Fiber-optic surface-enhanced Raman and fluorescence dual-mode detector for endoscopy systems

Abstract

The present invention provides a fiber-optic surface-enhanced Raman and fluorescence dual-mode detector for an endoscope system. It includes an input / output multimode optical fiber, a tapered optical fiber, and a metal film. The tapered optical fiber is formed by melt-drawing a multimode optical fiber, the undrawn end of the tapered optical fiber is connected to the input / output multimode optical fiber, and half of the side surface of the drawn end of the tapered optical fiber is coated with a metal film. The input / output multimode optical fiber transmits excitation light to the tapered optical fiber, and at the same time reversely transmits the surface-enhanced Raman signal and fluorescence signal received by the tapered optical fiber. The present invention can realize dual-mode detection of surface-enhanced Raman and fluorescence signals with high detection accuracy, and has the advantages of small size and high signal collection efficiency. It is expected to be well applied in endoscope systems.

Description

Technical Field

[0001] The invention belongs to the technical field of Raman and fluorescence detection, and in particular relates to an optical fiber type surface enhanced Raman and fluorescence dual-mode detector for an endoscope system. Background Art

[0002] Fluorescence detection has very high sensitivity and is suitable for trace analysis of various fluorescent substances, with excellent application scenarios in quantitative detection. However, fluorescence has a very broad emission peak, and the fluorescence spectra of different substances may highly overlap, reducing detection accuracy.

[0003] Compared to fluorescence detectors, Raman detectors have the advantages of no photobleaching, narrow bandwidth, and good stability. Raman spectroscopy provides unique vibrational fingerprint peaks of molecules, and the bandwidth of Raman characteristic peaks is usually in the range of 0.1nm, which is more than 100 times smaller than fluorescence. On the other hand, the inherent inefficiency of the Raman process can be overcome by exciting the localized surface plasmon resonance (LSPR) of plasmonic nanomaterials (mainly gold and silver), which leads to a significant enhancement of Raman scattering of molecules located near the metal surface (surface-enhanced Raman scattering, SERS).

[0004] In label-free diagnosis of cells and tissues, methods based on autofluorescence and light scattering are increasingly being utilized. Reduced nicotinamide adenine dinucleotide (NADH) and flavin are the main autofluorescent molecules. When excited by ultraviolet light, autofluorescence reflects their oxidation state and thus reflects cellular physiology. Autofluorescence detection has been used to study cellular hypoxia and mitochondrial dysfunction. In addition, based on different cellular metabolism and tissue characteristics, autofluorescence is increasingly being used for tumor detection in various organs, including bladder, lung, larynx, breast and skin. However, the fluorescence spectra of different tumor markers may highly overlap, which is not conducive to the in situ and trace detection requirements of precancer. In addition to fluorescence detection, Raman spectroscopy is also a suitable method for evaluating tumor cells or tissues. Raman spectroscopy provides molecular fingerprint peaks and has unique advantages in early cancer diagnosis. Summary of the Invention

[0005] Based on the technical features of fluorescence and Raman spectroscopy, the present invention proposes a fiber-optic surface-enhanced Raman and fluorescence dual-mode detector for endoscope systems. This detector can achieve dual-mode detection of SERS and fluorescence. By comparing and analyzing the detection results of fluorescence and SERS, it can make more accurate qualitative judgments on fluorescent substances. Furthermore, it enables quantitative detection of fluorescent substances with higher sensitivity and accuracy, enabling early, in-situ, and accurate diagnosis of diseases. To achieve the above detection objectives, the present invention adopts the following technical solutions:

[0006] A fiber-optic surface-enhanced Raman and fluorescence dual-mode detector for endoscopy systems includes an input / output multimode fiber, a tapered fiber, and a metal film. The tapered fiber is formed by melt-drawing a multimode fiber. The undrawn end of the tapered fiber is connected to the input / output multimode fiber, and half of the side surface of the drawn end of the tapered fiber is coated with a metal film. The input / output multimode fiber transmits excitation light to the tapered fiber, while simultaneously transmitting the surface-enhanced Raman or fluorescence signal received by the tapered fiber in the opposite direction.

[0007] The core diameter and cladding diameter of the input / output multimode optical fiber are 105 μm and 125 μm respectively, one end is connected to the undrawn end of the tapered optical fiber, and the other end is an SMA905 connector.

[0008] The tapered optical fiber is formed by melt-drawing a multimode optical fiber. Before drawing, the core diameter is 105 μm, the cladding diameter is 125 μm, the transition zone length is 300 μm, the waist diameter is 10 μm, and the waist length is 2 mm. The undrawn end is connected to the input / output multimode optical fiber, and half of the outer surface of the side of the drawn end is coated with a metal film.

[0009] The metal film has two layers. The first layer is a chromium film with a thickness of 10nm, which is plated on the outer surface of half of the side of the tapered optical fiber drawing end; the second layer is a gold film with a thickness of 50nm, which is plated on the outer surface of the chromium film.

[0010] Compared with the prior art, the present invention has the following beneficial technical effects:

[0011] The dual-mode detector uses inexpensive common multi-mode optical fiber, which has the advantages of low cost and simple production.

[0012] The main structure of the dual-mode detector is a tapered optical fiber with a very small volume.

[0013] The tapered optical fiber can increase the interaction area between the receiving end and the sample, and the surface enhanced Raman signal and fluorescence signal collection efficiency is high.

[0014] The dual-mode detector can combine surface-enhanced Raman spectroscopy and fluorescence spectroscopy for comparative analysis, avoiding the problem of background fluorescence interference in single-method detection, making the results of qualitative detection more accurate; further, it makes the sensitivity and accuracy of quantitative detection higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments or technical solutions of the present invention, the present invention is further described below with reference to the accompanying drawings and embodiments.

[0016] Figure 1 It is a schematic structural diagram of the dual-mode detector of the present invention.

[0017] In the figure, the numbers 1 are the input / output multimode optical fiber; 2 is the tapered optical fiber; 3 is the metal film, in which the chromium film is 10nm thick and is plated on half of the outer surface of the side of the tapered optical fiber, and the gold film is 50nm thick and is plated on the outer surface of the chromium film.

[0018] Figure 2 It is a schematic diagram of a device for detecting surface enhanced Raman spectroscopy of the present invention.

[0019] In the figure, reference numerals 4 denote a handheld Raman spectrometer and 5 denote a dual-mode detector.

[0020] Figure 3 It is a schematic diagram of a device for detecting fluorescence spectrum of the present invention.

[0021] In the figure, reference numerals 6 are LED light sources, 7 are optical fiber couplers, 8 are dual-mode detectors, 9 are bandpass filters, and 10 are optical fiber spectrometers.

[0022] Figure 4 This is an embodiment of the present invention in which surface-enhanced Raman spectroscopy of Rhodamine 6G is detected at one time.

[0023] Figure 5 This is an embodiment of the present invention in which the fluorescence spectrum of Rhodamine 6G is detected at one time.

[0024] Figure 4 and Figure 5 Medium, 10 -3 -10 -8 The concentration of Rhodamine 6G aqueous solution is 10 -3 , 10 -4 , 10 -5 , 10 -6 , 10 -7 , 10 -8 mol / L. DETAILED DESCRIPTION

[0025] The present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

[0026] See attached Figure 1 The manufacturing method and steps of the dual-mode detector are as follows: the first step: stripping 2 cm of the coating layer of the multimode optical fiber, using a pre-adjusted program to draw a cone on a special optical fiber fusion processing workstation, cutting at a suitable cone length to obtain a tapered optical fiber (2); the second step: plating a 10 nm thick chromium film on the half side surface of the drawn end of the tapered optical fiber (2); the third step: plating a 50 nm thick gold film on the outer surface of the chromium film; the fourth step: using a fusion splicer to fusion-splice the input / output multimode optical fiber (1) and the undrawn end of the tapered optical fiber (2).

[0027] Combine Figure 2 Introduce the specific working principle of dual-mode detector when used to detect surface enhanced Raman spectroscopy: Figure 2 As shown, the light emitted by the handheld Raman spectrometer (4) is transmitted by the input / output multimode optical fiber (1) of the dual-mode detector (5) to the tapered optical fiber (2), and reacts with the sample near the surface of the metal film (3) to generate surface-enhanced Raman scattering. The surface-enhanced Raman signal is collected by the tapered optical fiber (2), transmitted back to the input / output multimode optical fiber (1), and then transmitted to the handheld Raman spectrometer (4), thereby obtaining the surface-enhanced Raman spectrum of the sample.

[0028] Combine Figure 3 Introduce the specific working principle of the dual-mode detector when used to detect fluorescence spectra: Figure 3 As shown, the light emitted by the LED light source (6) is sequentially transmitted to the tapered optical fiber (2) through the optical fiber coupler (7) and the input / output multimode optical fiber (1) of the dual-mode detector (8), and interacts with the sample near the surface of the tapered optical fiber (2) that is not coated with a metal film, thereby exciting the sample to generate fluorescence. The fluorescence signal is collected by the tapered optical fiber (2), transmitted back to the input / output multimode optical fiber (1), and then transmitted to the optical fiber spectrometer (10) after filtering out the excitation light through the filter (9), thereby obtaining the fluorescence spectrum of the sample.

[0029] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. Fiber-optic surface-enhanced Raman and fluorescence dual-mode detector for endoscope systems, characterized by: The invention comprises an input / output multimode optical fiber (1), a tapered optical fiber (2), and a metal film (3); the core diameter of the input / output multimode optical fiber (1) is 105 μm, and the cladding diameter is 125 μm; the tapered optical fiber (2) is formed by melt-drawing the same multimode optical fiber as the input / output multimode optical fiber (1), and its undrawn end is connected to the input / output multimode optical fiber (1); half of the side surface of the drawn end of the tapered optical fiber (2) is coated with a metal film (3); the coated side surface can detect surface-enhanced Raman signals, and the uncoated side surface can detect fluorescence signals, thereby realizing a dual-mode detection function of the same device.

2. The optical fiber surface-enhanced Raman and fluorescence dual-mode detector for an endoscope system according to claim 1, characterized in that: One end of the input / output multimode optical fiber (1) is connected to the undrawn end of the tapered optical fiber (2), and the other end is an SMA905 connector.

3. The optical fiber surface-enhanced Raman and fluorescence dual-mode detector for an endoscope system according to claim 1, characterized in that: The tapered optical fiber (2) is formed by melt-drawing a multimode optical fiber. After drawing, the transition zone length is 300 μm, the cone waist diameter is 10 μm, the cone waist length is 2 mm, and half of the side surface of the drawn end is plated with a metal film (3).

4. The optical fiber surface-enhanced Raman and fluorescence dual-mode detector for an endoscope system according to claim 1, characterized in that: The metal film (3) has two layers. The first layer is a chromium film with a thickness of 10 nm, which is plated on the outer surface of the side half of the drawn end of the tapered optical fiber (2) and its function is to increase the bonding degree of the gold film; the second layer is a gold film with a thickness of 50 nm, which is plated on the outer surface of the chromium film and its function is to perform surface enhancement of the Raman signal.

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