RU204681U1 - Plasma sterilization device based on a high-frequency generator with adjustable electrodes - Google Patents

Abstract

The utility model relates to equipment for the sterilization of products and materials and can be used to generate high-frequency discharge plasma intended for low and medium power installations, namely, for sterilization of medical products, surface treatment of materials, application or deposition of thin-film coatings, processing and purification of harmful impurities from surface of the material, in medical and biological applications, etc. The essence of the utility model is to reduce the processing time of products and simplify the design of the device for effective sterilization by adjusting the parameters of the high-frequency discharge plasma generator and the possibility of changing the feed rate of the sterilization mixture.

Description

The utility model relates to equipment for the sterilization of products and materials and can be used to generate high-frequency discharge plasma intended for low and medium power installations, namely, for sterilization of medical products, surface treatment of materials, application or deposition of thin-film coatings, processing and purification of harmful impurities from material surfaces, in medical and biological applications, etc.

Known sterilization device using gas low-temperature plasma [1]. Plasma is created under reduced pressure using an RF discharge. Further, the plasma jet is transmitted to the chamber in which the sterilization object is located, where various microorganisms are inactivated: bacteria (including spore forms), viruses, fungi, etc.

The disadvantage of this device is that the sterilized object is essentially not affected by the plasma itself, but by the products of plasma-chemical reactions in the gas. In this device, a long exposure time is required to achieve the required degree of inactivation.

Known device for generating low-temperature plasma [2]. Low-temperature plasma is created in an environment containing nitrogen. In this case, a plasma jet acts on the sterilized object. Superoxide anionic radicals (O2 +). Plasma created during combustion react with protons (H-) in the liquid to form hydroperoxide radicals (HOO). Further, nitrogen and oxygen in the air combine and form, in combination with hydroperoxide radicals (HOO). pepoxynitrite (ONOO-) with high microbiocidal activity. Sterilization of objects is possible not only at reduced, but also at atmospheric pressure. This simplifies the design of the sterilization device, since there is no need to carry out an additional operation to evacuate air from the chamber and create a reduced pressure in it. However, with a corona discharge formed in a sharply inhomogeneous electric field, the homogeneity of the generation of charged and chemically active particles in the sterilization volume is not ensured, and these processes practically do not occur near the grounded electrodes on which the sterilized instrument is located.

The closest in technical essence to the claimed device is a sterilizer for sterilization with hydrogen peroxide vapor [3], which is selected as a prototype. The disadvantage of this method is the need to use microdosing systems for supplying the sterilization mixture and the ability to change the characteristics of the high-frequency generator (volt-ampere, energy, temperature) only by software without physical adjustments, which complicates the circuit design of the high-frequency generator.

In this device, the sealed chamber is pre-filled with a highly oxidizing peroxide mixture. The device has two electrodes. A medical instrument is installed on a grounded electrode. High voltage pulses are applied to the active electrode, under the action of which a glow discharge arises in the chamber, which forms electromagnetic fields, under the influence of which the instruments are sterilized.

The problem to be solved by the claimed device is to accelerate the processing time of products and simplify the design of the device for effective sterilization by adjusting the parameters of the high-frequency generator and the ability to change the feed rate of the sterilization mixture.

Distinctive features of the Plasma sterilization device based on a high-frequency generator with the use of adjustable electrodes in comparison with the prototype are achieved through the implementation of the following unique features:

changing the parameters of the high-frequency generator, including the carrier frequency, power, output waveform, and other parameters while maintaining the sterilization rate of the product (at a given level of guaranteed sterility) by adjusting the distance between the electrodes (i.e., by adjusting the gap between the electrodes , the ability to sterilize when changing operating modes of the high-frequency generator is preserved);

the product of the supply of the sterilization mixture without the use of microdosing pumps. This simplifies sterilization and reduces the cost of the sterilizing product. Regulation of the supply of the sterilizing mixture is carried out by controlling the degree of opening of the electromagnetic valves and regulating the temperature of the heater of the sterilization mixture.

The system for supplying the sterilization mixture is arranged as follows. The sterilization mixture is hermetically packed in a reservoir connected to two valves, previously opened and adjusted so that the consumption of the sterilization mixture during the sterilization process does not exceed the threshold values. The mixture is served in portions. Two solenoid valves, working in pairs, are installed one after the other between the intermediate tube with the connected heater of the sterilization mixture. At the beginning of the process, one of the solenoid valves opens. The sterilization mixture is fed into the intermediate tube and this solenoid valve closes allowing the mixture to warm up. Upon completion of heating, the second solenoid valve opens: the vapor of the heated mixture rushes to the low pressure area in the device chamber (the vacuum from the chamber has been previously evacuated), after which the second solenoid valve closes. The process of feeding a single portion of the mixture is complete and can be repeated if necessary. The regulation of the sterilization mixture is carried out without the use of microdosing pumps and, mainly, due to the regulation of the degree of opening of the electromagnetic valves for supplying the sterilization mixture and regulation of the temperature of the heater of the sterilization mixture. This simplifies the design of the sterilization device and reduces the cost of producing a single sterilization cycle.

FIG. 1 shows a device for plasma sterilization based on a high-frequency generator using adjustable electrodes, where: 1-insulated electrode; 2 - a table for samples; 3 - vacuum input of rotation; 4 - active electrode; 5 - observation window (gateway); 6 - cable entry: 7 - vacuum line; 8 - disc valve; 9 - matching device; 10 - high-frequency generator; 11 - vacuum chamber; 12 - vacuum pump; 13 - pressure sensor: 14 - tank with sterilization mixture; 15 - thermocouple; 16 - thermocouple controller; 17 - heater for sterilization mixture; 18, 20 - electromagnetic valves; 19 - tube for supplying the sterilization mixture.

An example of a specific implementation. To generate high-frequency discharge plasma used a device (Fig. 1) containing an insulated electrode 1 and an active electrode 4. made of stainless steel. The electrodes are oriented vertically. To the active electrode 4, through a WL400ZHN radio-frequency wire, an electrical signal from the high-frequency generator 10 is supplied through the matching 9. Sealed cable gland 6, made of brass, is connected to the active electrode 4. The active electrode 4 is installed parallel to the sample table 2 and is isolated from it bushing made of fluoroplastic grade FR4. The high frequency generator 10 operates within a frequency range of 1 to 30 MHz. The distance between the stage for samples 2 and the active electrode 4, regulated by the vacuum input 3. for a high-frequency generator with a frequency of 13.56 MHz with an amplitude of high-voltage voltages from 1 kW to 4 kW is set in the range of 0.3-1.0 cm (depending on the required output signal power). The limiting pressure for pumping out the vacuum in the vacuum chamber 11, supplied through the vacuum line 7 by means of the vacuum pump 12, corresponds to values of 0.1-0.7 mbar. Disk valve 8 is required to seal the vacuum line 7 from the side of the vacuum pump 12. The vacuum chamber 1 1 is made of stainless steel. Gateway 5 has quartz glass with a polarizing layer that filters out most of the VUV and UV radiation emitted during plasma combustion. The temperature of the heater of the sterilization mixture 17 is controlled by the thermocouple 15. The operation of the thermocouple 15 is controlled by the thermocouple controller 16 and is set at 24 ° C. Heating of the sterilization mixture supplied from the reservoir with the sterilization mixture 14 occurs in the sterilization mixture supply tube 19. The solenoid valves 18 and 20 operate according to the indicated modes. In this case, in a mode when both electromagnetic valves are closed, the mixture is heated for 2-5 seconds. The tube for supplying the sterilization mixture 19 is made of stainless steel and has an inner diameter of 1/4 inch. Pressure sensor 13 is a capacitive pressure gauge with a measuring range of 1-10 ^-4 mbar.

Thus, the proposed sterilization device allows you to effectively sterilize products, allowing you to change the current-voltage, energy, and temperature characteristics of the high-frequency signal to create plasma using a system of adjustable electrodes. The ability to change the feed rate of the sterilization mixture, coupled with the regulation of the parameters of the high-frequency generator, reduces the sterilization time. The simplified design of this device provides not only a longer MTBF of the product in comparison with the prototype, but also provides a better technical and economic efficiency of the device.

INFORMATION SOURCES:

1. RF patent No. 2074007, IPC A61L 2/14.

2. RF patent No. 167645. IPC Н05Н 1/24.

3. RF patent No. 2404813, IPC A61 L2 / 00.

Claims (1)

Plasma sterilization device based on a high-frequency generator using electrodes with the ability to regulate the discharge gap in the chamber, where the insulated electrode is made in the form of a counterpart of the table intended for installing samples, and is galvanically isolated from the active electrode by an insulator made of electrically non-conducting, chemically resistant material, and also has a vacuum line and a cable gland made of non-magnetic metal, while the cable gland is configured to supply a radio frequency signal to the end of the active electrode using a high-frequency generator, where the active and passive electrodes are made of corrosion-resistant materials and have the ability to change the position in spatial plane, the device is configured to supply the sterilization mixture in portions in the form of saturated steam from the reservoir to the vacuum chamber through the feed tube, the vacuum chamber is configured to create pressure using a vacuum pump and pressure control by a pressure sensor, the device is also configured to maintain the temperature of the sterilization mixture constant using a thermocouple controller, while the device is configured to control the feed rate of the sterilization mixture by the heater and the position of the electromagnetic valves.

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