CN101299020A - Optical gas sensor based on single polymer nano-wire - Google Patents

Abstract

The present invention discloses an optical gas sensor based on single polymer nano wire. One cone drawing micro-nano optical fiber is used for inputting the light to one end of the single polymer nano wire through the coupling area of evancent wave. The other cone drawing micro-nano optical fiber is used for outputting the light that is conducted by the single polymer nano wire through the coupling area of evancent wave at the other end of the single polymer nano wire to form the optical gas sensor which transmits the variation of optical signal. The optical gas sensor has the advantages of miniaturization, simple structure, high response speed, high sensitivity and low price. Currently the ammonia gas and nitrogen dioxide which has relative moisture from 5% to 95% and are ppm magnitude can be detected. The response speed of the optical gas sensor is faster than that of the traditional film sensor for 1-2 magnitude order.

Description

Optical gas sensor based on a single polymer nanowire

technical field

The invention relates to a sensor, especially an optical gas sensor based on a single polymer nanowire.

Background technique

Single polymer nanowire optical gas sensor is a new type of sensor, which is widely used in scientific research, industry, environment, medical treatment, military, food, hygiene and many other aspects, and has broad application potential and development prospects.

With the improvement of the optical fiber preparation process, low-loss micro-nano fibers have been prepared and have been applied to the fabrication of micro-nano photonics devices, among which micro-fiber ring resonators and all-fiber add-drop filters have been proven. At present, the gas sensing based on single nanowire has been realized in the world mainly based on electrical mechanism, such as single semiconductor nanowire and single polymer nanowire electrical gas sensor.

Contents of the invention

The object of the present invention is to provide an optical gas sensor based on a single polymer nanowire.

The technical scheme that the present invention solves its technical problem adopts is:

Use a tapered micro-nano fiber to input light into one end of a single polymer nanowire through the evanescent wave coupling region, and use another tapered micro-nano fiber to pass evanescent waves at the other end of the single polymer nanowire. The wave coupling region outputs light guided by a single polymer nanowire to form an optical gas sensor that transmits changes in light signals.

The tip diameters of the two tapered micro-nano fibers are both 0.1-2 μm.

The diameter of the polymer nanowire is 50-1000nm, and the sensing length is 10-500μm.

The beneficial effects that the present invention has are:

The single polymer nanowire sensor of the invention is an optical sensor, which has the characteristics of miniaturization, simple structure, fast response speed, high sensitivity and low price. At present, it can detect relative humidity of 5%-95%, ammonia gas and nitrogen dioxide in the order of ppm, and the response speed is 1 to 2 orders of magnitude faster than traditional thin film sensors

Description of drawings

Fig. 1 is a schematic diagram of the structure principle of the present invention.

Fig. 2 is a response diagram of polyacrylamide nanowires with a diameter of 410nm cycled between 75-88 relative humidity; the detection light wavelength is 532nm.

Fig. 3 is a graph showing the response of camphorsulfonated polyaniline/polystyrene nanowires with a diameter of 250nm to nitrogen dioxide at a concentration of 0.1-4ppm; the detection light wavelength is 532nm.

Fig. 4 is the ammonia gas response diagram of bromothymol blue-doped polymethylmethacrylate nanowires with a diameter of 270nm to a concentration of 3-28ppm; the detection light wavelength is 660nm.

In the figure: 1. Tapered micro-nano optical fiber, 2. Coupling area, 3. Coupling area, 4. Single polymer nanowire, 5. Tapered micro-nano optical fiber.

Detailed ways

As shown in Figure 1, the present invention uses a tapered micro-nano fiber 1 to input light to one end of a single polymer nanowire 4 through an evanescent wave coupling region 2, and uses another tapered micro-nano fiber 5 to transmit light to one end of a single polymer nanowire 4. The other end of the polymer nanowire 4 also outputs the light transmitted through the single polymer nanowire 4 through the evanescent wave coupling region 3 to form an optical gas sensor that transmits light signal changes.

The tip diameters of the two tapered micro-nano fibers are both 0.1-2 μm.

The diameter of the polymer nanowire is 50-1000nm, and the sensing length is 10-500μm.

The preparation process of the present invention is as follows:

(1) First, polymer nanowires with various functions are stretched from the polymer solution, and then the nanowires are cut and transferred under a microscope, placed on the required substrate, and passed through the micro operation to place the nanowires into the desired shape;

(2) Then put the nanowires placed on the substrate into a well-sealed container. There is a temperature and humidity meter inside the container to detect changes in the environment in the container. The container has ports for the gas to enter and exit. In order to facilitate the evanescent wave coupling, a specially designed device on the side of the container can not only ensure the tapered micro-fiber coupling nanowires but also make the container hermetic;

(3) Draw ordinary single-mode optical fiber by high-temperature drawing method to prepare micro-optical fiber with a tip diameter of 0.1-2 μm

(4) Put two tapered fiber probes deep into the sealed container, manipulate the micro-fiber under the optical microscope, and input and output light through the evanescent wave coupling region.

(5) A set of gas control system is designed to ensure that various gases to be analyzed enter and exit the sealed container and contact the nanowire. The optical signal output by the nanowire is monitored in real time by a photodetector.

Application examples:

A micro-fiber with a tip of about 100nm is prepared by high-temperature stretching method of ordinary single-mode optical fiber, and a nanowire with a diameter of 410nm is drawn from an aqueous solution of polyacrylamide. Sensors with a length of 200 μm were fabricated under an optical microscope. Fig. 1 is a schematic diagram of the structure and principle of the present invention; Fig. 2 is a response graph of the nanowire cycling between 75%-88% relative humidity. The response time is about 30ms. The detection light wavelength is 532nm.

A micro-fiber with a tip of about 500nm was prepared by high-temperature stretching of an ordinary single-mode optical fiber, and a nanowire with a diameter of 250nm was drawn from the chloroform solution of camphorsulfonated polyaniline/polystyrene. Sensors with a length of 500 μm were fabricated under an optical microscope. Fig. 3 is a response diagram of the nanowire to nitrogen dioxide at a concentration of 0.1-4ppm. The response time is about 7s. The detection light wavelength is 532nm.

A micro-fiber with a tip of about 1500nm was prepared by a high-temperature stretching method of an ordinary single-mode optical fiber, and a nanowire with a diameter of 900nm was pulled out from an acetone solution of polymethyl methacrylate doped with bromothymol blue. Sensors with a length of 25 μm were fabricated under an optical microscope. Fig. 4 is a diagram showing the response of the nanowire to ammonia gas at a concentration of 3-28ppm. The detection light wavelength is 660nm.

When the gas to be detected contacts the nanowire, it will penetrate into the nanowire and react with the polymer or the indicator inside, causing changes in the refractive index and absorption band of the nanowire, which in turn affect the intensity of light passing through the nanowire. . Therefore, the gas to be detected can be detected by detecting the output light intensity.

The specific embodiments above are used to explain the present invention, rather than to limit the present invention. Within the spirit of the present invention and the protection scope of the claims, any modification and change made to the present invention will fall into the protection scope of the present invention.

Claims (3)

1. An optical gas sensor based on a single polymer nanowire, characterized in that: a tapered micro-nano fiber is used to input light into one end of a single polymer nanowire through the evanescent wave coupling region, and another At the other end of a single polymer nanowire, the root tapered micro-nano fiber also outputs the light guided by a single polymer nanowire through the evanescent wave coupling region to form an optical gas sensor that transmits changes in optical signals. 2. An optical gas sensor based on a single polymer nanowire according to claim 1, characterized in that: the tip diameters of the two tapered micro-nano fibers are both 0.1-2 μm. 3. An optical gas sensor based on a single polymer nanowire according to claim 1, characterized in that: the diameter of the polymer nanowire is 50-1000 nm, and the sensing length is 10-500 μm.

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