WO2013055163A1

WO2013055163A1 - Plate for measuring zeta-potential of non-planar material and method for measurement thereof

Info

Publication number: WO2013055163A1
Application number: PCT/KR2012/008338
Authority: WO
Inventors: Jun Kim; Minjoung Kim; Yuseung Choi; Kyunghee Moon; Gitaeg Jeong
Original assignee: LG Electronics Inc
Current assignee: LG Electronics Inc
Priority date: 2011-10-14
Filing date: 2012-10-12
Publication date: 2013-04-18
Anticipated expiration: 2014-04-14
Also published as: KR101833813B1; KR20130040626A

Abstract

This specification relates to a measurement plate for measuring zeta-potential of a non-planar material using electrophoretic light scattering and a zeta-potential measurement method. To this end, a measurement plate for measuring zeta-potential of an object to be measured according to one exemplary embodiment is inserted into a conduit and faces a reference plate with a spaced distance. The measurement plate has a receiving recess formed at a surface facing the reference plate to mount the object to be measured therein. When a fluid containing charged particles flows in a space, which is formed as the measurement plate faces the reference plate within the conduit, in a first direction parallel to the surface of the measurement plate facing the reference plate, the zeta-potential of the object to be measured is measured based on speeds of the charged particles moving in the first direction.

Description

PLATE FOR MEASURING ZETA-POTENTIAL OF NON-PLANAR MATERIAL AND METHOD FOR MEASUREMENT THEREOF

The present disclosure relates to a plate for measuring a zeta-potential of a non-planar material, and a measurement method thereof.

Zeta-potential refers to a unit of an electrokinetic (electrodynamic) potential difference which is induced by a density difference of electric charges on a diffuse double layer having non-mobile water molecules contacting a surface of a charged material and mobile water molecules easy to come apart from particles. Zeta-potential measurement may allow for concrete understanding of a dissipation (distribution) mechanism, and act as an important factor in view of controlling electrostatic dissipation. The zeta-potential may be significantly used to understand a surface characteristic of a solid as well as a difference between choloidal particles. For example, the zeta-potential measurement is widely used in different fields, such as detergent, cosmetics, manufactured medicine, fiber, paint, new material and the like, which highly take into account an interface characteristic, such as a surface property measurement and an evaluation of surface processing effect with respect to a glass substrate as a material of a liquid crystal display.

The conventional zeta-potential analyzer may acquire a relatively accurate analysis result with respect to a sample having a simple form such as a form of a flat (planar) plate. However, in terms of a characteristic of an analysis system for measuring mobility of a material within an electromagnetic field, the analyzer may be difficult to be attached or placed on an introduction section of a target sample to be analyzed with a complicated form and also an analysis result for the target sample may be difficult to be interpreted.

In recent time, the measurement of the zeta-potential of a non-planar material is gradually needed. This is because an analysis of the zeta-potential is inevitably needed in order to examine a surface characteristic and a mechanism of Ultra Filtration (UF) membrane which is widely used in battery, food, water treatment and the like.

Various cases of measuring zeta-potential of hollow fiber membrane using a streaming potential measuring method have recently been reported. However, a material such as polymer or the like is so vulnerable to pressing to be easily deformed. Also, an empty space is formed within a measurement cell (this is a main cause of an analysis error), disabling acquisition of accurate zeta-potential.

Therefore, to obviate those problems, an aspect of the detailed description is to provide a plate for measuring a zeta-potential of a non-planar material using electrophoretic light scattering, and a method for measuring the zeta-potential.

To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a plate for measuring zeta-potential of an object to be measured, wherein the measurement plate may be inserted into a conduit to face a reference plate with a spaced distance and have a receiving recess formed on a surface facing the reference plate to mount the object to be measured therein. Here, when a fluid containing charged particles flows in a space, which is formed as the measurement plate faces the reference plate within the conduit, in a first direction parallel to the surface of the measurement plate facing the reference plate, the zeta-potential of the object to be measured may be measured based on speeds of the charged particles moving in the first direction.

In accordance with one aspect of the present disclosure, the object to be measured may be formed of a non-planar material, and the receiving recess may be recessed in correspondence with a shape of the object to be measured such that the object to be measured is mounted therein.

In accordance with one aspect of the present disclosure, the object to be measured may have a shape of a cylindrical tube having a hollow opening.

In accordance with one aspect of the present disclosure, the object to be measured may extend in the first direction and is mounted in the receiving recess.

In accordance with one aspect of the present disclosure, the zeta-potential of the object to be measured may be measured at a specific position in the first direction.

In accordance with one aspect of the present disclosure, the object to be measured may be provided in plurality, and the plurality of objects to be measured may be mounted in the receiving recess with being spaced apart from each other in a second direction.

In accordance with one aspect of the present disclosure, the first direction and the second direction may perpendicularly intersect with each other.

In accordance with one aspect of the present disclosure, the measurement plate may include a first member having the receiving recess, and a second member formed along an outer circumference of the first member to surround the first member. Here, the receiving recess may be formed on one surface of the first member, and the one surface of the first member having the receiving recess may be exposed to the outside.

In accordance with one aspect of the present disclosure, the first member and the second member may be formed of different materials from each other.

In accordance with one aspect of the present disclosure, the measurement plate may further include a sealing member formed along an outer circumference of the receiving recess to surround the receiving recess.

In accordance with one aspect of the present disclosure, the zeta-potential may be calculated by Equation

, where A’ denotes a constant in which a surface area of the object to be measured is reflected, Uobs denotes an electrical mobility of the particle, π denotes a circular constant, μ denotes viscosity of the fluid, and εd denotes permittivity.

In accordance with one aspect of the present disclosure, the A’ may be π/2 when the object to be measured has a shape of a cylindrical tube having a hollow opening.

In accordance with one exemplary embodiment of the detailed description, a measurement plate and a method for measuring zeta-potential are provided. With a receiving recess recessed in correspondence with a shape of an object to be measured such that the object to be measured can be mounted therein, even when the object to be measured is formed of a non-planar material, an accurate and reproducible zeta-potential of the non-planar material can be measured.

FIG. 1 is an exemplary view showing a system for measuring zeta-potential of an object (target) to be measured in accordance with exemplary embodiments;

FIG. 2 is a view showing a structure of a measurement plate in accordance with exemplary embodiments;

FIG. 3 is a view showing a structure of a measurement body and a zeta-potential measurement cell in accordance with one exemplary embodiment;

FIG. 4 is an exemplary view showing a measurement plate in accordance with a first exemplary embodiment;

FIG. 5 is a sectional view showing a structure of a measurement plate in accordance with a second exemplary embodiment;

FIG. 6 is an exemplary view showing a measurement plate in accordance with a third exemplary embodiment;

FIG. 7 is an exemplary view showing a method for measuring zeta-potential in accordance with a fourth exemplary embodiment; and

FIG. 8 is an exemplary view showing a method for correcting a zeta-potential measurement (calculation) equation in accordance with the fourth exemplary embodiment.

The technologies disclosed herein may be applied to measure zeta-potential of a non-planar material using electrophoretic light scattering. The technologies disclosed herein are not limited to this, and may be also applicable to all kinds of application fields of measuring zeta-potential of every material (or every object to be measured) the technological spirit of the technology can be applied.

A measurement plate for measuring zeta-potential of the non-planar material and a measurement method thereof relate to a technology capable of measuring zeta-potential of the non-planar material using a measurement plate having a receiving recess for mounting the non-planar material therein.

It should be noted that technological terms used herein are merely used to describe a specific embodiment, but not to limit the present invention. Also, unless particularly defined otherwise, technological terms used herein should be construed as a meaning that is generally understood by those having ordinary skill in the art to which the invention pertains, and should not be construed too broadly or too narrowly. Furthermore, if technological terms used herein are wrong terms unable to correctly express the spirit of the invention, then they should be replaced by technological terms that are properly understood by those skilled in the art. In addition, general terms used in this invention should be construed based on the definition of dictionary, or the context, and should not be construed too broadly or too narrowly.

Incidentally, unless clearly used otherwise, expressions in the singular number include a plural meaning. In this application, the terms "comprising" and "including" should not be construed to necessarily include all of the elements or steps disclosed herein, and should be construed not to include some of the elements or steps thereof, or should be construed to further include additional elements or steps.

In addition, a suffix "module" or "unit" used for constituent elements disclosed in the following description is merely intended for easy description of the specification, and the suffix itself does not give any special meaning or function.

Furthermore, the terms including an ordinal number such as first, second, etc. can be used to describe various elements, but the elements should not be limited by those terms. The terms are used merely for the purpose to distinguish an element from the other element. For example, a first element may be named to a second element, and similarly, a second element may be named to a first element without departing from the scope of right of the invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, and the same or similar elements are designated with the same numeral references regardless of the numerals in the drawings and their redundant description will be omitted.

In describing the present invention, moreover, the detailed description will be omitted when a specific description for publicly known technologies to which the invention pertains is judged to obscure the gist of the present invention. Also, it should be noted that the accompanying drawings are merely illustrated to easily explain the spirit of the invention, and therefore, they should not be construed to limit the spirit of the invention by the accompanying drawings.

Description of Zeta-potential Measurement System

Measurement of zeta-potential of an object (whose zeta-potential is to be measured) using electrophoretic light scattering uses electrophoretic and light scattering effects of particles.

Electrophoresis is a phenomenon that fine particles dispersed in an electrolyte solution are moved due to an electric field. Also, light scattering refers to a phenomenon that a frequency of light or sound wave shifts in proportion to speed of an object which is moving when the light or sound wave is collided with or reflected or scattered on the moving object (Doppler shift).

The measurement of the zeta-potential of the target to be measured using the electrophoretic light scattering is configured to calculate (measure) an average zeta-potential of the target by measuring translational speed of particles (or electrical mobilities of particles), which is caused by the electrophoresis within a uniform electric field, using the light scattering. The calculation (or measurement) method will be described in detail later with reference to FIGS. 7 and 8.

Various kinds of equipment (devices) used for measuring the zeta-potential of the object to be measured (simply object) may be present. For example, the measurement equipment may be Otsuka ELS-Z.

Here, a system for measuring the zeta-potential of the object to be measured may be configured within the measurement equipment (device).

Hereinafter, description will be given of a system for measuring zeta-potential in accordance with exemplary embodiments with reference to FIG. 1.

FIG. 1 is an exemplary view showing a system for measuring zeta-potential of an object (target) to be measured in accordance with exemplary embodiments.

As shown in FIG. 1, in measuring a zeta-potential of an object to be measured using the measurement equipment, there may be a measurement body 10, and a zeta-potential measurement cell 20 disposed within the measurement body 10 and having a conduit (path) through which fluid containing charged particles flows.

The zeta-potential measurement system may include a measurement plate 100, a reference plate 200 and a to-be-measured object (object or target to be measured, or simply object or target) 120.

Here, the to-be-measured object 120 may be received with being mounted onto the measurement plate 100. To this end, the measurement plate 100 may include a receiving recess 110 in which the object 120 can be mounted.

In accordance with the exemplary embodiment of the present disclosure, the measurement plate 100, the reference plate 200 and the object 120 may be inserted into the zeta-potential measurement cell 20.

Here, as the measurement body 10 having the zeta-potential measurement cell 20, in which the measurement plate 100, the reference plate 20 and the object 120 are inserted, may be mounted onto the measurement equipment, the zeta-potential may be measured. Accordingly, a system for measuring the zeta-potential may be implemented within the zeta-potential measurement cell 20.

Hereinafter, the measurement plate according to the exemplary embodiments will be described with reference to FIG. 2.

Description of Measurement Plate

A measurement plate according to exemplary embodiments is a plate for measuring a zeta-potential of a to-be-measured object. The measurement plate may be inserted into a conduit, and face a reference plate with a spaced distance therefrom. A receiving recess in which the to-be-measured object is mounted may be formed on a surface of the measurement plate facing the reference plate. When a fluid containing charged particles flows in a space, which is formed as the measurement plate faces the reference plate within the conduit, in a first direction parallel to the surface facing the reference plate, the zeta-potential of the object may be measured based on speed of the charged particles.

A structure of the conduit will be described later with reference to FIG. 3.

Also, a method for measuring zeta-potential in accordance with one exemplary embodiment will be described later with reference to FIGS. 7 and 8.

As aforementioned, the measurement plate 100 may be inserted into the zeta-potential measurement cell 20 which exists in the measurement body 10.

The to-be-measured object may be a non-planar material, and the receiving recess may be recessed in correspondence with a shape of the object such that the object can be mounted therein.

That is, the receiving recess may be formed in various shapes or patterns depending on the shape of the object. For example, when the object has a shape of a hollow cylindrical tube (hollow fiber membrane), the receiving recess may be a semi-circular recess. The various shapes of the receiving recess will be described later with reference to FIG. 6.

FIG. 2 is a view showing a structure of a measurement plate in accordance with exemplary embodiments.

As shown in FIG. 2(a), the measurement plate 100 may be a rectangular substrate. It may be obvious to a skilled person in the art that various shapes in addition to the rectangular shape may also be applied to the measurement plate disclosed herein.

The measurement plate 100 may include a receiving recess 110 in which the to-be-measured object can be mounted.

Also, the measurement plate 100 may further include a sealing member 130 formed along an outer circumference of the receiving recess 100 to surround the receiving recess 110.

The sealing member 130 may prevent a fluid which contains charged particles from flowing out of a conduit located within the zeta-potential measurement cell 20 when the fluid flows in a space, which is formed as the measurement plate 100 faces the reference plate 200 within the conduit.

FIG. 2(b) is a sectional view of the measurement plate 100.

As shown in FIG. 2(b), the receiving recess 110 has the rectangular shape for the sake of explanation. The receiving recess 110 may have various shapes depending on the shape of the object.

Hereinafter, description will be given of a measurement body and a zeta-potential measurement cell in accordance with one exemplary embodiment with reference to FIG. 3.

Measurement Body and Zeta-potential Measurement Cell according to One Exemplary Embodiment

A measurement body and a zeta-potential measurement cell in accordance with one exemplary embodiment may be applied to a zeta-potential measurement device (apparatus, equipment) using electrophoretic light scattering.

As aforementioned, the zeta-potential measurement system having the measurement plate, the reference plate and the object to be measured (or the to-be-measured object) may be implemented by the measurement body and the zeta-potential measurement cell.

FIG. 3 is a view showing a structure of a measurement body and a zeta-potential measurement cell in accordance with one exemplary embodiment.

Referring to FIG. 3, a measurement body may be mounted in the zeta-potential measurement device and a zeta-potential measurement cell 20 may exist within the measurement body 10.

FIG. 3(a) is a perspective view showing a structure of the measurement body 10. The measurement body 10 may include various constituent components, such as a substrate, connection openings and the like, which are detachably formed.

When the measurement body 10 is detached (separated), the measurement plate having the to-be-measured object mounted therein and the reference plate may be inserted into the zeta-potential measurement cell 20.

FIGS. 3(b) to 3(d) are upper, sectional and perspective views each showing the structure of the zeta-potential measurement cell 20.

As aforementioned, the zeta-potential measurement cell 20 may include a conduit 21 through which a fluid containing charged particles flows.

In a state that the measurement plate having the to-be-measured object mounted therein and the reference plate are inserted into the zeta-potential measurement cell 20, when a fluid containing charged particles flows in a space, which is formed as the measurement plate and the reference plate face each other within the conduit 21, in a first direction parallel to one surface of the measurement plate facing the reference plate, the zeta-potential of the object may be measured based on speed of the charged particles moving in the first direction.

For example, the first direction may be a direction from left to right sides within the conduit 21.

In the upper view of the zeta-potential measurement cell 20 as shown in FIG. 3(b), ‘a’ denotes a vertical length of the conduit 21 (or a vertical length of the measurement plate).

In the sectional view of the zeta-potential measurement cell 20 as shown in FIG. 3(c), ‘b’ denotes a thickness of the conduit 21 (or a width of a passage through which the fluid flows).

First Exemplary Embodiment

In a measurement plate in accordance with a first exemplary embodiment, the object to be measured may be provided in plurality, and the plurality of objects may be mounted in the receiving recess of the measurement plate with being spaced apart from each other in a second direction.

The first exemplary embodiment disclosed in this specification may be implemented by part or combination of configurations or steps included in the aforementioned exemplary embodiments or combinations of the exemplary embodiments. Hereinafter, duplicate description will be omitted to clearly describe the first exemplary embodiment.

FIG. 4 is an exemplary view showing a measurement plate in accordance with a first exemplary embodiment.

FIG. 4 shows a lower view (FIG. 4(a)) and a sectional view (FIG. 4(b)) each showing a structure of a measurement plate in accordance with the first exemplary embodiment.

The measurement plate 100 may include a receiving recess 110a in which an object to be measured is mounted. Also, the measurement plate 100 may further include a sealing member 130 formed along an outer circumference of the receiving recess 110a to surround the receiving recess 110a.

As aforementioned, the sealing member 130 may prevent the fluid which contains charged particles from flowing out of the conduit when the fluid flows in a space, which is formed as the measurement plate 100 and the reference plate 200 face each other within the conduit existing within the zeta-potential measurement cell 20.

According to the first exemplary embodiment, the object to be measured may have a shape of a cylindrical tube having a hollow opening. For example, the object may be a hollow fiber membrane. Here, the measurement plate 100 may have a receiving recess 110a corresponding to the cylindrical shape.

Also, the receiving recess 110a may be recessed such that the object can be mounted therein.

In accordance with the first exemplary embodiment, the object may be provided in plurality, and the plurality of objects may be mounted in the receiving recess of the measurement plate with being spaced apart from each other in a second direction.

The first direction and the second direction may perpendicularly intersect with each other.

Referring to FIG. 4(a), the receiving recess 110a may be divided into a plurality of regions, and the objects each having the cylindrical tube-like shape with the hollow opening may be mounted in the regions, respectively.

Here, the plurality of objects may be mounted in the receiving recess of the measurement plate with being spaced apart from each other in the second direction (see FIG. 4(b)).

As aforementioned, the fluid containing the charged particles flows in the first direction (e.g., a flowing direction from left to right sides within the conduit 21 of FIG. 3), so the second direction may intersect with the first direction in a perpendicular manner.

Also, in accordance with a variation of the first exemplary embodiment, the object may extend in the first direction and be mounted in the receiving recess 110a. For example, when the measurement plate 100 is fabricated by extending long in the first direction, the object 120 may be mounted long in the receiving recess 110a in the first direction. Hence, the zeta-potential of the object may be measured at various positions.

Second Exemplary Embodiment

A measurement plate according to a second exemplary embodiment may include a first member having a receiving recess, and a second member formed along an outer circumference of the first member to surround the first member. The receiving recess may be formed on one surface of the first member and the one surface of the first member having the receiving recess may be exposed to the outside.

The first member and the second member may be formed of different materials.

The second exemplary embodiment disclosed herein may be implemented by part or combination of configurations or steps included in the aforementioned exemplary embodiments or combinations of the exemplary embodiments. Hereinafter, duplicate description will be omitted to clearly describe the second exemplary embodiment.

FIG. 5 is a sectional view showing a structure of a measurement plate in accordance with a second exemplary embodiment.

As shown in FIG. 5, the object to be measured may have a shape of a cylindrical tube having a hollow opening. For example, the object may be a hollow fiber membrane.

In accordance with the second exemplary embodiment, a receiving recess 110a in which the object is mounted may be formed on one surface of the first member 140.

Also, according to the second exemplary embodiment, the second member 150 may be formed along an outer circumference of the first member 140 to surround the first member 140.

The first member 140 and the second member 150 according to the second exemplary embodiment may be formed of different materials. For example, the first member 140 may be formed of at least one of quartz, PP, PE and polytetrafluoroethylene (PTFE). Also, the second member 150 may be formed of at least one of quartz, PTFE, PFA, PE, PP and ABS. With no limit to those materials, it may be obvious to a person skilled in the art that the first member 140 or the second member 150 may be formed of various materials.

Third Exemplary Embodiment

A measurement plate in accordance with a third exemplary embodiment may include a receiving recess having various shapes. Therefore, when an object to be measured is a non-planar material, the receiving recess may be recessed in correspondence with a shape of the object such that the object can be mounted therein.

The third exemplary embodiment disclosed herein may be implemented by part or combination of configurations or steps included in the aforementioned exemplary embodiments or combinations of the exemplary embodiments. Hereinafter, duplicate description will be omitted to clearly describe the third exemplary embodiment.

FIG. 6 is an exemplary view showing a measurement plate in accordance with a third exemplary embodiment.

FIG. 6 shows measurement plates having receiving recesses in various shapes.

Referring to FIG. 6(a), the object has a shape of a cylindrical tube with a hollow opening. For example, the object may be a hollow fiber membrane.

Here, the receiving recess 110a may have a semi-circular shape to correspond to the cylindrical tube-like shape.

Referring to FIG. 6(b), the object may be formed of a planar material. Here, a receiving recess 110b may have a rectangular shape to correspond to the shape of the planar material.

Also, the measurement plate shown in FIG. 6(b) may be applied to a case where the object is a hollow fiber membrane. For example, a plurality of hollow fiber membranes having various radii may be mounted with being disposed in the receiving recess 110b in a line.

Referring to FIG. 6(c), the object may have a shape like a tube having a shape of triangular prism.

Here, a receiving recess 110c may have a V-groove shape to correspond to the shape of the tube with the shape of the triangular prism.

Hereinafter, description will be given in detail of a method for measuring zeta-potential using a measurement plate disclosed herein with reference to FIGS. 7 and 8.

Fourth Exemplary Embodiment

A method for measuring a zeta-potential of an object to be measured in accordance with a fourth exemplary embodiment may be characterized in that the zeta-potential is measured (calculated) by Equation

, where A’ denotes a constant in which a surface area of the object to be measured is reflected, Uobs denotes an electrical mobility (observed mobility) of a particle, π denotes a circular constant (circle ratio), μ denotes viscosity of the fluid, and εd denotes permittivity.

The fourth exemplary embodiment disclosed herein may be implemented by part or combination of configurations or steps included in the aforementioned exemplary embodiments or combinations of the exemplary embodiments. Hereinafter, duplicate description will be omitted to clearly describe the fourth exemplary embodiment.

FIG. 7 is an exemplary view showing a method for measuring zeta-potential in accordance with a fourth exemplary embodiment.

As shown in FIG. 7, a fluid which contains charged particles flows along the conduit 21 present in the zeta-potential measurement cell 20 in a first direction (e.g., a right direction of X-axis). FIG. 7 shows that the charged particles are charged into a minus (‘-’) polarity.

In accordance with the fourth exemplary embodiment, the zeta-potential may be measured at a specific position of the object to be measured in the first direction. That is, the zeta-potential may be measured at a point x1 as a specific position in the first direction (e.g., the right direction of X-axis).

As shown in FIG. 7, the fluid may flow in the first direction by an electric field which is generated by power applied from the outside. Here, the charged particles contained in the fluid may exhibit different moving speeds according to Z-axis.

For example, at a middle point of the conduit 21, the charged particles may move in the first direction. However, the charged particles may flow opposite to the first direction on a lower surface of the measurement plate 100 on which the object 120 is mounted.

This is because the surface of the object has the ‘minus (-)’ charge, and ‘plus (+)’ particles adsorbed onto the surface of the object attracts the charged particles based on the ‘-’ charge. Similarly, the charged particles may move on an upper surface of the reference plate 200 in an opposite direction to the first direction.

In accordance with the fourth exemplary embodiment, the zeta-potential may be calculated based on moving speeds (or electric mobilities) of the charged particles present within the conduit 21.

In detail, a distribution of the moving speeds (or electric mobilities) of the charged particles may be measured on the Z-axis of the conduit 21, and the visual mobility Uobs(Z) of the charged particle may be calculated based on the distribution. Here, Z may denote a position of the charged particle on the Z-axis based on the upper surface of the reference plate 200.

Here, the zeta-potential corresponding to the upper surface of the reference plate 200 may be an already known value. Hence, the Uobs(Z) may have a relative value, which is contrasted with the zeta-potential corresponding to the upper surface of the reference plate 200.

Upon calculation of the Uobs(Z), the zeta-potential of the object may be calculated using a relation between the visual mobility and the zeta-potential.

According to the fourth exemplary embodiment, the Uobs(Z) may be calculated by the following Equation (Mori·Okayama Equation).

Equation 1:

where Z denotes a position of the charged particle on the Z-axis based on the upper surface of the reference plate 200, A=1/[(2/3)-(0.420166/k)], k=a/b, a denotes a vertical length of the conduit 21 (or a vertical length of the measurement plate), b denotes a thickness of the conduit 21 (or a width of a passage through which the fluid flows), Up denotes an actual mobility of the charged particle, UO denotes an average flow rate of the fluid corresponding to the lower surface of the measurement plate and the upper surface of the reference plate, and ΔUO denotes a flow rate difference of fluid corresponding to the lower surface of the measurement plate and the upper surface of the reference plate.

For example, in FIG. 7, the UO may be (U1+U2)/2, and the ΔUO may be U2-U1.

Also, according to the fourth exemplary embodiment, the zeta-potential ξ may be calculated by the following Equation.

Equation 2:

where A’ denotes a constant in which a surface area of the object is reflected, Uobs denotes an electrical mobility (observed mobility) of a particle, π denotes a circular constant (circle ratio), μ denotes viscosity of the fluid, and εd denotes permittivity.

The A’ may be a constant which may vary according to the shape of the object.

For example, when the object is formed of a planar material, the A’ may be ‘1’. However, when the object is formed of a non-planar material, the A’ may have a different value other than ‘1’ by reflecting the surface area of the non-planar material.

Therefore, when the object is the non-planar material, the A’ may indicate correction of an equation for calculating the zeta-potential.

Hereinafter, description will be given of a process of calculating the A’ when the object is a hollow fiber membrane, with reference to FIG. 8.

FIG. 8 is an exemplary view showing a method for correcting a zeta-potential measurement equation in accordance with the fourth exemplary embodiment.

An area of a typical planar material, as shown in FIG. 8(a), may be obtained by ‘k×L’. Hence, the A’ may be a ratio between the area of the planar material and the area of the non-planar material.

Also, when the object 120 is the hollow fiber membrane, the surface area of the object 120 used for the calculation of the A’ may be a half of a cylindrical surface area.

Consequently, in FIG. 8, the A’ may be decided as follows.

Referring to FIG. 8(b), the number n of hollow fiber membranes may be k/2r.

Therefore, the surface area A of the object 120 may be calculated by the following Equation.

Equation 3:

where the A’ may be π/2 because of the ratio with the area of the planar material.

Also, in accordance with a variation of the fourth exemplary embodiment, the A’ may be a value decided by a zeta-potential measurement test according to a type of an object to be measured. For example, for a hollow fiber membrane, if the zeta-potential with the highest accuracy and reproducibility is measured when A’ is 1.5 decided by the zeta-potential measurement test of the hollow fiber membrane, the A’ may be decided as 1.5. In addition to this, various methods may be applied to decision of the A’, which is obvious to a person skilled in the art.

When the measurement plate according to the exemplary embodiments is applied to the measurement of the zeta-potential of the object to be measured, accurate and reproducible zeta-potential for the non-planar material may be measured and the conventional measurement system may be used as it is.

Also, the measurement plate according to the exemplary embodiments may prevent deformation of the object to be measured during measurement, enhancing measurement accuracy.

The measurement plate according to the exemplary embodiments may be applicable to various application fields. For example, the measurement plate may be applied to at least one of a curved surface of a glass substrate for a liquid crystal display, an etched semiconductor surface, a hollow fiber membrane, textile fiber, solid (tablet), medicine and new materials.

This description is intended to be illustrative, and not to limit the scope of the claims. Many alternatives, modifications, and variations within the metes and bounds of the claims will be apparent to those skilled in the art.

Claims

A plate for measuring zeta-potential of an object to be measured, wherein the measurement plate is inserted into a conduit to face a reference plate with a spaced distance and has a receiving recess formed on a surface facing the reference plate to mount the object to be measured therein,

wherein when a fluid containing charged particles flows in a first direction in a space formed as the measurement plate faces the reference plate within the conduit, the first direction being parallel to the surface of the measurement plate facing the reference plate, the zeta-potential of the object to be measured is measured based on speeds of the charged particles moving in the first direction.
The plate of claim 1, wherein the object to be measured is formed of a non-planar material, and

wherein the receiving recess is recessed in correspondence with a shape of the object to be measured such that the object to be measured is mounted therein.
The plate of claim 1, wherein the object to be measured has a shape of a cylindrical tube having a hollow opening.
The plate of claim 1, wherein the object to be measured extends in the first direction and is mounted in the receiving recess.
The plate of claim 1, wherein the zeta-potential of the object to be measured is measured at a specific position in the first direction.
The plate of claim 1, wherein the object to be measured is provided in plurality, and

wherein the plurality of objects to be measured are mounted in the receiving recess with being spaced apart from each other in a second direction.
The plate of claim 6, wherein the first direction and the second direction perpendicularly intersect with each other.
The plate of claim 1, wherein the measurement plate comprises:

a first member having the receiving recess; and

a second member formed along an outer circumference of the first member to surround the first member,

wherein the receiving recess is formed on one surface of the first member, and

wherein the one surface of the first member having the receiving recess is exposed to the outside.
The plate of claim 8, wherein the first member and the second member are formed of different materials.
The plate of claim 1, further comprising a sealing member formed along an outer circumference of the receiving recess to surround the receiving recess.
The plate of claim 1, wherein the zeta-potential is calculated by Equation

where A’ denotes a constant in which a surface area of the object to be measured is reflected, Uobs denotes an electrical mobility of the particle, π denotes a circular constant, μ denotes viscosity of the fluid, and εd denotes permittivity.
The plate of claim 11, wherein the A’ is π/2 when the object to be measured has a shape of a cylindrical tube having a hollow opening.