Human dielectric constant simulation liquid agent containing PEG laurate

Abstract

An object of the present invention is to provide a human body dielectric constant simulation liquid agent that maintains transparency over time, is difficult to be colloidalized, enables high-precision simulation without change in dielectric constant during use in a wide range of frequency bands. **Solution**: The present invention is a human body dielectric constant simulation liquid agent characterized by containing lauric acid PEG and water, wherein the lauric acid PEG is present in an amount of 25 to 50% by mass based on the total weight of the human body dielectric constant simulation liquid agent.

Description

Technical Field

[0001] The present invention relates to a human body dielectric constant simulation liquid agent used for creating a phantom for studying the interaction between electromagnetic waves and the human body. More specifically, it relates to a human body dielectric constant simulation liquid agent characterized by containing lauric acid PEG.

Background Art

[0002] When using a mobile phone or a wireless device in close proximity to the human body, the human body is exposed to electromagnetic waves and is affected by them. However, due to reasons such as the difficulty of reproducing the test or maintaining the same posture for a long time, it is difficult to use the human body to test this influence. Therefore, tests have been conducted using a phantom, which is a material having a dielectric constant similar to that of the human body and simulating the head or chest of the human body.

[0003] Also, SAR (Specific Absorption Rate) has been used as an index for evaluating the absorption of electromagnetic waves by the human body. SAR is the absorbed power per unit mass when exposed to electromagnetic waves. The measurement method of SAR is defined by the International Electrotechnical Commission (IEC), and the allowable value of SAR is indicated by the radio wave protection guidelines for mobile wireless terminals. And based on the IEC62209 standard, it is required to be within ±10% deviation for each frequency.

[0004] Furthermore, in recent years, with the expansion of the frequency band of mobile phones and the like, there has been a need for a human body dielectric constant simulation liquid agent to quickly perform a conformity evaluation of radio wave protection guidelines in a wide 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 simulation liquid agent of the present invention is used at a frequency of 650 to 1800 (MHz), it preferably further contains an inorganic salt, and lauric acid PEG is preferably present in an amount of 38 to 44% by mass based on the total weight of the human body dielectric constant simulation liquid agent. Also, when the human body dielectric constant simulation liquid agent of the present invention is used at a frequency of 1800 to 7000 (MHz), it preferably further contains an inorganic salt, and lauric acid PEG is preferably present in an amount of 34 to 40% by mass based on the total weight of the human body dielectric constant simulation liquid agent. Furthermore, when the human body dielectric constant simulation liquid agent of the present invention is used at a frequency of 3800 to 9000 (MHz), lauric acid PEG is preferably present in an amount of 32 to 38% by mass based on the total weight of the human body dielectric constant simulation liquid agent.

Advantages of the Invention

[0010] The human body dielectric constant simulation liquid agent of the present invention is characterized by containing lauric acid PEG which is also used as a facial cleanser etc., has high safety, and has little change in dielectric constant and conductivity at a wide frequency band up to 9 GHz, and can simulate the dielectric constant of the human body with high precision. Also, the human body dielectric constant simulation liquid agent of the present invention can maintain transparency even when used for a long time, so it is easy to visually observe the measurement location and can reduce the inaccuracy of the measurement test. Further, the human body dielectric constant simulation liquid agent of the present invention is composed only of lauric acid PEG, sodium chloride as an arbitrary inorganic salt, and water, and there is no need to add preservatives such as ethanol and benzalkonium chloride. Therefore, when the water content of the human body dielectric constant simulation liquid agent decreases, water can be added and reused for long-term use, and it is also eco-friendly. Due to these advantages, the human body dielectric constant simulation liquid agent of the present invention is useful for forming a phantom for investigating the influence of electromagnetic waves on the human body.

Brief Description of the Drawings

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Mode for Carrying Out the Invention

[0012] The human body dielectric constant simulation liquid of the present invention is an aqueous solution mainly composed of PEG laurate and water.

[0013] PEG laurate has a function of reducing the relative permittivity of the liquid with respect to the human body dielectric constant simulation liquid of the present invention. PEG laurate (polyethylene glycol laurate) is also used as a component of cosmetics and the like, and has high safety. In addition, lauric acid is considered to have antibacterial activity and is also suitable for long-term use in water. PEG laurate is an ester obtained by adding ethylene oxide to lauric acid. Since it is used in an aqueous solution, those having a large number of added moles of ethylene oxide, which increases hydrophilicity, that is, those having a high HLB indicating the degree of hydrophilicity are preferred. Examples of PEG laurate that can be used in the present invention include PEG-4 laurate, PEG-8 laurate, PEG-9 laurate, PEG-10 laurate, PEG-12 laurate, etc. Among them, PEG-10 laurate and PEG-12 laurate having high hydrophilicity are preferred, and PEG-12 laurate having higher hydrophilicity is more preferred.

[0014] The human body dielectric constant simulation liquid agent of the present invention contains lauric acid PEG in 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 simulation liquid agent of the present invention can further contain, as an optional component, inorganic salts such as sodium chloride (table salt), and as an additive. By adding the additive, the conductivity of the human body dielectric constant simulation liquid agent can be adjusted to a suitable range. These additives are usually desirably used in an amount of 2% by mass or less, preferably 1.4% by mass or less, of the human body dielectric constant simulation liquid agent.

[0016] The remainder of the human body dielectric constant simulation liquid agent of the present invention is water. As the water, it is preferable to use purified water such as distilled water, ion-exchanged water, deionized water, etc.

[0017] The human body dielectric constant simulation liquid agent of the present invention can simulate the dielectric constant of the human body in various frequency bands by changing its formulation. By increasing the amount of lauric acid PEG, the relative dielectric constant of the human body dielectric constant simulation liquid agent can be decreased. By appropriately adjusting these effects, the relative complex dielectric constant of the human body dielectric constant simulation liquid agent can be made to match the relative dielectric constant and conductivity of the human body in the desired frequency band. Also, by using table salt as an auxiliary, it becomes possible to match the relative dielectric constant and conductivity of the human body, especially the conductivity, with higher precision.

[0018] For example, regarding the human body dielectric constant simulation liquid agent used at a frequency of 650 to 1800 (MHz), the content of lauric acid PEG based on the total weight of the human body dielectric constant simulation liquid agent is preferably in the amount of 38 to 44% by mass, more preferably in the amount of 39 to 42% by mass, and it is preferable to contain table salt as the inorganic salt. Also, regarding the human body dielectric constant simulation liquid agent used at a frequency of 1800 to 7000 (MHz), the content of lauric acid PEG based on the total weight of the human body dielectric constant simulation liquid agent is preferably in the amount of 34 to 40% by mass, more preferably in the amount of 35 to 39% by mass, and it is preferable to contain table salt as the inorganic salt. Furthermore, regarding the human body dielectric constant simulation liquid agent used at a frequency of 3800 to 9000 (MHz), the content of lauric acid PEG based on the total weight of the human body dielectric constant simulation liquid agent is preferably in the amount of 32 to 38% by mass, and more preferably in the amount of 34 to 36% by mass.

[0019] As described above, the human body dielectric constant simulation liquid agent of the present invention has a simple composition containing only lauric acid PEG or further containing an inorganic salt such as sodium chloride as an optional component, has no deterioration due to spoilage, etc., and no component volatilization. Therefore, when water evaporates and the composition of the human body dielectric constant simulation liquid agent changes, it can be restored to the original composition by adding water, and as a result, it can be used for a long period of time.

[0020] (Electrical Characteristics and Standard Values (Target Values) of Biological Tissues) The electrical characteristics (relative permittivity and conductivity) of the standard values (target values) required for the human body dielectric constant simulation liquid agent are shown in FIG. 1 as the values of the human body model (IEC-IEEE_62209, pages 32, 33, Table 2) by the International Electrotechnical Commission. The (±10%) of the target value was set as the allowable range. Then, using the human body dielectric constant simulation liquid agent of the present invention, a simulated human body called a bioequivalent phantom was created, and the electrical characteristics [relative permittivity (ε) (%) and conductivity (σ) (S / m)] of the biological tissue were measured.

Examples

[0021] <1> Preparation of Human Body Dielectric Constant Simulation Liquid Agent (Example 1) Human Body Dielectric Constant Simulation Liquid Agent for 650 to 1800 (MHz) Band A human body dielectric constant simulation liquid agent suitable for use in the frequency band of 650 to 1800 MHz was prepared as follows. To 5847.4 g of ion-exchanged water, 4063.4 g of lauric acid PEG-12 and 89.2 g of sodium chloride were dissolved to form a human body dielectric constant simulation liquid agent in which lauric acid PEG-12: water: sodium chloride was 40.63%: 58.47%: 0.89%.

[0022] The electrical properties (relative permittivity and conductivity) of the obtained human body permittivity simulation liquid agent were measured using a coaxial open-end probe DAK3.5 manufactured by SPEAG. The measured values (solid line) in the frequency band of 650 to 1800 MHz are shown in FIG. 2 together with the standard values (dotted line) of the electrical properties shown in FIG. 1. The obtained human body permittivity simulation liquid agent showed electrical properties (relative permittivity and conductivity) that were in good agreement with the allowable range (±10%) of the target value.

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

[0024] The electrical properties (relative permittivity and conductivity) of the obtained human body permittivity simulation liquid agent were measured in the same manner as in Example 1. The measured values (solid line) in the frequency band of 1800 to 7000 MHz are shown in FIG. 3 together with the standard values (dotted line) of the electrical properties shown in FIG. 1. The obtained human body permittivity simulation liquid agent showed electrical properties (relative permittivity and conductivity) that were in good agreement with the allowable range (±10%) of the target value.

[0025] (Example 3) Human body permittivity simulation liquid agent for the 3800 - 9000 (MHz) band A human body permittivity simulation liquid agent suitable for use in the frequency band of 3800 to 9000 MHz was prepared as follows. To 6500.0 g of ion-exchanged water, 3500.0 g of lauric acid PEG-12 was dissolved to form a human body permittivity simulation liquid agent with lauric acid PEG-12: water being 35.00%: 65.00%.

[0026] The electrical properties (relative permittivity and conductivity) of the obtained human body permittivity simulation liquid agent were measured in the same manner as in Example 1, and the measured values (solid line) in the frequency band of 3800 to 9000 MHz are shown in FIG. 4 together with the standard values (dotted line) of the electrical properties shown in FIG. 1. The obtained human body permittivity simulation liquid agent showed electrical properties (relative permittivity and conductivity) that well matched the allowable range (±10%) of the target value.

[0027] (Comparative Example 1) Conventional human body permittivity simulation liquid agent To 6144 g of ion-exchanged water, 3059 g of polysorbate 85 (Tween 85) and 755 g of benzalkonium chloride were dissolved to form a human body permittivity simulation liquid agent.

[0028] <2> Observation of the change over time of the human body permittivity simulation liquid agent Regarding the human body permittivity simulation liquid agents of Example 2 and Comparative Example 1, in order to observe the change in appearance over time, they were left standing at 23 °C for 30 days (without a lid) to observe changes in appearance and the like. The conventional human body permittivity simulation liquid agent of Comparative Example 1 was transparent yellow throughout the liquid after preparation, and when left standing for 10 days, the entire liquid became turbid and it was difficult to visually recognize the probe. In contrast, the human body permittivity simulation liquid agent of Example 2 was transparent throughout the liquid after preparation and there was no color change, and even after being left standing for 30 days, it remained transparent and there was no discoloration. From this, it was confirmed that the human body permittivity simulation liquid agent of Example 2 maintains transparency even when left standing for a long time.

[0029] <3> Reuse example of the human body permittivity simulation liquid agent Also, when the human body permittivity simulation liquid agent of Example 2 was left standing at 23 °C for 30 days, due to water evaporation, the total weight of the human body permittivity simulation liquid agent decreased from 159.42 g to 138.89 g, and 20.53 g of water evaporated. Therefore, 20.53 g of water was added to return the total weight to 159.42 g, and when the electrical properties of this human body permittivity simulation liquid agent were measured, it showed substantially the same electrical properties (relative permittivity and conductivity) as the human body permittivity simulation liquid agent before water evaporation, confirming that the electrical properties were restored and it was reusable by adding water.

[0030] From the above, it has become clear that the human body dielectric constant simulation liquid agent of the present invention using [substance] exhibits electrical characteristics (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 human body dielectric constant simulation liquid agent of the present invention is useful for forming a phantom for investigating the influence of electromagnetic waves on the human body.

Claims

**Claim 1** A human body dielectric constant simulation liquid agent containing lauric acid PEG and water, wherein the lauric acid PEG is present in an amount of 25 to 50% by mass based on the total weight of the human body dielectric constant simulation liquid agent. **Claim 2** The human body dielectric constant simulation liquid agent according to claim 1, wherein the lauric acid PEG is present in an amount of 30 to 45% by mass based on the total weight of the human body dielectric constant simulation liquid agent. **Claim 3** The human body dielectric constant simulation liquid agent according to claim 1 or 2, wherein the lauric acid PEG is lauric acid PEG-12. **Claim 4** A human body dielectric constant simulation liquid agent containing lauric acid PEG, inorganic salt and water, and used at a frequency of 650 to 1800 (MHz), wherein the lauric acid PEG is present in an amount of 38 to 44% by mass based on the total weight of the human body dielectric constant simulation liquid agent. **Claim 5** A human body dielectric constant simulation liquid agent containing lauric acid PEG, inorganic salt and water, and used at a frequency of 1800 to 7000 (MHz), wherein the lauric acid PEG is present in an amount of 34 to 40% by mass based on the total weight of the human body dielectric constant simulation liquid agent. **Claim 6** A human body dielectric constant simulation liquid agent containing lauric acid PEG and water, and used at a frequency of 3800 to 9000 (MHz), wherein the lauric acid PEG is present in an amount of 32 to 38% by mass based on the total weight of the human body dielectric constant simulation liquid agent. **Claim 7** The human body dielectric constant simulation liquid agent according to any one of claims 4 to 6, wherein the lauric acid PEG is lauric acid PEG-12.

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