CN211235538U

CN211235538U - Novel micro-nano structure pH value sensor based on three-core optical fiber

Info

Publication number: CN211235538U
Application number: CN201922319389.7U
Authority: CN
Inventors: 何昊臻; 徐贲; 常冉
Original assignee: China Jiliang University
Current assignee: China Jiliang University
Priority date: 2019-12-20
Filing date: 2019-12-20
Publication date: 2020-08-11
Anticipated expiration: 2029-12-20

Abstract

The utility model discloses a novel micro-nano structure pH value sensor based on three-core optical fiber, which is characterized in that; the sensor comprises SMF 1, NCF 1, three-core fiber (TCF), NCF 2 and SMF 2 which are sequentially welded. After the fusion is complete, the TCF is heated and tapered. The diameter of the non-tapered part of the TCF is 125 μm, the three fiber cores are distributed in the same plane in parallel and at equal intervals, and the diameters of the fiber cores are equal. The sides of the TCF cone section were coated with a PAH/PAA multilayer polymer composite nanoparticle film. When the sensor is applied, the sensor is placed in a solution with a pH value to be measured, and the pH value of the solution to be measured can be demodulated by measuring the output spectrum of the sensor by using the fiber spectrometer. The utility model has the advantages of low in manufacturing cost, simple process, stability are high, compact structure, sensitivity is high, can be applied to the high accuracy measurement of pH value.

Description

Novel micro-nano structure pH value sensor based on three-core optical fiber

Technical Field

The utility model belongs to the technical field of the optical fiber sensing, concretely relates to novel micro-nano structure pH value sensor based on three-core optical fiber.

Background

Optical biochemical sensors are rapidly developing due to their important applications in environmental monitoring and clinical analysis. Among various types of biochemical sensors, a pH sensor is one of the most basic sensors. The pH value is one of important physicochemical parameters of the aqueous solution, and all natural phenomena, chemical changes and production processes related to the aqueous solution are closely related to the pH value, so that the control or measurement of the pH value has important significance in various fields such as biology, clinical medicine, ecology and the like. Although the titration method has been used for a long time, the development of micro-optical pH sensors remains a very active research topic. In recent years, optical fiber pH sensors have attracted more and more attention due to their advantages of small size, strong remote sensing capability, safety in-vivo measurement, and the like.

Fiber optic pH sensors can generally be divided into two broad categories, one type of fiber optic pH sensor being based on a pH indicator immobilized in a matrix material. Proposed pH indicators include acid dyes, fluorescein acrylamide, thymol blue, ethyl violet dyes, neutral red, eosin, mixtures of bispicramide and victoria blue, cresol red, mixtures of bromophenol blue and chlorophenol red, and the like. The optical properties of the indicator, including absorbance, fluorescence intensity, and fluorescence lifetime, can be used to determine the pH of the liquid being measured. Another class of fiber optic pH sensors is based on the morphology of nanostructured thin films, commonly referred to as swelling. Since the Refractive Index (RI) of a swellable membrane (e.g., hydrogel or polyelectrolyte deposited nanostructured material) is pH dependent, a pH sensor can be designed by measuring the external RI. Since most pH indicators operate in the ultraviolet visible range and most fiber optic assemblies operate in the near infrared range, a swellable membrane based fiber optic pH sensor is competitive because it is compatible with a fiber optic sensor network and the sensor is robust. Absorption or fluorescence type pH sensors have some inherent disadvantages, which are influenced by light intensity fluctuations, temperature and indicator concentration. Avoiding the use of indicators may well address the degradation problem due to bleaching or leaching of the indicator, making the indicator a long-term fiber optic sensor for online pH monitoring applications.

The existing pH sensor has certain defects, the traditional electrochemical pH sensor is easily interfered by electromagnetic signals, and the application of the traditional electrochemical pH sensor in the special fields of physiological sanitation, high acid-base environment and the like is limited; optical pH sensors utilizing indicators suffer from drawbacks such as indicator bleaching, leakage, etc. The optical fiber pH value sensor based on the nano-structure film has the advantages of small volume, no electricity, strong anti-electromagnetic interference performance, no pollution and the like, and has wide application prospect in the fields of various chemical reactions, environmental monitoring, biomedicine and the like.

Disclosure of Invention

In order to solve the defects of the prior art, the utility model provides a novel micro-nano structure pH value sensor based on three-core optical fiber has advantages such as sensitivity height, simple manufacture and compact structure.

The utility model discloses the technical scheme who adopts: a novel micro-nano structure pH value sensor based on a three-core optical fiber comprises a single mode fiber 1(SMF), a coreless fiber 1(NCF), a three-core optical fiber, a coreless fiber 2 and a single mode fiber 2 which are sequentially welded together. And after the fusion is finished, heating and tapering the three-core optical fiber, wherein the total length of the tapered section is 10-20 mm, and the diameter of the taper waist is 4-15 mu m. The diameter of the non-tapered part of the three-core optical fiber is 125 micrometers, the three fiber cores are distributed in the same plane in the optical fiber in parallel and at equal intervals, the interval is 15-30 micrometers, the diameters of the fiber cores are equal, and the value is 3-9 micrometers; the length of the coreless fiber is 500 to 1000 μm. The side surface of the tapered part of the three-core optical fiber is coated with a polyallylamine hydrochloride and polyacrylic acid (PAH/PAA) multilayer polymer composite nanoparticle film, and the thickness of the three-core optical fiber is 80-500 nm.

Compared with the prior art, the utility model beneficial effect be:

1. the preparation of the sensor only relates to the welding of the single-mode optical fiber, the coreless optical fiber and the three-core optical fiber, and has low cost and simple process. The surface-coated polyallylamine hydrochloride and polyacrylic acid (PAH/PAA) multilayer polymer composite nanoparticle film has lower temperature sensitivity, and can reduce the cross sensitivity of the sensor to the ambient temperature.

2. The utility model discloses in carried out the biconical taper to three-core fiber and handled, the diameter of three-core fiber awl waist department is little, has greatly improved the measuring sensitivity and the accuracy of sensor.

3. The sensor has compact structure and small volume, and reduces the requirement on the volume of a sample to be measured.

Drawings

The present invention will be further described with reference to the accompanying drawings and the detailed description.

Fig. 1 is a schematic structural diagram of the present invention.

In the figure: 1. single mode optical fiber 1, 2, coreless optical fiber 1, 3, three-core optical fiber, 4, coreless optical fiber 2, 5, single mode optical fiber 2, 6, PAH/PAA multilayer polymer composite nano particle film

FIG. 2 is a schematic cross-sectional view of an untapered portion of a three-core optical fiber, wherein three small circles represent three cores arranged in parallel.

Detailed Description

Fig. 1 is a schematic structural diagram of the present invention, which includes a single mode fiber 1(SMF), a coreless fiber 1(NCF), a three-core fiber, a coreless fiber 2 and a single mode fiber 2, which are sequentially welded together. And after the fusion is finished, heating and tapering the three-core optical fiber, wherein the total length of the tapered section is 10-20 mm, and the diameter of the taper waist is 4-15 mu m. The diameter of the non-tapered part of the three-core optical fiber is 125 micrometers, the three fiber cores are distributed in the same plane in the optical fiber in parallel and at equal intervals, the interval is 15-30 micrometers, the diameters of the fiber cores are equal, and the value is 3-9 micrometers; the length of the coreless fiber is 500 to 1000 μm. The side surface of the tapered part of the three-core optical fiber is coated with a polyallylamine hydrochloride and polyacrylic acid (PAH/PAA) multilayer polymer composite nanoparticle film, and the thickness of the three-core optical fiber is 80-500 nm. When in application, the sensor is placed in a solution with the pH value to be measured. The single-mode optical fiber 1 and the single-mode optical fiber 2 of the sensor are respectively connected with the broadband light source and the optical fiber spectrometer. Light from a broadband light source is coupled into a single-mode optical fiber 1, transmitted in the fiber core of the single-mode optical fiber, then enters a coreless optical fiber 1 to expand the beam, and then is coupled into a three-core optical fiber and divided into two parts, one part of the light is coupled into the fiber core of the three-core optical fiber, and the other part of the light is coupled into the cladding of the three-core optical fiber. Since the three-core fiber has a tapered structure, and particularly, the diameter of the taper waist is small, light propagating in the core is coupled into the cladding to a large extent while passing through the tapered region. The two parts of light pass through the three-core optical fiber and then are coupled into the single-mode optical fiber 2 through the coreless optical fiber 2 until being transmitted to the optical fiber spectrometer. Because the effective refractive indexes of the fiber core and the cladding of the three-core optical fiber are different, an interference phenomenon occurs when two parts of light transmitted by the fiber core and the cladding of the three-core optical fiber are combined, and the fiber spectrometer can directly measure the interference spectrum of the sensor. Further, the effective refractive index of the three-core fiber cladding is modulated by the refractive index of the surface coating. When the sensor is placed in acid-base liquid, the ionization state of the polyelectrolyte nano-coating of the PAH/PAA multilayer polymer composite nano-particle film is adjusted by pH value, the adjustment of the ionization state causes the density change of the polyelectrolyte nano-coating, and further causes the refractive index change of the nano-coating, thereby finally causing the resonance wavelength drift in the interference spectrum of the sensor. The pH value of the solution to be measured can be demodulated by measuring the drift amount of the resonance wavelength in the interference spectrum of the sensor by using the fiber spectrometer.

Claims

1. The utility model provides a novel micro-nano structure pH value sensor based on three-core fiber, includes single mode fiber 1(SMF), centreless optic fibre 1(NCF), three-core fiber, centreless fiber 2 and single mode fiber 2, is formed by their butt fusion in proper order, and wherein three-core fiber has the toper structure, and toper section total length is 10mm ~20mm, and the waist of a cone diameter is 4~15 mu m.

2. The novel micro-nano structure pH value sensor based on the three-core optical fiber according to claim 1, characterized in that: the diameter of the non-tapered part of the three-core optical fiber is 125 micrometers, the three fiber cores are distributed in the same plane in the optical fiber in parallel and at equal intervals, the interval is 15-30 micrometers, the diameters of the fiber cores are equal, and the value is 3-9 micrometers; the length of the coreless fiber is 500 to 1000 μm.

3. The novel micro-nano structure pH value sensor based on the three-core optical fiber according to claim 1, characterized in that: the side surface of the tapered part of the three-core optical fiber is coated with a polyallylamine hydrochloride and polyacrylic acid (PAH/PAA) multilayer polymer composite nanoparticle film, and the thickness of the three-core optical fiber is 80-500 nm.