KR102659165B1 - Method for creating a prosthetic finger based on digital techniques - Google Patents

Abstract

A digital method for producing a finger prosthesis is disclosed. The disclosed digital finger prosthesis manufacturing method includes a three-dimensional shape acquisition step of acquiring a three-dimensional shape for forming a finger prosthesis using photography and photogrammetry; A mold manufacturing step of manufacturing a mold for forming a finger prosthesis using the acquired three-dimensional shape; A finger prosthesis forming step of forming a finger prosthesis using the manufactured mold; And a post-processing and coloring step of post-processing and coloring the molded finger prosthesis, wherein the three-dimensional shape acquisition step includes using the zoom-in and zoom-out functions to adjust the size differently, and the finger of the subject to which the size measurement indicator is attached. A photographing step of taking pictures so that the features overlap from various angles, a matching step of extracting and connecting the feature points of the overlapping area through a matching process of the captured photos, and converting the feature points of the matched region into coordinates in 3D space to create a point cloud. It includes a step of forming point cloud data and a step of generating a three-dimensional shape of the finger based on the generated point cloud data.

Description

Method for creating a prosthetic finger based on digital techniques}

The present invention relates to a method of digitally manufacturing a finger prosthesis using photogrammetry.

Patients who have lost part of a finger can use a finger prosthesis. Typically, finger prostheses are used when the thumb or other fingers below the proximal phalanx are lost.

Meanwhile, the human hand is the part of the body that is most used in daily life, and the finger prosthesis worn is also bound to be easily worn and contaminated due to contact and friction with the outside. The finger prosthesis is made of silicone, which is harmless to the human body and can express the texture and color most similar to human skin because it is made for aesthetic purposes without function and is used by inserting it in the form of a thimble. However, if used for a long time, it becomes dirty, so it must be replaced periodically after a certain period of use.

Most amputees want the prosthesis to be similar in appearance to their remaining body parts and to be inexpensive. However, custom implants made by hand are bound to be priced high, putting an economic burden on the client. In order to produce implants with uniform quality variations without relying on individual skill levels, digital processes must be introduced, which can lower production costs.

In addition to aesthetic prostheses for finger amputees, research is being actively conducted to develop functional prostheses that incorporate robotic technology to complement the functional aspects of the fingers. The functional type can be divided into an electric type for completely amputated fingers or fingers that cannot perform their functions, and a passive type that utilizes the movement of some remaining joints. In the end, the result of combining the aesthetic type and the functional type is the psychological satisfaction of the client. and may help with physical improvement. Aesthetic prostheses manufactured through digital processing methods can contribute to enhancing aesthetics by producing a surface that merges with the functional prosthesis body because the finished prosthesis shape exists in three-dimensional space.

In relation to this, Prototech Co., Ltd. (https://www.prototech.co.kr:40007), a 3D printing 3D printer total solution company, has produced the color and texture of a human body model with a polyJet 3D printer. was promoted, and the material used at this time was a photocurable liquid resin made of rubber (soft). In the future, if continuous technological development allows printing with materials that are harmless to the human body and affordable and supplied to the market, the value of using digital work methods can increase. 3D shapes can also be greatly utilized for promotions in online spaces. An example is plica (https://www.plicar.io), which produces 3D realistic content for online shopping.

Research related to the production of finger prostheses can be research on the development of functional prosthetics, or patents on the production of aesthetic prosthetics can be found.

A technology to replicate the body part corresponding to the amputated area using 3D scanning technology has been proposed. However, since the 3D shape obtained through 3D scanning must go through a registration and editing process, professional personnel must be used, resulting in additional labor costs.

Registration number 10-0338835 (May 20, 2002)

The problem to be solved by the present invention is to provide a method of digitally manufacturing a finger prosthesis using photogrammetry.

A method of manufacturing a digital-based finger prosthesis according to one aspect of the present invention includes a three-dimensional shape acquisition step of acquiring a three-dimensional shape for forming a finger prosthesis using photography and photogrammetry; A mold manufacturing step of manufacturing a mold for forming a finger prosthesis using the acquired three-dimensional shape; A finger prosthesis forming step of forming a finger prosthesis using the manufactured mold; And a post-processing and coloring step of post-processing and coloring the molded finger prosthesis, wherein the three-dimensional shape acquisition step includes using the zoom-in and zoom-out functions to adjust the size differently, and the finger of the subject to which the size measurement indicator is attached. A photographing step of taking pictures so that the features overlap from various angles, a matching step of extracting and connecting the feature points of the overlapping area through a matching process of the captured photos, and converting the feature points of the matched region into coordinates in 3D space to create a point cloud. It includes a step of forming point cloud data and a step of generating a three-dimensional shape of the finger based on the generated point cloud data.

The form production step includes converting the 3D shape data acquired in the 3D shape acquisition step into a 3D model, printing the converted 3D model with a 3D printer, and measuring the size measurement index and actual size attached to the output 3D model. Comparing measurement indices, inverting the converted 3D model to create a 3D model of the finger prosthesis, reinforcing wrinkles, fingernails, or fingerprints or correcting the shape before or after inverting the 3D model, and creating a finger prosthesis It includes the steps of generating a formwork 3D model by applying difference modeling to the 3D model, and printing the formwork 3D model with a 3D printer to produce a formwork. The finger prosthesis forming step includes adding silicone rubber to the formwork. It is swollen and then hardened to form a finger prosthesis.

The post-processing and coloring step includes forming a fabric overlay, wherein an elastic ring-shaped fabric is overlaid on a pre-printed finger model, and a condensation reaction is applied to the fabric overlaid on the finger model. Apply silicone, insert the finger prosthesis formed in the finger prosthesis forming step onto the condensation-type silicone applied on the cloth, and cure the condensation-type silicone in a heated storage.

The present invention is easy to reflect the client's modification requirements during work because the three-dimensional shape of the finger prosthesis exists in virtual space. In addition, during the process of producing a finger prosthesis, work time can be reduced because molding results can be quickly transformed using a computer.

1 is a flowchart for generally explaining the method of manufacturing a digital-based finger prosthesis according to an embodiment of the present invention;
Figures 2 (A) and (B) are photos showing the hands of person A and person B to which the finger prosthesis will be applied, respectively.
Figures 3 and 4 are for explaining the three-dimensional shape acquisition step for forming a finger prosthesis using photography and portgrammetry;
Figure 5 is an image to sequentially explain the process of making a mold for forming a finger prosthesis;
Figure 6 is a photographic image to explain the process of forming a finger prosthesis using a mold;
Figure 7 is a photograph showing the process of forming the cloth padding on the finger prosthesis;
Figure 8 is photos showing the coloring process for the silicone prosthesis.

The advantages and features of the present invention and methods for achieving them will become clear by referring to the embodiments described in detail below along with the accompanying drawings.

However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms.

The examples herein are provided to make the disclosure of the present invention complete and to fully inform those skilled in the art of the scope of the invention.

And the present invention is only defined by the scope of the claims.

Accordingly, in some embodiments, well-known components, well-known operations and well-known techniques are not specifically described in order to avoid ambiguous interpretation of the present invention.

In addition, the same reference numerals refer to the same elements throughout the specification, and the terms used (mentioned) in the specification are for explaining embodiments and are not intended to limit the present invention.

In this specification, the singular also includes the plural unless specifically stated in the phrase, and elements and operations referred to as 'including (or, including)' do not exclude the presence or addition of one or more other elements and operations. .

Unless otherwise defined, all terms (including technical and scientific terms) used in this specification may be used with meanings that can be commonly understood by those skilled in the art to which the present invention pertains.

Additionally, terms defined in commonly used dictionaries are not interpreted ideally or excessively unless they are defined.

Hereinafter, preferred embodiments of the present invention will be described with reference to the attached drawings.

Referring to Figure 1, the digital-based finger prosthesis manufacturing method according to an embodiment of the present invention includes a three-dimensional shape acquisition step ( S10 ) for forming a finger prosthesis using a photograph, and a finger prosthesis using the acquired three-dimensional shape. It includes a step of manufacturing a mold for forming a prosthesis (S20), a step of forming a finger prosthesis using the manufactured mold (S30), and a step of coloring a finger prosthesis (S40).

As a preliminary step to producing a finger prosthesis, two subjects were selected.

The hand shape of people who have lost part of a finger is not uniform, but without considering the absence of a specific finger out of the five fingers for one hand, two people with a hand that has lost the proximal phalanx or lower or the middle phalanx of one finger are eligible. was selected.

Figures 2 (A) and (B) are photographs showing the hands of person A and person B to which the manufactured finger prosthesis will be applied. The hand shape of a person who has lost part of a finger is not uniform, but without considering the absence of a specific finger out of the five fingers for one hand, two people with a hand that lost the proximal phalanx or lower or the middle phalanx of one finger were applied. Subject A and applicable subject B were selected. Applicable person A is a person who has lost the middle phalanx or lower of the second finger of the right hand, and applicable subject B is a person who has lost the proximal phalanx or lower of the third finger of the left hand.

1. Acquisition of 3D shape for finger prosthesis molding

For Subject A and Subject B, pictures were taken using a digital camera focusing on the normal hand and the hand with the amputation site. The camera was fixed on a tripod and then connected to a dolly to make it easy to move without shaking. A circle was drawn on the floor centered on the chair on which the subject was sitting, the shooting points were divided and marked at equal intervals, and the image was taken by rotating it 360° around the y-axis of the subject so that a certain portion of the image overlapped. At this time, using the camera's zoom in and zoom out functions, each point was photographed three times so that the size of the photographed object was different, and the photograph shown in Figure 3 was obtained. In Figure 3, A-1 represents the right hand of person A, A_2 represents the left hand of person A, B_1 represents the right hand of person B, and B_2 represents the left hand of person B.

The accessibility of commercially available 3D scanner equipment is very low in many ways, including high price, low portability, incompatible software, and the requirement for expert knowledge to use the equipment. On the other hand, photogrammetry, which implements 2D photos taken from various directions and angles into 3D models, produces results through a 3D scanner without any additional equipment, as long as you have a tool that can acquire images such as a digital camera. It has the advantage of being able to obtain 3D modeling results at a similar level. In addition, photogrammetry was mainly used in the modeling process of extensive terrain, but recently it has also been widely used in modeling relatively small objects such as human or animal models. Because it is possible to produce 3D model data faster and more quickly than the production process through the traditional 3D modeling process, the scope of use of 3D modeling production methods based on photogrammetry technology is expanding to various areas.

Photogrammetry, which was generally used to create a 3D shape by taking pictures for surveying in the architectural or civil engineering fields, captures the motion of moving objects with the development of equipment and software technology that can acquire 3D information, creating virtual reality or augmented reality. It is progressing to the stage of creating reality. In order to restore 3D volumetric models of stationary and moving objects that are temporally related to the movements of people or animals in complex dynamic situations, a 3D volumetric capture system is used to set up multiple cameras and lights in advance and then shoot simultaneously. .

Although it is efficient to use a 3D volumetric capture system not only for moving objects but also for creating three-dimensional shapes at rest, it is not a facility equipment that can be purchased and used by individuals. Objects that cannot be fixed for a long time, such as people, are photographed instantaneously to create 3D data and create digital actors or virtual rests. However, if the area being photographed is part of the body, the 3D model can be restored with a single camera with the cooperation of the photographed subject. There are research results showing that. However, since the subject must not move during the filming period, a filming method that produces the best results in the minimum amount of time must be found.

As a result of matching images taken under different conditions with one camera, the height of the camera, which becomes the z-axis when rotating 360° around the y-axis of the subject's finger, was positioned upward so that it was not parallel to the end of the subject's finger. You have to do it. A circle with a diameter of 3m was drawn on the floor, and 32 shooting points were divided and marked at equal intervals. It was confirmed that 96 photos taken 3 times with different subject sizes for each 32 points generated the most accurate point cloud data (Figure 4).

Compared to the second finger, which can be photographed independently by holding one finger upright at a 90° angle, it is difficult to hold the third finger upright at a 90° angle, so it was photographed together with the other fingers with the fingers spread straight out and apart. For the third finger, there were areas where the point cloud data was not fully generated due to shadows caused by other fingers around it, so it was necessary to secure incomplete information through separate photography. Applicants must sit or lie down and lean on an object to support their hands, as they must keep their fingers still while filming is taking place. At this time, the camera must be fixed to a tripod and dolly to prevent it from shaking and then moved, so a distance of more than 1m is required between the subject and the camera. Therefore, when taking photos, the photos were taken with the shortest focusing distance of 1.2m and a telephoto lens with a focal length of 70-300mm. Photos should be taken with a wide overlapping range so that there are two or more feature points with the same correlation in the image. Foundation is applied to the surface of the target finger and then powder coated to create a skin-specific look. Reflection and scattering of light due to the translucent material must be minimized. Photos must be taken as quickly as possible while focusing on the target finger to generate high-density point cloud data without distorting the shape.

The generated point cloud data can be transformed into a mesh, exported, and then edited through a graphics program.

The ZBrush program is easy to edit because 3D data comes in solid solid form. At this time, 3D data larger than 1.5 GB cannot be loaded when loading in the file format OBJ, so if the capacity is large, you must reduce the capacity by running the Simplify tool menu in the RealityCapture program. The menus and task sequence used when building a 3D shape using Reality Capture are shown in [Table 1] below.

[Table 1]

In summary, the three-dimensional shape acquisition step for forming a finger prosthesis involves taking pictures of the subject's fingers under various conditions and angles while using the zoom-in and zoom-out functions to adjust the size differently, and matching the taken pictures. a matching step of extracting and connecting feature points in overlapping areas, a point cloud data forming step of converting feature points of the matched region into coordinates in 3D space to form point cloud data, and determining the target's normal hand based on the generated point cloud data. and generating a three-dimensional shape of the hand with the amputation site. To create a 3D shape, software that can three-dimensionally match photos is used. At the photo taking stage, the overlapping range is wide so that at least two feature points with the same correlation exist in the photo image for each of the subject's normal hand and the amputated hand. In the registration stage, feature points of the area are extracted to integrate multiple photos taken into one coordinate system, and the position and direction of each photo are adjusted based on this. Software for 3D shape creation converts point cloud data into a mesh and reconstructs the surface to create a 3D model. Additional processing, such as texture mapping based on point cloud data, can also be performed at this stage.

2. Manufacturing mold for finger prosthesis molding

The three-dimensional shapes of the normal hand and the amputated finger obtained for the finger prosthesis of subjects A and B were acquired, respectively. The three-dimensional shape of the finger corresponding to the amputated area is created by mirroring based on the x-axis using the ZBrush (ZBrush 2022) program to resemble the finger of the amputated area. At this time, there may be work to adjust the shape of the finger of the amputated area to fit the 3D shape of the amputated area obtained in advance.

Afterwards, modeling for the difference set was used as a sub function to enable slush molding of the finger shape of the amputated area rather than injection molding, and a mold was produced and extruded. Printed using an FDM 3D printer. In other words, a mold is produced by using the sub function to model the shape of the amputated finger as a difference set suitable for slush molding. The mold produced in this way was designed to be used for slush molding, not injection molding. The formwork is printed using an extrusion type (FDM) 3D printer.

Since the human body has functional movements for each part of the body that allow it to move in the most efficient way, it is said that for rehabilitation treatment to be effective, casts or prostheses must be made and worn to fit these movements. This is called a functional position, and the dictionary definition is “a posture in which functional impairment is minimal when performing various movements even if the joints do not move in that position.” A person's fingers do not always remain straight, but are naturally bent. When you raise your wrist with the back of your hand facing upward, your wrist and fingers naturally bend, which is an example of a functional position. Therefore, a finger prosthesis must be manufactured to fit this functional position.

Applicant A has no experience wearing a finger prosthesis, and Applicant B has experience wearing one. Applicant A has lost the middle phalanx or lower of the second finger of his right hand. If the product is manufactured so that the border touches the middle phalanx area, it must be fixed with adhesive when worn. Adhesives are inconvenient to use, and the interface is easily worn during attachment and detachment, shortening the lifespan and increasing the possibility of loss. Therefore, it must be made to go up to the proximal phalanx area and then fixed by wearing a ring or gloves, but since it is worn over the original finger, it is bound to be uncomfortable if it is made in a curved shape. Applicant B has lost the proximal phalanx of the third finger of his left hand and has no problems wearing a curved finger prosthesis.

For mold production, if you want to print an OBJ file imported into Zbrush at the same size as the actual size using a 3D printer, attach the cubes together and print the photographed cubes at 20mm in width x length x height. Just set the y and z axis lengths.

At this time, the setting value is not absolute, so it must be checked again if the photo used for registration changes.

To mold the finger prosthesis, silicone was poured into a mold and hardened, but the thickness of the silicone had to vary depending on the location and shape of the cut surface of the finger. Applicant A had to be worn by attaching it to an existing finger like a thimble, so it needed to be molded as thin as possible.

The STL file exported from Zbrush with the size ratio set to 100mm was the same as the actual size when printed after setting the y-axis length to 89mm in the slicing program. Afterwards, the form is designed using the 3D shape data through difference modeling. The output size of the mold used for silicone molding is 106mm.

In the case of Applicant B, a thickness was needed to maintain the shape of the prosthesis with an empty interior. The STL file exported with the size ratio set to 100mm in Zbrush was the same as the actual size when printed after setting the y-axis length to 112mm in the slicing program. However, the output size of the mold used for silicone molding is 85mm. Applicant A said that it was inconvenient to tighten the prosthesis when wearing it, so the mold had to be made larger, but Applicant B preferred that the joints be moderately tight and small in size so as not to be noticeable, so the mold had to be made small. In the end, the setting value that can output the same size as the actual size of the scanned finger cannot be applied to the mold output, so it is important to find the setting value of the mold that can mold silicon to suit the client's situation.

Applicant A had the second finger of his left hand, which corresponds to the amputated area, bent to one side. After temporarily wearing the manufactured prosthesis, he hoped that the curved shape would be corrected, and Applicant B manufactured it in a curved form and temporarily worn it, but the prosthesis was temporarily worn. The hope was to produce it in a curved shape. The ZBrush program can move, scale, and rotate using the gizmo 3D menu with a mask applied, so it meets the modification requirements of the applicator. It was easy to reflect and quickly produce results.

Figure 5 is a series of photographs to sequentially explain the formwork production process.

In Figure 5, A_1 to A_12 are photos to sequentially explain the process of manufacturing the form for manufacturing the finger prosthesis for the applicable person A, and in Figure 5, B_1 to B_12 sequentially explain the process of manufacturing the form for manufacturing the finger prosthesis for the applicable person B. These are photos for this purpose.

Each A_1 represents a photograph measuring the dimensions of the size measurement index used to acquire the three-dimensional shape of the amputated finger of Applicant A, A_2 represents the finger scanning data of Applicant A, and A_3 represents 3D printing using the scanning data. The results are shown, A_4 shows the process of checking the output size for comparison with the size of the measurement index, and A_5 shows the three-dimensional shape of the finger inverted and wrinkles, fingernails, and fingerprints reinforced in Zbrush to form the finger prosthesis of person A. A_6 represents the front of the shape-corrected finger prosthesis form in ZBrush, A_7 represents the back side of the shape-corrected finger prosthesis form, A_8 to 10 represent cube insertion as a previous step for difference modeling in Zbrush, A_11 represents the mold modeling results for the molding of the finger prosthesis applied to the amputated affected area of Applicant A by difference set in Zbrush, and A_12 represents the output results of the form for molded finger prosthesis applied to the amputated affected area of Applicant A.

In addition, B_1 each represents a photograph measuring the dimensions of the size measurement index that was used to acquire the three-dimensional shape of the amputated finger of subject B, B_2 represents the finger scanning data of subject B, and B_3 represents a photograph using the scanning data. B_4 represents the 3D printing results, B_4 represents the process of checking the output size for comparison with the size of the measurement index, and B_5 represents the inversion of the 3D shape of the finger, wrinkles, fingernails, and fingerprints in Zbrush to form the finger prosthesis of Applicant A. B_6 represents the side of the finger prosthesis shape corrected in ZBrush, B_7 represents the front of the finger prosthesis shape corrected in ZBrush, and B_8~10 represent cube insertion as a previous step for difference modeling in ZBrush. B_11 represents the result of mold modeling for forming the amputated finger prosthesis of Applicant B by difference set in Zbrush, and B_12 represents the output result of the mold for forming the amputated finger prosthesis of Applicant B.

The types of programs, menus, and work sequences used when producing the form are shown in [Table 2].

[Table 2]

Referring to Table 2 and Figure 5, the mold manufacturing steps for finger prosthesis molding include an imaging step, a registration step, a point cloud data forming step, and a three-dimensional image of a normal hand acquired by generating a three-dimensional shape based on the point cloud data. It includes the step of loading finger shape data, printing the finger, and checking the size. In addition, the mold making step includes deleting the cube used as a size measurement indicator in 3D data in ZBrush, and inverting the size-confirmed finger data with ZBrush's mirroring tool to select the finger corresponding to the applied area, that is, It includes obtaining finger prosthesis shape data (finger prosthesis model). At this time, a step of reinforcing wrinkles, fingernails, and fingerprints may be performed using tools in Zbrush before or after inversion of the shape data. Additionally, a step of correcting the shape of the finger prosthesis shape obtained by the inversion operation may be further performed. In addition, the form manufacturing method includes the steps of inserting the finger prosthesis shape model completed in Zbrush into a cube and then using difference modeling to model the form shape for forming the finger prosthesis, and exporting the form model as an STL file. Steps for printing with a 3D printer are provided.

3. Finger prosthesis molding

Silicone rubber is poured into a mold made by printing with a 3D printer, and finger prostheses that can be applied to Applicant A and Applicant B are formed.

Silicone rubber was divided into high temperature vulcanizing (HTV) and room temperature vulcanizing (RTV) types, which harden depending on temperature. However, as addition reaction type liquid silicone became more common, it is a product that is molded at the same temperature as high temperature curing silicone rubber. With the advent of this, it became impossible to classify based on temperature alone. Therefore, depending on the degree of polymerization of the raw polymer, it is classified into millable silicone rubber and liquid silicone rubber, and both materials can be used when manufacturing finger prostheses.

The biggest difference between mirrorable silicone rubber and liquid silicone rubber is the shape, which leads to differences in the devices used. Mirrorable silicone rubber is basically mainly used for press molding after roll mixing, and liquid silicone rubber is molded using an injection machine. Because mirrorable silicone rubber is heat-cured, it is also called high-temperature curing type, or HTV, HCR (high cured rubber), and HVR (high vulcanizing rubber). Since it is cheaper than the liquid type, it is widely used in the field of prosthetics and orthotics. . However, because pigments must be added to roll mixing to create color, it is difficult to create a translucent color similar to a person's skin and cannot be purchased in small quantities. Unlike the field of prosthetics and orthoses, customized implants that do not claim insurance benefits do not have the conditions to manufacture large quantities of implants, and the application area of the implants is not wide, so there may be difficulties with inventory problems of purchased silicone. Therefore, liquid type silicon is used in this embodiment.

Liquid silicone is a room temperature curing type and is divided into one-component type and two-component type depending on the packaging type. In the production of the finger prosthesis according to this embodiment, two-component addition reaction type (platinum cure silicone) silicone is used. RTV2 additive silicone uses a platinum compound as a catalyst, and is used in the medical field as it does not emit by-products. It is also used in the production of precise sculptures due to its relatively low shrinkage rate.

Compared to the silicone used when making implants attached to the face, finger prostheses are made using silicone, which has high hardness. In this example, KE-1300T (main material) and CAT-1300 (curing agent) from Shin-Etsu Silicone Korea Co., Ltd., which can be easily purchased in small quantities on the market, were used, and the silicone diluent that can control hardness was RTV- from the same company. THINNER was used. KE-1300T is a product with a hardness of 40 and uses RTV-THINNER to dilute the viscosity. As the amount added increases, the hardness changes.

Applicant A prioritized a comfortable fit with a thin and soft texture, so they wanted to find the minimum thickness of silicone that can maintain its shape. Applicant B focused on ensuring that the shape does not bend or break when moving the finger while wearing the silicone. I wanted to find the thickness of .

After adding RTV-THINNER to KE-1300T and mixing it, CAT-1300 was added and the mixed silicone was placed in a deaerator to remove air bubbles for 10 minutes, and then the liquid silicone was poured into the mold.

After leaving the liquid adhered to the inner wall of the mold and discarding the excess, it was turned over and left at room temperature for 20 minutes before being placed in a heated refrigerator to harden. RTV cures at room temperature, but the curing time can be shortened by applying heat, so it was preheated to 50°C and cured.

If the viscosity of silicone is high, it will not flow, but if the viscosity is low, it will flow out. Therefore, if you increase the amount of RTV-THINNER added, you can mold the silicone thinly, and if you decrease the amount, you can mold it thickly.

Even if you remove air bubbles by putting it in a deaerator, bubbles may form when pouring liquid silicone into the mold, so pour it in slowly.

To express a natural skin color, add and mix RTV-THINNER to KE-1300T, then mix foundation, oil paint, and flocking before adding CAT-1300 to express the basic color.

The amount of RTV-THINNER, pigment, and type of flocking used when molding silicone are shown in [Table 3] below.

[Table 3]

A_1 to A_9 in Figure 6 are photographs showing the forming process of the finger prosthesis.

B_1 to B_2 in Figures 6 show the process of temporarily wearing the finger prosthesis molded on the finger of person A, and C_1 to C_2 in Figure 6 show the process of temporarily wearing the finger prosthesis molded on the finger of person B. indicates.

4. Post-processing and coloring of the finger prosthesis

As mentioned above, after forming the finger prosthesis using a mold, each person A and B are asked to temporarily wear the corresponding finger prosthesis. Next, taking into account the wide surface overlaid on the finger, an additional step of forming a cloth overlay is performed on the inside of the finger prosthesis. The fabric padding portion may be formed by attaching and combining an elastic fabric made of nylon and spandex to the inner surface of the finger prosthesis.

For the step of forming the fabric overlay, first, the finger part of the glove made of thin material and a mixture of nylon and spandex is cut and overlaid on the pre-printed finger model. In this embodiment, the fabric is cut from a commercially purchased nylon and spandex mixed glove, but note that a special fabric of thin thickness that can be worn on the finger can also be made in advance into a ring shape and used. Next, apply liquid one-component condensation reaction type (tin cure silicone) silicone to the fabric covering the finger model, place the molded finger prosthesis on top of it, and place it in a heated refrigerator to quickly harden. RTV1 condensation type is crosslinked and hardened with moisture in the air, so it has adhesive strength when used in a single sealed container. KE-441K-T is a thin liquid product that is quickly absorbed into the fabric before curing. When it is removed after curing, the silicone that has soaked into the fabric remains on the finger model, so the fabric can be attached to prevent the inner wall of the finger prosthesis from becoming thick.

In the coloring step, in order to create a realistic skin color, a small amount of RTV1 condensed KE-45 was dissolved in regular thinner and then mixed with pigment to color the surface. Finger prosthetics can be easily contaminated, so they must be wiped with alcohol before use. After dissolving silicone in thinner and using the solution as a solvent to dissolve the oil paint and adhere it to the silicone surface, it cannot be erased.

After checking the size by inserting a ring gauge while wearing the finger prosthesis, a ring was made to cover the border, and one side is open so that the size can be adjusted.

D_1 to D_6 in Figure 7 show the process of forming the first padding portion on the inside of the finger prosthesis to be worn by person A, that is, attaching the fabric to the inside, and E_1 to E_6 in Figure 7 show the finger prosthesis to be worn by person B. It shows the process of attaching the cloth to the inside, that is, the process of forming the cloth padding.

F_1 in Figure 8 shows the pigment process prepared for coloring, F_2 in Figure 8 shows the coloring process, G_1 in Figure 8 shows the process of measuring the ring size of person A, and G_2 in Figure 8 shows the completion of person A. represents the completed finger prosthesis and ring, H_1 in FIG. 8 represents the process of measuring the ring size of person B, H_2 in FIG. 8 represents the completed finger prosthesis and ring of person B, and I_1 to 3 in FIG. 8 represent the process of measuring the ring size of person B. It shows the wearing state of the finger prosthesis of subject A, and J_1 to 3 in FIG. 8 shows the wearing state of the finger prosthesis of subject B.

5. Satisfaction survey results

The satisfaction survey consisted of four areas: accuracy, aesthetics, functionality, and convenience. In detail, a total of 20 questions were presented, with 5 questions for each area. The responses to these questions are 1 point for ‘strongly disagree’, 2 points for ‘agree’, 3 points for ‘average’, 4 points for ‘agree’, 5 points for ‘strongly agree’, and 5 points for degree of agreement. It was designed to be rated on a Likert scale.

As shown in [Table 4] below, as a result of a survey by area for application subjects A and B, the average satisfaction score was 4.2 points for accuracy, 4.1 points for aesthetics, 3.3 points for functionality, and 4.9 points for convenience.

Each of the manufactured finger prostheses was applied to Applicants A and B, and the hardness, thickness of the inner wall, and color were adjusted before completion, and were given to Applicants A and B along with a ring that could cover the border to be worn during daily life. After doing so, you can evaluate it.

[Table 4]

Of course, many other modifications and applications are possible to those skilled in the art within the scope of the basic technical idea of the present invention.

S10: Acquisition of 3D shape for manufacturing finger prosthesis
S20: Making molds for making finger prostheses
S30: Finger prosthesis molding
S40: Finger prosthesis post-processing and coloring

Claims (3)

A 3D shape acquisition step of acquiring a 3D shape for forming a finger prosthesis using photography and portgrammetry;
A mold manufacturing step of manufacturing a mold for forming a finger prosthesis using the acquired three-dimensional shape;
A finger prosthesis forming step of forming a finger prosthesis using the manufactured mold; and
It includes a post-processing and coloring step of post-processing and coloring the molded finger prosthesis,
In the mold manufacturing step, a mold for slush molding is manufactured, and in the finger prosthesis molding step, a finger prosthesis for slush molding is formed using the mold,
The three-dimensional shape acquisition step includes photographing a finger that is not independently erected at 90 degrees due to other fingers in a straight line with the fingers spaced apart,
The post-processing and coloring steps include forming a fabric overlay,
The step of forming the cloth padding part is,
An elastic ring-shaped fabric is overlaid on the pre-printed finger model.
Apply condensation-reactive silicone to the cloth overlaid on the finger model,
After inserting the finger prosthesis formed in the finger prosthesis forming step onto the condensation-reactive silicone applied on the cloth,
A digital-based finger prosthesis manufacturing method characterized by curing the condensation-reactive silicone. According to paragraph 1,
The three-dimensional shape acquisition step involves taking pictures of the subject's finger with a size measurement indicator from various angles so that the features overlap while using the zoom-in and zoom-out functions to adjust the size differently, and matching the taken pictures. A matching step of extracting and connecting feature points in overlapping areas through operations, a point cloud data forming step of converting feature points of the matched region into coordinates in 3D space to form point cloud data, and 3-point processing of fingers based on the generated point cloud data. A digitally based finger prosthesis manufacturing method comprising the step of generating a dimensional shape. According to paragraph 2,
The form production step includes converting the 3D shape data acquired in the 3D shape acquisition step into a 3D model, printing the converted 3D model with a 3D printer, and measuring the size measurement index and actual size attached to the output 3D model. Comparing measurement indices, inverting the converted 3D model to create a 3D model of the finger prosthesis, reinforcing wrinkles, fingernails, or fingerprints or correcting the shape before or after inverting the 3D model, and creating a finger prosthesis It includes the steps of generating a formwork 3D model by applying difference modeling to the 3D model, and printing the formwork 3D model with a 3D printer to produce a formwork. The finger prosthesis forming step includes adding silicone rubber to the formwork. A digital-based finger prosthesis manufacturing method characterized by forming a finger prosthesis by swelling and then hardening.