Liquid agent simulating human dielectric constant containing peg laurate

Abstract

An object of the present invention is to provide a liquid formulation simulating a human dielectric constant, which maintains transparency over time, is less likely to form a colloid, and enables highly accurate simulation in a wide frequency range without a change in dielectric constant during use.SOLUTION: The present invention is a human dielectric constant simulated liquid agent comprising PEG laurate and water, wherein the PEG laurate is present in an amount of 25 to 50% by mass based on the total weight of the human dielectric constant simulated liquid agent.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a liquid agent that mimics the dielectric constant of the human body, which is used to prepare a phantom for use in studying the interaction between electromagnetic waves and the human body, and more particularly to a liquid agent that mimics the dielectric constant of the human body, which contains PEG laurate. [Background technology]

[0002] When a mobile phone or other wireless device is used in close proximity to the human body, the human body is exposed to electromagnetic waves and is affected by them. However, it is difficult to use the human body to test these effects due to reasons such as the difficulty of test reproducibility and maintaining the same posture for a long period of time. Therefore, tests have been conducted using phantoms, which are made of materials with a dielectric constant similar to that of the human body and which simulate the human head or chest.

[0003] Furthermore, SAR (Specific Absorption Rate) has been used as an index to evaluate the absorption of electromagnetic waves by the human body. SAR is the amount of power absorbed per unit mass when exposed to electromagnetic waves. The method for measuring SAR is defined by the International Electrotechnical Commission (IEC), and the radio wave protection guidelines for mobile wireless terminals specify the allowable SAR values. Based on the IEC62209 standard, deviations are required to be within ±10% for each frequency.

[0004] Furthermore, in recent years, in response to the expansion of frequency bands for mobile phones and the like, there has been a need for human body dielectric constant simulating liquid agents to quickly evaluate compliance with radio wave protection guidelines over a wide frequency band.

[0005] Conventional human body permittivity simulating liquids use an aqueous solution of the nonionic surfactant Tween (see Patent Document 1). However, because mixing with water tends to cause colloidal formation, benzalkonium chloride or ethanol is typically added to emulsify the solution to prevent colloidal formation. However, such emulsified solutions tend to lose their original composition during use due to water evaporation or dust contamination, resulting in the precipitation of colloids and the resulting cloudy, opaque solution. Thus, conventional human body permittivity simulating liquids have had the problem of colloidal formation, which causes the solution to become cloudy and opaque, making it difficult to visualize the probe. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-78232 Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, an object of the present invention is to provide a liquid agent that mimics the dielectric constant of the human body, which maintains transparency over time, is resistant to colloidal formation, and allows for highly accurate simulation over a wide range of frequency bands without changes in dielectric constant during use. [Means for solving the problem]

[0008] The present invention relates to a human body dielectric constant mimicking liquid agent containing PEG laurate and water, characterized in that the PEG laurate is present in an amount of 25 to 50% by mass based on the total weight of the human body dielectric constant mimicking liquid agent. In the human body dielectric constant mimicking liquid agent of the present invention, the PEG laurate is more preferably present in an amount of 30 to 45% by mass based on the total weight of the human body dielectric constant mimicking liquid agent. The PEG laurate used in the present invention is preferably PEG-10 laurate or PEG-12 laurate.

[0009] When the human body dielectric constant simulating liquid agent of the present invention is used at a frequency of 650 to 1800 (MHz), it is preferable that it further contains an inorganic salt, and it is preferable that PEG laurate is present in an amount of 38 to 44 mass % based on the total weight of the human body dielectric constant simulating liquid agent. Furthermore, when the human body dielectric constant simulating liquid agent of the present invention is used at a frequency of 1800 to 7000 (MHz), it is preferable that it further contains an inorganic salt, and it is preferable that PEG laurate is present in an amount of 34 to 40 mass % based on the total weight of the human body dielectric constant simulating liquid agent. Furthermore, when the human body dielectric constant simulating liquid agent of the present invention is used at a frequency of 3800 to 9000 (MHz), it is preferable that PEG laurate is present in an amount of 32 to 38 mass % based on the total weight of the human body dielectric constant simulating liquid agent. [Effects of the Invention]

[0010] The human body dielectric constant simulating liquid agent of the present invention is characterized by containing PEG laurate, which is also used in facial cleansers, etc., and is highly safe, has little change in dielectric constant and conductivity over a wide frequency range up to 9 GHz, and can simulate the dielectric constant of the human body with high accuracy. Furthermore, the human body permittivity simulating liquid of the present invention maintains its transparency even after prolonged use, facilitating visual inspection of the measurement location and reducing inaccuracies in measurement tests. Furthermore, the human body permittivity simulating liquid of the present invention is composed only of PEG laurate, salt as an optional inorganic salt, and water, and does not require the addition of preservatives such as ethanol or benzalkonium chloride. Therefore, if the water content of the human body permittivity simulating liquid decreases, it can be reused by adding water, enabling long-term use and being eco-friendly. Due to these advantages, the human body dielectric constant simulating liquid agent of the present invention is useful for forming a phantom for investigating the effects of electromagnetic waves on the human body. [Brief explanation of the drawings]

[0011] [Figure 1]FIG. 1 is a diagram showing the electrical characteristics (relative permittivity and conductivity) of the standard values ​​(target values) required for a human body permittivity simulating liquid agent and the allowable range (±10%) at frequencies of 1000 to 9000 (MHz). [Figure 2] FIG. 1 is a diagram showing the measured values ​​of the relative permittivity and conductivity of the human body permittivity simulating liquid agent of the present invention, which is suitable for use at frequencies of 650 to 1800 (MHz), together with the standard values ​​(target values). [Figure 3] FIG. 1 is a diagram showing the measured values ​​of the relative permittivity and conductivity of the human body permittivity simulating liquid agent of the present invention, which is suitable for use at frequencies of 1800 to 7000 (MHz), together with the standard values ​​(target values). [Figure 4] FIG. 1 is a diagram showing the measured values ​​of the relative permittivity and conductivity of the human body permittivity simulating liquid agent of the present invention, which is suitable for use at frequencies of 3800 to 9000 (MHz), together with the standard values ​​(target values). DETAILED DESCRIPTION OF THE INVENTION

[0012] The liquid agent mimicking the dielectric constant of the human body according to the present invention is an aqueous solution containing PEG laurate and water as main components.

[0013] PEG laurate has the function of reducing the relative permittivity of the human body dielectric constant mimicking liquid formulation of the present invention. PEG laurate (polyethylene glycol laurate) is also used as an ingredient in cosmetics and is highly safe. Furthermore, lauric acid is believed to have antibacterial activity and is suitable for long-term use in water. PEG laurate is an ester formed by adding ethylene oxide to lauric acid. Since it is used in aqueous solution, PEG laurate with a large number of added moles of ethylene oxide, which increases hydrophilicity, i.e., a high HLB, which indicates the degree of hydrophilicity, is preferred. PEG laurates that can be used in the present invention include PEG-4 laurate, PEG-8 laurate, PEG-9 laurate, PEG-10 laurate, and PEG-12 laurate. PEG-10 laurate and PEG-12 laurate are preferred, with PEG-12 laurate being even more preferred, due to their high hydrophilicity.

[0014] The liquid agent that mimics the dielectric constant of the human body of the present invention contains PEG laurate in an amount within the range of 25 to 50% by mass, more preferably 30 to 45% by mass, based on the total weight of the liquid agent.

[0015] The human body dielectric constant simulating liquid of the present invention may further contain an inorganic salt such as sodium chloride (table salt) as an optional additive. By adding the additive, the conductivity of the human body dielectric constant simulating liquid can be adjusted within a suitable range. These additives are usually used in an amount of 2% by mass or less, preferably 1.4% by mass or less, of the human body dielectric constant simulating liquid.

[0016] The remainder of the human body dielectric constant simulating liquid agent of the present invention is water, which is preferably purified water such as distilled water, ion-exchanged water, or deionized water.

[0017] By varying the formulation, the human body permittivity simulating liquid of the present invention can simulate the permittivity of the human body in various frequency bands, including . Increasing the amount of PEG laurate can lower the relative permittivity of the human body permittivity simulating liquid. By appropriately adjusting these effects, the relative complex permittivity of the human body permittivity simulating liquid can be matched to the relative permittivity and conductivity of the human body in a desired frequency band. Furthermore, by supplementarily using table salt, it is possible to match the relative permittivity and conductivity, particularly the conductivity, with even greater precision to those of the human body.

[0018] For example, in the case of a human body dielectric constant simulating liquid agent used at a frequency of 650 to 1800 (MHz), the content of PEG laurate based on the total weight of the human body dielectric constant simulating liquid agent is preferably 38 to 44 mass%, more preferably 39 to 42 mass%, and further preferably contains table salt as an inorganic salt. Furthermore, for a human body dielectric constant simulating liquid agent used at a frequency of 1800 to 7000 (MHz), the content of PEG laurate based on the total weight of the human body dielectric constant simulating liquid agent is preferably 34 to 40 mass %, more preferably 35 to 39 mass %, and it is also preferable that the liquid agent contains table salt as an inorganic salt. Furthermore, for a human body dielectric constant simulating liquid agent used at a frequency of 3800 to 9000 (MHz), the content of PEG laurate based on the total weight of the human body dielectric constant simulating liquid agent is preferably 32 to 38 mass%, more preferably 34 to 36 mass%.

[0019] As explained above, the human body permittivity simulating liquid agent of the present invention has a simple composition containing only PEG laurate or, optionally, inorganic salts such as salt, and is not subject to deterioration due to putrefaction or the like, and is not subject to component volatilization. Therefore, even if the composition of the human body permittivity simulating liquid agent changes due to evaporation of water, the original composition can be restored by adding water, and as a result, the liquid agent can be used for a long period of time.

[0020] (Electrical properties of biological tissue and standard values ​​(target values)) The electrical properties (dielectric constant and conductivity) of the standard values ​​(target values) required for the human body dielectric constant simulating liquid are the values ​​for the human body model (IEC-IEEE_62209, Table 2 on pages 32 and 33) set by the International Electrotechnical Commission and are shown as standard values ​​(target values) in Figure 1. The tolerance range is set to ±10% of the target value. Then, a simulated human body called a biological tissue equivalent phantom was created using the human body dielectric constant simulating liquid of the present invention, and the electrical properties of biological tissue [relative dielectric constant (ε) (%) and conductivity (σ) (S / m)] were measured. [Example]

[0021] <1> Creation of a liquid agent that mimics the dielectric constant of the human body (Example 1) Human body dielectric constant simulating liquid for the 650 to 1800 (MHz) band A human body permittivity simulating liquid suitable for use in the 650 to 1800 MHz frequency band was prepared as follows: 4063.4 g of PEG-12 laurate and 89.2 g of salt were dissolved in 5847.4 g of ion-exchanged water to form a human body permittivity simulating liquid with a PEG-12 laurate:water:sodium chloride ratio of 40.63%:58.47%:0.89%.

[0022] The electrical properties (dielectric constant and conductivity) of the obtained human body permittivity simulating liquid were measured using a SPEAG coaxial open-ended probe DAK3.5, and the measured values ​​(solid lines) in the frequency band of 650 to 1800 MHz are shown in Figure 2 together with the standard values ​​(dotted lines) of the electrical properties shown in Figure 1. The obtained human body permittivity simulating liquid showed electrical properties (dielectric constant and conductivity) that were in good agreement with the allowable range (±10%) of the target values.

[0023] (Example 2) Human body dielectric constant simulating liquid for the 1800 to 7000 (MHz) band A human body permittivity simulating liquid suitable for use in the 1800-7000 MHz frequency band was prepared as follows: 3685.3 g of PEG-12 laurate and 39.8 g of sodium chloride were dissolved in 6274.9 g of ion-exchanged water to form a human body permittivity simulating liquid with a PEG-12 laurate:water:sodium chloride ratio of 36.85%:62.75%:0.40%.

[0024] The electrical properties (dielectric constant and conductivity) of the obtained human body permittivity simulating liquid were measured in the same manner as in Example 1, and the measured values ​​(solid lines) in the frequency band of 1800 to 7000 MHz are shown in Figure 3 together with the standard values ​​(dotted lines) of the electrical properties shown in Figure 1. The obtained human body permittivity simulating liquid exhibited electrical properties (dielectric constant and conductivity) that were in good agreement with the allowable range (±10%) of the target values.

[0025] (Example 3) Human body dielectric constant simulating liquid for the 3800 to 9000 (MHz) band A human body permittivity simulating liquid suitable for use in the 3800 to 9000 MHz frequency band was prepared as follows: 3500.0 g of PEG-12 laurate was dissolved in 6500.0 g of ion-exchanged water to form a human body permittivity simulating liquid with a PEG-12 laurate:water ratio of 35.00%:65.00%.

[0026] The electrical properties (dielectric constant and conductivity) of the obtained human body permittivity simulating liquid were measured in the same manner as in Example 1, and the measured values ​​(solid lines) in the frequency band of 3800 to 9000 MHz are shown in Figure 4 together with the standard values ​​(dotted lines) of the electrical properties shown in Figure 1. The obtained human body permittivity simulating liquid exhibited electrical properties (dielectric constant and conductivity) that were in good agreement with the allowable range (±10%) of the target values.

[0027] (Comparative Example 1) Conventional liquid agent simulating the dielectric constant of the human body 3059 g of polysorbate 85 (Tween 85) and 755 g of benzalkonium chloride were dissolved in 6144 g of ion-exchanged water to prepare a liquid agent simulating the dielectric constant of the human body.

[0028] <2> Observation of changes over time in a liquid that mimics the dielectric constant of the human body To observe changes in appearance over time, the human body permittivity simulating liquid agents of Example 2 and Comparative Example 1 were left at 23°C for 30 days (uncapped), and the changes in appearance were observed. After preparation, the conventional human body permittivity simulating liquid agent of Comparative Example 1 was transparent yellow overall. After leaving it for 10 days, the entire liquid became cloudy, making it difficult to see the probe. In contrast, after preparation, the human body permittivity simulating liquid agent of Example 2 was transparent overall with no color change, and remained transparent and undiscolored even after leaving it for 30 days. This confirmed that the human body permittivity simulating liquid agent of Example 2 maintained its transparency even when left for a long period of time.

[0029] <3> Example of reuse of human body dielectric constant simulating liquid Furthermore, when the human body dielectric constant simulating liquid of Example 2 was left at 23°C for 30 days, the total weight of the human body dielectric constant simulating liquid dropped from 159.42g to 138.89g due to water evaporation, and 20.53g of water evaporated. Then, 20.53g of water was added to bring the total weight back to 159.42g, and the electrical properties of this human body dielectric constant simulating liquid were measured. The electrical properties (relative permittivity and electrical conductivity) were found to be approximately the same as those of the human body dielectric constant simulating liquid before the water evaporation, confirming that the electrical properties were restored by adding water and that the liquid could be reused.

[0030] From the above, it has become clear that the human body dielectric constant simulating liquid agent of the present invention using (I) exhibits electrical properties (relative dielectric constant and conductivity) that are in good agreement with the target values ​​and can be used in a wide frequency range. [Industrial Applicability]

[0031] The liquid agent for simulating the dielectric constant of the human body according to the present invention is useful for forming a phantom for investigating the influence of electromagnetic waves on the human body.

Claims

1. A human body dielectric constant simulating liquid agent comprising PEG laurate and water, wherein the PEG laurate is present in an amount of 25 to 50 mass % based on the total weight of the human body dielectric constant simulating liquid agent.

2. 2. The human body dielectric constant simulating liquid according to claim 1, wherein the PEG laurate is present in an amount of 30 to 45% by mass based on the total weight of the human body dielectric constant simulating liquid.

3. 3. The liquid agent according to claim 1, wherein the PEG laurate is PEG-12 laurate.

4. A human body dielectric constant simulating liquid agent used at a frequency of 650 to 1800 (MHz), comprising PEG laurate, an inorganic salt, and water, wherein the PEG laurate is present in an amount of 38 to 44 mass % based on the total weight of the human body dielectric constant simulating liquid agent.

5. A human body dielectric constant simulating liquid agent used at a frequency of 1800 to 7000 (MHz), comprising PEG laurate, an inorganic salt, and water, wherein the PEG laurate is present in an amount of 34 to 40 mass % based on the total weight of the human body dielectric constant simulating liquid agent.

6. A human body dielectric constant simulating liquid agent used at a frequency of 3800 to 9000 (MHz), comprising PEG laurate and water, wherein the PEG laurate is present in an amount of 32 to 38 mass % based on the total weight of the human body dielectric constant simulating liquid agent.

7. 7. The liquid agent according to claim 4, wherein the PEG laurate is PEG-12 laurate.

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