RU2806626C1 - Relative air humidity sensor based on polyaniline thin film - Google Patents

Abstract

FIELD: instrumentation.

SUBSTANCE: thin-film organic sensor of relative air humidity is made on a dielectric substrate with current interpenetrating contacts of a comb-type copper deposited on it, on which a conductive polymer film is deposited, while the polymer film is made on the basis of a polyaniline derivative - poly-2-[(2E)- 1-methyl-2-buten-1-yl]aniline.

EFFECT: fast measurement in a wide range of relative air humidity.

1 cl, 2 dwg

Description

The invention relates to the field of measuring technology, namely to a device based on organic moisture-sensitive elements and a humidity sensor containing such moisture-sensitive elements.

A known humidity sensor is on a dielectric substrate with interpenetrating comb electrodes, onto which a sensitive coating is applied from a mixture of two polymers - polysilanoaniline and polyaniline in a ratio of 9:1. [RF Patent N 2 088 914 C1, IPC G 01 N 27/30. Date of publication 08/27/1997].

The disadvantages of such a sensor include the need to maintain the redox state. Another disadvantage is the use of chrome contacts, which are difficult to manufacture.

A known invention is a polymer resistor-type humidity sensor made from an aqueous dispersion of nanopolyaniline. The sensor has a ceramic substrate, multiple photomasks to create interpenetrating comb gold electrodes, a moisture-sensitive thin film is applied to these gold electrodes, the moisture-sensitive thin film is a composite high molecular weight moisture-sensitive material of nanopolyaniline and polyvinyl alcohol (PVA) in water. [Patent CN101799441A. MCP G 01 N 27/12. Date of publication 08/11/2010].

The disadvantages of such a sensor include its expensive gold contacts and the complex synthesis of moisture-sensitive material in the form of polyaniline nanotubes.

The closest to the proposed one is a sensor for the analysis of gaseous substances, in which a sensitive coating is applied to interpenetrating comb electrodes in the form of a film consisting of a mixture of three conducting polymers: polystanumaniline, polysilanoaniline and polyaniline in a mass ratio of 7:4:2. [RF Patent N 2 209 424. MCP G 01 N 27/12. Date of publication: 07/27/2003].

The disadvantages of such a sensor include the need for additional adjustment of selective changes in the electrophysical parameters of the synthesized sensitive coating when exposed to infrared radiation of a certain wavelength, and the complexity of the technology for forming a complex sorbent.

The objective of the invention is to provide a wide range of measured relative air humidity, good linearity of current-voltage characteristics, high response speed and low hysteresis, reduce power consumption when measuring relative air humidity and simplify the manufacture of a humidity sensor.

The technical result of the invention is a quick measurement over a wide range of relative air humidity.

The problem is solved, and the technical result is achieved by a thin-film organic sensor of relative air humidity, made on a dielectric substrate with current interpenetrating comb-type copper contacts applied to it, on which a moisture-sensitive film of a conductive polymer is applied, which, unlike the previous one, is made on the basis of a polyaniline derivative, namely poly-2-[(2E)-1-methyl-2-buten-1-yl]aniline.

The essence of the invention is illustrated by drawings, where in Fig. Figure 1 shows a general view of the relative humidity sensor. In fig. Figure 2 shows the calibration graph of the sensor.

In fig. Figure 1 shows a sensor that consists of: a glass-ceramic substrate 1 on which interpenetrating comb electrodes 2 are made of copper with a gap of 50 μm and a film 3 of a moisture-sensitive substance - a polyaniline derivative poly-2-[(2E)-1-methyl-2- buten-1-yl]aniline.

In fig. Figure 2 shows the calibration current-voltage characteristic of the sensor. The relative humidity sensor for measuring humidity works as follows. A constant voltage is applied to the sensor and the current flowing through the polyaniline film is measured. Under the influence of humidity, the current changes, the values of which are calibrated as a percentage of relative air humidity.

All measurements of the sensor parameters were carried out at room temperature, using air as a carrier gas. The calibration characteristic is measured in the range of relative humidity 10-90%. The dependence of the current flowing through the sensor on relative humidity is almost linear. The average sensitivity of the sensor is 125 nA/%.

The sensor response time does not exceed 10 s. Determined experimentally by sharply reducing the humidity in the test chamber.

The production of a thin-film organic sensor includes the following steps:

1) cleaning the surface of the substrate in an ultrasonic bath, drying in an oven;

2) thermal spraying in vacuum of interpenetrating comb-type contacts made of copper;

3) creation of a thin film of a polyaniline derivative in the area of the gap between the contacts by centrifugation, polymerization of polyaniline in an oven.

The invention has a number of advantages, namely that:

1) a polyaniline derivative, namely poly-2-[(2E)-1-methyl-2-buten-1-yl]aniline, is characterized in that its use increases the selectivity of the humidity sensor in a mixture with other gases;

2) current-voltage characteristics are linear throughout the entire range of measurement of relative air humidity;

3) polyaniline derivative has a large specific surface area, which is beneficial for absorbing and desorption of moisture from the environment, thereby accelerating the moisture absorption and dehumidification response speed, and the response time is shorter;

4) The preparation process of moisture-sensitive material is simple, and the cost of the material is lower, suitable for mass production;

5) simplification of sensor manufacturing due to the use of only one pair of interpenetrating comb-type contacts;

6) the sensitive polyaniline film does not require heating, and after measurements it quickly heals itself and is ready for the next measurement. Due to the lack of energy consumption for heating and maintaining the redox reaction, the energy efficiency of sensors based on poly-2-[(2E)-1-methyl-2-buten-1-yl]aniline increases.

So, the claimed invention makes it possible to provide a wide range of measured relative air humidity, has good linearity of the current-voltage characteristic, high response speed and low hysteresis, and is also characterized by low power consumption and simplified manufacturing technology of the humidity sensor.

Claims (1)

Thin-film organic sensor of relative air humidity, made on a dielectric substrate with current interpenetrating comb-type copper contacts applied to it, on which a film of conductive polymer is applied, characterized in that the film is made on the basis of a polyaniline derivative, namely poly-2-[(2E )-1-methyl-2-buten-1-yl]aniline.