JP6006984B2 - Electroadhesive element and method of manufacturing the same - Google Patents

Description

  The present invention relates to an electroadhesive element and a manufacturing method thereof, and more particularly to an electroadhesive element suitable for application to a power transmission device such as a clutch, a damper, and an actuator, a braking device, and the like, and a manufacturing method thereof.

  Conventionally, an ER fluid that exhibits a so-called electrorheological (hereinafter referred to as ER) effect in which an apparent viscosity is increased by applying a voltage is known. Since the viscosity of the ER fluid can be reversibly changed by changing the applied voltage, and the response to the change in voltage is excellent, an ER element in which the ER fluid is disposed between a pair of electrodes. In this form, it is expected to be used as an electronic component applicable to power transmission devices such as clutches, dampers, and actuators, braking devices, and the like.

  However, since the ER fluid is usually in a form in which dispersed phase particles (ER particles) are dispersed in an electrically insulating dispersion medium such as silicone oil, the ER particles settle and aggregate when left standing for a long period of time. As a result, the shear stress varies and it is difficult to obtain a stable ER effect.

  Therefore, an electroadhesive element in which an electroadhesive effect (EA effect) is obtained using ER gel so as to obtain more stable performance has been proposed (for example, Patent Documents 1 and 2 and Non-patent Documents). 1).

  Such an ER gel is composed of, for example, an electro-rheological fluid such as silicone oil, that is, a silicone gel formed by gelling the ER fluid. (Coating particles) is dispersed (see, for example, Patent Document 3).

  In addition, the inventors have found that the resin between the outermost mesh sheets has an electric adhesive force when a high voltage is applied to an element in which polymer mesh sheets are laminated and filled with a silicon resin or the like between them. (Non-patent document 2).

JP 2005-255701 A JP 2008-266407 A JP 2001-26793 A

Proceedings of the Annual Meeting of the Japan Society of Mechanical Engineers 2009 (2) (September 2009) 109-110 Precision Engineering Society 2011 Spring Conference Academic Lectures Proceedings (issued March 1, 2011) 1003-1004 H. Sato, T .; Kakinuma, J .; S. Go, S .; Shoji, “In-channel 3-D micromesh structures using masklcss multi-angle exposure and their microfilter application”, Sensors & Actuators A, Vol. 111 (2004) pp 87-92 H. Sato, T .; Kakinuma, J .; S. Go, S .; Shoji, “A novel fabrication of in-channel 3-D micromesh structure using maskless multi-angle exposure and its microfilter application”, 16th Int. Conf. On Micro Electro Mechanical

  However, since the ER gel used in the former Patent Documents 1 to 3 and Non-Patent Document 1 has a structure in which ER particles, which are fine particles, are dispersed in a silicone gel, performance varies depending on the dispersion state. In addition, since the ER particles are special as described above, there is a problem that the cost of the particles themselves is high.

  On the other hand, the electric adhesive sheet using the mesh sheet proposed in the latter non-patent document 2 can exhibit a stable electric adhesive effect and can realize a reduction in cost. It was not easy to make the surface of the pressure-sensitive adhesive sheet with irregularities within several μm, and the mesh sheet itself was bent by heat treatment, so that a surface with high flatness was not obtained, and a wide pressure-sensitive adhesive area was not obtained.

  Non-Patent Documents 3 and 4 propose a multi-tilted back exposure method for producing a micro / nano precision three-dimensional fine network structure using photolithography technology. It has only been considered to use the fine mesh structure as it is as a microfluidic control element such as a microfilter or a microreactor.

  The present invention has been made to solve the above-mentioned conventional problems, and realizes a stable mechanical structure with high surface accuracy and can exhibit a stable electroadhesive effect and its manufacture. It is an object to provide a method.

The present invention includes a substrate having an electrode, are regularly densely arranged and fixed on a substrate, filled to fill a plurality of rod-shaped fine struts, the struts on the substrate, high having viscoelasticity molecular substance consists, the substrate of the struts on the opposite side and cross-section having countless projections are arranged on the surface of the polymeric material, the substrate of the strut surface opposite with electric adhesion The above-mentioned problem is solved by an electroadhesive element characterized by the above.

  Here, the support column may be an inclined support column that is formed obliquely with respect to the surface of the substrate and intersects with each other.

  In addition, a three-dimensional fine network structure in which the intersections of the inclined pillars farthest from the substrate are aligned with the surface of the polymer substance can be obtained.

Further, the structure angle formed by the support with respect to the surface of the substrate can be set to 30 degrees or more and less than 90 degrees.

The present invention also includes a step of manufacturing a plurality of rod-shaped fine pillars regularly and densely arranged and fixed on a substrate by a back exposure method, and a polymer material having viscoelasticity on the substrate. A method of manufacturing an electroadhesive element in which the surface of the support column opposite to the substrate has an electric adhesive force. is there.

  Here, a three-dimensional fine network structure in which unit units having inclined columns that are formed obliquely with respect to the surface of the substrate are repeated along the surface of the substrate is obtained by a multiple inclined back exposure method. By manufacturing, the post can be formed.

  The polymer substance may be silicone gel, urethane rubber or butadiene rubber.

  The substrate can be a transparent substrate.

  The substrate may be a substrate that also serves as one electrode.

  In the present invention, for example, by using a three-dimensional fine network structure manufactured by a multiple inclined back exposure method, a stable surface shape is realized, so that not only a wide adhesive area compared to ER gel is obtained, but also tertiary Since the original fine mesh structure plays the role of a framework, the mechanical strength is also improved. Therefore, a stable mechanical structure with high surface accuracy can be realized, and a stable electroadhesive effect can be realized with a simple manufacturing method.

The flowchart which shows the procedure of embodiment of the 1st manufacturing method of the electroadhesive element which concerns on this invention Sectional drawing which similarly shows the 1st manufacturing process Photograph showing an example of the manufactured three-dimensional fine network structure The figure which shows the effect | action of embodiment of the electroadhesive element which concerns on this invention. The top view which shows the example which also confirmed the adhesion phenomenon The figure which similarly shows the measurement result of adhesive strength The figure which similarly shows the example of the relationship between the position of the surface of a three-dimensional fine network structure, and the intersection of an inclined support | pillar Diagram showing analysis model for structural angle Figure showing comparison of structural angle and change in electric field strength Diagram showing analysis model for distance between intersections Figure showing comparison of distance between intersections and change in electric field strength The flowchart which shows the procedure of embodiment of the 2nd manufacturing method of the electroadhesive element which concerns on this invention Sectional drawing which similarly shows the 2nd manufacturing process

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 (flow chart) and FIG. 2 (cross-sectional view showing the manufacturing process) show a first manufacturing method of the electroadhesive element 25 according to the present invention.

  First, in step 100 of FIG. 1, as shown in FIG. 2A, a metal is vapor-deposited on a transparent substrate (for example, a glass substrate) 10 and patterned to form a photomask 12. This photomask 12 determines the shape of the column 21 constituting the three-dimensional fine mesh structure (also referred to as a three-dimensional mesh structure) 20. This photomask 12 also serves as one electrode when the EA effect is exhibited later.

  The metal to be deposited is chromium, for example, but other metals such as aluminum and copper may be used. In addition, the photomask 12 is desirably smaller than the transparent substrate 10 in consideration of the uniformity of thickness at the time of applying a resist, which will be described later. In the present embodiment, the cross-sectional shape of the support column 21 is not particularly limited, and may be circular or square.

  Next, the process proceeds to step 110 in FIG. 1, and as shown in FIG. 2B, a photoresist (for example, SU-8, which is a thick film resist for forming a high aspect ratio structure generally used in the MEMS field) 14 is formed. For example, it is applied by spin coating and a baking process is performed. The photoresist 14 is applied to the photomask 12 side of the transparent substrate 10. The thickness of the photoresist 14 is determined in consideration of the height of the support column 21 and the structure angle θ.

Next, the routine proceeds to step 120, where the transparent substrate 10 is provided with an inclination (θ _{1 in the} figure) corresponding to the structure angle θ that is an angle formed by the support column 21 with respect to the substrate surface, and the transparent substrate 10 on which the photoresist 14 is placed. Electromagnetic waves are irradiated from the back side (side where the photomask 12 does not exist). Here, the electromagnetic wave may be of a wavelength that can cure the photoresist 14, and does not depend on the type. For example, visible light and ultraviolet light can be raised. If it is SU-8 of a present Example, the ultraviolet-ray with a wavelength of about 350-400 nm is suitable.

Next, when further irradiating the electromagnetic wave, the process proceeds to step 130, the inclination angle is changed to θ ₂ , for example, and the process returns to step 120 to repeat the irradiation of the electromagnetic wave at a necessary angle / number of times ((c) and (d in FIG. 2). 2)). In FIG. 2, the struts 21 are formed only in the one-dimensional direction, but it goes without saying that the struts 21 may be formed in the two-dimensional direction by repeating irradiation of electromagnetic waves three or more times.

The magnitude of the tilt angle (θ ₁ , θ _2, etc.) is appropriately selected depending on the structure angle θ, the length of the support column 21, the material of the applied photoresist 14, the material of the transparent substrate 10, and the like. The structural angle θ needs to be 30 ° or more in order to obtain EA characteristics. More preferably, it is 60 ° or more. Further, when the structural angle θ is 90 °, the support column 21 is not inclined, but if there is no problem in the strength of the support column, the structural angle θ may be 90 °.

  When it is determined in step 140 that the irradiation of electromagnetic waves has been completed, the process proceeds to step 150, where the photoresist 14 is developed, and as shown in FIG. A body 20 is obtained. In this figure, one inclined strut 21 intersects with a plurality of other inclined struts 21. As a result, there are a plurality of intersections 22, but even if the inclined strut 21 intersects with another one inclined strut 21. That is, the number of intersections may be one.

  By performing multiple exposures by the multiple inclined back exposure method used here, a three-dimensional mesh structure 20 in which fine inclined columns 21 intersect can be produced. An example of the manufactured three-dimensional mesh structure 20 is shown in FIG.

  The three-dimensional mesh structure 20 is produced in various shapes by changing the thickness of the photoresist 14, the pattern of the photomask 12 (the diameter and interval of the columns 21, the arrangement pattern of the columns 21), the exposure angle, and the number of exposures. Is possible. Moreover, although it is a very simple method, since there is no gap between the transparent substrate 10 and the photoresist 14, a pattern accuracy equivalent to that of contact exposure can be obtained. In addition, the method of manufacturing the three-dimensional mesh structure 20 is not limited to this.

  Next, the routine proceeds to step 160, and as shown in FIG. 2 (f), the gap between the three-dimensional mesh structure 20 is filled with, for example, the silicone gel 23, whereby the electroadhesive element 25 is obtained. In filling the silicone gel 23, a frame or the like may be provided outside the three-dimensional mesh structure 20 as necessary. The silicone gel 23 is filled with an appropriate amount so that the intersection 22 of the inclined column 21 is slightly above the surface of the silicone gel 23. If the intersection 22 is not slightly above the surface of the silicone gel 23, the EA effect cannot be exhibited sufficiently.

  The silicone gel 23 can be formed by cross-linking silicone oil with a cross-linking agent and gelling.

Examples of the silicone oil include dimethyl silicone oil, fluorine-modified silicone oil, and phenyl-modified silicone oil. These may be used alone or in combination of two or more. Examples of the fluorine-modified silicone oil include polysiloxane having a trifluoropropyl group (CF ₃ C ₂ H ₄ —), polysiloxane having a nonafluorohexyl group (C ₄ F ₉ C ₂ H ₄ —), and cyclic poly Examples include siloxane compounds.

  As the crosslinking agent, for example, acetylene having an unsaturated bond, ethylene, propylene, butadiene, isoprene, isocyanate and the like are used.

  In addition to silicone gel, it is also conceivable to use viscoelastic urethane rubber or butadiene rubber.

  In the three-dimensional mesh structure 20, it can be assumed that the intersection (the apex in the case of θ = 90 °) of the surface of the polymer material (here, the silicone gel 23) of the inclined column 21 is an alternative to the ER particles. Moreover, since it is a three-dimensional structure using a photolithography technique, there is no bending of the mesh sheet due to heat treatment, which is a problem of the electroadhesive (EA) element using the mesh sheet proposed in Non-Patent Document 2. The accuracy of the height of the three-dimensional mesh structure 20 depends on the accuracy of the resist film thickness to be applied. However, if spin coating is used, the accuracy of the resist film thickness is greatly improved. A surface with much higher accuracy than that of the EA element can be obtained.

  When a voltage is applied between the upper and lower electrodes to the electroadhesive element 25 thus manufactured, the silicone gel 23 rises so as to cover the surface of the intersection 22 as shown in FIG. Sex is obtained.

  A glass electrode (also referred to as an upper electrode) (not shown) is placed on the produced electroadhesive element 25, a voltage is applied between the transparent electrode (electrode) 10 serving also as the photomask 12 and the glass electrode, and an optical microscope ( When the surface condition was observed using a magnification of 450 times, an instantaneous and reversible electroadhesion phenomenon was confirmed as shown in FIG. By changing the resist film thickness, the applied voltage at which the adhesion phenomenon can be confirmed can be adjusted.

  The measurement result of adhesive force is shown in FIG. It was confirmed that the adhesive force increased in proportion to the applied electric field. Here, the adhesive force is a value of a shearing force per unit area when the electric adhesive element 25 is fixed and the upper electrode (glass electrode) is slid at a constant speed.

  Further, when the relationship between the surface of the three-dimensional mesh structure 20 and the intersecting point 22 farthest from the transparent substrate 10 of the inclined column 21 (at the top of the figure) is examined, as shown in FIG. Good adhesion was obtained when 22 matched. On the other hand, when the surface is above the intersection point 22 as shown in FIG. 7B, or when the surface is below the intersection point 22 as shown in FIG. Was inferior.

  In order to investigate the influence of the structural angle θ, the electric field distribution was analyzed for θ = 60 ° shown in FIG. 8A and θ = 80 ° shown in FIG. 8B. The analysis conditions are shown in the following table.

  When the relationship between the electric field strength and the distance from the silicone gel surface was measured in the case of the structural angle θ = 60 ° and 80 °, the relationship shown in FIG. 9 was obtained.

  As described in Non-Patent Document 1, when an electric field acts on the dielectric surface, the magnitude of the force generated on the dielectric surface basically depends on the electric field strength. The same applies to the force acting on the surface of the resist support according to the present invention. Looking at FIG. 9 showing the y-direction component perpendicular to the silicone gel surface, the electric field strength increases as the shape approaches the upper electrode in either shape, but the shape with a structural angle θ of 60 ° is closer to the apex. The electric field strength is strong. This indicates that the EA effect obtained depends on the size of the structural angle θ, but the EA effect occurs at any angle. If the structural angle θ is 30 ° or more, the EA effect is exhibited.

  The number of support columns 21 per unit is preferably 3 or more in order to ensure mechanical strength, but is not limited to 3 and is filled with 4 or more or a polymer substance such as silicone gel. Therefore, it may be two or less. When the structural angle θ is 90 °, the support column 21 does not incline but stands upright on the transparent substrate 10. Even in this case, the EA effect is exhibited on the surface of the silicone gel 23. Therefore, only one support column 21 may be used as long as it stands upright.

  Furthermore, in order to consider the influence of the distance a between the intersections 22 (vertices in the figure) of the inclined support columns 21, the distance a between the intersections is changed, and the delta type shown in FIG. 10A and FIG. The electric field distribution was analyzed using the two cross-type models shown. In FIG. 11A (delta type) and FIG. 11B (cross type), the vertical axis represents the electric field strength, and the horizontal axis represents the distance from the surface of the silicone gel. In both figures, although there are some errors, it can be seen that the values are almost the same. From this, it is considered that there is almost no influence on the electric field intensity even if the intersection distance is changed.

  FIG. 12 (flow chart) and FIG. 13 (cross-sectional view showing the manufacturing process) show a second manufacturing method of the electroadhesive element 25 according to the present invention. The difference from the first manufacturing method is that the electroadhesive element 25 is produced on a substrate 50 different from the transparent substrate 10. The substrate 50 also serves as one electrode.

  Specifically, first, in step 200 of FIG. 12, as shown in FIG. 13A, the photoresist 14 is applied on the substrate 50 to be the lower electrode by, for example, spin coating, and a baking process is performed.

  Next, the process proceeds to step 220, and as shown in FIG. 13B, the photoresist 14 of the substrate 50 turned upside down is brought into close contact with the transparent substrate (for example, glass substrate) 10 on which the photomask 12 has been formed.

Next, the routine proceeds to step 230, and as shown in FIG. 13C, the transparent substrate 10 is provided with an inclination (θ _{1 in the} figure) corresponding to the structural angle θ that is an angle formed by the support column 21 with respect to the substrate surface. An electromagnetic wave, for example, an ultraviolet ray is irradiated from the back side (the lower side of the figure) of the transparent substrate 10 on which the resist 14 is placed.

Next, the process proceeds to step 240, and as shown in FIG. 13 (d), the inclination angle is changed to, for example, θ ₂ and the process returns to step 230 to repeat the irradiation of ultraviolet rays at the required angle and number of times ((c) ( d) twice).

  When it is determined in step 250 that the necessary number of irradiations of ultraviolet rays has been completed, the process proceeds to step 260 where the photoresist 14 is developed to obtain the three-dimensional mesh structure 20 composed of the columns 21.

  Next, the process proceeds to step 270, the unnecessary transparent substrate 10 and photomask 12 are removed, and the three-dimensional mesh structure 20 as shown in FIG. 13E is completed.

  Next, the process proceeds to step 280, and as shown in FIG. 13 (f), the gap between the three-dimensional mesh structure 20 is filled with a polymer substance such as silicone gel 23, whereby the electroadhesive element 25 is obtained.

  According to this method, the photomask 12 can be used a plurality of times, and the first manufacturing method eliminates the need for a photomask manufacturing process that is required every time the electroadhesive element is manufactured, thus simplifying the manufacturing process. And the effect of cost reduction can be obtained.

DESCRIPTION OF SYMBOLS 10 ... Transparent substrate 12 ... Photomask 14 ... Photoresist 20 ... Three-dimensional fine mesh (three-dimensional mesh) structure 21 ... Support | pillar 22 ... Intersection 23 ... Silicone gel 25 ... Electroadhesive element 50 ... Substrate θ ... Structural angle a ... Intersection space

Claims (12)

A substrate having an electrode, are regularly densely arranged and fixed on a substrate, filled to fill a plurality of rod-shaped fine struts, the struts on the substrate, a polymer material having viscoelasticity, Consists of
A cross section having innumerable protrusions on the side opposite to the substrate of the support column is arranged on the surface of the polymer substance,
An electroadhesive element characterized in that the surface of the support opposite to the substrate has an electroadhesive force.   The electroadhesive element according to claim 1, wherein the support columns are inclined support columns that are formed obliquely with respect to the surface of the substrate and intersect each other.   3. The electroadhesive according to claim 2, wherein an intersection point of the inclined column that is farthest from the substrate is a three-dimensional fine network structure that is arranged in alignment with the surface of the polymer substance. element.   The electroadhesive element according to claim 2 or 3, wherein a structural angle formed by the support with respect to the surface of the substrate is 30 degrees or more and less than 90 degrees.   The electroadhesive element according to any one of claims 1 to 4, wherein the polymer substance is silicone gel, urethane rubber, or butadiene rubber.   The electroadhesive element according to claim 1, wherein the substrate is a transparent substrate.   The electroadhesive element according to claim 1, wherein the substrate is a substrate that also serves as one of the electrodes. A step of manufacturing a plurality of rod-shaped fine columns regularly and densely arranged and fixed on the substrate by a backside exposure method,
Filling the substrate with a polymer material having viscoelasticity so as to embed the struts;
A method of manufacturing an electroadhesive element , wherein the surface of the support opposite to the substrate has an electric adhesive force .   Manufacturing a three-dimensional fine network structure in which unit units having inclined support columns formed obliquely with respect to the surface of the substrate are repeated along the surface of the substrate by a multiple inclined back exposure method The method of manufacturing an electroadhesive element according to claim 8, wherein the support column is formed by:   The method for producing an electroadhesive element according to claim 8 or 9, wherein the polymer substance is silicone gel, urethane rubber, or butadiene rubber.   The method for manufacturing an electroadhesive element according to claim 8, wherein the substrate is a transparent substrate.   The method for manufacturing an electroadhesive element according to claim 8, wherein the substrate is a substrate that also serves as one electrode.