RU2661611C1 - Method of creating a sensor element on the basis of the microresonator of porous silicon for the detection of explosive vapors - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention relates to physics. Method comprises introducing into the microresonator of porous silicon organic polymers of the class of polyphenylenevinilenes, the microresonator of porous silicon being placed on the bottom of a metal container, which is filled with a solution of an organic polymer at a concentration of 0.1–1 mg/ml in an organic solvent, after which an inert gas is pumped into the vessel and the excess pressure is maintained at a level of 1–9 bar for 10–100 minutes at a fixed temperature from the range of +10 °C to +50 °C.

EFFECT: simplification, increase of reliability and reduction of process costs are achieved.

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Description

The invention relates to the field of nanotechnology and physics, in particular to a method for creating a luminescent sensor element. The method can be used to create highly sensitive explosive sensors. The proposed method leads to increased uniformity of penetration and reduced consumption of organic polymer introduced into the microcavity, compared with the known methods for creating sensor elements from porous silicon.

The known method, "the study of the optical properties of polymers introduced into a porous matrix based on silicon" (Cheylan S. et al. Optical study of polymer infiltration into porous Si based structures // Proc. Of SPIE Vol. 6593, 2007. C. 65931K) . In this method, organic polymers are introduced into a monolayer of porous silicon by applying a drop of a polymer solution to the surface of a porous silicon matrix. The disadvantage of this method is the heterogeneity of the introduction, which cannot be achieved due to the inhomogeneous distribution of a drop of solution over the surface of the sample. As a result, the efficiency decreases and a spread in the characteristics of the sensor element appears.

The closest method is, "Fluorescent hybrid devices based on porous silicon microresonators for detecting explosives" (Levitsky IA et al. Fluorescent polymer-porous silicon microcavity devices for explosive detection // Appl. Phys. Lett. 2007. T. 90. No. 4. C. 41904.). This method involves introducing an organic polymer into a microcavity based on porous silicon. The introduction of an organic polymer occurs by applying a drop of a polymer solution in a vacuum to the porous surface of a microresonator. After application, the polymer is removed by spin-coating, and then the chamber is filled with nitrogen with atmospheric pressure. This method is selected as a prototype of the proposed solution.

The main disadvantage of the above method is the lack of uniform conditions for introducing a solution of an organic polymer into a microcavity at different parts of its surface, which leads to a decrease in the efficiency and reliability of the sensor element. Also the disadvantages of this method include the high consumption of a solution of the polymer used, which leads to an increase in resource consumption.

The technical result of the invention is to simplify the method of creating a sensor element based on a microcavity made of porous silicon and to increase reliability, reduce the resource consumption of the polymer injection process, by reducing the spread of the main characteristics of the sensor element.

The specified technical result is achieved by the fact that in the method of creating a sensor element based on a porous silicon microcavity for detecting explosive vapors, a porous silicon microcavity is placed at the bottom of a metal container, which is filled with a solution of an organic polymer with a concentration of 0.1-1 mg / ml in an organic solvent, after which an inert gas is injected into the container and the overpressure is maintained at the level of 1-9 bar for 10-100 minutes at a fixed temperature from the range from + 10 ° С to + 50 ° С.

In the particular case, toluene is used as an organic solvent.

Chloroform is also used as an organic solvent.

This technical result allows to reduce the consumption of organic polymer, since the sample is placed on the bottom of the tank, so a small amount of polymer is poured. In this experimentally selected concentration of a solution of an organic polymer in an organic solvent in the range of 0.1-1 mg / ml provides a high luminescent signal and high penetrating power. An inert gas pressure is injected into the metal container, which does not interact with the organic polymer. A minimum pressure of 1 bar ensures uniform polymer injection, which in turn significantly affects the quality of the sensor element. The maximum pressure limit of 9 bar is selected experimentally and determines a threshold above which the rate of introduction of the polymer does not change, but the design of the installation is significantly complicated. At the same time, the application of pressure below 10 minutes leads to a decrease in the luminescent signal of the sensor element, thereby reducing its effectiveness. If the application time of pressure exceeds 100 minutes, a polymer film is formed on the surface of the sample, thereby deteriorating the characteristics of the sensor element. The temperature conditions are experimentally selected in such a way as to ensure the stability of the luminescent signal and a certain viscosity. It is worth noting that the speed and accuracy of the detection of explosive vapor depends on the magnitude of the luminescent signal, and the viscosity affects the uniformity of the introduction of the polymer, the advantages of which are discussed above. Thus, the minimum value is a temperature of + 10 ° C. Temperature values above + 50 ° C lead to a decrease in the power of the luminescent signal of the polymer introduced into the microresonator.

Examples of specific implementations of the proposed method

In FIG. 1 shows a setup diagram for introducing a polymer into a microcavity.

Tube for supplying nitrogen pressure - 1; metal capacity - 2; organic polymer solution - 3; porous silicon microcavity - 4;

In FIG. 2 shows the distribution of the luminescence amplitude of the introduced polymer as a function of the distance from the center of the microresonator.

Application example

This method is implemented using the installation shown in FIG. 1. The metal container is filled with a solution of an organic polymer from the class of polyphenylvinylene with a concentration of 0.1 mg / ml in toluene. This concentration allows for high penetration and luminescent signal of the polymer. The volume of the solution is 1.5 ml. Then, a sample of a microresonator based on porous silicon is immersed in a container with a polymer at the bottom. At the next stage, the container with the polymer solution and microresonator is heated to a temperature of 30 ° C. This temperature provides the necessary viscosity of the organic polymer and is maintained throughout the entire polymer injection process. Then, through the tube - 1, especially pure nitrogen is pumped into the tank. Nitrogen does not chemically interact with the organic polymer and with the porous silicon microresonator. The pressure value is maintained at the level of 1.5 bar, thus creating the conditions for uniform polymer incorporation. The time during which the overpressure is maintained is 100 minutes. During this time period, the necessary amount of polymer penetrates into the microcavity to provide a high luminescent signal of the sensor element. Also, at a given time of administration, a film does not form on the surface of the microresonator, which prevents the uniform penetration of the polymer, which in turn reduces the quality of the sensor element. The uniformity of polymer injection is shown in FIG. 2, which shows the distribution of the luminescence amplitude of the introduced polymer as a function of the distance from the center of the microresonator. The deviation of the intensity from the maximum is not more than 30%. At the edge of the sample, the polymer luminescence intensity may be lower due to edge effects associated with the manufacturing quality of microresonators. At the final stage, the nitrogen supply pipe is disconnected. A sample of a microresonator is extracted from a container with a polymer solution using tweezers. Then the microcavity is placed on a clean surface and dried under normal conditions from the remnants of the polymer solution.

Thus, this method allows to reduce the consumption of organic polymer, which allows to reduce resource consumption. Also, due to experimentally selected parameters: polymer concentration, overpressure, overpressure time, and temperature conditions, the polymer can be uniformly introduced over the surface of a porous silicon microresonator, which leads to an increase in reliability and a decrease in the spread of the main characteristics of the sensor element.

Claims (3)

1. A method of creating a sensor element based on a porous silicon microcavity for detecting vapors of explosives, comprising introducing polymers of the polyphenylene-vinylene class into a porous silicon microcavity, characterized in that the porous silicon microcavity is placed at the bottom of a metal container, which is filled with an organic polymer solution with concentration of 0.1-1 mg / ml in an organic solvent, after which an inert gas is pumped into the tank and an overpressure of 1-9 bar per ton is maintained chenie 10-100 minutes at a fixed temperature within the range from + 10 ° C to 50 ° C. 2. The method according to p. 1, characterized in that toluene is used as an organic solvent. 3. The method according to p. 1, characterized in that chloroform is used as an organic solvent.

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