RU170770U1 - SENSITIVE ELEMENT OF FIBER-OPTICAL THERMOMETER FOR MEASURING THE TEMPERATURE OF THE INTERNAL ENVIRONMENT OF A HUMAN ORGANISM - Google Patents

Abstract

The utility model relates to measuring technique and can be used in fiber optic thermometers to measure the temperature of the internal environment of the human body. A sensitive element of a fiber-optic thermometer for measuring the temperature of the internal environment of the human body, filled with a thermometric substance in the form of a transparent cycloaliphatic epoxy resin brand "ERL 4221", is claimed. According to the present utility model, the thermometric substance is located in the cavity of the end of the optical fiber freed from the core. A reflective plate is attached to the end wall of the cavity of the core free of the end of the optical fiber by applying a thin layer of non-toxic transparent adhesive to the end wall of the end of the optical fiber. Non-toxic transparent glue is used to protect the reflective plate from mechanical deformation, from the aggressive chemical internal environment of the human body. The reflection plate is used to reflect optical radiation entering the cavity of the end of the optical fiber freed from the core, in order to direct the optical radiation back to the optical fiber core and further to the photodetector. The outer surface of the sensor element of the fiber-optic thermometer has a non-toxic black light-absorbing coating to increase the ability of the sensor to absorb the thermal radiation of biological parts of the internal environment of the human body in order to reduce the thermal constant of the heating time of the sensor element of the fiber optic thermometer and, accordingly, increase the speed of the fiber optic thermometer based on the proposed sensitive element. The technical result is an increase in the speed of a fiber-optic thermometer based on the proposed sensitive element, the safety of measuring the temperature of the internal environment of the human body using a fiber-optic thermometer. 1 s.p. f-ly, 1 ill.

Description

The utility model relates to measuring equipment, mainly to medical equipment, and can be used in fiber optic thermometers to measure the temperature of the internal environment of the human body.

An analogue is a sensitive element of a medical fiber-optic thermometer [Krasyuk B.A. Light guide sensors. M., Engineering, 1990, § 4.3, pp. 126-128], used for continuous monitoring of the temperature of living tissue subjected to heating by high-frequency currents. The sensitive element of the fiber-optic thermometer is a short glass capillary, not more than 2 cm long, closed at one end, filled inside with a thermometric substance, into which the end of the optical fiber freed from the sheath is inserted. With a change in the temperature of the medium surrounding the capillary, the temperature of the oil in the capillary changes and the refractive index of this liquid increases or decreases, which naturally leads to a change in the intensity of the light that exits through the end of the fiber core and partially returns to this core after reflection from the “bottom” of the capillary.

The main disadvantage of the analogue is that the capillary of the sensitive element is made of glass, therefore, when measuring the temperature of the internal environment of the human body using a fiber-optic thermometer based on the sensitive element in the form of a glass capillary, care must be taken.

The prototype is a sensitive element of a fiber optic thermometer for measuring the temperature of the internal environment of the human body [RF patent No. 161461, IPC G01K 11/32, publ. 04/20/2016, bull. No. 11]. The sensing element of the fiber-optic thermometer is made in the form of a sealed container filled with a thermometric substance, in the cavity of which is placed the end of the optical fiber freed from the sheath, while the sealed container is made in the form of a polymer capillary made of non-toxic polyvinyl chloride, while as a thermometric substance a transparent cycloaliphatic epoxy resin was used, the refractive index of which linearly depends on the temperature of the internal environment of the human body a, and the end of the optical fiber freed from the sheath is configured to, with an increase or decrease in the temperature of the internal environment of the human body, change the reflectivity and transmittance of the interface “the end of the optical fiber freed from the sheath is a thermometric substance”. As non-toxic polyvinyl chloride, plasticized medical polyvinyl chloride of the PM-1/42 honey brand was used, and a transparent cycloaliphatic epoxy resin of the ERL 4221 brand was used as a thermometric substance.

The main disadvantages of the prototype are: unknown geometric dimensions (length and outer diameter) of the polymer capillary of the sealed container of the sensing element of the fiber optic thermometer, which is associated with measuring temperature in hard-to-reach places, which include biological sections of the internal environment of the human body, polymer capillary of the sealed container the sensing element of the fiber optic thermometer does not have a light-absorbing coating, which, in turn, increases the thermal time constant nor heating of the sensitive element and, accordingly, reduces the speed of the fiber optic thermometer.

The objective of the utility model is to develop the design of the sensitive element of the fiber-optic thermometer, which eliminated the main disadvantages of the analogue and prototype.

The technical result is to increase the speed of a fiber optic thermometer based on the proposed sensitive element, the safety of measuring the temperature of the internal environment of the human body using a fiber optic thermometer.

The technical result is achieved by the fact that in the sensitive element of the fiber-optic thermometer for measuring the temperature of the internal environment of the human body, filled with a thermometric substance in the form of a transparent cycloaliphatic epoxy resin brand "ERL 4221", according to this utility model, the thermometric substance is located in the cavity of the end freed from the core optical fiber, which allows to reduce the diameter of the sensing element to the size of the diameter of the protective coating of the optical fiber, and about the end free of the core of the optical fiber is made with the possibility, with increasing or decreasing temperature of the internal environment of the human body, changing the reflectivity and transmittance of the interface “optical fiber core - thermometric substance”, changing the reflectivity of the interface “thermometric substance - optical fiber sheath”, a reflective plate is attached to the end wall of the cavity of the end of the optical fiber freed from the core by applying a thin layer of non-toxic transparent glue on the end wall of the end of the optical fiber, non-toxic transparent glue is used to protect the reflective plate from mechanical deformations, the aggressive chemical internal environment of the human body, the reflective plate is used to reflect optical radiation entering the cavity of the end of the optical fiber freed from the core, in order to direct optical radiation back to the core of the optical fiber and further to the photodetector, the outer surface of the of the fiber optic thermometer element has a non-toxic black light-absorbing coating to increase the ability of the sensitive element to absorb the thermal radiation of biological parts of the internal environment of the human body in order to reduce the thermal time constant of heating the sensitive element of the fiber optic thermometer and, accordingly, increase the speed of the fiber optic thermometer by the basis of the proposed sensitive element.

A thin metal film, for example, based on silver, aluminum or gold, is used as a reflective plate. As a non-toxic transparent adhesive, a non-toxic transparent epoxy adhesive compound of the PEO-10K-20/0 brand was used. As an optical fiber, a multimode stepped quartz fiber with a core diameter of 0.3 mm, a sheath diameter of 0.6 mm, a diameter of the protective coating of 0.8 mm, a core refractive index of 1.47, and a sheath refractive index was used. equal to 1.45.

The essence of the utility model is illustrated by the drawing (Fig. 1), which shows the design of the proposed sensitive element.

In FIG. 1 numbers indicate:

1 - thermometric substance,

2 - cavity freed from the core end of the optical fiber,

3 - the core of the optical fiber,

4 - optical fiber

5 - reflective plate,

6 - a thin layer of non-toxic transparent glue,

7 - non-toxic black light-absorbing coating,

8 is an optical fiber sheath,

9 - a protective coating of the optical fiber,

A, B, C, D are geometric points indicating the boundaries of the cavity of the end of the optical fiber freed from the core, the boundaries of the sections “optical fiber core - thermometric substance” and “thermometric substance - optical fiber sheath”,

P ₁ - the power of the optical radiation entering the cavity freed from the core end of the optical fiber,

P ₂ - the power of optical radiation emerging from the cavity freed from the core end of the optical fiber,

T _vs - the temperature of the internal environment of the human body,

T _tv is the temperature of the thermometric substance,

n _tv is the refractive index of a thermometric substance,

n _with the refractive index of the core of the optical fiber,

n _about - the refractive index of the shell of the optical fiber,

d _c - the diameter of the core of the optical fiber,

d _about - the diameter of the sheath of the optical fiber,

d _s - the diameter of the protective coating of the optical fiber.

The difference of the present sensor optical fiber thermometer is that the thermometric substance 1 is arranged in the cavity 2 released from the core 3 end of the optical fiber 4, thereby reducing the diameter of the sensing element to a diameter size d _s protective cover 9 of optical fiber 4 and freed from the core 3, the end of the optical fiber 4 is configured to, when the temperature T increases or decreases in the _entire internal environment of the human body, reflective and transmittance changes the boundary of the interface “core 3 of the optical fiber 4 is a thermometric substance 1” (in Fig. 1 the boundary of the section “core 3 of the optical fiber 4 is a thermometric substance 1” corresponds to the side AC, denoted by geometric points A, C), changes in the reflectivity of the interface "Thermometric substance 1 - shell 8 of the optical fiber 4" (in Fig. 1, the boundary "thermometric substance 1 - shell 8 of the optical fiber 4" corresponds to the sides AB and CD, indicated by geometric points A, B, C, D), a reflective plate 5 is attached to the end wall of the cavity 2 of the end of the optical fiber 4 freed from the core 3 by applying a thin layer of non-toxic transparent glue 6 to the end wall of the end of the optical fiber 4, non-toxic transparent glue 6 is used to protect the reflective plate 5 from mechanical deformations, an aggressive chemical the internal environment of the human body, a reflective plate 5 is used to reflect optical radiation entering the cavity 2 of the optic end freed from the core 3 fiber 4, in order to direct optical radiation back to the core 3 of the optical fiber 4 and then to the photodetector, the outer surface of the sensor element of the fiber optic thermometer has a non-toxic black light-absorbing coating 7 to increase the ability of the sensor to absorb thermal radiation of biological parts of the internal environment of the human body in order to reduce the thermal constant of the heating time of the sensitive element of the fiber-optic thermometer and, accordingly o, increase the speed of a fiber optic thermometer on the basis of the proposed sensor.

As a reflective plate 5, a thin metal film is used, for example, based on silver, aluminum or gold. As a non-toxic transparent adhesive 6, a non-toxic transparent epoxy adhesive compound of the PEO-10K-20/0 brand was used. As the optical fiber 4, a multimode stepped quartz fiber with a diameter d _{c of the} core 3 equal to 0.3 mm, a diameter d _{about the} cladding 8 equal to 0.6 mm, a diameter d _{about the} protective coating 9 equal to 0.8 mm, and a refractive index was used n _{from the} core 3, equal to 1.47, the refractive index n _{about the} shell 8, equal to 1.45.

As thermometric substance 1 used transparent cycloaliphatic epoxy resin brand "ERL 4221" [RF patent No. 161461, IPC G01K 11/32, publ. 04/20/2016, bull. No. 11]. The chemical name of the transparent cycloaliphatic epoxy resin brand "ERL 4221" is as follows:

"ERL 4221" = 3,4-epoxycyclohexylmethyl-3 ', 4'-epoxycyclohexanecaloxyrate.

The refractive index n _{t of a} transparent cycloaliphatic epoxy resin brand “ERL 4221” is associated with the temperature T in the _entire internal environment of the human body with the following dependence:

n _tv = 1.5062-3.6576⋅10 ^-4 T _total .

In medicine, for diagnosing the temperature of human organs and tissues, the temperature region in the range + 32 ... + 44 ° С is of the greatest importance. When the temperature changes by 1 ° C, the refractive index n _{t of a} transparent cycloaliphatic epoxy resin of the ERL 4221 grade changes by approximately 0,00037. The sensitivity of the fiber optic thermometer based on the proposed sensing element is 0,00037 ° C ^-1 .

The principle of operation of the proposed sensitive element (see Fig. 1) as part of a fiber optic thermometer is as follows.

In optical fiber 4, optical radiation propagates at a critical angle of total internal reflection θ _cr determined by the arcsine of the ratio of the refractive index n _{about the} sheath 8 of the optical fiber 4 to the refractive index n _{from the} core 3 of the optical fiber 4: θ _cr = arcsin (n _r / n _s ) .

As the temperature of the thermometric substance 1 located in the cavity 2 of the end of the optical fiber 4 freed from the core 3 increases or decreases, the reflectance and transmission capacity of the interface “core 3 of optical fiber 4 - thermometric substance 1” changes (in Fig. 1 the interface is “core” 3 optical fiber 4 - thermometric substance 1 "corresponds to the side of the speaker, indicated by geometric points A, C), changes in reflectivity of the interface" thermometric substance property 1 is a shell 8 of an optical fiber 4 "(in Fig. 1, the boundary of the section" thermometric substance 1 - shell 8 of an optical fiber 4 "corresponds to the sides AB and CD indicated by geometric points A, B, C, D). Accordingly, the power of the optical radiation P ₁ entering the cavity 2 of the end of the optical fiber 4 freed from the core 3, and the power of the radiation P ₂ exiting from it, will differ significantly in value. This is due to the fact that the power of the optical radiation P ₂ emerging from the cavity 2 of the end of the optical fiber 4 freed from the core 3 depends on the reflectivity and transmission capacity of the interface “core 3 of the optical fiber 4 is a thermometric substance 1”, changes in the reflectivity of the interface "Thermometric substance 1 - the shell 8 of the optical fiber 4", which, in turn, change with increasing or decreasing temperature T _TV thermometric substance 1.

Thus, the use of the end of the core 3 of the optical fiber 4, a thin metal film, for example, based on silver, aluminum or gold, as a reflective plate 5 for directing optical radiation back to the core 3 of the optical fiber 4 and further to the photodetector, non-toxic transparent epoxy PEO-10K-20/0 adhesive compound for protecting the reflective plate 5 from mechanical deformations, the aggressive chemical internal environment of the human body, non-toxic black light-absorbing its coatings to increase the ability of the sensitive element to absorb thermal radiation of biological parts of the internal environment of the human body, multimode stepped quartz fiber with a diameter d _{c of the} core 3 equal to 0.3 mm, a diameter d _about shell 8 equal to 0.6 mm, a diameter d _about a protective coating 9 equal to 0.8 mm, a refractive index n _{from the} core 3 equal to 1.47, a refractive index n _{about the} sheath 8 equal to 1.45, as an optical fiber 4 will allow, in comparison with the analogue and prototype, to improve performance in window-based optical thermometer proposed sensor, safety of human body's internal environment temperature measurement via fiber optic thermometer.

Claims (2)

1. A sensitive element of a fiber-optic thermometer for measuring the temperature of the internal environment of the human body, filled with a thermometric substance in the form of a transparent cycloaliphatic epoxy resin brand "ERL 4221", characterized in that the thermometric substance is located in the cavity of the end of the optical fiber freed from the core in order to reduce the diameter sensitive element to the size of the diameter of the protective coating of the optical fiber, while free from the core end of the optical fiber with the possibility, with increasing or decreasing temperature of the internal environment of the human body, changing the reflectivity and transmittance of the “optical fiber core - thermometric substance” interface, changing the reflectivity of the “thermometric substance - optical fiber sheath” interface, to the end wall of the cavity freed from optical fiber end cores attach a reflective plate by applying a thin layer of non-toxic transparent adhesive to the end the end of the optical fiber, non-toxic transparent glue is used to protect the reflective plate from mechanical deformations, the aggressive chemical internal environment of the human body, the reflective plate is used to reflect optical radiation entering the cavity of the end of the optical fiber freed from the core, in order to direct the optical radiation back to the core of the optical fiber and further to the photodetector, the outer surface of the sensor element of the fiber optic thermometer a non-toxic light-absorbing black coating for increasing the ability of the sensor to the absorption of heat of radiation of biological sites internal environment of the human body. 2. The sensitive element according to claim 1, characterized in that a thin metal film is used as a reflective plate, for example, based on silver, aluminum or gold, a non-toxic transparent epoxy adhesive compound of the PEO-10K-20 brand is used as a non-toxic transparent adhesive / 0, a multimode stepped quartz fiber with a core diameter of 0.3 mm, a sheath diameter of 0.6 mm, a diameter of the protective coating of 0.8 mm, and a core refractive index of th 1.47, shell a refractive index of 1.45.

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