RU2327984C1 - Multi-channel piezo sensor "electronic nose" - Google Patents

Abstract

FIELD: physics; mechanics.

SUBSTANCE: multi-channel piezo sensor "electronic nose" consists of detection cell in the form of a cylinder with branch pipes for liquid and gas mixtures input, and a cap with circle-wise set of clamps for piezo sensors with different sorbent film coatings, oscillators and detectors of piezo sensor signals. At that, 3-4 or more hermetic detection cells with the same geometric parameters are put together in a common case, the upper end of which carries cell caps with piezo sensors, while the down end carries independent piezo sensor oscillators set in such pattern that each detection cell contains identical piezo sensors with different oscillation frequencies: one cell for piezo sensors with low-frequency oscillation, another for medium frequencies, third for high frequencies, fourth for ultrahigh frequencies. Integrated microprocessors register and process simultaneously signals of all piezo sensors in all cells, and pass the results into memory of a computer or other device, while piezo sensor adjustment is controlled with the help of light indicators placed at the upper panel of the case in circle close to the caps of each cell.

EFFECT: enables analysis of gas samples with various composition and decreases measurement time.

1 tbl, 1 dwg

Description

The invention relates to techniques for the analysis of multicomponent gas media, liquid and solid bodies containing volatile organic and inorganic compounds, and can be used to increase the selectivity, sensitivity and expressness of the analysis of multicomponent mixtures while maintaining ease of detection.

The closest in technical essence and the achieved effect is a gas analyzer based on a piezosorption matrix detection cell, consisting of a housing, which is made in the form of a cylinder with a lid, on which there are holders for sensors with various film coatings of sorbents, the pipe for introducing the liquid mixture is perpendicular in relation to the nozzle for introducing a gaseous mixture, while the nozzles are equipped with polyurethane gaskets, and the cap is connected to the cylindrical body via With a thread, the cell is connected to devices for exciting oscillations and fixing sensor signals [T. Kuchmenko Pat. No. 2267775 Russia, IPC G01N 27/12 - No. 2004106385; Claim March 4, 2004; publ. 01/10/2006. Bull. No. 01 // Inventions, 2006. No. 1].

The disadvantages of the existing gas analyzer are the impossibility of establishing differences in the composition of multicomponent gas mixtures if any substances are contained in them at the microconcentration level, insufficient sensitivity of detection of samples with a low concentration of volatile components, low reproducibility of the analysis results when varying the base frequency of the sensor oscillations in the range F ° = (5 ÷ 50) MHz in the set of one matrix, restrictions on the selection of the optimal number and order of sensors in the matrix, s significant “noises” from the electronic circuit of the gas analyzer.

The technical task of the invention is a significant (by 1-2 orders of magnitude) increase in the sensitivity of micro-weighing of gases and vapors, the selectivity of determining volatile compounds in gas mixtures due to the (2-n) -fold increase in the number of measuring elements without changing the geometric parameters of the gas analyzer body; the possibility of establishing minor differences in the composition of complex multicomponent mixtures; 3 times or more reduction in the time of measurement, processing of the analytic signal of the gas analyzer, decision making while maintaining the conditions for analysis in both flow (dynamic) and static (stationary) modes, increasing the metrological reliability of measurements, reducing the level of "noise" from the electronic circuit .

The technical task of the invention is achieved by the fact that in a multi-channel "electronic nose" on piezosensors, consisting of a detection cell made in the form of a cylinder with nozzles for introducing liquid and gaseous mixtures, with a lid, in which there are holders for piezosensors with various film coatings of sorbents and devices for exciting oscillations and fixing the signals of piezosensors, it is new that 3-4 or more hermetically sealed detection cells having the same geometric parameters They are united by a common case, in the upper part of which cell covers with piezosensors are mounted, and in the lower part - piezosensor oscillation generators independent of each other, and the oscillation generators are selected so that each detection cell contains a set of identical piezosensors with different oscillation frequencies: one cell with low oscillation frequencies of piezosensors, the other with medium oscillations, the third with high oscillation frequencies, the fourth with ultra-high oscillation frequencies of piezoelectric sensors, built-in microprocessors CSIRO and treated all signals pezosensorov simultaneously in all cells that are transferred into the computer memory, or other device, and the correct setting pezosensorov controlled through light indicators located on the top of the cabinet in a circle next to the lid of each cell.

The technical result consists in the fact that in the proposed multichannel "electronic nose" on piezosensors, analysis of gaseous samples of various compositions is possible, including slightly different from each other, containing detectable components at the level of microconcentrations, the selectivity of determination of volatile compounds in gas mixtures significantly increases due to two-n-fold increase in the number of sensors while maintaining the volume of the detection cell body, but increasing the number of cells to 3-4 or more, the measurement time is reduced I, processing the signals of all piezosensors and the resulting analytical information more than 3 times due to the fact that it is possible almost simultaneously (with an interval of 2-5 s) to analyze the same or different samples under identical conditions, similar to measuring with several identical instruments At the same time, it remains possible to carry out the analysis both in flow and in static measurement modes, the “noise” from the electronic circuit is significantly reduced due to the use of oscillation excitation circuits independently working from each other pezosensorov.

Figure - General diagram of a gas analyzer.

The multi-channel “electronic nose” on piezosensors consists of a housing 1, on the top panel 2 of which are mounted covers 3, on which holders 4 for piezosensors 5 with various sorbent films are arranged in a circle. Oscillators 6 of all piezosensors operate independently of each other. On the top panel 2 of the housing 1 in a circle next to the covers 3 of each cell are indicators 7, the number of which is equal to the number of holders for piezosensors. When you turn on the device to the network using the cord 8 and button 9 on the top panel of the "electronic nose", the generators of all quartz (piezosensors) begin to work. When the piezosensor is installed in the holder on the cell lid, the corresponding indicator light 7 lights up. The indicators allow the operator to quickly control the correct installation of the piezosensor in the holder, and the numbering of the LEDs indicates the order in which they are placed in the cell. The generators are selected so that a set of identical piezosensors with different oscillation frequencies is placed in each detection cell, for example, 5–10 MHz (low-frequency cell I), 8–25 MHz (mid-frequency cell II), 25–50 MHz (high-frequency cell III), 50 ÷ 100 MHz (microwave cell IV). There can be several cells of each type. Using threads on the covers and cylindrical bodies 10, each cell of a multi-channel "electronic nose" is sealed. The input of the analyzed gaseous sample, the regeneration of each cell after analysis is carried out through the nozzles 11. The microprocessors simultaneously record the signals of all piezosensors in all cells (from the 1st to the i-th for each cell) in pairs of the analyzed sample or without load. The signals are converted and transmitted to a computer or other device via cable 12, are calculated according to a certain algorithm and are formed into a kinetic “visual imprint” of the smell, which is the total response of the matrix of piezosensors and carries analytical information.

The multi-channel “electronic nose” on piezosensors works as follows.

For the analysis of gas samples or equilibrium gas phases over solid or liquid samples, the device is connected to the network using a cord 8. Oscillation generators 6 are connected to each cover 3 on the top panel 2 of the housing 1 to control the generation of each of, for example, 8-12 piezosensors 5 ( 8-12 on each cover) and fixing their responses. The generators are selected so that a set of identical piezosensors with different oscillation frequencies is placed in each detection cell, for example, 5–10 MHz (low-frequency cell I), 8–25 MHz (mid-frequency cell II), 25–50 MHz (high-frequency cell III), 50 ÷ 100 MHz (microwave cell IV). Depending on the task, you can simultaneously use two or more cells with the same set of piezosensors for analyzing two samples at once. After installing the piezosensors in the holders 4 on the covers of the selected cells, turn on the button 9. If the piezosensors are installed correctly in all the slots of the holders, all the indicator lights 7. The cylindrical bodies 10 are screwed onto the covers to create tightness. The analyzed gas or liquid sample is injected with a syringe through the upper pipe 11. The responses of all connected piezosensors are recorded, converted by built-in microprocessors and transmitted via cable 12 to the IBM COM port. Using a special program, they process the received responses, convert them into charts or figures, compare them with the data bank and make decisions based on the results of the analysis.

To regenerate the piezosensors and the housing, after the signals are recorded, the cell is purged with clean carrier gas or with dried air.

A comparison of some characteristics of the proposed technical solution and the closest analogue is presented in the table.

The proposed multi-channel "electronic nose" on piezosensors allows you to:

1) to analyze gaseous samples of various compositions, including slightly different from each other, containing detectable components at the level of microconcentrations;

2) significantly increase the selectivity of determination of volatile compounds in gas mixtures due to a two-n-fold increase in the number of sensors while maintaining the volume of the body of the detection cell, but increasing the number of cells to 3-4 or more;

3) to reduce the time of measuring, processing the signals of all piezosensors and the final analytical information by more than 3 times due to the fact that it is possible almost simultaneously (with an interval of 2-5 s) to analyze the same or different samples under identical conditions, similar to measuring on several identical instruments, while metrological reliability of measurements is significantly increased;

4) control the measurement sensitivity and change it by 1-2 orders of magnitude, using piezosensors with low (5-10 MHz) or ultrahigh (50-100 MHz) base frequencies;

5) maintain the ability to conduct analysis in both flow and static measurement modes;

6) significantly reduce the "noise" from the electronic circuit.

Table Comparison of the characteristics of the proposed technical solution and prototype Comparison options Prototype Technical solution Analysis of gas samples in flow and static modes Available Available Sample analysis of complex composition Available Available The establishment of small differences in the composition of complex mixtures Impossible maybe Determination of microconcentrations of the main components or impurities Difficult Possible on high-frequency and ultra-high-frequency cells Measurement Sensitivity Change Limited Widely possible Simultaneous analysis of 2 or more identical or different samples Impossible. The analysis is only sequential with preliminary cell regeneration. Available. Significantly increases the metrological reliability of measurements.

Claims (1)

A multi-channel “electronic nose” on piezosensors, consisting of a detection cell made in the form of a cylinder with nozzles for injecting liquid and gaseous mixtures, with a lid, in which there are holders for piezosensors with various film coatings of sorbents and devices for exciting oscillations and fixing signals piezosensors, characterized in that 3-4 or more hermetically sealed detection cells having the same geometric parameters are united by a common housing, in the upper part of which there is the covers of cells with piezosensors are located, and the oscillation generators of piezosensors are independent of each other, and the oscillation generators are selected so that each detection cell contains a set of identical piezosensors with different vibration frequencies: one cell with low oscillation frequencies of piezosensors, and the other with medium oscillation frequencies, the third - with high oscillation frequencies, the fourth - ultra-high oscillation frequencies of piezosensors, built-in microprocessors capture and process the signals of all ezosensorov simultaneously in all cells, which are transmitted to a computer or other memory devices, and install the correct pezosensorov controlled through light indicators located on the top of the cabinet in a circle next to the lid of each cell.