A SERS microfluidic detector embedded with gold nanoparticles

Abstract

The present invention provides a SERS microfluidic detector embedded with gold nanoparticles and a device preparation method. The SERS microfluidic detector is made of a transmission multimode optical fiber and a Teflon tube. The device preparation method mainly includes: using electrostatic adsorption force to temporarily fix the gold nanoparticles on the inner wall of the Teflon tube; using a heating and softening method to embed the gold nanoparticles on the inner wall of the Teflon tube; using a melting collapse method to connect the Teflon tube with the transmission multimode optical fiber; using a laser ablation method to process a liquid sample outflow hole on the side of the Teflon tube, so as to obtain a SERS microfluidic detector. The present invention uses the structure of a microfluidic channel to increase the interaction length between light and liquid samples; uses gold nanoparticles to amplify Raman signals; and uses the liquid core optical waveguide principle to reduce the transmission loss of Raman signal light, so that the detector has a better Raman spectrum detection effect on liquid samples, and has the advantages of high sensitivity, small sample amount, convenient measurement, high repeatability, etc.

Description

Technical Field

[0001] The invention relates to the fields of surface enhanced Raman scattering (SERS) detection technology, microfluid detection technology and optical fiber sensing technology, and in particular to a SERS microfluid detector embedded with gold nanoparticles and a device preparation method. Background Art

[0002] The characteristic of Raman spectroscopy detection technology is that it can accurately study the structural information of substances at the molecular level, and has the advantages of non-destructive, high sensitivity, and short detection time. At the same time, because the Raman spectrum of water is offset far, the use of Raman spectroscopy to detect samples in solution can be unaffected by water. However, the traditional Raman signal is very weak, making it difficult to detect trace substances in liquids.

[0003] SERS spectroscopy detection technology is a common Raman spectroscopy detection technology. It has been widely studied and applied because of its ability to enhance extremely weak Raman signals. It has played an increasingly important role in the fields of life sciences, medical diagnosis, food testing, and environmental monitoring. The SERS technology originally placed the sample on a rough metal substrate (gold, silver or copper). The substance to be tested came into contact with the metal substrate to produce the SERS effect and obtain an enhanced Raman signal. However, due to the limited contact area between the substrate and the substance to be tested, the detection effect is often poor and the efficiency is very low. Later, the SERS detection technology used metal nanoparticles as the substrate, but because the range of the excitation light was very small, only a small spot of a few to tens of square microns, the number of samples to be tested that were excited was small, and the SERS detection efficiency was not high. Summary of the invention

[0004] In order to overcome the shortcomings of the prior art, the present invention provides a SERS microfluidic detector embedded with gold nanoparticles and a device preparation method. The structure of the microfluidic channel is used to increase the interaction length between the excitation light and the liquid sample to be tested, the gold nanoparticles are used to amplify the Raman signal, and the liquid core optical waveguide principle is used to reduce the transmission loss of the Raman signal light, and finally a SERS detection method with high sensitivity, small sample amount, convenient measurement and high repeatability is obtained.

[0005] The first purpose of the present invention is to disclose a SERS microfluidic detector embedded with gold nanoparticles, comprising a transmission multimode optical fiber, a liquid sample outflow hole, a Teflon tube, gold nanoparticles and a liquid sample inflow end; the transmission multimode optical fiber is connected to the Teflon tube, the inner wall of the Teflon tube is relatively evenly embedded with gold nanoparticles, and the side wall of the Teflon tube is provided with a liquid sample outflow hole for waste liquid outflow.

[0006] The transmission multimode optical fiber of the present invention is used as a channel for light to enter the Teflon tube and is also a channel for SERS signal to exit. The core diameter of the multimode optical fiber is 110 μm and the cladding diameter is 125 μm.

[0007] The Teflon tube of the present invention is used as a microfluidic channel of a detector and forms a liquid core optical waveguide with an inner diameter of 203 μm, an outer diameter of 254 μm, a length of 2 cm, and a refractive index of 1.29.

[0008] The gold nanoparticles of the present invention are in powder form, and the particle diameter is 20-30nm.

[0009] The second purpose of the present invention is to disclose a method for preparing a SERS microfluidic detector embedded with gold nanoparticles, the steps are as follows: temporarily fix the gold nanoparticles on the inner wall of a Teflon tube by electrostatic adsorption, disperse the gold nanoparticles more evenly by ultrasonic vibration, then soften the Teflon tube by heating, make the gold nanoparticles slightly sink into the softened inner surface of the Teflon tube, and after cooling and hardening, obtain a microfluidic detection channel with gold nanoparticles embedded on the inner surface. Use an optical fiber fusion splicer to melt and collapse the Teflon tube, connect it with a multimode optical fiber, and finally use a laser ablation method to punch a hole on the side of the Teflon tube to form a liquid sample outflow hole, and finally obtain a SERS microfluidic detector embedded with gold nanoparticles.

[0010] The heating temperature for softening the Teflon tube of the present invention is 200-210° C., and the heating time for maintaining the temperature is 8-10 minutes.

[0011] The connection between the Teflon tube and the multimode optical fiber described in the present invention is completed by using a manual mode of an optical fiber fusion splicer. The transmission multimode optical fiber is inserted into the Teflon tube by about 5 mm, and the overlapping part is discharged to cause the Teflon tube to melt and collapse and be tightly connected with the transmission multimode optical fiber.

[0012] The liquid sample outflow hole of the present invention is located 50 μm away from the fusion point of the transmission multimode optical fiber and the Teflon tube, and is obtained by ablating the side of the Teflon tube using a laser processing system. The diameter of the liquid sample outflow hole is 90 μm.

[0013] The beneficial effects of the present invention are: a SERS microfluidic detector with embedded gold nanoparticles, the Teflon tube has the functions of a microfluidic channel and a liquid core optical waveguide at the same time, the structure of the microfluidic channel increases the interaction length between the excitation light and the liquid sample to be tested, and the gold nanoparticles in the microfluidic channel amplify the Raman signal. The application of the liquid core optical waveguide principle reduces the transmission loss of the Raman signal light, greatly improving the sensitivity of the SERS microfluidic detector, and also has the advantages of a small amount of sample to be tested, fast detection speed, and repeated use. The preparation method based on the above-mentioned SERS microfluidic detector is simple and easy to operate, low in cost, and convenient for mass production. Based on the above-mentioned SERS microfluidic detector, the detection process is simple, and the light is directly focused on the end face of the transmission multimode optical fiber for transmission, so that the utilization rate of the focused excitation light is high, and it can fully contact the sample to be tested, so as to achieve stable and efficient detection of trace samples, avoiding the risk of traditional liquid samples being difficult to focus. In the field of medical testing, we integrate the probe into the multimode optical fiber, which enables real-time detection within the endoscope, breaking the deadlock that the endoscope is only used for "seeing" and truly realizing the advantages of the endoscope's measurement technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of the SERS microfluidic detector structure. DETAILED DESCRIPTION

[0015] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0016] See attached Figure 1 The invention relates to a SERS microfluidic detector embedded with gold nanoparticles, comprising: a transmission multimode optical fiber (1), a liquid sample outflow hole (2), a Teflon tube (3), gold nanoparticles (4) and a liquid sample inflow end (5). The transmission multimode optical fiber (1) is connected to the Teflon tube (3), the inner wall of the Teflon tube (3) is uniformly embedded with gold nanoparticles (4), and the side wall of the Teflon tube (3) is provided with a liquid sample outflow hole (2) for waste liquid outflow. During the detection process, the liquid sample to be tested flows into the Teflon tube (3) from the liquid sample inflow end (5) and fills the Teflon tube (3), and the light emitted by the Raman spectrometer is incident into the Teflon tube (3) through the transmission multimode optical fiber (1), so that the liquid sample to be tested in the Teflon tube (3) is excited, and the generated Raman spectrum signal is amplified by the gold nanoparticles (4), and the Raman signal is confined in the Teflon tube (3) and received by the end face of the transmission multimode optical fiber (1), and then transmitted to the Raman spectrometer to obtain the SERS spectrum of the liquid sample to be tested.

[0017] See attached Figure 1The preparation method of a SERS microfluidic detector based on embedded gold nanoparticles provided by the present invention comprises: temporarily fixing the gold nanoparticles (4) on the inner wall of a Teflon tube (3) by electrostatic adsorption, dispersing the gold nanoparticles (4) more evenly by ultrasonic vibration, and then softening the Teflon tube (3) by heating at a temperature of 200-210° C. and maintaining the temperature for 8-10 minutes, so that the gold nanoparticles (4) slightly sink into the softened inner surface of the Teflon tube (3), and after cooling and hardening, a microfluidic detection channel with the gold nanoparticles (4) embedded on the inner surface is obtained. Using an optical fiber fusion splicer, one end of a transmission multimode optical fiber (1) is placed in the Teflon tube for about 5 mm, and discharge is performed based on the overlapping part to melt and collapse the Teflon tube (3) and connect it to the transmission multimode optical fiber (1). Finally, a hole is punched on the side of the Teflon tube (3) by laser ablation to form a liquid sample outflow hole (2), and finally a SERS microfluidic detector embedded with gold nanoparticles is obtained.

[0018] Those skilled in the art clearly know that according to the method of the present invention, a variety of trace liquid molecules can be stably and efficiently detected, and can be combined and optimized in design when there is no conflict in the technical features.

Claims

1. A SERS microfluidic detector embedded with gold nanoparticles, characterized in that The detector comprises a transmission multimode optical fiber (1), a liquid sample outflow hole (2), a Teflon tube (3), gold nanoparticles (4) and a liquid sample inflow end (5); the liquid sample to be tested flows into the Teflon tube (3) from the liquid sample inflow end (5), and fills the Teflon tube (3); light emitted by a Raman spectrometer is incident into the Teflon tube (3) through the transmission multimode optical fiber (1), so that the liquid sample to be tested in the Teflon tube (3) is excited, and the generated Raman spectrum signal is amplified by the gold nanoparticles (4); the Raman signal is confined in the Teflon tube (3) and is received by the end face of the transmission multimode optical fiber (1), and then transmitted to the Raman spectrometer to obtain a SERS spectrum of the liquid sample to be tested; The gold nanoparticles (4) are temporarily fixed to the inner wall of the Teflon tube (3) by electrostatic adsorption, and then dispersed more evenly by ultrasonic vibration. The Teflon tube (3) is softened by heating, so that the gold nanoparticles (4) slightly sink into the softened inner surface of the Teflon tube (3). After cooling and hardening, a microfluidic detection channel with the gold nanoparticles (4) embedded in the inner surface is obtained; the transmission multimode optical fiber (1) is connected to the Teflon tube (3) by a melting collapse method and is obtained by a fiber fusion splicer; the liquid sample outflow hole (2) is obtained by laser ablation on the side of the Teflon tube (3); The heating temperature for softening the Teflon tube (3) is 200-210° C., and the heating time for maintaining the temperature is 8-10 minutes; The connection between the transmission multimode optical fiber (1) and the Teflon tube (3) is completed using a manual mode of an optical fiber fusion splicer. The transmission multimode optical fiber (1) is inserted into the Teflon tube (3) by 5 mm, and the overlapping part is discharged so that the Teflon tube (3) melts and collapses to be tightly connected with the transmission multimode optical fiber (1).

2. The SERS microfluidic detector embedded with gold nanoparticles according to claim 1, characterized in that: The transmission multimode optical fiber (1) has a core diameter of 110 μm and a cladding diameter of 125 μm.

3. The SERS microfluidic detector embedded with gold nanoparticles according to claim 1, characterized in that: The Teflon tube (3) has an inner diameter of 203 μm, an outer diameter of 254 μm, a length of 2 cm, and a refractive index of 1.

29.

4. The SERS microfluidic detector embedded with gold nanoparticles according to claim 1, characterized in that: The gold nanoparticles (4) are in powder form, and the particle diameter is 20 to 30 nm.

5. The SERS microfluidic detector embedded with gold nanoparticles according to claim 1, characterized in that: The liquid sample outflow hole (2) is located 50 μm away from the fusion point between the transmission multimode optical fiber (1) and the Teflon tube (3), and is obtained by ablating the side of the Teflon tube (3) using a laser processing system. The diameter of the liquid sample outflow hole (2) is 90 μm.

Images