers enter the optical fiber channels of the PDMS substrate after passing through the beam filtering system 17 composed of capillaries respectively. The excitation light enters the front end face of the PDMS substrate 13 containing three bare quartz optical fibers after being expanded and then passing through the aperture diaphragm with three small holes. The three bare quartz optical fibers include the first bare quartz optical fiber 10, the second bare quartz optical fiber 11, and the third bare quartz optical fiber 12.

[0028] Each of the optical fiber channels includes at least three microfluidic channels (more microfluidic channels can be set according to actual needs). Each of the microfluidic channels is provided with an inlet and an outlet for the fluid. The inlets include the first fluid inlet 18, the second fluid inlet 19, and the third fluid inlet 20, and the outlets include the first fluid outlet 21, the second fluid outlet 22, and the third fluid outlet 23. The inlets and outlets of each fluid are connected to an external micro pump.

[0029] The nine microfluidic channels respectively form three microfluidic channel groups, including the first microfluidic channel group 24, the second microfluidic channel group 28, and the third microfluidic channel group 32. The first microfluidic channel group 24 includes the first microfluidic channel 25, the second microfluidic channel 26, and the third microfluidic channel 27. The second microfluidic channel group 28 includes the fourth microfluidic channel 29, the fifth microfluidic channel 30, and the sixth microfluidic channel 31. The third microfluidic channel group 32 includes the seventh microfluidic channel 33, the eighth microfluidic channel 34, and the ninth microfluidic channel 35.

[0030] A method for realizing simultaneous detection of multiple ions includes the following steps:

[0031] Step (1): A continuous wave laser generates excitation light, which passes through an expanding system composed of lenses with focal lengths of f 1 and f 2 respectively. The expanded excitation light enters the front end face of the PDMS substrate containing three bare quartz optical fibers after passing through the aperture diaphragm with three small holes. The refractive index of the bare quartz optical fiber is n 1;

[0032] Step (2): A water-soluble liquid cladding medium to be detected is respectively injected into the third microfluidic channel 27, the sixth microfluidic channel 31, and the ninth microfluidic channel 35 through a micro pump. The refractive index of the water-soluble liquid cladding medium to be detected is n 3;

[0033] Step (3): After the excitation light enters the end face of the optical fiber, it enters the beam filtering system composed of a capillary tube containing a dye solution and propagates continuously along the axial direction of the optical fiber in a total reflection manner. Its evanescent field interacts with the fluorescent probe molecules in the microfluidic channel to achieve the simultaneous detection of multiple trace ions. The refractive index of the dye solution is n 2, and the n 1 > n 2 > n 3.

[0034] The first microfluidic channel 25 contains a blue light quantum dot fluorescent probe CdSe / ZnS-PEG-NH2 for generating a reference light; the second microfluidic channel 26 contains a blue light quantum dot fluorescent probe CdSe / ZnS-PEG-NH2 and other ions except the ion Pb 2+ to be detected for generating a control light; the third microfluidic channel 27 contains a blue light quantum dot fluorescent probe CdSe / ZnS-PEG-NH2, the ion Pb 2+ to be detected, and other ions except Pb 2+ for generating a detection signal. Among them, other ions except the ion Pb 2+ to be detected are called interfering ions.

[0035] The fourth microfluidic channel 29 contains green light CdSe / ZnS-PEG-COOH for generating a reference light; the fifth microfluidic channel 30 contains green light CdSe / ZnS-PEG-COOH and other ions except the ion Hg 2+ to be detected for generating a control light; the sixth microfluidic channel 31 contains CdSe / ZnS-PEG-COOH, the ion Hg 2+ to be detected, and other ions except Hg 2+ for generating a detection signal. Among them, other ions except the ion Hg 2+ to be detected are called interfering ions.

[0036] The seventh microfluidic channel 33 contains red light CdSe / ZnS-GSH for generating a reference light; the eighth microfluidic channel 34 contains red light CdSe / ZnS-GSH and other ions except the ion Fe 3+ to be detected for generating a control light; the ninth microfluidic channel 35 contains red light CdSe / ZnS-GSH, the ion Fe 3+ to be detected, and other ions except Fe 3+ for generating a detection signal. Among them, other ions except the ion Fe 3+ to be detected are called interfering ions.

[0037] The fluorescent probe described above is a quantum dot, carbon quantum dot, gold nanoparticle, organic dye or fluorescent protein, and its emission range is any one or more within the visible light range (380 - 760 nm), and its solvent is water.

[0038] The ion to be detected described above is Pb 2+ , Cu 2+ , Hg 2+ , Fe 3+ , Fe 2+ One or more of them, or F - , ClO - , NH4 + , CO3 2- One or more of them.

[0039] When detecting the above ions, the required fluorescent probe needs to be chemically modified to a certain extent according to the fluorescence quenching mechanism of the specific ion to be detected.

[0040] After selecting a specific fluorescent probe or chemically modifying the fluorescent probe according to actual needs, it is possible to simultaneously detect one or more of Pb 2+ , Cu 2+ , Hg 2+ , Fe 3+ , Fe 2+ One or more of them or F - , ClO - , NH4 + , CO3 2- One or more of them simultaneously.

[0041] Example 1

[0042] The continuous wave (CW) laser generates excitation light 1 - 5, which passes through an expanding beam system 8 composed of lenses 6 - 7 with focal lengths of f 1 and f 2 respectively. The expanded light enters an aperture stop with three small holes and then enters the front end face of a PDMS substrate 13 containing three optical fibers 10 - 12 respectively. After the excitation light enters the optical fiber end face, it enters a beam filtering system 17 composed of capillaries 14 - 16 containing dye solution and propagates continuously along the optical fiber axis in a total reflection manner. Its evanescent field interacts with the fluorescent probe molecules in the microfluidic channel to achieve simultaneous detection of multiple trace ions. Each microfluidic channel includes an inlet (18 - 20) and an outlet (21 - 23). In the first microfluidic channel group 24 (including microfluidic channels 25 - 27), it is used to detect the first ion Pb 2+, where the first microfluidic channel 25 only contains the blue light quantum dot fluorescent probe CdSe / ZnS-PEG-NH2 for generating reference light; the second microfluidic channel 26 contains the blue light CdSe / ZnS-PEG-NH2 and related interfering ions on the basis of the first microfluidic channel 25 for generating control light; the third microfluidic channel 27 contains the blue light CdSe / ZnS-PEG-NH2, related interfering ions and the ion Pb to be detected on the basis of the second microfluidic channel 26 2+ . The second microfluidic channel group 28 (including microfluidic channels 29-31) is used to detect the second ion Hg 2+ , where the fourth microfluidic channel 29 only contains the green light CdSe / ZnS-PEG-COOH for generating reference light; the fifth microfluidic channel 30 contains the green light CdSe / ZnS-PEG-COOH and related interfering ions on the basis of the fourth microfluidic channel 29 for generating control light; the sixth microfluidic channel 31 contains the CdSe / ZnS-PEG-COOH, related interfering ions and the ion Hg to be detected on the basis of the fifth microfluidic channel 30 2+ . The third microfluidic channel group 32 (including microfluidic channels 33-35) is used to detect the third ion Fe 3+ , where the seventh microfluidic channel 33 only contains the red light CdSe / ZnS-GSH for generating reference light; the eighth microfluidic channel 34 contains the red light CdSe / ZnS-GSH and related interfering ions on the basis of the seventh microfluidic channel 33 for generating control light; the ninth microfluidic channel 35 contains the red light CdSe / ZnS-GSH, related interfering ions and the ion Fe to be detected on the basis of the eighth microfluidic channel 34 3+ .

Claims

1. An optical fiber optofluidic detection system that can be used for simultaneous detection of multiple ions, characterized in that It includes a continuous-wave laser, a beam expander system (8), a diaphragm (9), a beam filtering system (17), and a PDMS substrate (13). The beam expander system (8) consists of a first lens (6) and a second lens (7) with focal lengths of f 1 and f 2 respectively, and the f 1 < f 2. The excitation light generated by the laser passes through the above beam expander system; The diaphragm (9) is composed of an aperture diaphragm with three small holes. The beam filtering system (17) is composed of three capillaries with a length of 0.2 - 2 cm. The capillaries include a first capillary (14), a second capillary (15), and a third capillary (16). At least three optical fiber channels are engraved on the PDMS substrate (13). Three bare quartz optical fibers are respectively implanted into the optical fiber channels of the PDMS substrate. And a beam filtering system (17) composed of capillaries is added to the front ends of the optical fibers. The pumping light enters the front end face of the PDMS substrate (13) containing three bare quartz optical fibers after being expanded and passing through the aperture diaphragm with three small holes. The three bare quartz optical fibers include a first bare quartz optical fiber (10), a second bare quartz optical fiber (11), and a third bare quartz optical fiber (12). Each of the optical fiber channels described above includes at least three microfluidic channels; each of the microfluidic channels is provided with an inlet and an outlet for the fluid. The inlet includes a first fluid inlet (18), a second fluid inlet (19), and a third fluid inlet (20), and the outlet includes a first fluid outlet (21), a second fluid outlet (22), and a third fluid outlet (23). The inlet and outlet of each fluid are connected to an external micropump; the refractive index of the bare quartz optical fiber is n 1; the refractive index of the water-soluble liquid cladding medium to be detected is n 3; the capillary contains a dye solution, and the refractive index of the dye solution is n 2, and the n 1 > n 2 > n 3.

2. The detection system for simultaneously detecting multiple ions according to claim 1, characterized in that The nine microfluidic channels respectively form three microfluidic channel groups, including a first microfluidic channel group (24), a second microfluidic channel group (28), and a third microfluidic channel group (32). The first microfluidic channel group (24) includes a first microfluidic channel (25), a second microfluidic channel (26), and a third microfluidic channel (27). The second microfluidic channel group (28) includes a fourth microfluidic channel (29), a fifth microfluidic channel (30), and a sixth microfluidic channel (31). The third microfluidic channel group (32) includes a seventh microfluidic channel (33), an eighth microfluidic channel (34), and a ninth microfluidic channel (35).

3. A method for simultaneously detecting multiple ions by the detection system according to claim 2, characterized in that It includes the following steps: Step (1): A continuous-wave laser generates excitation light, which passes through a beam expander system composed of lenses with focal lengths of f 1 and f 2 respectively. The expanded excitation light enters an aperture stop with three small holes and then enters the front end face of a PDMS substrate containing three bare quartz optical fibers. The refractive index of the bare quartz optical fiber is n 1; Step (2): Inject the water-soluble liquid cladding medium to be detected into the third microfluidic channel (27), the sixth microfluidic channel (31), and the ninth microfluidic channel (35) respectively through a micropump. The refractive index of the water-soluble liquid cladding medium to be detected is n 3; Step (3): After the excitation light enters the end face of the optical fiber, it enters the beam filtering system composed of a capillary tube containing a dye solution and propagates continuously along the axial direction of the optical fiber in a total reflection manner. Its evanescent field interacts with the fluorescent probe molecules in the microfluidic channel to achieve the simultaneous detection of multiple trace ions. The refractive index of the dye solution is n 2, and the n 1 > n 2 > n 3.

4. The detection method according to claim 3, characterized in that The first microfluidic channel (25) contains a blue light quantum dot fluorescent probe CdSe / ZnS-PEG-NH2 for generating reference light; the second microfluidic channel (26) contains a blue light quantum dot fluorescent probe CdSe / ZnS-PEG-NH2 and a probe for detecting ions Pb 2+ Other ions other than the above are used to generate control light; the third microfluidic channel (27) contains blue light quantum dot fluorescent probe CdSe / ZnS-PEG-NH2, the ion to be detected Pb 2+ and Pb 2+ Ions other than ions are used to generate detection signals.

5. The detection method according to claim 3, wherein The fourth microfluidic channel (29) contains green light CdSe / ZnS-PEG-COOH for generating reference light; the fifth microfluidic channel (30) contains green light CdSe / ZnS-PEG-COOH and Hg 2+ Other ions other than the ions are used to generate control light; the sixth microfluidic channel (31) contains CdSe / ZnS-PEG-COOH, the ion to be detected Hg 2+ and Hg 2+ Ions other than ions are used to generate detection signals.

6. The detection method according to claim 3, characterized in that The described seventh microfluidic channel (33) contains red light CdSe / ZnS-GSH for generating reference light; the eighth microfluidic channel (34) contains red light CdSe / ZnS-GSH and other ions except the ion Fe to be detected for generating control light; the ninth microfluidic channel (35) contains red light CdSe / ZnS-GSH, the ion Fe to be detected, and other ions except Fe for generating detection signals. 3+ The described seventh microfluidic channel (33) contains red light CdSe / ZnS-GSH for generating reference light; the eighth microfluidic channel (34) contains red light CdSe / ZnS-GSH and other ions except the ion Fe to be detected for generating control light; the ninth microfluidic channel (35) contains red light CdSe / ZnS-GSH, the ion Fe to be detected, and other ions except Fe for generating detection signals. 3+ and Fe 3+ except for generating detection signals.

7. The detection method according to claim 3, wherein The fluorescent probe is a quantum dot, a carbon quantum dot, a gold nanoparticle, an organic dye, or a fluorescent protein, and its emission range is any one or more within the visible light range (380 - 760 nm), and its solvent is water.

8. The detection method according to claim 3, wherein The multiple trace ions described are Pb 2+ , Cu 2+ , Hg 2 + , Fe 3+ , Fe 2+ or more than one of the above, or F - , ClO - , NH4 + , CO3 2- or more than one of the above.

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